Biology in science

Earthquake

noreply@blogger.com (Chayan Das) — Sun, 1 Jan 2012 04:51:00 -0800

EARTHQUAKE

Earthquake is defined as shaking or vibrating of the earth surface. The shaking may vary between a very small tremor to a violent vibration. It cannot be forecasted and it occurs suddenly.

Nepal has experienced numerous earthquakes in the past. Some of the earliest recorded earthquakes was that one which occurred in the month of October in the year 2011. Hundreds of people from Nepal, India and Tibet lost their lives and a lot of houses and properties were destroyed.

Earthquake waves (seismic waves) can be classified into body wave and surface wave. The wave inside the earth is called body wave and that at the surface of the earth is called surface wave. Body wave is made up of both primary or push wave and secondary wave.

TYPES OF EARTHQUAKE

On the basis of the nature of shaking earthquakes are classified into vertical and horizontal. In vertical earthquake, the vibration is up and down and in horizontal earthquake, the vibration is lateral. Horizontal earthquake is more devastating than the vertical earthquake because collapsing of buildings occurs more in it.

Measurement of earthquake:

Seismograph is a computerized instrument which is used for recording seismic movement on seismogram. Seismogram is a graph paper in which seismic movements are recorded. By the study of this seismogram, seismologists calculate the time, magnitude origin, intensity, frequency ,etc. of earthquakes. Magnitude of earthquake is measured in the unit termed Richter scale.

Causes of earthquake

1. Tectonic activities

2. Volcanic activities

3. Local activities

Effects of earthquake

1. Earthquakes may form cracks on the earth’s surface and weaken the rocks for landslide.

2. It destroys life and property.

3. It destroys development structures like roads,, communication networks, etc.

4. Sometimes it also becomes a cause of fire.

5. It may change the physical structure of land.

6. Due to earthquake, when landslide occurs in rivers it causes flood.

7. During earthquake, water sources will be contaminated and causes diseases.

Safety measures of earthquakes:

1. Earthquake resistant buildings should be built.

2. During the time of earthquake, we should move to open spaces.

3. If we are inside house during earthquake, we should protect ourselves by hiding under table, chair, etc.

Landslides

noreply@blogger.com (Chayan Das) — Sun, 1 Jan 2012 04:50:00 -0800

Landslides

Landslide is a natural process in which rocks debris or parts of land move downwards under force of gravity. In other words the sliding down of a piece of land under force aces of gravitational pull on a mountain or hillside is called landslide .It occurs mostly in hills and mountains usually in rainy season. It is also caused by earthquake, and human activities like explosion of dynamite, cultivation on slopes, deforestation etc.

Causes of landslide

The major causes of landslide are the followings;

When water flows forcibly on the steep surfaces of hills, and mountains, form streams.

They weaken the hills, and it becomes a major cause of landslide in the region.

1. Deforestation is another cause of landslide. The roots of plant grip the soil and the trees works as breakers for running water to slow down their speed. Due to deforestation the hill become naked and rocks are eroded from the hills which is followed by landslide.

2. The Himalaya is a young mountain series which has weak rock formation.

3. Sometimes earthquake and volcanic eruption also cause landslide.

4. When water flows in high speed In hilly rivers and streams, It carries away the loose soil from the sides.

5. Intensive grazing also minimizes vegetation on slopes and it leads to landslide.

6. Sometimes landslides occur in mines.

7. Weathering is a process in which rocks are weakened due to change in temperature and the effects of chemical on rocks.

