Jhankaar'Education Point

Class 7 Science NCERT Chapter 3 Solution

2021-01-05T22:45:00.000+05:30

Chapter 3 Fibre To Fabric

Here is some important points and answer of chapter 3 Fibre To Fabric NCERT science of class 7 which helps students to better understand topics of chapter 3 Fabric to Fibre.

Keywords:-

a) Cocoon:- Caterpillar of silkmoth turn in pupa and covered themself in a outer covering made by protein that outer cover is known as cocoon.

b)Fleece:-Hairs of wool yeilding animals are known as fleece.

c) Reeling:- Converting of hairs or silk in thread and roll them is known as reeling.

d) Scouring:- Washing or remaining dust particles from removed hairs of animals is called scouring.

e) Sericulture:- Rearing of silkmoth for getting silk is known as sericulture.

f)Silk moth:- Bee like insects which provide silk are called silk moth.

g) Shearing:- Removing of hairs of wool yielding animals is known as shearing.

h)Silk worm:- Larva of a silk moth is also known as silk worm.

i)Sorting:- Seperating of wood fibre according to their texture is known as sorting.

j)Rearing:- Keeping animals and provide protection and nutrition to them is known as rearing.

These are the important keynotes of Chapter 3 Fibre to Fabric

Here is the Solution Of textbook CHAPTER 3

fibre to fabric.

Exercise Questions-

Ques 1. You must be familiar with the following nursery rhymes:

i)'Baa baa black sheep, you any wool.'

ii)'Mary had a little lamb, whose fleece was white as snow.

Answer the following

a) Which parts of the black sheep have wool?

b)What is meant by the white fleece of the lamb?

Ans.a) hairs

b) white hairs

Ques 2. The silkworm is (a) a caterpillar, (b)a larva. Choose the correct option.

(i)a (ii)b (iii)both a and b (iv) neither a nor b

Ans. iv)neither a nor b

Ques 3. Which of the following does not yield wool?

i) yak (ii)camel. (iii)Goat. (iv)Willy dog

Ans. Wolly dog.

Ques 4. What is meant by the following terms?

i) Rearing:- keeping animals and provide protection and nutrition to them is known as rearing.

ii) Shearing:- Removing of hairs of wool yielding animals is known as shearing.

iii) Sericulture:- Rearing of silkmoth for getting silk is known as sericulture.

Ques 5. Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.

Shearing,________,sorting, ________, _______, ________.

Ans. Shearing, souring, sorting, carding, dyeing, spining.

Ques 6. Make sketches of the two factors in the life history of the silk moth which are directly related to the production of silk.

Ans.

Ques 7. Out of the following which are the two terms related to silk production?

Sericulture, floriculture, moriculture, apiculture, and silviculture.

Hints: i) silk production involves cultivation of mulberry leaves and rearing silkworms.

ii) Scientific name of mulberry is Morus alba.

Ans. i) Sericulture

ii) Moriculture

Ques 8.Match the words of Column I with those given in Column II.

Column I. Column II

i)Scouring. (a)Yields silk fibres

ii) Mulberry. (b)wool yielding animal

iii)Yak (c)food of silk worm

iv)Coccon (d) Reeling

(e)cleaning sheared skin

Ans. i)cleaning sheared skin

ii) food of silk worm

iii)wool yielding animal

iv) yields silk fibres.

Ques 9. Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.

Down

(D) 1: Thorough washing.

2:Animal fibre.

3:Long thread like structure.

Across

(A) 1:Keeps warm.

2:Its leaves are eaten by silkworms.

3:Hatches from egg of moth.

Ans. Down

D) 1) thorogh washing Souring.

2) Animal fibre Silk and wool.

3) Long thread like structureFibre.

Across

A)1. Keeps warm Wool.

2) Its leaves are eaten by Silkworm Mulberry.

3) Hatches from egg moth Catterpillar.

This is the complete solution and explaination of Chapter 3 FIBRE TOFABRIC of Class 7 Science NCERT.

We are here to solve your queries.

Contact us if you have any doubt.

Related links

Class 9 Science Chap 1Notes

Class 7 Science NCERT Chap 2

2021-01-02T00:00:00.000+05:30

CHAPTER 2 NUTRITION IN ANIMALS

Here is some important points and answer of chapter 2 NUTRITION IN ANIMALS NCERT science of class 7 which helps students to better understand topics of chapter 2 NUTRITION IN ANIMALS.

Keywords:-

a) Absorption:- Absorbing of digested food by the small intestine is known as Absorption.

b)Amoeba:- It is unicellular organism which can change its shape.

c) Assimilation:- Transfer of digestion food and its utilisation is known as assimilation.

d)Egestion:- Removing out waste from body is known Egestion.

e)Bile:- A yellowish liquid release from liver.

f)Villi:-Finger like projection present in small intestine help in absorb digested food.

g)Digestion:- The break down of complex form of food into simple form is known as Digestion.

h) Ruminant:- The animals which chew cud are called Ruminants.

These are the important keynotes of Chapter 2 Nutrition in Animals.

Here is the Solution Of textbook CHAPTER 2 Nutrition In Animals.

Exercise Questions-

Ques 1. Fill in the blanks:-

a)The main steps of nutrition in humans are _________,___________,__________and ________.

b)The largest gland in the human body is _________.

c)The stomach releases hydrochloric acid and ________ juices which act on food.

d)The inner wall of the small intestine has many finger like outgrowth called __________.

e)Amoeba digests its food in the _________.

Ans.a) ingestion,digestion, absorption, assimilation and egestion.

b)liver

c)gastric

d)villi

e)food vacoule

Ques 2. Mark 'T' if the statement is true and 'F' if it is false.

a)Digestion of starch starts in the stomach.(T/F)

b)The tongue helps in mixing food with saliva.(T/F)

c)The gall bladder temporarily stores bile.(T/F)

d)The Ruminants bring back swallowed grass into their mouth and chew it for some time.

(T/F)

Ans. a) False

b) True

c)True

d)True

Ques 3. Tick (✓) mark the correct answer in each of the following:-

a)Fat is completely digested in the

i)stomach

ii)Mouth

iii)Small intestine

iv)Large intestine

Ans. Small intestine

b)Water from the undigested food is absorbed mainly in the

i)stomach

ii)foodpipe

iii)small intestine

iv) large intestine

Ans.iv) large intestine

Ques 4. Match the items of column I with those given in Column II.

Column I. Column II

Food Components. Product(s) of digestion

a) Carbohydrates. i)Fatty acids and glycerol

b)Proteins. ii)Sugar

c)Fats. iii)Amino acids

Ans. a) Sugar

b)Amino acids

c)Fatty acids and glycerol

Ques 5. What are villi? What is their location and function?

Ans. Villi are finger like projection present in small intestine help in absorption of digested food and send to all parts of body.

Ques 6. Where is the bile produced? Which component of the food does it help to digest?

Ans. Bile is produced in liver and store in gall bladder. It help in the digestion of fats.

Ques 7. Name the type of carbohydrates that can be digested by ruminants but not by humans. Give the reason also.

Ans. Cellulose is a type of carbohydrates which can not digest by humans because only ruminants are having a special structure called rumen with bacteria which help in the digestion of cellulose.

Ques 8. Why do we get instant energy from glucose?

Ans. We get instant energy from glucose because it is a simpler type of carbohydrates which do not take time in break down.

Ques 9. Which part of the digestive canal is involved in:-

i) Absorption of food

ii) Chewing of food

iii)killing of bacteria

iv) Complete digestion

v)Formation of faeces

Ans. i) VILLI(small intestine)

ii) mouth

iii)stomach

iv) small intestine

v) large intestine

Ques 10. Write one similarity and one difference the nutrition in amoeba and human beings.

Ans. Similarity-

Both human and amoeba used digestive juice for digest it food.

Difference-

Human chew their food but amoeba does not chew their food.

Ques 11. Match the items of Column I with suitable items in Column II.

Column I. Column II

a)Salivary gland. i)Bile juice

b)Liver. ii) storage of undigested food

c) Liver. iii)Saliva secretion

d)Rectum. iv)Acid rain

e)Small intestine. v) Digestion is completed.

f)large intestine. vi) absorption of water. vii)Release of faeces

Ans. a) saliva secretion

b) acid release

c)bile juice of secretion

d)storage of undigested food

e)digestion is completed

f) absorption of water

Ques 12. Label fig. 2.11 of the digestive system.

Ans.

Ques 13. Can we survive only on raw,leafy vegetables/ grass?

Ans. No, we can not survive on leafy vegetables or grasses because our body required different Types of nutrition which all we don't get from it and also our body is not able to digest cellulose which present in grass.

This is the complete solution and explaination of Chapter 2 NUTRITION IN ANIMALS of Class 7 Science NCERT.

We are here to solve your queries.

Contact us if you have any doubt.

You can also Access-

Class 9 Science Chap 1Notes

Class 8 Science Chap 7 Solution

Class 8 Maths Chap1 Solution

Class 7 Science NCERT CHAPTER 1 Solution

2020-12-30T00:17:00.002+05:30

CHAPTER 1 NUTRITION IN PLANTS

Here is some important points and answer of chapter 1 NUTRITION IN PLANTS NCERT science of class 7 which helps students to better understand topics of chapter 1 NUTRITION IN PLANTS.

Keywords:-

1) Autotrophic:- The mode of nutrition in which organisms organism can make their food by them self from simple substance are called autotrophic.

2) Chlorophyll:- Green pigment which present in leaves and captures the energy of sunlight is called Chlorophyll.

3)Heterotrophs:- Organisms take food from others like plants and other animals are called Heterotrophs.

4)Host:-Organisms on which other organism live and take their nutrients are called host.

5)Insectivores:- Those plants which take their some nutrients from insects by trapping them are called Insectivores.

6) Nutrient:- Energy giving components like Protein, carbohydrate etc are called nutrients.

7) Nutrition:- Nutrition is mode of take food by an organism and its utilisation by bodybuilding.

8) Parasite:- Organism which take food from host plants (without killing them) are called parasite. Example:- cuscuta.

9) Photosynthesis:- synthesis of food in the presence of sunlight and Chlorophyll with the help of carbon dioxide and water this process is called photosynthesis.

10)Saprotrophs:- Organism which take their nutrients from dead and decaying matter are called Saprotrophs.

11)Saprotrophic:- Saprotrophs are drive their food by dead and decaying matter this mode of nutrition is called Saprotrophic.

12) Stomata:- Tiny pores of leaf surface help in absorb gases like CO2, O2 and release extra water are called stomata.

These are the important keynotes of Chapter 1 Nutrition in Plants.

Here is the Solution Of textbook CHAPTER 1 Nutrition In Plants.

Exercise Questions-

Ques 1. Why do organisms need to take food?

Ans. Living organisms need to take food for their survival. Food is essential for the growth and development of an organisms. The energy we get from food can be used to carry out various activities.

Ques 2. Distinguish between a parasite and a saprotroph.

Ans. Parasite

Parasite are organisms that depend upon another organism(host) for food and cause harmful effects or diseases to the host.

Example:- Cuscuta(amarbel) , mosquito and head lice.

Saprotroph

Saprotroph are organisms that obtain nutrition from dead and decaying organic matter.

Example:- Fungi and some bacteria.

Ques 3. How would you test the presence of starch in leaves?

Ans. Starch is formed in a green leaf during photosynthesis. Take a fresh green leaf from a plant during day time. Boil it for five minutes and place it in alcohol(spirit). Chlorophyll being soluble in spirit comes out of the leaf leaving behind a colour less leaf. Put a drop of iodine Solution on the blenched leaf. A blue black spot is formed, showing the presence of starch in the leaf.

Ques 4. Give a brief description of the process of synthetis of food in green plants.

Ans. Green plants manufacture food by a process called Photosynthesis.

The process of photosynthesis is represented by:-

The essential for photosynthesis are:-

I) Chlorophyll in a green leaf.

II) Sunlight.

III)Water absorbed by the plants from the soil.

IV)Carbon dioxide absorbed from the air by the leaf through the stomata present on it.

Products:-

I) The products in a green leaf is glucose sugar (C6H12O6)

II)Water vapour

III)Oxygen

Ques 5.Show with the help of a sketch that the plants are the ultimate source of food.

Ans.

Ques 6. Fill in the blanks:-

a)Green plants are called ________ since they synthesise their own food.

b) The food synthesised by the plants is stored as __________.

c)In photosynthesis solar energy is captured by the pigment called ________.

d) During photosynthesis plants take in _________ and release _________.

Ques 7. Name the following:-

I)A parasitic plant with yellow,slender and tubular stem.

II)A plant that has both autotrophic and heterotrophic mode of nutrition.

III)The pores through which leaves exchange gases.

Ans.I)Cuscata

II) pitcher plant

III) stomata

Ques 8. Tick the correct answer:-

a)Amarbel is an example of

i)autotroph

ii)parasite

iii) saprotroph

iv)host

Ans. ii)host

b)The plant which traps and feeds on insects is:-

i) Cuscata

ii)China rose

iii)Pitcher plant

iv) rose

Ans. iii) pitcher plant

Ques 9. Match the items given in column I with those in column II:

Column I. ColumnII

i)Chlorophyll. a)Bacteria

ii) Nitrogen. b)Heterotrophs

iii)Amarbel. c) Pitcher plant

iv)Animals. d)Leaf

v)Insects. e) Parasite

Ans.

i)------d)

ii)-------a)

iii)--------c)

iv)---------b)

v)-------------e)

Ques 10. Mark 'T' if the statement is True and 'F' if it is False:

i)Carbon dioxide is released during photosynthesis.(T/F)

ii)Plants which synthesise their food themselves are called saprotrophs.(T/F)

iii)The product of photosynthesis is not a protein.(T/F)

iv)Solar energy is converted into chemical energy during photosynthesis.(T/F)

Ans. I)True

ii) False

iii) True

iv) True

Ques 11. Choose the correct option from the following:-

Which part of the plant takes in carbon dioxide from the air for photosynthesis?

I)root hair

ii)Stomata

iii)leaf veins

iv)sepals

Ans. ii) stomata

Ques 12. Choose the correct option from the following:

Plants take carbon dioxide from the atmosphere mainly through their:

i) roots

ii) stem

iii) flowers

iv)leaves

Ans (iv) leaves

This is the complete solution and explaination of Chapter 1 NUTRITION IN PLANTS of Class 7 Science NCERT.

We are here to solve your queries.

Contact us if you have any doubt.

You can also Access-

Class 9 Science Chap 1Notes

Class 8 Science Chap 7 Solution

Class 8 Maths Chap1 Solution

Class 7 Science NCERT Chap 14 Solution

2020-12-28T22:52:00.001+05:30

Chapter 14 ELECTRIC CURRENT AND ITS EFFECTS

Here is answer of chapter 14 ELECTRIC CURRENT AND ITS EFFECTS NCERT science of class 7 which helps students to better understand topics of chapter 14 ELECTRIC CURRENT AND ITS EFFECTS.

Exercise Questions-

Ques 1.Draw in your notebook the symbols to represent the following components of electrical circuits: connecting wires switch wires, switch in the OFF position, bulb, cell, switch in the ON position and battery.

Ans.

Ques 2. Draw the circuit diagram to represent the circuit shown in figure.

Ans.

Ques 3. Figure 14.22 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.

Ans. To construct a battery, the negative terminal of one cell should be connected to the positive terminal of the other cell. Therefore the cells should be connected as shown in figure.

Ques 4. The bulb in the circuit shown in Fig 14.23 does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.

Ans. Terminals of the battery should be connected properly. Positive terminal of one battery should be connected to the negative terminal of another battery.

Ques 5. Name any two effect of electric current.

Ans. A current carrying conductor can show a heat effect and a electron magnetic effect which can be considered as the two effects of electric current.

Ques 6. When the current is switched on through a wire, a compass needle kept nearby gets deflected from the north south position. Explain.

Ans. A current carrying wire creates a magnetic field around it. The needle of a compass is a tiny magnet which points in a north south direction with a compass needle nearby and current is allowed to pass through it, the magnetic field of the compass needle, hence it shows a deflection.

Ques 7. Will the compass needle show deflection when the switch in the circuit shown by Fig 14.24 is closed?

Ans. From the given circuit we observe that there is neither a cell nor a battery. Hence, there is no source of electricity. Through the switch in the circuit is closed,there is no passage of current. Hence, it does not show any effect on the magnetic needle kept close by the circuit.

Ques 8. Fill in the blanks:-

a)Longer line in the symbol for a cell represents its _______ terminal.

b) The combination of two or more cells is called a _______.

c) When current is switched 'on' in a room heater,it__________.

d)The safety device based on the heating effect of electric current is called a _______.

Ans. a) positive

b)battery

c)produces heat

d) fuse

Ques 9. Mark 'T' if the statement is True and 'F' if is False:-

a)To make a bsttery of two cells,the negative terminal of one cell is connected to the negative terminal of the other cell.(T/F)

b)When the electric current through the fuse exceeds a certain limit,the fuse wire melts and break.

c)An electromagnet does not attract a piece of iron(T/F)

d)An electric bell has an electromagnet.(T/F)

Ans. a)false

b)True

c)false

d)True

Ques 10. Do you think an electro magnet can be

used for seperating plastic bags from a garbage heap? Explain.

Ans. No, an electro magnet cannot be used for seperating plastic bags from garbage heap. Electromagnets are used to seperate magnetic materials from the junk. As, plastic is a non magnetic materials it cannot be seperated from the junk using electromagnets.

Ques 11. An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire.Would you agree? Give reasons for your response.

Ans. Wires made from some special materials melt quickly and break when large electric currents are passed through them. These materials are used in electric fuses which prevent fires and damage to electric fuses which prevent fires and damage to electric appliances.

Therefore, I would not agree to replace a fuse by a piece of wire has particular properties. Any wire has particular properties. Any wire cannot act as fuse wire. We should always use proper uses which have been specified for particular applications, carrying the ISI mark which indicates that the advice is manufactured according to standard.

Ques 12.Zubeda made an electric circuit using a cell holder shown in Fig.14.4 a switch and a bulb. When she put the switch in the 'ON'position, the bulb did not glow. Help Zubeda in identifying the possible defects in the circuit.

Ans. Possible defects can be as follows:-

a)The two cells may not be connected properly.

b)The rubber band used in the cell holder is unable to hold the cells in contacts with each other and the circuit is incomplete and current is not following in the circuit.

The following conditions are to be satisfied for the bulb to glow:-

a)The positive terminal of the cell should be connected to the negative terminal of another cells.

b) Check the wire connections properly.

c) Check the condition of the bulb whether it is working or fused.

Ques 13. In the circuit shown in Fig.14.25.

I)Would any of the bulb glow when the switch is in the Off position?

Ans. No bulb will glow when the switch is in the Off position are there is no current in the circuit

Unless and untill the switch is in the ON position no bulb will glow.

ii) What will be the order in which the bulbs A, B and C will glow. When the switch is moved to the ON position?

Ans. When the switch is in the ON all the bulbs will glow at the same time as they are connected to the same battery and switch.

This is the complete solution and explaination of Chapter 14 ELECTRIC CURRENT AND ITS EFFECT of Class 7 Science NCERT.

We are here to solve your queries.

Contact us if you have any doubt.

You can also Access-

Class 9 Science Chap 1Notes

Class 7 NCERT SCIENCE Chap 18

2020-12-25T22:07:00.001+05:30

Chapter 18 Waste Water Story

Here is some important points and answer of chapter 18 Waste Water Story NCERT science of class 8 which helps students to understand topics of chapter.The answer of textbook question of CHAPTER 18 Waste Water Story of CLASS 8 SCIENCE NCERT help students to better understand the topics of chapter.

Important Points:-

1) Aeration:- Cleaning of waste water with the help of moving air instrument is called aeration.

2)Aerobic bacteria:- Bacteria which do respiration in the presence of oxygen is called aerobic respiration.

3) Anaerobic Bacteria:- Bacteria which do respiration in the presence of oxygen is called anaerobic respiration.

4)Biogas:- Gas which release during waste water treatment from sludge and use as fuel is known as biogas.

5) Contaminant:- Impurities or waste particles is called contaminant.

6) Sanitation:- Proper disposal of waste and human extract without harming environment is called sanitation.

7)Sewage:- Waste or used water which released from houses, hospitals,schools etc.

8)Sewer:- Network of small and large drain is called sewer.

9) Sewage:- A way or big drain is called drain.

10)Sludge:- Human, animals solid extract which remain and convert in urea.

11)Waste water:- Untreated or water which released after use is called waste water.

Exercise Questions-

1.Fill in the blanks:

a) Cleaning of water is a process of removing ________

b)Waste water released by houses is called________.

c)Dried_______ is used as manure.

d)Drains get blocked by _______and _______.

Ans. a) Pollutants

b) Sewage

c)Sludge

d) oil and fat

Ques 2. What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

Ans. Sewage is the waste released from homes, factories and other activities in which water is used, it is a mixture of suspended organic and inorganic solids, nutrients and some microorganisms. Micro organisms like bacteria that cause Cholera and typhoid and microbes that cause dysentery, are present in sewage water. Hence, untreated sewage should not be discharged into rivers and seas as it may lead to the spread of diseases.

Ques 3. Why should oils and fats be not released in the drain? Explain.

Ans .Cooking oils and fats harden the pipes and block them they clog the soil pores in an open, there by reducing it water filtering capacity. Hence, oils and fats should not be released into a drain.

Ques 4. Describe the steps involved in getting clarified water from waste water.

Ans. The steps involved in getting clarified water are as follows:-

I)Waste water is passed through bar screens that remove large objects like rags, plastic bags, cans etc.

II) Water then moves to a grit and sand removal tank here, the speed of water is reduced to allow sand,grit and small stones to settle.

III) This water is then allowed to settle in a large tank is stopped towards the centre, solid waste, like faeces, settles at the bottom and is removed by a scraper as sludge.

IV) A skimmer is used to remove solids like oil or grease.

V) Water cleared this way is called clarified water.

Ques 5. What is sludge? Explain how it is treated.

Ans. Sludge is solid waste like faeces that is removed by using a scraper it is the leftover of clarified water the sludge is transfered to a special tank containing anaerobic bacteria. Decomposition of sludge occurs here and biogas released. Biogas thus produced is used as fuel on to produce electricity.

Ques 6. Untreated human excreta is a health hazard. Explain.

Ans. Due to poor sanitation facilities, a very large section of people defecates in open areas, near railway tracks or rivers. This may cause water and soil pollution. Thus, surface water as well as ground water as polluted. Ground water is a source of water for wells, tube wells and rivers. Water borne diseases like Cholera, polio, hepatitis and meningitis spread due to this pollution. Hence, untreated human excreta is a source of contagious and a health hazard.

Ques 7. Name two chemicals used to disinfect water.

Ans. Two chemicals used to distinct water are chlorine and ozone.

Ques 8. Explain the function of bar screens in a waste water treatment plant.

Ans. The first step in waste water treatment is the physical removal of large objects. Waste water is first passed through bar screens and thereby objects like plastic bags, rags cans and napkins are removed.

Ques 9. Explain the relationship between sanitation and disease.

Ans. Proper sanitation is very important for maintaining hygienic conditions in society. Many contagious diseases occurs. Due to poor sanitation and contamination of drinking water and food. So, sanitation is directly related to the society's health.

Ques 10. Outline your role as an active citizen in relation to sanitation.

Ans. I) We should not scatter litter anywhere.

II) If proper disposal of waste is not available outside, carry it home and throw it into the dustbin.

III)We should try to educate rural people about the benefits of proper sanitation.

IV) Diseases the relation between sanitation and disease to bring awareness among friends.

Ques 11. Here is a crossword puzzle:- Good luck!

Across

3.Liquid waste products

4.Solid waste extracted in sewage treatment.

6.A word related to hygiene.

8.Waste matter discharged from human body.

Down

1.Used water.

2.A pipe carrying sewage.

5.Microorganisms which causes Cholera.

7.A chemical to disinfect water.

Ans. Across

3.Sewage

4. sludge

6.Sanitation

8.Excreta

Down

1.Excreta

2.Sewer

5.Bacteria

7.ozone

Ques 12. Study the following statement about ozone:-

a) It is essential for breathing of living organisms.

b)It is used to disinfect water.

c)It absorbs ultraviolet rays.

d)It's proportion in air is about 3%.

Which of these statements are correct?

I) (a),(b) and (c)

II) (b) and (c)

III) (a) and (d)

IV)all four

Ans. ii (b) and (c)

THE SOLUTION OF CHAPTER 18 WASTE WATER STORY OF SCIENCE NCERT OF CLASS 7 IS GIVEN ACCORDING TO LATEST SYLLABUS CBSE 2020-2021.

FOR ANY QUERY CONTACT US.

Class 7 Science NCERT Chapter 17 SOLUTION

2020-12-24T22:33:00.001+05:30

Chapter 17 Forests:Our Lifeline

Here is some important points and answer of chapter 17 Forests: Our Lifeline NCERT science of class 8 which helps students to understand topics of chapter.The answer of textbook question of CHAPTER 17 Forests:Our Lifeline of CLASS 8 SCIENCE NCERT help students to better understand the topics of chapter.

Keynotes of CHAPTER 17 OF CLASS 8 SCIENCE:

a)Canopy:- The branches of tall trees look like a roof over other plants in forest are called canopy.

b)Crown:- Branchy part of a tree above the stem is known as crown.

c)Composers:- Microorganisms who convert dead and waste of plants and animals into humus are called Composers.

d) Deforestation:- Removing or cutting down of forests is called deforestation.

e)Humus:- Dead plants and animals convert into dark colour soil is called Humus.

f) Regeneration:-Growing again plants is called regeneration.

g)Seed Dispersal: Moving of seeds from one to another place by different means like animals,birds and air etc.

h)Soil erosion:-Removing of upper layer of soil through air and water is called soil erosion.

These are the important keynotes of Chapter 17 Forests: Our Lifeline.

Here is the Solution Of textbook CHAPTER 17 FORESTS: Our Lifeline.

Ques1. Explain how animals dwelling in the forest help it grow and regenerate.

Ans.A wide variety of animals help the forest to grow and regenerate in the following ways:-

a) Dropping of the birds and animals waste helps herbs and shrubs to grow during in the rainy season.

b)Decomposers like bacteria and fungi help in the formation of humus that provides nutrients to growing plants.

c)Birds and animals help in the dispersal of seed and fruits.

Ques 2. Explain how forests prevent floods.

Ans. Forest play a very important role in checking soil erosion. The roots of the trees in the forest hold the soil as well as water. Forests act as a natural absorber of rain water as the root system of trees allows rain water to seep into the soil. This rainwater as the logged in the water table. Thus, forests help to prevent floods and maintain a regular supply of water to the water sources.

Ques 3. What are decomposers? Name any two of the. What do they do in the forest?

Ans. Decomposers are organisms that act on dead plants and animals and convert them into dark coloured substance called humus. Bacteria and some fungi act as Decomposers.

They play a key role in releasing the nutrients present in dead plants and animals into the soil.

These nutrients are absorbed by the roots of the other developing plants. Thus, decomposers help in maintaining the nutrients cycle in the ecosystem.

Ques 4. Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere?

Ans. Forest consist of a variety of plants take in carbon dioxide and release oxygen during the process of photosynthesis. The oxygen is taken by animals that in turn release carbon dioxide. In this way, the balance between carbon dioxide and oxygen is maintained in the atmosphere. Thus, forests are known as green lungs.

Ques 5. Explain why there is no waste in a forest.

Ans. Forest include autotrophs, heterotrophs, saprotrophs and decomposers. Autotrophs prepare their own food from nutrients available in the soil,while heterotrophs depend upon autotrophs or other heterogeneous. Saprotrophs act upon dead and decaying matter. When autotrophs and heterotrophs die,decomposers act upon them and form humus. Humus consists of nutrients that are again used up by autotrophs. Thus, there is no waste in a forest.

Ques 6. List five products we get from forests?

Ans. A wide variety of products are obtained from a forest five of them are as follows:-

a)paper

b)honey

c)gum

d)lac

e)fibre

Ques 7. Fill in the blanks:-

a) The insects, butterflies, honeybees and birds help flowering plants in ___________

b)A forest is a purifier of _______ and ______.

c)Herbs from the ________ layer with forest.

d)The decaying leaves and animal drappings in a forest enrich the _________.

Ans.a)pollination

b)air and water

c)lowest

d)soil

Ques 8. Why should we worry about the conditions and issues related to forests far from us?

Ans. Forests inevitable assets of the biosphere, forests check soil erosion, prevent floods and maintain the balance of carbon dioxide and oxygen in the atmosphere, it supports a wide variety of plants, animals and microorganisms . Global issues like global warming, extinction of species and floods depend directly or indirectly upon forests. Hence, we should worry about conditions and issues related to forests far from us.

Ques 9. Explain why there is a need of variety of animals and plants in a forest.

Ans. A variety of plants and animals from different levels of the food chain in the forest ecosystem wild species of plants and animals are generally found in forests, thus a variety of animals and plants are needed to maintain biodiversity in the environment.

Ques 10. In fig. 17.15 the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:- atmosphere,clouds, rain,oxygen , carbon dioxide, plant, trees, animals ,roots, under ground water, water label.

Ans.

Ques 11. Which of the following is not a forest product?

a)Gum

b)Plywood

c)Sealing wax

d)Kerosene

Ans. Kerosene

Ques 12. Which of the following statements is not correct?

i)Forests protect the soil from erosion.

ii)Plants and animals in a forest are not dependent on one another.

iii)Forests influence the climate and water cycle.

iv)Soil helps forests to grow and regenerate.

Ans.ii)Plants and animals in a forest are not dependent on one another.

Ques 13. Micro-organisms act upon the dead plants to produce

i)sand

ii)mushrooms

iii)humus

iv)wood

Ans. iv) Wood

THE SOLUTION OF CHAPTER 17 FORESTS:OUR LIFELINE OF SCIENCE NCERT OF CLASS 7 IS GIVEN ACCORDING TO LATEST SYLLABUS CBSE 2020-2021.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 7 SCIENCE NCERT CHAPTER 13 SOLUTION

2020-12-19T23:34:00.000+05:30

CHAPTER 13 MOTION AND TIME

Here is some important points and answer of chapter 13 MOTION AND TIME NCERT science of class 7 which helps students to better understand topics of chapter 13 MOTION AND TIME.

1) Non-Uniform motion:- An object cover a proper distance in different time interval is known as Non- Uniform Motion.

2) Oscillation:- Movement by pendulum from its 'O' exists B point and B point to 'O' axis and again to A point and from A point to 'O' axis is known as Oscillation.

3) Simple Pendulum:- A simple pendulum consist a small metals ball, a thread and a stand.

4)Speed:- Distance covered by a vehicle in time is called speed.

5)Time period:- Total time taken by an object for complete its task (work) is known as time period.

6)Uniform motion:- When an object cover proper distance in definite time interval is known as Uniform Motion.

7) Speedometer:- Meter in vehicle which show its speed known as Speedometer.

8)Odometer:- Meter which show total distance covered by vehicle is called odometer.

These are some important points about the Chapter 13 Motion And Time of Class 7 Science NCERT.

Here is the Solution Of Textbook Questions of Chapter 13 Motion And Time.

Exercise Questions-

Ques 1. Classify the following as motion along a straight line, circular or oscillatory motion.

i)Motion of your hands while running.

ii)Motion of a horse pulling a carton a straight road.

iii) Motion of a child in a merry-go-round.

iv) Motion of a child on a see-saw.

v) Motion of the hammer of an electric bell.

vi) Motion of a train on a straight bridge.

Ans. i) Oscillatory Motion

ii) Straight Line Motion

iii) Circular Motion

iv) Oscillatory Motion

v) Oscillatory Motion

vi) Straight line Motion

Ques 2. Which of the following are not correct?

i)The basic unit of time is second.

ii)Every object moves with a constant speed.

iii) Distances between two cities are measured in kilometres.

iv)The time period of a given pendulum is not constant.

v)The speed of a train is expressed in m/h.

Ans. Incorrect Statement are

ii) Every object moves with constant speed.

iv) The time period of a given pendulum is not constant.

v) The speed of a train is expressed in m/h.

Ques 3. A simple pendulum takes 32s to complete 20 oscillations. What is the time period of the pendulum?

Ans. Time taken by the pendulum to complete 20 oscillations in 32s.

Time period of the pendulum= T

Time period=Total Time Taken/ Number of Oscillations

Time period=32/20 =1.6 second

Ques 4. The distance between two stations is 240km. A train takes 4 hours to cover this distance. Calculate the speed of the train.

Ans. Distance between two stations=240 km

Time taken by the train to cover the distance =4 hours

Speed = Distance/Time

Speed=240/4

=60km/h

Therefore, the speed of the train 60km/h.

Ques 5. The odometer of a car reads 57321.0km when the clock shows the time 8:30AM. What is the distance moved by the car,if at 08:50AM, the odometer reading has changed to 57336.0km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also.

Ans. Ist reading of odometer at 08:30AM. = 57321.0km

IInd reading of odometer at 08:50AM. =57336.0km

Total distance travelled= 57336.0km–57321.0km

=15 km.

Total time taken= 08:50AM –08:30AM

=20min

Speed=Distance/Time

Speed=15km/20km =0.75km/min

We know, 60min =1hour

=20/60

15km×3/1 = 45km/hr.

Ques 6. Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2m/s. Calculate the distance between her house and the school.

Ans. Salma takes total time=15 min

Salma's speed=2m/s

We know 1min=60 second

So, 15×60=900second

Speed=Distance/Time

So, distance=Time×Speed

=900×2m/s

=1800m/s

We know 1km=1000m

So, 1800/1000= 1.8km

Distance of school from Salma's house

=1.8km

Ques 7.Show the shape of the distance time graph for the motion in the following cases.

i) A car moving with a constant speed.

Ans. Shape of car on graph for motion in given case is.

ii)A car parked on a side road.

Ans. Shape of car on graph for the motion is.

Ques 8. Which of the following relations is correct?

i) Speed=Distance×Time

ii) Speed=Distance/Time

iii) Speed=Time/ Distance

iv) Speed=1/Distance ×Time.

Ans. ii)Speed =Distance/Time.

Ques 9.The basic unit of time is:

i)km/min

ii)m/min

iii)km/h

iv)m/s

Ans. iii)Km/h

Ques 10. A car moves with a speed of 40km/h for 15 minutes. The total distance covered by the car is:

i)100km

ii)25km

iii)15km

iv)10km

Ans. ii) 25km

Ques 11. Suppose the two photographs,shown in Fig. 13.1 and fig.13.2,had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.

Ans. Given 100m=1cm

Car moved 1.4cm =1.4×100= 140m

Time take by car =10second

Speed = Distance /Time

=140/10= 14m/s

As speed of the car is 14m/s

Ques 12. Fig. 13.15 shows the distance time graph for the motion of two vehicles A and B. Which one of them is moving faster?

Ans. According to the diagram, speed = Distance/time which marked A is with green colour and B is red colour. According to this, car A covered more distance than car B in same time. So speed of car A will be faster.

Ques 13. Which of your following distance time graphs shows a truck moving with speed which is not constant?

Ans. iii) is the correct answer.

THE SOLUTION OF CHAPTER 13 MOTION AND TIME OF SCIENCE NCERT OF CLASS 7 IS GIVEN ACCORDING TO LATEST SYLLABUS CBSE 2020-2021.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 7 Science NCERT CHAPTER 11

2020-12-17T23:11:00.006+05:30

CHAPTER 11 TRANSPORTATION IN ANIMALS AND PLANTS

Here is some important points and answer of chapter 11 Transportation in Animals and Plants NCERT science of class 7 which helps students to better understand topics of chapter 11 Transportation in Animals and Plants.

Keywords

1) Artery:- Blood vessels which carry oxygenated from heart to body cell are called Artery.

2) Blood vessels:- Tube like network which transport blood to all parts of our body are called blood vessels.

3) Capillary:- Thin tube like structure which join artery and veins are called Capillary.

4) Excretion:- The process of removing waste product in cell of living organisms is known as Excretion.

5) Circulatory system:- The System which help in transport substance to all parts of body in human being is known as Circulatory System.

6) Haemoglobin:- Red pigment present in blood cells help in taking oxygen is known as haemoglobin.

7)Heart break:- Rhytimically contraction and relaxation heart make a heartbeat.

8)Pulse:- Throbbing movements due to entering of blood in artery with pressure is form of pulse.

9)Red Blood Cells:- Kind of cell which present in blood containing haemoglobin and provide red colour to blood are known as Red Blood Cells.

10) Root Hair:- Hair like structure present in root of plant help in absorption of water and minerals are called root hairs.

11) Stethoscope:- A device used by doctors for measuring and counting heartbeats.

12)Urea:- Kind of waste remove from the body.

13)Vein:- Tube like structure which carry deoxygenated blood (C02 rich) blood from body cells to heart are called Veins.

14)White blood cell:- Kind of Cell present in blood fight against germs are called White Blood Cells. It is also known as soldiers of body.

These are some important points about the Chapter 11 Transportation in Animals and Plants of Class 7 Science NCERT.

Here is the Solution Of Textbook Questions of Chapter 11 Transportation in Animals and Plants.

Exercise Questions-

Ques 1. Match structures given in Column I with functions given in Column II.

Column I Column II

i)Stomata. a) Absorption of water ii)Xylem. b) Transpiration

iii)Root hairs. c) Transport of food

iv)Phloem. d) Transport of water

Ans. a) Transpiration

b) Transport of water

c) Absorption of water

d)Transport of water

Ques 2. Fill in the blanks:-

i)The blood from the heart is transported to all parts of the body by the _________

ii) Haemoglobin is present in ___________

iii)Arteries and veins are joined by a network of __________

iv)The rhythmic expansion and contraction of the heart is called ___________

v)The main excretory product in human beings is ___________

vi)Sweat contains water and _________

vii) Kidneys eliminate the waste materials in the liquid form called _________

viii) Water reaches great heigts in the trees because of suction pull caused by_________

Ans.i) arteries

ii) red blood

iii) capillary

iv) heartbeat

v) urea

vi) salt

vii) urine

viii) transpiration

Ques 3. Choose the correct option:-

a) In plants,water is transported through

i)stem

ii)phloem

iii)stomata

iv)root hair

Ans. Xylem

b)Water absorption through roots can be increased by keeping the plants.

i)in the shade

ii) in dim light

iii)under the fan.

iv)covered with a polythene bag

Ans. Under the fan

Ques 4. Why is transport of material necessary in a plant or in an animal? Explain.