8. Landslide is caused by flood and destruction of dams.

Effects of landslides:

Landslide affects the human beings and other organisms directly as well as indirectly. Life and property are both destroyed by it. Some major effects of landslides are mentioned below:

1 It sweeps the agricultural land and sometimes becomes for the death of people and domestic animals.

2. When landslides blocks the flow of water in rivers or streams, it may cause flood.

3. It destroys development structures like roads, communication network, bridges ,etc.

4. It pollutes sources of water.

5. It reduces forest and leads to deforestation and reduction of wildlife.

6. It deposits sediment on agricultural land as a result the land becomes infertile.

Flood

noreply@blogger.com (Chayan Das) — Sun, 1 Jan 2012 04:48:00 -0800

Flood

When the dry land is filled with water overflowing from rivers or lakes or oceans, it is called flood. In short, flood means the overflowing of water. During monsoon the rivers overflow due to the heavy rain and cover the agricultural fields and destroy crops. The flooded rivers only not destroy crops but also sweep away the land and property. Flood is caused by deforestation, heavy rainfall, out bursting of glacial lake and intensive grazing.

Causes of flood

1. Heavy rainfall is one of the major causes of flood. When it rains heavily for a longtime, the earth’s surface cannot absorb all the water and it flows downwards. A very large amount of water is stored in glacial lakes in the mountain region

2. Sometimes landslides occur in streams and rivers and it blocks the flow of water in them to cause flood.

3. Deforestation is also one of the major causes of flood. Forests help to absorb surface water in the soil. When forest decreases the absorbing capacity of soil also decreases and the excessive water flows as flood.

4. Countries having oceans face flood by cyclones(sea storm)

5. Tsunami is an extensive and often very destructive Ocean wave caused by an earthquake that exists under the surface of the sea.

Effects of flood

1. It decreases fertility of lands by depositing debris on fertile lands.

2. Flood destroys life and their habitats.

3. It damages individual and public property.

4. It damages development structures like bridges, roads, buildings.

5. It causes landslides and soil erosion.

6. It destroys natural vegetation and habitat of wildlife.

7. It causes epidemic diseases like dysentery, typhoid, diarrhea, etc.

Preventive measures of flood

1. Construction of dyke ( flood embankments) parallel to the rivers is preferred for the blockage of flood.

2. Watershed is that river, pond, lake, etc..in which the rainwater of particular region is collected.

3. Intensive grazing and deforestation must be controlled.

4. By the prediction of flood we can also save life and property and for this, flood measuring stations should be made at flood regions.

5. The glacial lakes should be drained out to minimize damages.

Mosquito and its life cycle

noreply@blogger.com (Chayan Das) — Sun, 1 Jan 2012 04:46:00 -0800

Mosquito and its lifecycle

Mosquitoes are found all over the world but they are mostly common in humid and temperate climate. They annoy at night. Their biting is painful and irritating. They act as vectors and transmit diseases like malaria, filarial, yellow fever, etc. The culex and the anopheles are the are the two main genera of mosquitoes found in Nepal .

Structure

The body of mosquito is very soft, small. and covered with scales. The body is divided intbeo three parts. They are:

1. Head: Head is very small and almost spherical which is joined with the thorax by means of a short and narrow neck. The head bears a pair of compound eyes, a pair of antenna and mouth parts.

2. Thorax: Thorax consists of three parts. They are prothorax, mesothorax and metathorax. Thorax bears three parts of jointed legs and a single pair of wings,

3. Abdomen: It is made up of nine segments. The abdomen posses an anal opening and a genital opening.

Lifecycle of mosquito

Lifecycle of mosquito completes in four phases:

1. Eggs: Mosquitoes copulate at evening during flight. After copulation, female mosquitoes lay their eggs in stagnant water of ponds and ditches. They lay 50-100 eggs at a time. Eggs are glued together to form a small floating raft.

2. Larva: Eggs are hatched into larvae within 2-3 days under suitable conditions. They emerge from lower end of each egg and are also known as wriggler because of their caterpillar like movements. The body of a larva is divided into head, thorax and abdomen.

3. Pupa; about a week(6-7 days), the larva moults for the last time and develops into pupa. Body of pupa is comma shaped. Body is divided into two parts. The anterior swollen part is called cephalothorax and the posterior elongated hook-like structure is abdomen. Within 2 to 7 days, it metamorphoses into a mosquito.

4. Adult mosquito: The pupa stage lasts for a short duration. After completion of metamorphosis, the pupa develops the body organs inside it and a imago is formed. Imago is a complete insect stage in which the completely young mosquito is formed. Imago emerges when the pupal skin splits.