Ans. Hence, transport of materials is necessary for the proper growth and development of plants and animals.

Ques 5. What will happen if there are no platelets in the blood?

Ans. Blood platelets are one of the components of blood that help in the clotting of blood. They are a source of thromboplastin which is necessary for the clotting of blood. The absence of platelets in the blood could lead to excessive bleeding and loss of blood.

Ques 6.What are stomata? Give two functions as stomata?

Ans. The stomata are tiny pores present on the surface of leaves. The functions of stomata are:-

a) Exchange of gases such as Carbon dioxide and oxygen.

b) Help in evaporation of excess water from leaf surface by Transportation.

Ques 7. Does transpirtation serve any useful function in the plants? Explain.

Ans. Transpirtation is the evaporation of excess water from the surface of a leaf, through the stomata.

Transpirtation produces a cooling effect and thus saves the plant from the hot sun. The evaporation of water from leaves generates a transpirtational pull or section forces that can pull water from the roots to the top of the tree.

Ques 8. What are the components of blood?

Ans. Blood is fluid connective tissue.

The components of blood are:-

1)Red blood cell(RBC)

2)White Blood Cells (WBC)

3) Platelets (thrombocytes)

All that cells are suspended in fluid called plasma.

Ques 9. Why is blood needed by all the parts of a body?

Ans. Blood, helps in transportation of digested food, gases like oxygen and carbon dioxide,hormones and water to all parts of the body.

It helps in the removal of waste materials to be excreted from the body. It also helps in protecting the body from infection and diseases.

Blood helps the body at a uniform temperature.

Ques 10. What makes the blood look red?

Ans. Blood looks bright red due to the presence of an iron rich pigment called haemoglobin in red blood cells.

Ques 11. Describe the function of the heart.

Ans. The heart is a muscular pumping organ that functions to circulate blood in the body. The human heart is four chambered heart. There are two upper chambers called atria and two lower chambers called ventricles. Deoxygenated bluish red blood blood from different parts of the body is brought to the right ventricles for purification after oxygenation. After oxygenation in the lungs, pure blood is carried to the left atrium and to the left ventricle. The left ventricle supplies pure blood to different parts of the body.

Ques 12. Why is it necessary to excrete waste products?

Ans. During life's activities, the body produces a variety of materials that are not required within the body, they need to be pushed out as metabolic wastes. If these wastes are not removed from the body, they may became toxic and may lead to a diseased condition.

Hence, it is necessary in excrete waste products.

Ques 13. Draw a diagram of the human excretory system and label the variously parts.

Ans.

THE SOLUTION OF CHAPTER 11 TRANSPORTATION IN ANIMALS AND PLANTS OF SCIENCE NCERT OF CLASS 7 IS GIVEN ACCORDING TO LATEST SYLLABUS CBSE 2020-2021.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 7 SCIENCE NCERT CHAPTER 10 Solution

2020-12-15T23:26:00.000+05:30

CHAPTER 10 RESPIRATION IN ORGANISM

Here is some important points and answer of chapter 10 RESPIRATION IN ORGANISM NCERT science of class 7 which helps students to better understand topics of chapter 10 RESPIRATION IN ORGANISM.

KEYNOTES OF CHAPTER 10:

a) Aerobic Respiration:- When glucose break down in energy in the presence of oxygen is known as Aerobic Respiration.

b) Anaerobic Respiration:- When glucose break down in energy in the absence of oxygen is known as Anaerobic Respiration.

c) Breathing Rate:- Total number of inhalation and exhalation (breathe) in one minute is called Breathing Rate.

d) Cellular Respiration:- Break down of glucose into energy in side of cell is known as Cellular Respiration.

e) Exhalation:- Releasing out of CO2 from nostril is known as Exhalation.

f) Gills:- Breathing organ of aquatic animals.

g) Lungs:- Breathing organ of some animals who lives on land like human, cow, dog, monkey, etc.

h) Inhalation:- Taken oxygen through the nostril is called Inhalation.

I)Spiracles:- Small opening on insects body help in taken and releasing air are called Spiracles.

j) Trachea:- Pipe line structure present in organism help in transfer of air.

k)Ribs:- Bony structure which protects to lungs.

l) Diaphragm:- A large muscular sheet which seperate chest cavity and abdomen.

Exercise Questions-

Ques 1. Why does an athlete breathe faster and deeper than usual after finishing the race?

Ans.An athelete runs faster during a race. The demand for energy and oxygen in high. Oxygen should reach all parts of the body. Hence, an athlete breathes faster and deeper than usual after finishing the race, to meet the demand for oxygen.

Ques 2. List the similarities and differences between aerobic and anaerobic respiration.

Ans. The similarity between aerobic and anaerobic respiration is that both break down the food to release Carbon dioxide and energy.

The difference between them are as follows:-

Aerobic Respiration

1) Food is broken down in the presence of oxygen.

2) The end products are water, carbon dioxide and energy.

example:- Human Beings.

Anaerobic Respiration

1) Food is broken down in the absence of oxygen.

2)The end products are alcohol, carbon dioxide and energy.

Example:- yeast

Ques 3. Why do we often sneeze when we inhale a lot of dust laden air?

Ans. When we inhale air containing dust particles, the particles get trapped in the hair present in our nostrils. Sometimes, these particles may pass through the hair and enter the nasal cavity. They irritate the mucus lining of the nasal cavity and as a result we sneeze. Sneezing expels the foreign particles from the inhaled air and dust free clean enters our body.

Ques 4. Take three test tubes. Fill 3/4th of each with water. Label them A,B and C. Keep a snail in test tube B and in C. Keep snail and plant both. Which test tube would have the highest concentration of CO2?

Ans. Test tube A will be show highest concentration of C02 because snail release C02 during respiration in test tube B the water plant will take in C02. In test tube C the snail take in 02 and release C02 which is taken up by the plant. Their by reducing the amount of gases.

Ques 5. Tick the correct answer:-

(a) In cockroaches, air enters the body through

i)lungs

ii)gills

iii)spiracles

iv)skin

Ans. Spiracles

b)During heavy exercise, we get cramps in the legs due to the accumulation of

a)carbon dioxide

b)lactic acid

c) alcohol

d)water

Ans.lactic acid

c)Normal range of breathing rate per minute in an average adult person at rate is

a)9-12

b)15-18

c)21-24

d)30-33

Ans. 15-18

d) During exhalation,the ribs

a) move outwards

b)move downwards

c) move upwards

d) do not move at all

Ans. Move downwards

Ques 6. Match the items in Column I with those in Column II:-

Column I Column II

a)Yeast. i)Earthworm

b) Diaphragm. ii) Gills

c)Skin. iii)Alcohol

d)Leaves. iv)Chest cavity

e)Fish. v)Stomata

f)Frog. vi)Lungs and skin

g) Cockroach. vii)Trachea

Ans. a)Alcohol

b) Chest cavity

c)Earthworm

d)Stomata

e)Gills

f)Lungs and Skin

g)Trachea

Ques 7. Mark 'T' if the statement is true and'F'if it is False:-

i) During heavy exercise the breathing rate of a person slows down.(T/F)

ii) Plants carry out photosynthesis only during the day and respiration only at night.(T/F)

iii) Frogs breathe through their skins as well as their lungs.(T/F)

iv)The fishes have lungs for respiration.(T/F)

v)The size of the chest cavity increases during inhalation. (T/F)

Ans. i) False

ii) False

iii) False

iv) False

v) True

Ques 8. Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction- upwards,downwards,or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

a) The air tube of insects.

b)Skelton structure surrounding chest cavity.

c) Muscular floor of chest cavity.

d) Tiny pores on the surface of leaf.

e)Small openings on the sides of the body of an insect.

f)The respiratory organs of human beings.

g) The openings through which we inhale.

h)An anaerobic organism.

i) An organism with tracheal system.

Ans. a) Tracheae

b) Ribs

c) Diaphragm

d) Stomata

e) Spiracles

f) Lungs

g) Nostril

h) Yeast

I) Ant

Ques 9. The mountaineers carry oxygen with them because:

a) At an altitude of more than 5km there is no air.

b)The amount of air available to a person is less than that available on the ground.

c)The temperature of air is higher than that on the ground

d)The pressure of air is higher than that on the ground.

Ans. b) The amount of air available to a person is less than that available on the ground.

This is the complete solution and explaination of Chapter 10 Respiration in Organisms of Class 7 Science NCERT.

We are here to solve your queries.

Contact us if you have any doubt.

You can also Access-

Class 9 Science Chap 1Notes

Class 9 SCIENCE NCERT Chap 6 Tissue Solution

2020-12-13T23:05:00.001+05:30

Chapter 6 Tissue

Here is the answer of chapter 6 Tissue of NCERT science of class 9.The complete solution of CHAPTER 6 Tissue is given here which is prepared subject expert.

Block Questions Page No- 69

Ques 1. What is tissue?

Ans. Tissue is a group of cells that are similar in structure and are organised together to perform specific task.

Ques 2. What is the utility of tissue in multicellular organisms?

Ans. In unicellular organisms, a single cell performs all the basic function such as respiration,movement, excretion, digestion,etc. But in multicellular organisms, cells are grouped to form tissues. This tissues are specialized to carry out a particular function at a place in the body. For example: the muscle cell form muscular tissue which help in movement, nerve cells form the nervous tissue which helps in transmission of message. This is known as division of labour that multicellular organisms. It is because of my division of labour that multicellular organisms are able or perform all functions efficiently.

Page no- 73

Ques 1. Name types of simple tissue.

Ans. Simple Permanent tissues are of three types. Parenchyma, schlerenchyma and collemchyma. Parenchyma Tissue is of further two types- aerenchyma and chlorenchyma.

Ques 2. Where is apical meristem found?

Ans. Apical meristem is present at the growing tips of stem and roots. Their main function is to initiate growth in new cells of seedlings at the tips of roots and shoots.

Ques 3. Which tissue makes up the husk of coconut?

Ans. The husk of coconut is made up of Sclerenchyma.

Ques 4. What are the constitute of phloem?

Ans. Phloem is the food conducting tissue in plant. It is made up of four components.

I)Sieve tubes

II) Companion cells

III)Phloem parenchyma

IV) Phloem fibres

Page No 78

Ques 1. Name the tissue responsible for the movement of our body.

Ans. The muscular tissue is responsible for the movement of our body.

Ques 2. What does a neuron looks like?

Ans. A neuron consist of a cell body with a nucleus and cytoplasm. It has two important extensions known the axon and dendrites. An area is a long thread like extension of nerve cell that transmits impulses. Thus, the neuron transmits impulses away from the cell body. Whereas the dentrites recieve nerve impulses. This coordinated functions help in transmitting impulses very quickly.

Ques 3. Give three features of cardiac muscles.

Ans Three features a cardiac muscles are:-

I) cardiac muscles are involuntary muscles that contract rapidly but do not yet fatigued.

II) They control the contraction and relaxation of the heart.

III) The cell of cardiac muscles are cylindrical, branched and uninucleated.

Ques 4. What are the function of areolar tissue?

Ans. Function of areolar tissue:-

I) it helps in supporting internal organ.

II) it helps in repairing the tissue of skin and muscles

Exercise

Ques 1. Define the term 'Tissue'.

Ans. The group of cells similar in structure that work together to achieve a particular function form of tissue. This group of cell has a common origin.

Ques 2. How many type of element together make up the xylem tissue? Name them.

Ans. xylem is a complex tissue. It is made up of following four kind of cells or elements

a) tracheids

b) vessels

c) xylem parenchyma

d) xylem fibres

Ques 3. How are simple tissues different from complex tissue in plants?

Ans. Simple tissues are made up of one type of cell which coordinate to perform a common function complex tissues are made up of more than one type of cell. All these coordinate to perform a common function.

Ques 4. Difference between parenchyma, collenchyma and Sclerenchyma on the basis of their cell wall.

Ans.

The following are the differences based on cell wall between different tissues:

Parenchyma	Collenchyma	Sclerenchyma
Cell walls are thin and made up of cellulose	Cell walls are thick at the edges due to the deposition of pectin	Cell walls are thick due to the deposition of lignin

Ques 5. What are the functions of stomata?

Ans. The small pores present in the epidermis of the leaf are stomata. Stomata are enclosed by two kidney shaped cell called guard cell.

Function of stomata:-

•exchange of gases,particularly CO2 and O2 with atmosphere.

•Loss of water in the form of vapour during evaporation.

Ques 6. Diagrammatically show the difference between three types of muscles fibres.

Ans. There are three types of Muscles Fibre. they are as follows;

1.Cardiac Muscles

a) It is present in heart.

b)It is involuntary in nature.

c)The muscles fibres are branched.

2.Smooth Muscles

a)It is found in lungs and alimentary canal.

b)It is involuntary in nature.

c)It has 1 nuclei.

d)it is spindle shaped.

3.Striated Muscles

a)It is connected with bones.

b)It is voluntary in nature.

c)It poses many nuclei.

d)Striated muscles are branched.

Ques 7. What is the specific function of Cardiac Muscles?

Ans. Cardiac muscles are involuntary muscles which show characteristics of both smooth and striated muscles. These muscles occur in the wall of heart.

Functions of Cardiac Muscles:-

• Cardiac muscles contract and relax rapidly, rhythmically, and tirelessly throughout life.

•The contraction and relaxation of heart muscles help to pump and distribute blood to various part of the body..

Ques 8. Difference between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.

Ans.The following are the differences between different types of muscles based on their structure and location in the body.

Character	Striated muscles	Un-striated muscles	Cardiac muscles
Shape/Structure	Long, cylindrical, non – tapering. They are un-branched.	Long and tapering. They are un – branched.	Cylindrical and non – tapering. They are branched.
Location in body	Hands, legs and skeletal muscles	Wall of stomach, intestine, ureter and bronchi	Heart
Dark and light bands	Present	Absent	Present but less prominent

Ques 9. Draw a labelled diagram of Neuron.

Ans. The diagram of Neuron.

Ques 10. Name the following:-

a) Tissue that form inner lining of our mouth.

b) Tissue that connects muscles to bones in humans.

c) Tissue that transfer food in plants.

d) Tissue that stores fat in our body.

e) Connective tissue with fluid matrix.

f)Tissue present in brain.

Ans.a) Squamous epithelium

b) Tendon

c) phloem

d) Adipose tissue

e) Blood

f) Nervous tissue

Ques 11. Identify the types of tissues in the following:

Skin, bark of tree , bone , lining of kidney tubule , vascular bundle.

Ans. Skin- stratified squamous epithelium

Bark of tree- cork protective tissue

Bone - connective tissue

Lining of kidney tubule - Cuboidal epithelium ( Cuboidal epithelium tissue)

Vascular Bundle- complex permanent tissue (phloem and xylem)

Ques 12. Name the regions in which parenchyma tissue is present.

Ans. Parenchyma is simple permanent tissue of angiospermic plants. It is present in cortex and pith of stem and roots, it is also present in mesophyll of leaves when it contains chlorophyll. It is called chlorenchyma found in green leaves.

Ques 13. What is the role of epidermis plants?

Ans. Epidermis is a protective tissue of angiospermic plants. It provide protection to underlying tissue. Epidermis forms outer covering of various plants organ such as roots, stems, leaves and flowers and remains in direct contact with the environment. Any substance wheater solid, liquid and gas can enter into plants or move outside only after passing through this layer. Epidermis helps in absorption, secretion , gaseous exchange and transpiration. It helps in preventing the entry of pathogens.

Ques 14. How does a cork act as a protective tissue?

Ans. The cork cells are dead cell and do not have any intercellular space. The cell wall of the cork slice are coated with suberin (a waxy substance)

suberin make these cell impermeable to water and gases cork is protective in function. It protects underlying tissue from infection and mechanical injury.

Ques 15. Complete the following chart.

Ans.The complete chart is given below:-

These are the complete notes of CHAPTER 13 WHY DO WE FALL ILL OF SCIENCE NCERT CLASS 9. Hope these notes helpful to better understand the CHAPTER 6 TISSUE.

FOR ANY PLEASE CONTACT US-

We are here to solve your queries-

Related links

Class 9 Science Chap 1Notes

Class 9 SCIENCE NCERT Chap -13 WHY DO WE FALL ILL IMPORTANT NOTES

2020-12-03T22:44:00.004+05:30

CHAPTER 13 WHY DO WE FALL ILL

This article brings you the CBSE Class 9 Science notes on chapter 13 'WHY DO WE FALL ILL'. These chapter notes are prepared by the subject expert and cover every important topic from the chapter. In between these notes, questions are provided. Students must solve these questions to test their understanding about the learned topics. These questions will help you to track your preparation level and get a hold on the subject.

In this chapter 13 'WHY DO WE FALL ILL'we cover following topics -

•Health,

•Disease

•Acute Disease

•Chronic Disease

• Difference between Acute and Chronic Disease

•Causes of Diseases

•Non Infectious Disease

• Infectious Disease

•Types of disease with example

•Communicable Disease

•Principles of Treatment

•Immunity

•Prevention of Diseases

Important Notes Of CHAPTER 13 'WHY DO WE FALL ILL' of CLASS 9 SCIENCE NCERT for 2020-21.

Health :- It is a state of being well enough to function well physically mentally and socially.

Disease:- (Disturbed Ease) means being uncomfortable one or more systems of the body will change,give rise to"symptoms"(cause loose motions,pus formation,headache,fever, breathelessness, vomiting,fits,,uncounciousness,inflamation, swelling and general effects- a doctor looks for the basis of symptoms. Disease are basically two types- Acute disease and Chronic disease.

Acute Disease:- The disease which lasts for only a short period of time is called Acute Disease. Example:- Common Cold.

Chronic Disease:- The Disease which lasts for long period of time is called Chronic Disease.

Example:- Tuberculosis.

Difference Between Acute Disease and Chronic Disease

Acute Disease:-

•They are short duration.

•Patient recover completly after the cure.

•There is no loss of weight or feeling of tiredness afterwards.

•There is short duration loss of work and efficiency.

Chronic Disease:-

•They are long lasting disease.

•The patient does not recover completly.

•There is often loss of weight or feeling of tiredness.

•There is a prolonged loss of work and efficiency.

Causes of Disease:- Most of the disease have many causes rather than one single cause,like unclean water,nourishment, genetic differences,genetic abnormalities.

Example:- Based on the causes disease are of two types:- Non infections disease and infectious Disease.

Non infectious Disease:- Not caused by infectious agents, mostly internal and non infectious cause.

Example:- Cancer.

Infectious Disease:- Caused by infectious agents.

Types of disease and its example:-

1.Bacterial Disease:- Typhoid, Cholera, Tuberculosis, Acne, Anthrax.

2.Viral Disease:- Common cold, influenza, dengue fever, AIDS, Japanese encephalitis(brain fever).

3. Fungal Disease:- Skin Disease.

4.Protozoan Disease:- Malaria(Plasmodium),kaalazar(leishmania), sleeping sickness(trypanosoma).

5.Worm Disease:- Ascariosis(round worm),elephantiasis(wucheria).

Communicable Disease:- The infectious disease spread by agents are called as communicable Disease.

Types of Disease with example.

1. Air borne Disease :- Pneumonia, common cold, tuberculosis.

2.Water borne Disease:- Cholera, Hepatitis.

3.Sexual Disease:- HIV, Syphilis.

4.Animal borne Disease:- Rabbies( vector- the animal carrying infectious agents from a sick person to another patenticle host without getting affected. Example:- Mosquito carrying malaria parasite.

Principle of Treatment:-

•Antibiotics- Many bacteria makes a cell wall to protect themselves. The antibiotic (penicillin) blocks the biochemical pathways. Antibiotics do not work against viral infections, antiviral medicine is harder than making antibacterial medicines because virus has only few biochemical mechanism of their own other medicines bring down fever,reduce pain or loose motions. We can take bed rest to conserve energy.

Principles Of Prevention:- Following three limitations are normally confronted while treating an infectious disease.

•Once someone has disease, their body function are damaged and may never recover completly.

•Treatment will take time which means that someone suffering from disease will likely to have bedridden for some time even if we can give proper treatment.

•The person suffering from an infectious disease can serve as the source from where the infection may spread to other people.

General ways of preventing infectious disease.

•Air borne- We can prevent exposure by providing living conditions that are not overcrowded.

•Water Borne:- Prevented by providing sale drinking water. This is done by treating the water. This is done by treating the water to kill any microbial contamination.

•Vector Borne:- We can provide clean environment which would not allow mosquito breeding.

Immunity:- Even in cells their is repair mechanism called immunity. Immune cell manage to kill of the infectious agents. Small pox disease is eliminated by developing memory cell for particular infection. The microbes called 'vaccine'.

The basis of immunization:- If you had small pox once. There was no chance of suffering from its again proper nutrition is essential to maintain body immunity. There are vaccines against tetanus, diphtheria,whooping cough,measles,polio and many other diseases.

Prevention of Diseases:- It is better than cure hygine. It is the basic key to maintain good health.

These are the complete notes of Chapter 13 Why Do We Fall ILL of Science Of Class 9. This is according to the latest syllabus of CBSE 2020-21.

•Block questions of CHAPTER 13 Why Do We Fall ILL of Class 9 Science NCERT.

Page no-178

Ques 1. State any two conditions essential for good health.

Ans.Health is the state of being well enough to function well physically,mentally and socially.

Therefore,for good health.

I)One should be disease free.

II)There should be social equality and harmony which are essential for individual health particularly for social and mental health.

Ques 2. State any two conditions essential for being free of diseases.

Ans.I) Remain away from specific and particular cause for discomfort or disease for which personal and public cleanliness and good physical environment are necessary.

II)Proper and sufficient food necessary for functioning of cell and tissues of body.

Ques 3.Are the answers to the above questions necessarily the same or different?Why?

Ans. The answers to above questions are different because a person may be free of disease but not be good mentally,socially and economically.

Page No-180

Ques 1. List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present,would you still go to the doctor?Why or why not?

Ans. Common symptoms,which identicable sickness are:-

I)Headache

II)Cough and

III)Loose Motion

Even seeing one symptoms, I will go to doctor.

Reason:- A single symptoms is the sign in a disease on delaying. It may lead to serious illness. For example:- headache may mean meningitis.

Ques 2. In which of the following case do you think the long term effects on your health are likely to be most unpleasant?

•if you get jaundice,

•if you get lice,

•if you get acne.

Why?

Ans. Jaundice, because it is chronic disease and takes time to be cured. Moreover, jaundice effects the whole body and it takes long time to be healthy.

Page no- 186

Ques 1. Why are we normally advised to take bland and nourishing food when we are sick?

Ans. Infectious disease show a lack of success of the immune system of the body. For the functioning of immune system properly sufficient nourishment and easily digestable food is necessary for a sick person.

Ques 2. What are the different means by which infectious diseases are spread?

Ans. Infection causing microbes travel from patient to person through:-

i)Air:- Sneezing or coughing since little droplets are thrown which they reach another person through air. Example: common cold, pneumonia, etc.

ii)Water:- Contiminated water carries disease causing microbes which cause infection on its wage. Example disease such as Cholera.

iii) Sexual contact:- Disease such as Syphilis or AIDS are transmitted by sexual contact from one person to the other.

iv) Animals:- These are intermediaries called vectors transmitting disease from a patient to the host. Example mosquito (from anopheles mosquito) cause spread of malaria.

Ques 3. What precautions would you take in your school to reduce the incidence of infectious diseases?

Ans.i) Preventing overcrowding classes.

ii) Providing safe drinking water.

iii) Cleanliness in the school premises and also in the classroom.

iv) Use of handkerchief or towel while an infected student in sneezing or coughing.

v)Use of clean toilets.

vi) Not to allow water to stagnate in school or around the school to avoid mosquito breeding.

vii) To get vaccinated whenever programmes organised for inoculation against various diseases.

viii) Not eating food exposed to flies, mosquitoes, etc.

Ques 4. What is immunization?

Ans. Introduction of mild type of infection(microbes) or killed infectious microbes into the body by vaccination/by others means to activate the immune system against a particular infection/ disease is called immunization.

Ques 5. What is the immunization programes available at the neared health center in your locality? Which of these disease or the major health problems in your area?

Ans. Immunization programes

I) BCG vaccine against tuberculosis.

II)Polio drops against polio.

III) Vaccination against chicken pox.

IV) Vaccination against Hepatitis.

V) DPT vaccination against diptheria, whooping cough and tetanus.

vi) Immunisation against measles.

Major health problem are hepatitis, chicken pox, tuberculosis, tetanus.

These are the complete notes of CHAPTER 13 WHY DO WE FALL ILL OF SCIENCE NCERT CLASS 9. Hope these notes helpful to better understand the CHAPTER 13 WHY DO WE FALL ILL.

FOR ANY PLEASE CONTACT US-

We are here to solve your queries-

Related links

Class 9 Science Chap 1Notes

Chap 6 TISSUE Science NCERT CLASS 9 Notes

2020-12-03T22:32:00.005+05:30

Chapter 6 Tissue

This article brings you the CBSE Class 9 Science notes on chapter 6 'TISSUE '. These chapter notes are prepared by the subject expert and cover every important topic from the chapter. In between these notes, questions are provided. Students must solve these questions to test their understanding about the learned topics. These questions will help you to track your preparation level and get a hold on the subject.

In this chapter 6'TISSUE'we cover following topics -

Tissue

Plant Tissue and it's types

Meristems

Types of Meristems

Permanent Tissue and it's types

Animal Tissue and it's classification

Muscular Tissue

Nervous Tissue

Important Notes Of CHAPTER 6 'Tissue' of CLASS 9 SCIENCE NCERT for 2020-21.

•Tissue:- Tissue is a group of cell having similar origin, structure and function. Study of tissue is called histology.

In unicellular organism(amoeba) single cell performs all basic functions, whereas in multicellular organism(plants and animals) show division of later as plant tissue and animals tissue.

• Plant tissue are two types:- Meristems and permanent tissue.

1)Meristems:- The meristem are the tissue having the power of all division. It is found on these region of the plant which grows.

•Types of Meristem:-

a)The Apical Meristem:- It is present at the growing tips of the stems and roots and increase the length.

b)The Lateral Meristem:- It is present at the lateral side of the stem and rest (cambium) and increases the girth.

c)The intercalary Meristem:- Present at internodes or base of the leaves and increase the length between the nodes.

2) Permanent Tissue:- It is of two types simple permanent tissue and complex permanent tissue.

a)Simple Permanent Tissue:- it is subdivided as:-

I)Parenchyma:- Tissue provided the support to plants. They are loosely packed and has large intercellular space.

• Parenchyma with chlorophyll which perform photosynthesis is called as chlorenchyma.

• The parenchyma with large air space to give buoyancy is called as arenchyma. Parenchyma also stores food and water.

II)Collenchyma:- Tissue provide mechanical support thickened at the corners have very little intercellular space it allows easy bending of various parts of a plant without breaking.

III) Sclerenchyma:- Tissues make the plant hard and stiff thickened due to lignin and no inter cellular space. Cells of this tissues are dead and commonly seen in the husk of coconut.

iv)Gaurd cell and epidermal tissues:-The tissue aids in the protection and exchange of gases.Gaurd cell kidney shaped in dicots, dumb cell shaped in monocots to gaurd the stomata.The epidermal tissue of roots in absorbtion of water and minerals.The epidermal tissues in desert plants have a thick waxey coating of lutin with waterproof quality .The epidermal tissues from the several layer thick cork or the bark of the tree.

(b)Complex permanent tissue-The complex tissues are exists of more than one type of cell.All these cells coordinate to perform a common function.

They are subdivided as:-

i)Xylem:-It consists of trachieds, vessels, xylem parenchyma and xylem fibres-The cell have thick walls.

Function:-aids in construction of water and minerals.

ii)Phloem-It consists of tubes, companion cells, phloem parenchyma and phloem fibres.

Function:-Phloem transports food material to other part of the plants.

7)Animal tissue-Sub divided as epithelial tissue,connective tissue,muscular tissue and nervous tissue.

i)Epithelial tissue-It is protective covering forming a continous sheet simple epithelium is the one which is extremely then in one layer whereas stratified epithelium are arranged in patterns of layer.

Depending on shape and functions they are classified as:-

A)Squamous epithelium in the lining of mouth and esophagus.

B)Cuboidal epithelium in the lining of kidney tubules and salivary gland.

C)Columnar epithelium in the intestive and columnar epithelium with cilia in the lining of respiratory tract.

D)Glandular epithelium in the glands aids in a special functions as gland cells which can secreath at epithelial surface.

Connective tissue-five types such as:-

A)Blood=The blood is a fluid connective tissue plotid plasma has RBC=(red blood cell) WBCs(white blood cells) and platelets.Blood plasma contains proteins,salts and harmones.Blood flows and transport gases,digestive food, harmones and waste material.

B)Bones=The bone is a connective tissue with hard matrix, composed of calcium and phosphorus a bone is connected by another bones with another connective tissue called ligaments a bone is connected by muscles with another connective tissue called tendon.

C)Cartilage=The cartilage is a connective tissue with solid matrix composed of protein and sugar it is commonly seen in nose,ear,trachea and larynx.

D)Areolar connective tissue=It is found between the skin and muscles around the blood vessels.It support enternal organs and aids in repairs of tissues.

E)Adipose connective tissues-it is found with fat gloules fan the storage of fats it acts as insulates.

8)Muscular tissues=They have special contractile protiens responsible for movement.Three types such as:-

-Striated muscle/skeletal muscle/voluntary muscles

They are cylindercal, un-branched and multinucleated. They have dark bands and light bands.

-Unstriated muscles/smooth muscles/involuntary muscle

They are commonly called as smooth muscles,having no striations(dark bands/light bands are absent) commonly found alimentary canal, uterus, iris of an eye.They are spindle shaped.Involuntary in nature.

Cardiac muscles=They are commonly called as heart muscles,cylinderical, branched and uni-nucleates.Involuntary in nature.

9)Nervous tissue-The tissue respond to stimuli.The brain,spinal cord and nerves are composed of nervous tissue or neurons.A neuron consists of cell body,cytoplasm, nucleus, dentrine, axon, nerve ending.The neuron impulse allow us to move or muscles whom we want to respond to stimuli.

Try Question Answer:-

Ques 1.Which structure protect the plant body against invasion of particles?

Ques 2. Why does the skin of your finger shrink when you wash clothes for a long time?

Ques 3. Why is endo cytosis found in animals only?

Ques 4. Why are lysosomes known as SUICIDAL BAG OF A CELL?

These are the complete notes of CHAPTER 6 TISSUE OF SCIENCE NCERT CLASS 9. Hope these notes helpful to better understand the CHAP 6 TISSUE.

FOR ANY PLEASE CONTACT US-

We are here to solve your queries-

Related links

Class 9 Science Chap 1Notes

Class 9 NCERT SCIENCE Chap 5 The Fundamental Unit of Life Solution

2020-11-19T23:42:00.003+05:30

Chapter 5 The Fundamental Unit of Life

Here is the answer of chapter 5 The Fundamental Unit of Life of NCERT science of class 9.The complete solution of CHAPTER 5 The Fundamental Unit of Life is given here which is prepared subject expert.

Block Questions.(page no.- 59)

Ques 1. Who discovered cell and how?

Ans. Robert Hooke discovered the cell. He observed the cell in a cork slice with the help of a primitive microscope.

Ques 2. Why is cell called the structural unit of life?

Ans. Cell constitute various component of plants and animals a cell is the smallest unit of life and is capable of all living functions. Cell are the building blocks of life. This is the reason why cell are referred to as the basic structural and functional unit of life. All cells varies in shape and size and activity they perform in fact, the shape and size of a cell is related to the specific functions they perform.

Block Questions Page no- 61

Ques 1.How do substance like CO2 and water move in and out of the cell? Discuss.

Ans.It is because of the diffusion and osmosis process in the cell. Through diffusion CO2 enters in the cell and by the process of Osmosis the water molecules moves from an area of high water concentration through a particle permeable membrane.

Ques 2. Why is plasma membrane called selectively permeable membrane?

Ans.The plasma membrane allows or permits the entry and exist of source material in and out of the cell. It also prevents movement of source other materials. The cell membrane therefore is called a selectively permeable membrane.

Page No. 63

Ques 1. Fill in the gaps in the following table illustrating difference between prokaryotic and eukaryotic cells.

Ans.

Prokaryotic Cell

Eukaryotic Cell

1. Size: Generally small (1-10 μm)

1 μm = 10-6m

2. Nuclear region:

______________________________

and known as ___________________

3. Chromosome: single

4. Membrane-bound cell organelles absent.

1. Size: Generally large (5-100 μm)

2. Nuclear region: well defined and surrounded by a nuclear membrane.

3. More than one chromosome.

4. ______________________________

______________________________

Solution:

Prokaryotic Cell

Eukaryotic Cell

1. Size: Generally small (1-10 μm)

1 μm = 10-6m

2. The nuclear region is poorly defined due to the absence of a nuclear membrane and known as the nucleoid.

3. There is a single chromosome.

4. Membrane-bound cell organelles absent.

1. Size: Generally large (5-100 μm)

2. Nuclear region: well defined and surrounded by a nuclear membrane.

3. There are more than one chromosomes.

4. Membrane-bound cell organelles present.

Page no-65

Ques 1. Can you name two organelles we have studied that contain their own genetic material?

Ans. Mitochondria and Plastids are two Organelles that contain their own genetic material.

Ques 2. If the organism of a cell is destroyed due to some physical or chemical influence,what will be happen?

Ans. Cell is the smallest unit of life which is capable of all living functions if the organism of cell is destroyed due to some physical or chemical influence then the ability of the cell by to perform all living function such as respiration , nutrition, excretion etc.would be affected.

Ques 3. Why are lysosomes known as Suicidal bags?

Ans . Lysosomes are membrane bound vesicular structure that contain powerful digestive enzymes. These enzymes are capable of breaking down any foriegn food particle or microbes entering the cell. Some time,Lysosomes can cause self destruction of a cell by releasing these digestive enzymes within the cell. Hence, they are also known as Suicidal Bags.

Ques 4. Why are proteins synthesized in the cell.

Ans. Proteins are synthesized in the Ribosomes in the cell.

Exercise Questions-

Page No. 67

Ques 1. Make a comparison to write down ways in which plant cells are different from animal cells.

Ans. The cells of plant and animal have the following differences:-

Animal Cell-

a) Animal cells are generally small in size.

b) Cell wall is absent.

c) Except the protozoan ,euglena, no animal cell posses plastids.

d) Vacuoles in animal cells are many small and temporary.

e) Animal cells have a single, highly complex and permanent golgi apparatus.

f)Animal cells have centrosome and centrioles.

Plant Cell-

a) Plant cells are larger than animal cells.

b) The plasma membrane of plant cell is surrounded by a rigid cell wall of cellulose.

c) Plastids are present.

d) Most mature plant cells have a permanent and large central sap vacuoles.

e) Plant cells have many simple unit of Golgi apparatus called dictyosomes.

f) Plant cells lack centrosomes and centrioles.

Ques 2. How do prokaryotic cell different from eukaryotic cells?

Ans. Prokaryotic Cell

a) Cell size is generally small (1-10mm).

b) Nuclear region is called nucleoid and is not surrounded by a nuclear membrane.

c) Only a single chromosome is present.

d) Nucleolus is absent.

e) Membrane bound cell organelles are absent.

f) Cell division by fission or budding (no mitosis).

Eukaryotic Cell

a) Cell is generally large (5-100mm).

b) Nuclear material is surrounded by a nuclear membrane.

c) More than one chromosome present.

d) Nucleolus is present.

e) Membrane bound cell Organelles.

f) Cell division mitotic or meiotic.

Ques 3. What would happen if plasma membrane ruptures or breaks down?

Ans. Plasma membrane is selectively permeable membrane of the cell that maintain its homeostasis, i.e. constant internal composition of the cell. If it ruptures or break down the constant internal chemical composition of the cell will be last and it will not be able perform its basic function. Such a cell with ruptured plasma membrane is killed.

Ques 4. What would happen to the life of a cell if there is no Golgi apparatus?

Ans. The material synthesised in the ER are stored, modify, packaged and dispatched to various targets inside and outside the cell through Golgi apparatus packs products in vesicles,the secretary vesicles. In some cases complex sugar. example:- cellulose may be made from simple sugar in Golgi apparatus. The Golgi apparatus is also involved in the formation of the cell which will not be possible if Golgi apparatus is not there.

Ques 5. Which organelle is known as the power house of the cell? Why?

Ans. Mitochondria are known as the Powerhouse of the cell because they contain enzymes that are needed for stepwise oxidation of food stuffs. Carbohydrates,fats and lipids present in cell to CO2 and water oxidation of food release energy which is used to form high energy ATP(Adinosine triphosphate) molecules ATP is known as energy currency of the cell and it is used as cellular fuel. Energy stored in ATP is used to bring about energy requiring activities of the cell such as photosynthesis protein synthesis and muscles contraction.

Ques 6. Where do lipids and proteins constituting the cell membrane get synthesised?

Ans. Rough endoplasmic Reticulum (RER) :- Synthesise protein constituting cell membrane.

Smooth endoplasmic Reticulum (SER):- Synthesise lipid consulting cell membrane.

Ques 7. How does Amoeba obtain its food?

Ans. Amoeba has flexible cell membrane it enables amoeba to engulf food by the process called Endocytosis.

Ques 8. What is osmosis?

Ans. The diffusion of water or solvent through a semi permeable membrane from a solution of lower concentration of solutes to a solution of higher concentration of solutes to which the membrane is relatively impermeable is called Osmosis.

Ques 9. Carry out the following osmosis experiment:

Take four peeled potato halves and each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,

a)Keep cup A empty

b)Put one teaspoon sugar in cup B

c)Put one teaspoon salt in cup B

d)Put one teaspoon sugar in the boiled potato cup D

Keep these for two hours. Then observe the four potato cups and answer the following:

i)Explain why water gathers in the hollowed portion of B and C.

ii)Why is potato A necessary for this experiment?

iii) Explain why water does not gather in the hollowed out portions of A and D.

Ans.i) Water accumulates hollowed in the portion of B and C as the difference in water concentration is observed. Therby, endosmosis occurs as the cell acts as a semi permeable memebrane.

ii)Potato A is essential in this experiment as it is significant to compare different scenarios seen in

potato cups B, C and D. The potato A in this experiment clearly shows that the potato cavity on itsown cannot bring about water movement.

iii)Cup in A does not show any change in the water flow concentration for osmosis to occur, which requires the concentration to be higher than the other. Cells in cup D are dead, thus there is noexistence of a semipermeable membrane for water flow. Consequently, osmosis does not occur.

10. Which type of cell division is required for growth and repair of body and which type is involved in formation of gametes?

Ans. There are two ways in which a cell divides:

Mitosis

Meiosis

Mitosis is the type of cell division that is involved in the growth and repair of body whereas meiosis is a type of cell division which results in the formation of gametes.

These are some extra Questions of Chapter 5 The Fundamental Unit of life of class 9 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 9 Science Chap 1Notes

Class 8 Science Chap 9 Solution

Class 8 Science Chap 13 Solution

Class 9 Science Chap 6 Solution

Class 8 NCERT Science Chap 16 Solution

2020-11-09T22:17:00.007+05:30

Chapter 16 Light

Here is the answer of chapter 16 LIGHT of NCERT science of class 8.The complete solution of CHAPTER 16 LIGHT is given here which is prepared subject expert. Some important extra questions and important points about Chapter 16 are also given.

Ques1:-Suppose you are in a dark room can you see object in the room? Can you see object outside the room.Explain.

Ans 1. When we are in a dark room, we cannot see the object in the room because there is no light being reflected by the object.However, we can see the object outside the room because they reflect light falling on them.

Ques2:-Differentiate between regular and diffused reflection does diffused reflection mean the failure of the law of reflection.

Ans 2.In regular reflection, all the rays that are reflected from the surface are parallel to each other. In diffused reflection the reflected light consists of rays that are not parallel to each other. Diffused reflection does not mean the failure of the law of reflection. Diffused reflection occurs when the surface is rough.

On a rough surface the angle of incidence change from one ray to the other.

Ques 3. Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes.Justify your answer in each case.

a)Polish wooden table.

b)Chalk Powder

c) Cardboard Surface

d) Marble floor with water spread over it

e)Mirror

f)Piece of Paper

Ans.a) The wooden table that has been a polished regular reflection. The surface that have been recently polished can be a Good example of a smooth surface. The wooden table that has been polished has a smooth surface.

b) White Chalk Powder that is used in school - Diffused reflection.

Chalk Powder spread on surface is an example of irregular surface. Hence,it is rough.Therfore,the diffused reflection will appear from chalk Powder.

c) Cardboard Surface- Diffused Reflection

The surface of the Cardboard is a kind of irregular surface. Hence, the diffused reflection will take place from a cardboard surface.

d) Marble floor- Regular reflection

Marble floor can be a good example of a surface that is regular. Because water make the creamic glossy. Thus, the reflection that are regular occur on this surface.

e) Mirror- Regular Reflection

A mirror has a very smooth surface hence it gives a regular reflection.

f)Piece of Paper- Diffused Reflection

Although a piece of paper may look smooth,it has many irregularities on its surface. Because of this reason,it will give you a diffused reflection.

Ques 4. State the Law of Reflection.

Ans. The law of reflection states that:-

a) The angle of incidence and angle of reflection both are always equal to one another.

b) The reflected ray, the incident ray, the ray normal to the reflective surface at the point of incidence all come on the same plane.

Ques 5. Describe an activity to show that the incident ray,the reflected ray and the normal at the point of incidence lie in the same plane.

Ans.On a table,place a plane Mirror perpendicular to the plane of the table.Make a small hole in a paper and hold it perpendicular to the plane of the table. Try to do this experiment in a dark room. Make one more piece of paper which is on the table. Now beam light rays with the help of torch through the small hole such that the beam of light hits the normal at the bottom of the mirror. The ray of light will be reflected in a light rays from the hole are incident on the mirror.Looking at the piece of paper on the table, we can easily show that the incident ray,the reflected ray and the normal at the point of incidence lie in the same plane.

Ques 6. Fill in the blanks in the following:-

a) A person 1m in front of a plane Mirror seems to be_______m away from his image.

b) If you touch your _______ ear with right hand in front of plane mirror it will be seen in the mirror that your right ear is touched with _________.

c)The size of the pupil becomes_________ when you see in dim light.

d) Night birds have__________ cones than rods in their eyes.

Ans. a) 2

b) Left, Left hand

c) Large

d) Fewer

Choose the correct option in Questions 7-8

Ques 7. Angle of incidence is equal to the angle of reflection.

a) Always

b) Sometimes

c) Under special conditions

d) Never

Ans 7. Always.

Ques 8. Image formed by a plane mirror is

a) virtual,behind the mirror and enlarged.

b) virtual, behind the mirror and of the same size as the object.

c) real at the surface of the mirror and enlarged.

d) real, behind the mirror and of the same size as the object.

Ans 8. Virtual,behind the mirror and enlarged.

Ques 9. Describe the construction of Kaleidoscope.

Ans. Three rectangular mirror strips are joined together to form a prism as shown in the figure. This prism is placed inside a circular wooden tube whose length is slightly longer than the length is the prism. One end of the tube is closed with a cardboard disc with a hole at the centre,and at the other end is closed with a plane glass plate. On this glass plate, several small piece of colured bangles are placed. This end is closed by a round glass plate,so that there is sufficient space for the bangle pieces to move.

Ques 10. Draw a labelled sketch of the Human eye.

Ans.

Ques 11. Gurmit wanted to perform activity 16.8 using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher's advise?

Ans. The laser beam produced by a laser torch has high energy that can damage the retina of the eye. Hence, the teacher advised Gurmit not to use laser torch.

Ques 12. Explain how you can take care of your eyes.

Ans. a) Get your eyes checked regularly by an eye specialist.

b) Do not look at sun on bright light directly.

c) Do not read in insufficient light.

d) When foreign particles enter your eyes,do not rub them; instead wash them with clean water.

e)While watching TV, do not sit very close to it.

Ques 13. What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?

Ans. The angle between an incident ray and its reflected ray is twice the angle of incidence. Hence, in this case,the angle of incidence is 45°.

Ques 14. How many image of a candle will be formed if it is placed between two parallel plane mirror seperate by 40cm?

Ans. An infinite number of images of a candle will be formed if it is placed between two parallel plane mirror. The number of image formed does not depend on the distance between the mirror.

Ques15 .Two mirrors meet at right angles.A ray of light is incident on one at an angle of 30 as shown in the figure.Draw the reflected ray from the second mirror.

Ans. The first law of reflection is used to obtain the path of reflected light.

It can be observed that the given ray of light will reflect from the second mirror at an angle of 60°.

Ques16 Bhoojo stand at A just on the side of the plane mirror as shown in Fig.16.20. can he see himself in the mirror? also can he see the image of objects situated at P,Q and R.

Ans 16.Bhoojo cannot see himself in the mirror he can see the images of the object situated at P and Q, but cannot see the image of R.

Ques17 A)Find out the position of the image of an object situated at A in the plane mirror.

B)Can paheli at B see this image?

C)Can bhoojo at C see this image?

D)When paheli moves from B to C, where does the image of A move?

Ans17 A)The image of A is formed behind the mirror at the same distance as A is in the front of the mirror.

B)Paheli at B can see the image of A.

C)Boojho at C can see the image of A.

D)When paheli moves from B to C,the image of A does not move.

This is the complete solution of CHAPTER 16 LIGHT. This is according to latest syllabus of CBSE 2020-21.

Here's some important points about the CHAPTER 16 LIGHT of class 8 Science NCERT.

Define the terms:-

1)Luminous bodies- The bodies which emits light on thier own are called luminous bodies.The sun, stars, burning candle, filament of electric bulb etc are called luminous bodies.

2)Non luminous bodies-The bodies which do not emit light on thier own but reflects the light falling on them are called non-luminous bodies. Forex:-moon.

3)Opaque-A body which obserbs some of light falling on it and reflects the remaining are called opaque.

4)Transparent body-A body which permits maximum amount of light to pass through them and reflects very little amount of them.

5)Translucent body-A body which partially allow the light to penetrate it and reflects the remaining light.

6)Eye lens-The eye lens is a convex lens made up of transparent jelly like material,the eye lens is held in position by cilliary muscles.

7)Cornea-It is transparent spherical membrane infront of the eye,light enters eye through cornea.

8)Spectrum-The spliting of white lights into seven colours is called spectrum of light.

These are some important points of Chap 16.

Here's is some extra Questions about the Chapter 16 LIGHT of NCERT SCIENCE CLASS 8.

Extra ques/answers

Ques 1 Why is the moon not considered as luminous bodies?

Ans1 The moon is not considered as luminous body, because it does not emit its own light, it reflects the light of the sun.

Ques2 Write three uses of plane mirror?

Ans2] 1)As a looking mirror.

2)As a reflector in solar cookers.

3)For signaling by army personnel.

Ques3 Write three characteristics of image formed by plane mirror.

Ans3]1) Image is virtual it means it cannot be seen on screen.

2) Image is erect and is of the same same size as that of the object.

3)Image is formed as far behind the mirror as the object is.

These are some extra Questions of Chapter 15 SOME NATURAL PHENOMENA of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 9 Science Chap 1Notes

Class 8 Science Chap 9 Solution

Class 8 Science Chap 13 Solution

Class 8 NCERT SCIENCE Chap 17 SOLUTION

2020-11-03T22:38:00.005+05:30

CHAPTER 17 STARS AND THE SOLAR SYSTEM

Here is the answer of chapter 17 STARS AND THE SOLAR SYSTEM of NCERT science of class 8.The complete solution of CHAPTER 17 STARS AND THE SOLAR SYSTEM is given here which is prepared subject expert. Some important extra questions and important points about Chapter 17 are also given.

Ques 1. Why does phases of the moon occur?

Ans. We can see the moon due to the reflection of sunlight incident on it towards us. Hence, we can see only the part of the moon that reflects light towards us. As the position of the moon changes from day to day. Sunlight portion of the moon facing the earth changes too and this cause the phases of moon.

Ques 2. In which part of the sky can you find venus if it is visible as a evening star?

Ans. We can find venus in the western part of the sky after sunset as an evening star.

Ques 3. Name the largest planet of the solar system?

Ans. Jupiter is the largest planet in the solar system.

Ques 4. What is constellation? Name any two constellation.

Ans. A group of stars that appear to form a pattern in the sky is known as constellation.

The orion and the Ursa major are two examples of constellation.

Ques 5. Draw sketches to show the relative positions of prominent stars in:-

a) Ursa major

b) Orion

Ans. a) One of the most famous constellation you can see during summers in the early part of the night is the Ursa major. It is also known as Big dipper great bear and saptarishi it consists of seven prominent star three in the handle and four in its Bowl as shown in fig below.

b) The orian can be seen during winter late in the evening. It is also known as a hunter. The orion consists of eight prominent stars as shown in the figure.

Ques 6. Name two objects other than planets that are members of solar system.

Ans. Meteors and asteriods are the objects that are members of solar system.

Ques 7. Explain how can you locate the pole star with the help of Ursa Major?

Ans. First locate the position of Ursa major and identify the two bright stars at the end of it bowl shape. Imagine a line connecting these two stars, when this line is extended towards north it meet a bright star. This bright star is the pole star.

Ques 8. Do all stars in the sky move? Explain.

Ans. No, all the stars in the sky except pole star, appear to move from east to west. This is due to the rotation of earth from West to east about its axis of rotation. The pole star is situated above and along the axis of the earth, to the north and hence it appears to be at rest and can be observed from any place in the northern hemisphere.

Ques 9. Why is the distance between stars expressed in light years? What do you understand by the understand by the statement that a star is eight years away from the earth.

Ans. Distance between the star is too large to measure with normal units of distance. They are also inconvenient to express in kilometre. So it is expressed in light years. A light year is the distance travelled by light in one year. When we say that a star is eight light year away from earth. It means that the distance between the star and earth is equal to the distance travelled by the light in eight years. It will take us eight years to travel from earth to that star if we travel at the speed of light.

This is the complete solution of Textbook Questions of Chapter 17 STARS AND THE SOLAR SYSTEM of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 9 Science Chap 1Notes

Class 8 Science Chap 9 Solution

Class 8 Science Chap 13 Solution

Class 9 NCERT Science Chap 5 THE FUNDAMENTAL UNIT OF LIFE NOTES

2020-10-31T22:43:00.024+05:30

CHAPTER 5 THE FUNDAMENTAL UNIT OF LIFE

ANIMAL CELL

PLANT CELL

This article brings you the CBSE Class 9 Science notes on chapter 5 'FUNDAMENTAL UNIT OF LIFE'. These chapter notes are prepared by the subject expert and cover every important topic from the chapter. In between these notes, exercise questions are provided. Students must solve these questions to test their understanding about the learned topics. These questions will help you to track your preparation level and get a hold on the subject.

In this chapter 5 'FUNDAMENTAL UNIT OF LIFE we cover following topics -

Discovery of cell, Cell, Classification of organisms on the basis of Cell, Shape and size of the Cell, Diffusion, Osmosis, Types of Osmosis , Types of Osmotic Solutions, Plasma membrane or Cell membrane, Cell Wall, Function of Cell wall, Nucleus, Types of plastids, Cytoplasm, Cell Organelles, Functions of Vacuoles and Plastids, Types of Endoplasmic Reticulum.

Important Notes Of CHAPTER 5 'FUNDAMENTAL UNIT OF LIFE of CLASS 9 SCIENCE.

1) Discovery Of Cell-

•Cells were first discovered by ROBERT HOOKE in 1665. He observed the cell in a cork slice with the help of a primitive microscope.

• Leeuwenhoek(1674) with the improved microscope discovered the free living cells in pond water for first time.

• Robert Brown (1831) discovered the nucleus of the cell.

•Purkinje in 1839 coined the term 'protoplasm' for the fluid substance of the cell.

• The cell theory of plant and animal and that the cell is the basic unit of life, was presented by Schleiden(1838) and Schwan(1839).

•The cell theory was further expanded by Virchow(1855) by suggestimg that all cell arise from pre existing cell.

• With the discovery of the electrone microscope in 1940, it was possible to observe the complex structure of the cell and its various organelles

2) Cell:- Cell is the structural and functional unit of life

3) Cell organisms are classified as :-

• Unicellular:- Organisms which are made up of single cell.

•Multicellular:- Organisms which are made up of many cell.

eg:- Plants, animals and fungi.

4) Shape and size of the Cells:- Some cells can change their shapes like amoeba, WBC but plants and animal cells have almost fixed shapes.

a) Smallest Cell- PPLG (Mycoplasma)

b) Largest Cell- Ostrich Cell.

c) Longest animal Cell- Nerve Cell

5) Diffusion :- Movement of solute particles from higher concentration to lower concentration is called Diffusion.

Example:- Exchange of gases during respiration.

6) Osmosis:- The movement of solvent particles from lower concentration to higher concentration in presence of semi permeable membrane is called Osmosis.

Example:- Absorption of water by roots.

7) Types of Osmosis:-

a) Endosmosis:- Movement of water inside cell is called Endosmosis. It takes place when cell is placed in low concentration solution.

b) Exosmosis:- Movement of water out from cell is called Exosmosis. It takes place when cell is placed in high concentration Solution.

8) Types of osmotic solution:-

a) Hypotonic:- The solution which have lower concentration than others.

b) Hypertonic:- The solution which have higher concentration than others.

c)Isotonic:- The solution which have equal concentration than others.

9) Plasmic membrane or cell membrane:-

• It is outermost delicate covering of cell.

•It is also called selectively permeable membrane or semi permeable membrane because it allows entry of selective substance only.

• It is made up of a bi- lipid layer of proteins.

10) Cell Wall:- Rigid, semi elastic, semi transparent and protective covering present outside the plasma membrane in plant cell, fungi and prokaryotic. It is made up of cellulose in plants, fungal cellulose.

11) Function of Cell Wall:-

•It provides shapes to the cell.

•It provide mechanical strength to plants.

• Protect against pathogens and mechanical injury.

•Growth of the cell wall determines the growth of cell.

• Cell wall prevents bursting of cell on endosmosis.

12) Nucleus:-

The nucleus was the first organelle to be discovered. Nucleus consist of nuclear membrane, chromosomes,chromatin,nucleolus, ribosomes.

13) Types of plastids:-

• Chloroplasts:- These plastids are green due to the presence of chlorophyll pigment, and hence are responsible for photosynthesis.

• Chromoplasts:- These are coloured plastids containing pigments. Other than chlorophyll are found in fruits,flower,roots and stressed and aging leaves and are responsible for their distinctive color.

•Leucoplasts:- Leucoplasts are colourlrss plastids that store pods they are found in storage organs such as Fruits, tubers and seeds.

14) Cytoplasm:- The cytoplasm is the fluid content inside the plasma membrane. It also contains many speacialised specific function for the cell.

15) Cell Orgaelles:- Cell organelles perform specific function with in a cell. They are enclosed by membrane. Some important examples of cell organelles are endoplasmic reticulum, mitochondria,golgi apparatus, lysosomes, plastids and vacuoles.

•Endoplasmic Reticulum:-

a) Network of tubular and vesicular structure which are interconnected with one another.

b) Some parts are connected to the nuclear membrane,while others are connected to the cell membrane.

c) Two Types- Smooth(lacks ribosomes) and Rough( with ribosomes).

d) It gives internal support to the cytoplasm.

• Golgi Body:-

a) Discovered by Camillo Golgi.

b) Formed by stacks of 5-8 membranous sacs.

c) Sacs are usually flattened and are called cristernae.

d) It has two ends:- Sis face situated near the endoplasmic reticulum and trans face situated near the cell membrane.

•Plastids:-

a) Plastids are double membrane bound organelle found inside plants and some algae.

b) They are responsible for activities related to making and storing food.

c) They often contain different types pigment that can change the colour of the cell.

• Mitochondria:-

a) Mitochondria is known as the Powerhouse of the Cell.

b) Mitochondria have two membrane covering.

c) The outer membrane is porous while is other membrane is deeply folded.

•Vacuoles:-

a) Vacuoles are storage sacs for solid or liquid content.

b) Vacuoles are small sized animals cell which plant cell have very large vacuoles.

c) Vacuoles can hold food for later use or waste for removal.

•Lysomes:-

a) Small, spherical, single membrane sac.

b) Found throughout the cytoplasm.

c) Filled with hydrolytic enzymes.

d) Occurs in most, animal cell and in few.

16) Functions of Vacuoles and Plastids:-

a)Vacuoles:

• The vacuoles is the storage structure in a cell.

•It can hold food for later use or waste for removal.

•In plant cells the vacuole can also store water.

b) Plastids:

•Plastids provide colour to fruits and flowers.

•They help in storage of proteins, Starch and oil.

• Plastids trap solar energy to manufacture food through the process of photosynthesis.

17. Types of Endoplasmic Reticulum:

•Rough Endoplasmic Reticulum (RER)

It has Ribosomes on its surface. The RER synthesiser (makes) and packages proteins.

•Smooth Endoplasmic Reticulum:-

It does not contain ribosomes. The SER helps in the storage of proteins and lipids.

These are the complete notes of CHAPTER 5 THE FUNDAMENTAL UNIT OF LIFE OF SCIENCE NCERT CLASS 9. Hope these notes helpful to better understand the CHAP5 THE FUNDAMENTAL UNIT OF LIFE.

FOR ANY PLEASE CONTACT US-

We are here to solve your queries-

Related links

Class 9 Science Chap 1Notes

Class 8 Science NCERT Class 15 Solution

2020-10-30T21:20:00.001+05:30

CHAPTER 15 SOME NATURAL PHENOMENA

Here is the answer of chapter 15 SOME NATURAL PHENOMENA of NCERT science of class 8.The complete solution of CHAPTER 15 SOME NATURAL PHENOMENA is given here which is prepared subject expert. Some important extra questions and important points about Chapter 15 are also given.

Select the correct option in Questions 1 and 2.

1.Which of the following cannot be charged easily by Friction?

a) A plastic scale.

b) A copper rod.

c)An inflated balloon.

d) A woollen cloth.

Ans. b) A copper rod

Ques 2. When a glass rod is rubbed with a piece of silk cloth the rod

a) and the cloth both acquire positive charge.

b) becomes positively charged while the cloth has a negative charge.

c) and the cloth both acquire negative charge.

d) becomes negatively charged while the cloth has a positive charge.

Ans. b) becomes positively charged while the cloth has a negative charge.

Ques 3. Write T against True and F against False in the following statements.

a) Like charges attract each other.(T/F)

b) A charged glass rod attract a charged plastic straw. (T/F)

c) Lightning conductor cannot protect a building from lightning (T/F)

d) Earthquake can be predicted in advance.(T/F)

Ans.a) False

b) True

c) False

d) False

Ques 4. Sometimes a cracking sound is heard while taking off a sweater during winters.Explain.

Ans. The sweater get changed due to friction while taking the sweater off. These charges get discharged producing cracking sound.

Ques 5. Explain why charged body loses its charge. If we touches it with our hand.

Ans. The human body is a conductor. So when we touch a charged body. The charge passes through our body to the ground and the body looses its charge.

Ques 6. Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on its scale. Would it be recorded by a seismograph? It is likely to cause much damage?

Ans. The destructive energy of an earthquake is measured on the Richter scale. An earthquake measuring 3 on this scale can be recorded by a seismograph. It does not cause much damage.

Ques 7. Suggest three measures to protect ourselves from lightning.

Ans. I) Lighting conductors should used to protect buildings.

II) Do not take bath under running tap water when there is a chance of lightning to occur.

III) Do not stand under trees when there is a chance of lightning to occur.

Ques 8. Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another

charged balloon?

Ans. When a charged balloon is placed near another charged balloon. They repel each other due to the like charges present on them. However,a charged balloon will attract an uncharged balloon because it include an unlike charge on the near surface of the uncharged balloon.

Ques 9. Describe with the help of a diagram an instrument which can be used to detect a charged body.

Ans. When a charged body is placed in contact with the metal sphere of the electroscope, it gets charged due to conduction. The leaves of the metal foil develop like charges and they diverges. The divergence of the leaves of the metal foil shows that the body put in contact with the sphere of the electroscope is charged if there is no divergence then the body is not charged.

Ques 10. List three states in India where earthquake are more likely to strike?

Ans. In India, earthquake are most likely to strike in Gujarat, Assam and Kashmir.

Ques 11. Suppose you are outside your home and an earthquake strikes. What precautions would you take to protect yourself.

Ans. When outside the home,find a clear spot free from buildings,trees and power lines drop down to the ground.

If you are in a car, do not come out of it,slowly drive it to a safe place.

Ques 12. The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out that day. Would you carry an umbrella? Explain.

Ans. The umbrella has a metallic rod with a sharp point if there is lighting it would be dangerous to move under the umbrella. I would not carry an umbrella when going out the day on which the weather department has predicted

a thunderstorm.

This is the complete solution of CHAPTER 15 SOME NATURAL PHENOMENA. This is according to latest syllabus of CBSE 2020-21.

Here's some important points about the CHAPTER 15 SOME NATURAL PHENOMENA of class 8 Science NCERT.

IMPORTANT POINTS:-

a) Electroscope:- An instrument used to detect electrical charge on a body.

b) Lightening:- A high energy Spark produced in the sky accompained by a large amount of heat and light.

c)Lightening conductor:- A metallic conductor fixed on high rise building to protect them from lightening by conducting the atmospheric electricity into the earth.

d)Thunder:- A loud sound produced due to the rapid expansion of air caused by heat produce during lightening.

e) Earthing:- The process of discharging atmospheric electricity through a metallic conductor into the earth is called Earthing.

f) Earthquake:- An earthquake is sudden shaking or trembling of earth which lasts for a very short time.

g)Richter Scale:- A scale on which power of earthquake is measured in terms of magnitude.

h) Seismograph:- An instrument which is used to record seismic waves which produces tremors on the surface of the earth.

These are some important points of Chap 15.

Here's is some extra Questions about the Chapter 15 SOME NATURAL PHENOMENON of NCERT SCIENCE CLASS 8.

Extra Questions:-

Ques 1. Why does tiny bits of paper attracts towards a comb when rubber against your dry hairs?

Ans. Because when the comb is rubbed against dry hairs then it gets electrically charged and when it brings near to tiny bits of paper it attracts the tiny bits of paper.

Ques 2. Write two damaging effect of lightening.

Ans.a) When lightening strikes a building or tree it can set them on fire.

b) Lightening can cause death of living beings.

Ques 3. How does Lightening take place between the clouds?

Ans. Due to condensation the clouds are formed. When two clouds of positive and negative static charges approach each other a electric charges flows from one cloud to another an intense sparks of electricity is seen in the sky such an electric spark is known as electric discharge of lightning.

Ques 4.How does Lightening conductor prevent damage to building during lightening?

Ans. When highly charged clouds passes over a tall building it induces an opposite charge on the lightening conductor. This charge quickly flow to the earth through the copper strip thus the lightening discharge is prevented as the builder is saved from damage.

Ques 5. What causes an earthquake?

Ans. Earthquake are caused due to the movement in tectonic plates deep inside the earth crust. Tremors on the earth can also be caused when volcanic erupt or an underground nuclear explosion.

Ques 6. What are seismic or fault zone?

Ans. Since, earth quake are caused by the movement of plates the boundary of the plates are the weak zone.Where earthquake are more likely to come these weak zones are also known as Seismic or fault zone.

Ques 7. Write five steps to protect yourself from earthquake.

Ans. a)Take shelter under a table and stay there till the shaking stops.

b) Stay away from tall and heavy objects that may fall on you.

c) If you are on bed do not get up. Protect your head with pillow.

d) Find a clear spot, away from building trees and overhead power lines. Drop to the ground.

e) If you are in a car or a bus, do not come out. Ask driver to drive slowly.

Ques 8. Write any three measures to make a 'quake safe building'.

Ans. a) Consult qualified architect and structural engineer.

b) It is better if the cupboards and shelves are fixed to the walls,so that they do not fall easily.

c)Be careful where you hang wall clocks, photo frames, water heater etc. So that in the event of an earthquake, they do not fall on people.

These are some extra Questions of Chapter 15 SOME NATURAL PHENOMENA of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 9 Science Chap 1Notes

Class 9 NCERT SCIENCE Chap 1 SOLUTION

2020-10-28T22:22:00.001+05:30

CHAPTER 1 MATTER IN OUR SURROUNDINGS

Chapter 1 MATTER IN OUR SURROUNDINGS of SCIENCE NCERT of CLASS 9 complete solution and some important points are given. This will help student to better understand the topic and can easily solve the problems related to CHAPTER 1 MATTER IN OUR SURROUNDINGS Class 9.

SOME IMPORTANT POINTS OF CHAPTER 1 MATTER IN OUR SURROUNDINGS

I) Melting point:- The temperature at which solid melts to became a liquid at the atmospheric pressure is called its melting point.

II) Fusion:- The process of melting that is change of solid state into liquid states is also known as fusion.

III) Latent Heat Of vapourisation:- The amount of heat energy that is required to change 1kg of liquid into gas(vapour) at its boiling point is known as latent heat of vapourisation.

IV) Latent heat of Fusion:- The amount of heat energy that is required to change 1kg of solid into liquid at atmospheric pressure as its melting point is known as latent heat of Fusion.

V) Boiling Point:- The temperature at which a liquid starts boiling at the atmosphere pressure is known as its boiling point.

VI) Latent heat:- It is a heat energy which is absorbed by ice without showing any rise in temperature is known as latent heat.

VII) Sublimation:- A change of state directly from solid to gas without changing into liquid state (or vice versa) is called Sublimation.

These are some important points of CHAPTER 1 MATTER IN OUR SURROUNDINGS of Class 9 Science NCERT.

Here is the answer of textbook Questions of Chapter 1 MATTER IN OUR SURROUNDINGS.

Block questions (PageNo. - 3)

Ques 1. Which of the following are matter?

Chair,Air,love,smell,hate,almonds,thought,cold,lemon, water,smell of perfume.

Ans. Chair,air,almonds, smell of perfume.

Ques 2. Give reasons for the following observation:-

The smell of hot sizzling food reaches you several metres away,but to get the smell from cold food you have to go close.

Ans. This happens because the rate of diffusion of hot gases(released by the hot food) is much faster as in case of cold food.

Ques 3. A diver is able to cut through water in a swimming pool,which property of matter does this observation shows?

Ans. This shows that through there is strong force of attraction between the particles of water in rest position but by applying more force,diver is able to cut through water in a swimming pool.

Ques 4. What are the characteristics of particles of matter?

Ans. I) Particles of matter are very small.

II) Particles of matter have space between them.

III) Particles of matter are continuously moving.

IV) Particles of matter attract each other.

(Page No.6)

Ques 1. The mass per unit volume of a substance is called density,(density= mass/ volume) Arrange the following in order of increasing density- air, exhaust from chimneys, honey, water,chalk, cotton and iron.

Ans. Air < exhaust from chimneys < cotton < water < honey < chalk < iron.

Ques 2. a) Tabulate the difference in the characteristics of states of matter.

b) Comment upon the following rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

Ans. a) (a) The difference in the characteristics of the three states of matter.

Characteristics	Solid	Liquid	Gas
Shape	Fixed shape	No Fixed shape	No Fixed shape
Volume	Fixed volume	Fixed volume	No Fixed volume
Intermolecular force	Maximum	Less than solids	Very less
Intermolecular space	Very less	More than solids	maximum
Rigidity/Fluidity	Rigid/cannot flow	Can flow/not rigid	Can flow/not rigid
Compressibility	negligible	compressible	Highly compressible

Ans b) Rigidity:- The tendency of a substance to retain/ maintain their shape subjected to outside force.

Compressibility:- The matter has intermolecular space.The external force applied on the matter can bring the article closer.This property is called Compressibility.Gases and liquid are compressible.

Fluidity:- The tendency of particles to flow is called fluidity. Liquid and gases are flow.

Filling of Gas container:- Gases have particles which vibrate randomly in all the directions. The gas can fill the container.

Shape:- Solid have maximum intermolecular force and definite shape whereas liquid and gases take the shape of container.

Kinetic energy:- The energy possessed by particles due to their motion is called kinetic energy.Molecules of gases vibrate randomly as they have maximum kinetic energy.

Density:- It is defined as mass per unit volume,the solid have highest density.

Ques 3. Give reason:-

a) A gas fill completly the vessel in which it is kept.

b) A gas exerts pressure on the wall of the container.

c) A wooden table should be called a solid.

d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.

Ans.a) It is so because the particles of Gas have high kinetic energy and they are free to move.

b) In the gaseous state the particles move about randomly at high speed due to this random movement particles hit each other and also the wall of the container. Thus, the gas exerts pressure on the wall of the container.

c) It has definite shape, distinct boundaries,fixed volume and negligence compressibility.

d)It is because the particles of air have large space between them and very less force of attraction. While in a block of wood particles are closely packed

Ques 4. Liquid generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.

Ans. Ice is solid but its density is lower than water due to its structure. The molecules in solid makes a cage like structure with lot of vacant space,this makes ice float on water.

(Page No. 9)

Ques 1. Convert the following temperature to celsius scale:-

a)300k

b) 573k

Ans. a)0°C = 273k

300k = 300-273

=27°C

b) 0°C = 273 k

573k = 573-273

= 300°C

Ques 2. What is the physical state of water at:-

a) 250°C

b) 100°C

Ans.a) Water will be gas(water vapour) at 250°C.

b) Water will be liquid and gas both.

Ques 3. For any substance,why did the temperature remain constant during the change of stale?

Ans. It is so because the heat get used up in changing the state of overcoming the force of attraction between the particles.

(Page No.10)

Ques 1. Why does a desert cooler cool better on a hot dry day?

Ans. On the hot dry day temperature is high and humidity is low. So the rate of evaporation of heat is faster. Particles of water absorbs energy from the surrounding to regain energy lost during the evaporation. This absorption of energy from surrounding makes the surrounding cool.

Ques 2. How does the water kept in an earthern pot became cool during summer?

Ans. It is because earthern pot contains mining holes it abosrbs heat from the water and evaporate in the surrounding and thus makes the water cool.

Ques 3. Why does our palm feel cold when we put some acetons on petrol or perfume on it?

Ans. The particles of acetone on perfume gain energy from our palm on surrounding and evaporation cause the palm to feel cool.

Ques 4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

Ans . It is so because the surface area of saucer is more than a cup. So, the rate of evaporation of heat is faster from a saucer rather than a cup.

Ques 5. What type of clothes should we wear in summer?

Ans. We should wear cotton clothes in summer because cotton is a good absorber of water which helps is absorbing sweat and exposing it into the atmosphere for easy evaporation.

Exercise Questions-

Ques 1. Convert the following temperature to celsius scale:

a) 293K

b) 470K

Ans. a) 0°C = 273 k

293K= 293-273

=20°C

b) 0°C = 273k

470°C = 470-273

= 197°C

Ques 2. Convert the following temperature to the Kelvin scale:

a) 25°C

b) 373°C

Ans. a)0°C= 273k

25°C= 25+273

=298K

b) 0°C=273k

373°C=373+273

=646K

Ques 3. Give reason for the following observation:-

a) Napthalene balls disappear with time with out leaving any solid.

b) We can get the smell of perfume sitting several metres away.

Ans.a) Napthalene balls disappear with time with out leaving any solid because of the process of sublimation. Napthalene balls are converted into vapour (gas).

b) We can get the smell of perfume sitting several metres away because of the process of diffusion. The particles of perfume mixed with the surrounding (air).

Ques 4. Arrange the following substance in increasing order of force of attraction between the particles- water,sugar,oxygen.

Ans. Oxygen(gas)<water<(liquid)<sugar(solid) increasing order of force of attraction.

Ques 5. What is the physical state of water at-

a)25°C

b)0°C

c)100°C

Ans. a) liquid

b)ice(solid)

c) water vapour (gas)

Ques 6. Give two reasons to justify:

a) Water at room temperature is a solid.

b) An iron almirah is a solid at room temperature.

Ans.a) I) It is so because water has no fixed shape but it is has fixed volume.

II) It takes the shape of the container.

b) I) It is highly rigid and it has definite shape.

II) It has fixed volume and distinct boundaries.

Ques 7. Why is ice at 273k more effective in cooling than water at the same temperature?

Ans. Ice at 0°C or 273k is more effective in cooling than water at the same temperature because ice is a solid and during the conversion of solid into liquid,energy is with drawn, surrounding resulting in cooling. Therefore,ice is more effective in cooling than water at the same temperature.

Ques 8. What produces more severe burn, boiling water on stream?

Ans. Stream produces severe burn because particles of stream have absorb extra energy in the form of latent heat of vapourisation.

Ques 9. Name A,B,C,D,E and F in the change in its state.

Ans. A= Fusion or Melting

B= Evaporation or vapourisation

C= Condensation

D=Solidification

E= Sublimation

F= Sublimation

This is the complete solution of CHAPTER 1 MATTER IN OUR SURROUNDINGS. This is according to latest syllabus of CBSE 2020-21.

Here's some extra questions are given according to CHAPTER 1 MATTER IN OUR SURROUNDINGS of class 9 Science NCERT.

Ques 1. What is Matter?

Ans. Matter is something which occupy space and have mass and volume.

Ques 2. What is Diffusion?

Ans. Intermixing of particles of two different types of matter their own is called diffusion.

Ques 3. Why is rubber band called a solid through it changes its shape on stretching?

Ans. A rubber band changes shape under force and regains the same shape when the force is removed. If excessive force is applied, it breaks.

Ques 4. Why are sugar and salt crystals called solid through they take the shape of the jar.

Ans. The shape of each individual sugar or salt crystal remains fixed, whether we take it in our hand put it in a plate or in a jar.

Ques 5. Why sponge is considered as a solid through it can be compressed?

Ans. A sponge has minute holes in which air is trapped when we press it the air is expelled out and we are able to compress it.

Ques 6. What are the properties of solid?

Ans. Solid have a definite shape, distinct boundaries, fixed volume, negligible compressibility and they are rigid.

Ques 7. Why is rate of diffusion higher in liquid than that of solid?

Ans. The rate of diffusion of liquid is higher than that of solid to fact that in the liquid state. Particles move freely and have greater space between each other as compared to particles in the solid state.

These are some extra Questions of Chapter 1 MATTER IN OUR SURROUNDINGS of class 9 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 8 NCERT Science Chap 13 Solution

2020-10-23T22:35:00.002+05:30

CHAPTER 13 SOUND

Here is the answer of chapter 13 SOUND of NCERT science of class 8.The complete solution of CHAPTER 13 SOUND is given here which is prepared subject expert. Some important extra questions and important points about Chapter 13 are also given.

Textbook questions:-

Ques1. Choose the correct answer.

(1) Sound can travel through

a)Gases only

b)Solids only

c)Liquids only

d)Solids, liquids and gases

Ans 1.Solids, liquids and gases.

Ques 2) Voice of when of the following is likely to have minimum frequency?

a)Baby girl

b)Baby boy

c)A man

d)A woman

Ans.2 Baby girl

Ques 3. In the following statements, tick 'T' against those which are true and 'F' against those which are false.

a)Sound cannot travel in vaccum. (T/F)

b)The number of oscillations per second of a vibrating object is called its time period. (T/F)

c)If the amplitude of vibration is large, sound is feeble. (T/F)

d)For Human ears, the audible range is 20Hz to 20,000Hz.(T/F)

e)The lower the frequency of vibration, the higher is the pitch. (T/F)

f)Unwanted or unpleasant sound is termed as music. (T/F)

g)Noise pollution may cause partial hearing impairment. (T/F)

Answers .

a)T

b)F

c)F

d)T

e)F

f)F

g)T

Ques 4.Fill in the blanks with suitable words:-

a)Time taken by an object to complete one oscillation is called ------------.

b)Loudness is determined by the ---------- of vibration.

c)The unit of frequency is ---------.

d)Unwanted sound is called --------.

e)Shrillness of a sound is determined by the -----------of vibration.

Answers .

a)Time period

b)Amplitude

c)Hertz

d)Noise

e)Pitch

Ques 5. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

Ans 5. Number of oscillations = 40

Time taken = 4seconds

Frequency = number of oscillations /time

= 40/4

= 10Hz

Ques 6. The sound from a mosquito is produced when its vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?

Ans 6. Number of vibration in 1 second = 500

Therefore, frequency = 500Hz

Time period = 1/frequency

=1/500

=0.002second

Ques7 Identify the part which vibrates to produce sound in the following instruments.

a)Dholak

b)Sitar

c)Flute

Answers.

a)Stretched membrane

b)Stretched string

c)Air column

Ques8 What is the difference between noise and music? Can music become noise sometimes?

Ans 8. The unpleasant sound is called noise. Whereas pleasant sound is called music. Noise can produce so much health hazards, whereas music brings about soothing effect.

Ques 9. List sources of noise pollution in your surroundings.

Ans 9. The sources of noise pollution are automobiles, loud speakers, aeroplanes, machine etc.

Ques 10 .Explain in what way noise pollution is harmful to human.

Ans 10. Noise pollution causes:-

1)Temporary or permanent deafness

2)Blood pressure

3)Lack of concentration

Ques 11. Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.

Ans 11. I would suggest my parents to buy the house which is three lanes away from the roadside. This would protect us from noise pollution which is maximum at roadside building.

Ques 12. Sketch larynx and explain its function in your own words.

Ans 12. The other name of larynx is voice is box. It is present at the upper end of the windpipe. The function of larynx is to produce sound.

Ques13 Lightening and thunder take place in the sky at the same time and at the same distance from us. Lightening is seen earlier and thunder is heard later. Can you explain why?

Ans 13.The speed of light is much greater than the speed of sound. Hence, lightening is seen earlier and thunder is heard later, even through both are produced at the same time and same place.

This is the complete solution of CHAPTER 13 SOUND. This is according to latest syllabus of CBSE 2020-21.

Here's some important points about the CHAPTER 13 SOUND of class 8 Science NCERT.

IMPORTANT POINTS:-

1)Frequency :- The number of oscillation in seconds is called frequency. The SI unit of frequency is Hertz.

2)Amplitude:- The maximum displacement of a vibrating body from its mean position on either side.

3)Time period:- The time taken by a vibrating body to complete an oscillation is called time period. It is denoted by T.

4)vibration:- Vibration is defined as to and fromotion of the body in the same path about its mean position.

5)Pitch:- Characterstics of sound that depends upon the frequency of vibration.

6)Noise:- Sound produces by irregular vibration which is unpleasant to ears.

7)Decible:- A unit to measure the loudness of the sound.

8)Music:- Sound produced by regular vibrations which is pleasant to ears in music.

These are some important points about the Chapter 13 SOUND of Class 8 Science.

Here's some extra questions are given according to CHAPTER 13 SOUND of class 8 Science NCERT.

Extra Question/Answers

Ques 1.What happens when you ring the bell of your bicycle?

Ans 1. When we ring the bell of bicycle it starts vibrating and produces sound.

Ques 2. Which part of our throat produces sound?

Ans 2 .The sound of our voice is produced by the vibration of two vocal cords in our throat causes by air coming from lungs.

Ques 3. How sound is produced in a radio or television?

Ans 3.The sound in a radio or television is produced by the vibration of tjin diaphragm of a speaker.

Ques 4.Which part of a bee and mosquito produced buzzing sound?

Ans 4.The buzzing sound of a bee and mosquito is produced by the vibration of their wings.

Ques 5. What is the range of audible sound vibrations for normal human ears?

Ans 5. The range of audible sound vibration for normal human ear is 20Hz to 20,000Hz.

Ques 6.What is the range of ultrasonic vibrations?

Ans 6.The range of ultrasonic vibration is more than 20,000Hertz.

Ques 7.Name the characterstics which help us distinguish between Men and woman voice?

Ans 7.Pitch.

Ques 8.Why should we not put any pointed or hard thing in our ear?

Ans 8.Beacause it tears the eardrum.The tearing of ear drum can make a person deaf.

Ques 9.Suggest four ways of minimizing noise?

Ans 9.a)The machines which produced minimum noise should be used.

b)The factories should not be in town sheep area.

c) Fire crackers should be banned.

d)Domestic appliances should be lubricated.

Ques 10. What is noise pollution ?State two ways in which noise produced in home?

Ans 10 . The persistence of unwanted sound or loud noise in the environment which sometimes had harmful effects on human health is termed as Noise pollution.

The two ways in which noise is produced in home are:-

1)Radio and television when put on high volumes.

2)Air coolers, air conditions etc cause noise pollution.

These are some extra Questions of Chapter 13 SOUND of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 8 NCERT SCIENCE Chap 12 Solution

2020-10-22T22:09:00.001+05:30

Chapter 12 Friction

Here is the answer of chapter 12 FRICTION of NCERT science of class 8.The complete solution of CHAPTER 12 FRICTION is given here which is prepared subject expert. Some important extra questions are also given with their answers.

Textbook Questions

Ques1 Fill in the blanks.

(a) Friction opposes the ________between the surfaces in contact with each other.

b)Friction depends on the ________of surfaces.

c)Friction produces __________.

d) Sprinkling of powder on the carrom board ______ friction.

e) Sliding friction is ________than the static friction.

Answers.

a)Motion

b)nature

c)heat

d )Reduces

e) Less

Ques2. Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order.Their arrangements are given below. Choose the correct arrangement.

a) Rolling, static, sliding

(b) Rolling, sliding, static
c) Static, sliding, rolling
(d) Sliding, static, rolling

Ans2.c) static,sliding,rolling

Static friction is greater than the sliding friction and sliding friction is greater than the rolling friction.

Ques3 .Alida runs her toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor . The force of friction acting on the car on different surfaces in increasing order will be

(a) Wet marble floor, dry marble floor, newspaper, towel
(b) Newspaper, towel, dry marble floor, wet marble floor
c)Towel, newspaper, dry marble floor, wet marble floor
(d) Wet marble floor, dry marble floor, towel, newspaper

Ans3(a) Wet marble floor, dry marble floor, newspaper, towel
The force of friction acting on the car will be the maximum on the towel and minimum on the wet marble floor. The force of friction acting on the car increases gradually from wet marble floor to dry marble floor, newspaper and towel spread on the floor. Hence, the increasing order of frictional force is wet marble floor, dry marble floor, newspaper and towel.

Ques 4 .Suppose your writing desk is tilted a little.A book kept on it starts sliding down show the direction of friction force acting on it.

Ans 4. When the book is placed on the top of a tilted desk. It starts sliding down and the direction of frictional force acting on it is upwards along the surface of the desk.

Ques 5. You spill a bucket of soapy water on a marble floor accidently.Would it make it easier or more difficult for you to walk on the floor?Why?

Ans 5. When you spill a bucket of soapy water on the marble floor it makes walking on the floor more difficult. The soapy water reduces the friction between the feet and the floor due to which the feet do not get the necessary grip to walk on the floor.

Ques6 Explain why sportsman use shoes with spikes.

Ans 6. Sportsman uses shoes with spikes to get the better grip on the ground. The spikes at the bottom of the shoes increase the friction between shoes and the ground which provides the required grip.

Ques 7. Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?

Ans 7. Iqbal and Seema are pushing similar boxes but of different weight on the same floor. The force required to push the forces depends on their weight because the frictional force on the surface is directly proportional to its weight. More is the weight of the box, greater is the force required to push it. Hence, Seema will have to apply more force to push the box.

Ques 8. Explain why sliding friction is less than static friction.

Ans 8. To move a surface over another surface, the interlocking of the irregularities between the surface will be smoothened, reducing the friction. Hence, sliding friction is less than static friction.

Ques 9.Give examples to show that friction is both a friend or a foe.

Ans 9. The friction between feet and the ground help us to walk, similarly the friction between our hands and object provides a grip to hold them and the friction between a chalk and a board help us to write on the board. Friction causes a great wear and tear of the surface in contact. Hence, friction is both a friend or a foe.

Ques 10.Explain why objects moving in fluids must have special shapes

Ans 10. The frictional force on an object in the fluids which is referred to as drag depends upon the nature of the fluids and the shape of the object. The object which has steamlined shape have less friction in a given fluid. Hence, the object moving in the fluid must have special shapes to reduce friction due to fluids.

This is the complete solution of CHAPTER 12 FRICTION. This is according to latest syllabus of CBSE 2020-21.

Here's some extra questions are given according to CHAPTER 11 FRICTION of class 8 Science NCERT.

Extra question /answers

Ques 1. What do you mean by the term of friction? What is the cause of friction?

Ans 1. If a body exerts a force on another body placed in its contact in a direction parallel to the contact force, the force is called the force of friction.
The friction is caused by irregularities on the two surface in contact even those surfaces which appears very smooth have large number of minute irregularities.

Ques 2. Write the properties of friction?

Ans 2 .1)Friction is produced only when one body is made to move upon the another body.
2)It always tries to prevent movement and tries to stop the body.
3)It wears the surface of contact of 2 bodies.
4)It is always in the direction opposite to the direction of motion.

Ques 3 .What are the types of friction?

Ans 3. Friction is of three types:-
1) Static friction:- When we apply a force on a body to make it move the force applied is balanced by the force of friction such force of friction is called static friction.
2) Sliding friction:- The force of friction acting between the two surfaces when one of them just slides over another surface with a uniform speed is called sliding friction.
3) Rolling friction:- When a body is placed over the other body like a roller or a wheel and is allowed to move this is called rolling function.
Example:-The suitcases and travelling bags are provided with small wheels.

Ques 4. What is a drag?

Ans 4.The frictional force exerted by fluids is known as drag.

Ques 5. Write five advantages of friction?

Ans 5. 1)Friction help us in running and Walking.
2)Friction helps in writing and making drawings.
3)Friction produces heat, a matchstick lights up due to the friction against the side of match box.
4)Wood can be cut because of friction between the axe and wood.
5)The shoes of athlete are provided with spikes to prevent slipping.

Ques 6. What is a lubricant?

Ans 6. A material which reduces the force of friction when applied between two surfaces in contact is known as lubricant.

Ques 7.why is it difficult to climb a greasy pole?

Ans 7. It is difficult to climb a greasy pole because grease reduces friction so there will be less friction between the hands and feat of the person climbing the pole.

Ques 8.Why old and smooth tyres discarded?

Ans 8. Old and smooth tyres are discarded because their surface is wear out which makes the tyres more slippery.

Ques 9.Why we sprinkle talcume powder on a carrom board?

Ans 9.When we sprinkle talcume powder on a carrom board the depressions on the surface of the board and coins of carrom get filled with powder which makes the surface smoother and reduces friction, between the board and coins of carrom.

Ques 10. Why aeroplanes and ships body is streamlined?

Ans 10. Friction due to air or water is reduced by using streamlined shapes in aeroplanes or ships. A streamlined shape is narrow in front and broader at the back.

These are some extra Questions of Chapter 11 FRICTION of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 8 NCERT SCIENCE Chap 11 solution

2020-10-20T23:38:00.001+05:30

CHAPTER 11 FORCE AND PRESSURE

Here is some important points and answer of chapter 11 FORCE AND PRESSURE NCERT science of class 8.These important points help the student to better understanding of the topic of CHAPTER 11 FORCE AND PRESSURE OF CLASS 8. The complete solution of CHAPTER 11 FORCE AND PRESSURE is given here which is prepared subject expert.

Important Points:-

a) Force:- A push or pull of an object is called force.

b) Nature of Force:- Force applied on an object in the same direction add to one another and if two forces acting on an object in opposite direction then the net force is the difference of between the two forces.

c) Contact force:- When a force is applied physically through a direct contact between two object.

Example:- Muscular force and Frictional Force.

d) Non contact force:- When a force is applied between bodies without being in contact with each other are known as non contact force. For example:- electrostatic force and gravitational force.

e) Muscular force:- It is a contact force which is applied by the muscles of the body. For example:- While lifting the school bag you apply force using muscles of your arm.

f) Frictional Force:- The force acting between two surface in contact and tends to oppose motion is called frictional Motion. It is a contact force which slows down or stops the moving object. For example:- Rolling ball on the ground stops due to friction.

g) Electrostatic force:- Force applied by a charge body on another changed or unchanged body is called electrostatic force. For example:- a straw rubbed by a paper attracts another shtraw which is not rubbed.

h) Magnetic force:- The force exerted by a magnet on a piece of metal or another magnet is known as Magnetic force. Example:- Magnet attracts piece of iron without being in contact with it.

i) Gravitational force:- The force exerted by earth due to which object falls on the earth is called the Force of Gravity or Gravitational force.

These are some important points of CHAPTER 11 FORCE AND PRESSURE of Class 8 Science NCERT.

Here is the answer of textbook Questions of Chapter 11 FORCE AND PRESSURE.

Ques 1. Give two examples each of situations in which you push or pull to change the state of motion of object.

Ans. A Boy kicking a football at rest, and the force exerted on a perambulator to move it from rest, are example of push.

The force exerted by a bullock on a cart and the force exerted to drag a chair are the examples for pull.

Ques 2. Give two examples of situation in which applied force causes a change in the shape of an object.

Ans. Squeezing a lemon and inflating a balloon are examples in which applied force cause a change in shape of an object.

Ques 3. Fill in the blanks:-

a) To draw water from a well,we have to ______ at the rope.

b) A charged body __________ an uncharged body towards it.

c) To move a loaded trolly we have to ________ it.

d) The north pole of a magnet __________ the north pole of the other magnet .

Ans. a) Pull

b) Attracts or pull

c) Pull or push

d) Repels or push

Ques 4. An archer stretches her how while taking aim at the target. She then release the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statement using the following terms.

a) To stretch the bow, the archer applied the force that causes the change in its _________.

b) The force applied by the archer to stretch the bow, is an example of _________force.

c) The type of force responsible for a change in the state of motion of the arrow is an example of__________ force.

d) While the arrow move towards its target, the force acting on it are due to __________ and that due to ________ of air.

Ans. a) Shape

b) Muscular

c) Contract

d) Friction

Ques 5. In the following situation identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.

a) Squeezing a piece of lemon between the fingers to extract it's juice.

b) Taking out paste from the toothpaste tube.

c) A load suspended from a spring while it's other end is on a hook fixed to a wall.

d) An athlete making a high jump to clear the bar at a certain height.

Ans.a) The agent exerting the force is the fingers. The object on which the force acts is the lemon. And the effect of the force is the extraction of the juice from the lemon.

b) The agent exerting the force is the fingers of the hand. The object on which the force acts is the toothpaste tube. And the effect of the force is extraction of the paste from the toothpaste tube.

c) The agent exerting the force is the weight of the suspended load the object on which the force acts is the spring. And the effect of the force is the stretching of spring along its length.

d) The agent exerting the force is the reaction of the ground on the athlete. The object on which the force acts is the athlete and the effect of the force is athlete.

Ques 6. A blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering effect the price of iron?

Ans. When the Blacksmith hammers a hot piece of iron the force due to hammering change the shape of the iron piece.

Ques 7. A inflated balloon was pressed against a wall after it had been rubbed with a piece of synthetic fibre. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?

Ans. When the inflated balloon is rubbed with a piece of synthetic cloth. It get changed due to friction. When the balloon is pressed against the wall,the electronic force between the balloon and the wall is responsible for the attraction between the balloon and the wall.

Ques 8. Name the forces acting on a plastic bucket containing water held above ground level in your hand. Discuss why the force acting on the bucket do not bring the change in its state of motion.

Ans. The force acting on a plastic bucket containing water held above ground level in my hand are:-

i) The gravitational force of attraction on the bucket exerted by the earth acting vertically downwards.

ii) The reaction of the hand on the bucket acting vertically upwards. The two forces are equal in magnitude and opposite in direction so there resultant force on the bucket is zero. Hence, they do not bring about any change in the buckets state of motion.

Ques 9. A rocket has been fixed upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.

Ans. When a rocket is fired upwards, the two forces acting on it immediately after leaving the launching are:-

I) The gravitational force of attraction exerted on the rocket by the earth, acting vertically downwards.

II) The thrust exerted by the ejecting gases on the rocket acting vertically upwards.

Ques 10. When we press the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to

a) pressure of water.

b) gravity of the earth.

c) shape of rubber bulb.

d) atmospheric pressure.

Ans.d) atmospheric pressure.

This is the complete solution of CHAPTER 11 Force and Pressure. This is according to latest syllabus of CBSE 2020-21.

Here's some extra questions are given according to CHAPTER 11 Force and Pressureof class 8 Science NCERT.

Ques 1. Define pressure and write it's formula.

Ans. Pressure is defined as the force acting or a unit area of the surface is called pressure.

Pressure= Force/Area.

Ques 2. What are the factors in which pressure in solid depends?

Ans. Pressure in solid depends on the force and the area on which it acts. The smaller the area,larger will be the pressure for the same force, if the force is greater than pressure will also be greater for same area.

Ques 3. What are the two factors on which pressure in liquid depends?

Ans. Pressure in liquid depends upon two factors:-

I) The height of the liquid columns.

II) Density of the liquid.

Ques 4. What are fluids?

Ans. The matter that has a tendency to flow are known as Fluids. All liquids and gases are fluids.

Ques 5. What are atmospheric pressure?

Ans. The pressure exerted by air of atmosphere is called the atmospheric pressure.

These are some extra Questions of Chapter 11 Force and Pressure of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 8 NCERT Science Chapter 18 Solution

2020-10-18T22:21:00.003+05:30

CHAPTER 18 POLLUTION OF AIR AND WATER

Here is some important points and answer of chapter 18 POLLUTION OF AIR AND WATER NCERT science of class 8 which helps students to better understand the topics of chapter.

Important Points:-

i) Pollution:- The contamination of any natural resources by unwanted substance or impurities is called Pollution.

ii) Global warming:- Increase in the average temperature of the earth due to green house effect and other reason is called Global Warming.

iii) Green house effect:- The availity of the earth's atmosphere to trap and reflect radiation of the sun is called Green house effect.

iv) Air Pollution:- When air got contaminated by impurities is known as Air pollution.

v) Chemical Contimination:- The chemical which are created disturbance in environment are known as Chemical Contimination.

vi) Pollutants:- Particles or substance which creates disturbances in the environment resources such as water, soil,etc are called pollutants.

vii) Portable water:- Water which is safe for drinking is known as Portable Water.

viii) Water Pollution:- Contamination of water by harmful substance is known as Water Pollution.

These are some important points of CHAPTER 18 POLLUTION OF AIR AND WATER of Class 8 Science NCERT.

Here is the answer of textbook Questions of Chapter 18 POLLUTION OF AIR AND WATER .

Ques. 1 What are the different ways in which water gets contaminated?

Ans. Water gets contaminated in the following ways:-

i) Many industries discharge the harmful chemicals into rivers and and streams.

ii) Chemical fertilizers, pesticides and weedicides used in agriculture dissolve in water and seeps into the ground to pollute ground water. They also get washed into the water bodies from the fields.

iii) Throwing of untreated sewage containing disease causing germs directly into the rivers.

iv) Hot water released into water bodies from power plants and industries.

Ques. 2 At an individual level how can you help reduce air Pollution?

Ans. At an individual level,we can do the following things to reduce air Pollution:-

I) Public vehicles should be used instead of private vehicles.

II) CNG and unleaded petrol should be used instead of ordinary petrol and diesel.

III) Create awarness about air pollution by talking to our family members, friends and colony members.

IV) Plants should be planted to reduce the air Pollution and deforestation of trees should be avoided.

Ques.3 Clear transparent water is always fit for drinking. Comment.

Ans. No, water which looks clear and transparent may not be clear and can carry disease causing germs and dissolved impurities. Therefore, such water is not fit for from and has to be purified to make it fit for drinking.

Ques 4. You are a member of the municipal body of your town make a list of measure that would help your town to ensure the supply of clean water to all its residents.

Ans. Some of the measure that would help our town to ensure the supply of clean water to all its residues are as follows:-

I) The water should be purified to make it fit for drinking.

II) The pipes through which water get wasted due to leakage.

III) Chlorine tablets should be supplied to water to kill microscopic organism.

IV) The water tanks used for storing drinking water should be cleaned periodically.

V) The water supply pipes should be away from sewage pipes.

Ques 5. Explain the difference between pure air and polluted air.

Ans. Pure Air

Air is a moisture of gases pure air contains 78% by volume nitrogen, 21% of oxygen and small amount you carbon dioxide,argon ,water vapour,methane, etc. Pure air is good for plants and animals growth.

Polluted Air

Polluted Air contains varied percentage of various gases that are harmful to living organisms. Polluted air is harmful for plants and animals growth.

Ques 6. Explain circumstances leading to acid rain. How does acid rain affect us?

Ans. Pollutants like sulphur dioxide and nitrogen dioxide liberated into the air by industries react with water vapour in air to form sulphuric acid and nitric acid these acids come down as rain called Acid Rain.

Effects of Acid Rain.

i) Acid rain cause direct damage to leaves of plants.

ii) Acid rain cause damage to fresh water life which decrease the fish population in lakes.

iii) Acid Rain damage building and historical monuments.

iv) Acid Rain remove basic nutrients such as Calcium from the soil.

Ques.7. Which of the following is not a green house gas?

a) Carbon dioxide

b)Sulphur dioxide

c) Methane

d) Nitrogen

Ans. Nitrogen

Ques 8. Describe the green house effect in your own word?

Ans. In a nursery,the green house gases trap the sun's heat and heat is not allowed to get out.

Therefore, the green house get warmed up. Similarly the atmosphere on the earth traps the heat of the sun and warms up the surface of the earth. This is called the 'green house effect'. Due to this life was possible on the earth but now it is effecting life as it increase the temperature of the atmosphere,atmospheric gases like CO2 if increased in required percentage, cause the green house effect other gases that cause the green house effect are methane, nitrous oxide, water vapour, etc.

Ques 9. Prepare a brief speech on global warming. You have to deliver the speech in your class.

Soln:

The increase in the average temperature of the Earth’s surface is known as Global warming. It occurs due to the increased concentration of greenhouse gases in the atmosphere. The greenhouse gases include methane, CO2, and water vapour. These gases trap the solar radiations released back by the earth, which results in keeping our planet warm and helps in human survival. However, an increase in these gases can lead to an increase in the earth temperature resulting in global warming.

Ques 10. Describe the threat to the beauty of the Taj Mahal.

Soln:

The major threat to the Taj Mahal is the acid rain. When the acid rain falls on the Taj, which is completely made of marble, they react with marble to form a powder like substance which is then washed away by the rain. This phenomenon is known as marble cancer. In addition, the soot particles emitted from the Mathura oil refinery located near Agra is leading to the yellowing of Taj Mahal marble.

Ques 11.Why does the increased level of nutrients in the water affect the survival of aquatic organisms?

Ans. The fertilizers used in agriculture get dissolved in water bodies from the field. to grow.Nitrates and phosphates in the fertilizer serve as nutrients for the algae to grow.When algae die,they are decomposed by the bacteria they serve as food for bacteria,leading to decrease in oxygen level in water.This effect the survival of the aquatic animal.

This is the complete solution of CHAPTER 18 Pollution Of Air And Water. This is according to latest syllabus of CBSE.

Here's some extra questions are given according to CHAPTER 9 Pollution Of Air An Water of class 8 Science NCERT.

Ques 1.How does boiling purify water?

Ans. Water contains disease causing microbes when water is boiled the micro organism die due to high temperature such water is consider pure and portable water.

Ques 2. Write a short note on Smog?

Ans. Smog is a moisture of fog and smoke and it is formed when oxide of sulphur and nitrogen along with other pollutants combine with fog. Smog is seen as thick fog like layer it causes breathing problems, asthma , wheezing cough, etc.

Ques 3. Why the growth of algae in water bodies is considered a threat to aquatic life?

Ans. Algae grow in water bodies. They increase rapidly in water bodies,that are rich in nutrients washed away from the agriculture fields. When these algae die. They serve as food for bacteria and in the process. The oxygen dissolved in water is used up. The aquatic life is affected due to reduce oxygen levels. Hence the growth of algae in water bodies is considered a threat to aquatic life.

Ques 4. What do you understand by water borne diseases?

Ans. Disease that spread through water are water borne diseases. The carrier or the causative organisms of such diseases breed and spread the disease through water. For example- Cholera, typhoid, jaundice, dengu,amoebiasis ,etc.

These are some extra Questions of Chapter 18 POLLUTION OF AIR AND WATER of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 8 NCERT Science Chap 10 Solution

2020-10-14T00:14:00.002+05:30

CHAPTER 10 REACHING THE AGE OF ADOLESCENCE

Chapter 10 Reaching The Age of ADOLESCENCE SCIENCE NCERT of CLASS 8 complete solution and some important points are given. This will help student to understand the topics of CHAPTER 10 REACHING THE AGE OF ADOLESCENCE of Class 8. Students can solve the textbook Questions easily and understand all the important points of chapter.

Important Points:-

a) Adam's apple:- At puberty, the voice box begin to grow in boys and develop as a large voice box this developed part seen at the throat known as Adam's apple.

b) Adolscence:- The period of life when reproductive maturity is growing up is called Adolscence.

c) Adernalin :- Kind of gland which release hormone to adjust body from when we are facing emergency situation stress.

d) Balanced Diet:- A diet which contain all nutritional value like carbohydrates, fats, vitamins etc.is known as balanced diet.

e) Endocrine gland:- The glands which release their secretion direct in blood are known as endocrine gland.

f) Hormone:- Chemical substance which helps body in development and growth.

g) Insulin:- Kind of hormones which released by pancreas help in the maintain of sugar level in blood.

h) Pitutary gland:- The gland which release growth hormones and also controls secretion of other glands like thyroid, Adernalin is known as Pitutary gland.

i) Puberty:- The changes which occur during th age of Adolescence is known as Puberty.

j)Sex chromosomes:- The chromosomes which are responsible for the determination of sex of the foetus are known as Sex chromosomes.

These are the important points about the Chapter 10 REACHING THE AGE OF ADOLESCENCE it helps students to understand the chapter.

The solution of textbook questions of Chapter 10 REACHING THE AGE OF ADOLESCENCE of Class 8 is given below.

Ques 1. What is the term used for secretion of endocrine glands responsible for changes taking place in the body.

Ans. Hormones are secretion of endocrine gland responsible for changes taking place in the body.

Ques 2. Define adolescence.

Ans. The period of life when the body undergoes

changes leading to reproductive maturity is called Adolescence.

Ques 3. What is mensuration? Explain.

Ans. The monthly discharge of blood from uterus of a non pregnant women from puberty to menopause is called mensuration. The menstrual cycle is controlled by hormones . The cycle include the maturation of the egg its release, thickening of the uterine wall and its breakdown if pregnancy does not occur. Mensuration occurs once in about 28 to 30 days.

Ques 4. List changes in the body that take place at puberty.

Ans.a) Height and weight increases.

b) Muscles became stronger.

c) Change in the body shape with broader shoulders.

d)Vocal cords get thicker and longer in boys.

e) They attain mental, intellectual and emotional maturity , learning capacity increases.

f)Sweat and oil glands became more active.

g)Males develop a moustache and a beard.

h) Reproductive function begins with the release of follicle stimulating.

Ques 5. Prepare a table having two columns depicting the names of the endocrine glands and hormones secreted by them.

Ans.

Endocrine glands	Hormones
1. Pituitary gland	Growth hormones,follicle stimulating hormone,leutenizing hormones, vasopressin, oxytocin, prolactin
2. Ovaries	Estrogen, Progestrone
3. Testes	Testosterone
4. Thyroid	Thyroxine, calcitonim
5. Pancreas	Insulin,Gulcagon
6. Adrenal glands	Adrenaline

Ques 6. What are sex hormones? Why are they named so? State their function.

Ans. The hormones that are responsible for the male and female secondary sexual characters are called Testosterone in males and estrogen and progesterone in females are sex hormones. Sex hormones are named so as they have an effect on the sexual features of an organism.

Function:-

Sex steriods play important role in inducing the body changes known as primary sex characteristic and secondary sex characteristics.

Ques 7. Choose the correct option.

a) Adolescents should be careful about they eat, because

i) proper diet develops their brains.

ii)proper diet is needed for the rapid growing taking place in the body.

iii) Adolescents feel hungry all the time.

iv) taste buds are well developed in teenagers.

b) Reproductive age in women starts when their

i) mensuration starts.

ii) breasts start developing.

iii) body weight

iv)height increases

c) The right meal for Adolscents consists of

i) Chips,noodles,coke

ii) chapati, dal, Vegetables

iii) rice,noodles and burger.

iv) vegetables cutlets,chips and lemon drink.

Ans. a) proper diet is needed for the rapid growth taking place in their body.

b) breasts start developing.

c) chapati,dal, vegetables.

Ques 8. Write notes on-

a) Adam's apple

b) Secondary sexual characters

c) Sex determination in the unborn baby.

Ans.a) At puberty, the voice box or the larynx begin to grow. Boys develop larger voice boxes. The growth of voice box in boys can be seen as protruding part of the throat called the Adam's apple.

b) A characteristic of animals that differs between the male and female sexes is called secondary sexual characters. Males have change in voice, broadening of shoulders,beard are secondary sexual characters.

c) Zygote is the instruction for determining the sex of the baby. This instruction is present in the thread like structures called Chromosomes in the fertilised egg. Two chromosomes out of these are sex chromosomes name X and Y a female has two X chromosome while a male has one X and one Y chromosomes. When a sperm containing a X chromosome fertilise ,the egg would have two X chromosomes and develop into a female Child.

If the sperm contributes a Y chromosome to the egg(ovum) at fertilisation, the zygote would develop into a male Child.

9. Word game :

Use the clues to work out the words.

Across

3. Protruding voice box in boys

4. Glands without ducts

7. Endocrine gland attached to brain

8. Secretion of endocrine glands

9. Pancreatic hormone

10. Female hormone

Down

1. Male hormone

2. Secretes thyroxine

3. Another term for teenage

5. Hormone reaches here through blood stream

6. Voice box

7. Term for changes at adolescence

Soln:

Across

Adam’s apple
Endocrine
Pituitary
Hormone
Insulin
Estrogen

Down

Testosterone
Thyroid
Adolescence
Target site
Larynx
Puberty

This the complete solution of CHAPTER 10 REACHING THE AGE OF ADOLESCENCE OF CLASS 8 SCIENCE NCERT .The solution is prepared by subject expert and the solution is given according to latest CBSE SYLLBUS.

FOR ANY QUERY CONTACT US

YOU CAN ALSO ACCESS

Class 8 Science NCERT Chap 9 Solution

2020-10-13T22:21:00.002+05:30

CHAPTER 9 REPRODUCTION IN ANIMALS

Chapter 9 REPRODUCTION IN ANIMALS of SCIENCE NCERT of CLASS 8 complete solution and some important points are given. This will help student to understand the topics of CHAPTER 9 REPRODUCTION IN ANIMALS of Class 8. Students can solve the textbook Questions easily and understand all the important points of chapter.

Important points:-

a) Asexual Reproduction:- The mode of reproduction in which single parent is taking place is known as Asexual Reproduction.

b) Binary fission:- This is a kind of asexual Reproduction in which parent cell split (divide) into two daughter cells is known as Binary fission.

c) Budding:- In hydra, new individual develop from bud. This method of asexual reproduction is known as Budding.

d) Eggs:- Eggs are female reproductive gametes.

e) Embryo:- Developing stage of zygote is called embryo.

f) External Fertilisation:- When the fertilisation take place outside from the female body is known as External Fertilisation.

g) Fertilisation:- Fusion of male and female gametes is called Fertilisation.

h) Foetus:- Completely developed stage of an embryo in which all body parts completely developed identifiable is called Foetus.

i) Internal Fertilisation:- When the fertilisation take place inside the female body is called internal fertilisation.

j) Metamorphosis:- The transformation of earlier stage to post stage through drastic changes is called Metamorphosis.

k) Oviparous animals:- Animals which are laying eggs are known as Oviparous animals.

l) Sexual reproduction:- Reproduction in which both male and female take part is known as sexual Reproduction.

m) Sperms:- Male reproductive gamete.

n) Viviparous animals:- Animal which are giving birth to young ones are known as Viviparous animals.

o) Zygote:- Fertilised egg is known as Zygote.

These are the important points about the Chapter 9 REPRODUCTION IN ANIMALS it helps students to understand the chapter.

The solution of textbook questions of Chapter 9 REPRODUCTION IN ANIMALS of Class 8 is given below.

Ques 1. Explain the importance of reproduction in organism.

Ans. a) Reproduction is essential for the continuation of species.

b) Reproduction is essential for the continuation of similar kind of individual generation after generation.

c) Reproduction ensures the survival of all living things.

Ques 2. Describe the process of fertilisation in human beings.

Ans. Fertilisation is the process by which the nucleus of a sperm fuses with the nucleus of an egg. In human fertilisation occur in the fallopian tube of the female reproductive tract. Such fusion of the egg and the sperm is called fertilisation. Once the head of the sperm is inside the egg and the tail of the sperm off. A Fertilised egg cell is known as Zygote.

Ques 3. Choose the most appropriate answer.

a) Internal fertilisation occurs.

(i) in female body.

(ii) outside female body.

(iii) in male body.

(iv) outside male body.

b) A tadpole develops into an adult frog by the process of

(i) Fertilisation

(ii) metamorphosis

(iii) embedding

(iv) budding

c) The number of nuclei present in a zygote is

(i) none

(ii) one

(iii) two

(iv) four

Ans. a) in female body

b) metamorphosis

c)one

Ques 4. Indicate whether the following statement are True (T) or False (F).

(a) Oviparous animals give birth to young ones.

(b) Each sperm is a single cell.

(c) External fertilisation takes place in frog.

(d) A new human individual develops from a cell called gamete.

(e) Egg laid after fertilisation is made up of single cell.

(f) Amoeba reproduces by budding.

(g) Fertilisation is necessary even in asexual reproduction.

(h) Binary fission is a method of asexual reproduction.

(i) A zygote is formed as a result of fertilisation.

(j) An embryo is made up of a single cell.

Ans.(a) False

(b) True

(c) True

(d) False

(e) True

(f) False

(g)False

(h)True

(i) True

(j)False

Ques 5. Give two differences between a zygote and a foetus.

Ans. Zygote

a) Fertilised ovum is called Zygote.

b) It is singled celled.

c) It is earliest stage of development.

d) It is formed by the fusion of male and female gametes.

e) The zygote divide several times to form an embryo.

Foetus

a) The stage of the embryo in which all parts of body can be identified is called Foetus.

b) It is multicellular.

c) It is the last developmental stage of an organism.

d) The foetus stage occurs after the embryo stage.

e) Foetus mainly undergoes internal change.

Ques 6. Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Ans. Asexual Reproduction :- Reproduction that involve only a single parent is called asexual reproduction. It occurs with out the union of male and female gametes.

Budding and Binary fission are method of asexual reproduction in animals.

a) Budding:- Hydra reproduces by budding. Small budges develop on hydra as buds and later form new individual.

b) Binary fission :- This is a kind of asexual reproduction in which parent cell split(divide) into two daughter cell is known as Binary fission.

Ques 7. In which female reproductive organ does the embryo get embedded?

Ans. The embryo get embedded in the female reproductive organ called uterus.

Ques 8. What is metamorphosis? Give example.

Ans. The transformation of the larva into an adult through drastic changes is called metamorphosis.

For example:- Silkworm and frog.

Ques 9. Differentiate between internal fertilisation and external fertilisation.

Ans. Internal fertilisation

a) It occurs inside the female body.

b) Gametes are released by adults into a female reproductive tract.

c) Less number of offspring.

d) Example - Mammals, reptilr,birds, worms and insect.

External Fertilisation

a) The eggs and sperms come together outside of the parent bodies.

b) Gametes are released by adults into the water.

c) More number of offspring.

d) star fish, frog and many fishes.

10. Complete the crossword puzzle using the hints given below.

Across

1. The process of the fusion of the gametes.

6. The type of fertilisation in hen.

7. The term used for bulges observed on the sides of the body of hydra.

8. Eggs are produced here.

Down

2. Sperms are produced in these male reproductive organs.

3. Another term for in vitro fertilisation.

4. These animals lay eggs.

5. A type of fission in amoeba

Soln:

Across

1) Fertilization

6) Internal

7) Buds

8) Ovary

Down

2) Testis

3) Zygote

4) Oviparous

5) Binary

This is the complete solution of CHAPTER 9 Reproduction in Animals. This is according to latest syllabus of CBSE 2020-21.

Here's some extra questions are given according to CHAPTER 9 Reproduction in Animals of class 8 Science NCERT.

Ques 1. What is IVF?

Ans. IVF is in-vitro fertilisation. This process have been taking place outside of female body in which zygote form by the artificial method and develop for a week after it place in mothers uterus and take birth as a normal baby. This process is also know as Test Tube Baby.

Ques 2. How do zygote form?

Ans. When sperms enters in female body and reach to uterus one sperms fuse with egg cell and form a zygote.

Ques 3. Write the name of all reproductive parts of male and female bodies.

Ans. Male. Female

a) Penis. a) Oviduct

b) Testis. b) Ovary

c)Sperm duct. c) Uterus

These are some extra Questions of Chapter 9 REPRODUCTION IN ANIMALS of class 8 Science NCERT.

FOR ANY QUERY CONTACT US.

RELATED LINK

Class 9 Science Chap 1Notes