When mating occurs between male and female, the female starts laying eggs. The complete lifecycle from eggs to adult in several days.

LANDSLIDES

noreply@blogger.com (Chayan Das) — Fri, 30 Dec 2011 23:37:00 -0800

Landslides

Causes of landslide

The major causes of landslide are the followings;

When water flows forcibly on the steep surfaces of hills, and mountains, form streams.

They weaken the hills, and it becomes a major cause of landslide in the region.

2. The Himalaya is a young mountain series which has weak rock formation.

3. Sometimes earthquake and volcanic eruption also cause landslide.

4. When water flows in high speed In hilly rivers and streams, It carries away the loose soil from the sides.

5. Intensive grazing also minimizes vegetation on slopes and it leads to landslide.

6. Sometimes landslides occur in mines.

7. Weathering is a process in which rocks are weakened due to change in temperature and the effects of chemical on rocks.

8. Landslide is caused by flood and destruction of dams.

Effects of landslides:

Landslide affects the human beings and other organisms directly as well as indirectly. Life and property are both destroyed by it. Some major effects of landslides are mentioned below:

1 It sweeps the agricultural land and sometimes becomes for the death of people and domestic animals.

2. When landslides blocks the flow of water in rivers or streams, it may cause flood.

3. It destroys development structures like roads, communication network, bridges ,etc.

4. It pollutes sources of water.

5. It reduces forest and leads to deforestation and reduction of wildlife.

6. It deposits sediment on agricultural land as a result the land becomes infertile.

ASCARIASIS

noreply@blogger.com (Chayan Das) — Thu, 8 Dec 2011 01:17:00 -0800

ASCARIASIS

Ascariasis is a disease caused by a common intestinal roundworm Ascaris lumbricoides. It is cosmopolitan, mostly prevalent in tropics and subtropics, such as in China, India and south East Asia including Nepal. It is most common in persons with unhygienic habits.

Causative organisms

Ascariasis is an intestinal communicable disease caused by an intestinal parasite known as Ascaris lumbricoides. The adult worm lives in the lumen of the small intestine (jejunum) of man.

Morphology

MALE:

It measures about 15-25 cm in length. The tail-end of the male is curved ventrally in the form of a hook having a conical tip. The genital pore opens into the cloaca from which two curved copulatory spicules protrude.

FEMALE:

It is longer than the male and measures 25-40 cm in length. The posterior extremity is neither curved nor pointed but it is conical and straight.

The egg-laying capacity of a mature female has been found to be enormous, liberating about 2000000 eggs daily.

Mode of infection

Mode of infection is feco-oral. Embryonated egg is the infective stage.Infection may occur by drinking contaminated water

The incubation period is variable from few weeks to months.

Pathogenicity:

(1) Indigestion, abdominal discomfort

(2) Appendicitis

(3) Gastric ulcers

(4) Loss of weight

(5) Acute colic pain

(6) Person becomes weak and anemic

(7) Vomiting and mild temperature

Treatment and control

(1) It is treated with anti-helminth drugs such as piperazine, mebendazole, albendazole

(2) Proper disposal of human faeces

(3) Treatment of parasitized individuals

(4) Avoid using raw materials and contaminated water.

TYPHOID

noreply@blogger.com (Chayan Das) — Thu, 8 Dec 2011 01:15:00 -0800

TYPHOID (ENTERIC FEVER)

Typhoid is transmitted through contaminated food and water. It is also spread by intestinal discharges. Any person carrying Salmonella typhi in his intestinal tract can also spread the disease to others even though the person himself may not be suffering from typhoid. These are healthy carriers. Flies also play role in transmitting bacteria.

Incubation period

The incubation period is two weeks on an average.

Symptoms of typhoid

(a) Persistent high fever that lasts for 2-3 weeks and then slowly declines onwards.

(b) Intestine shows lesions, hemorrhage and ulceration.

(d) Death may occur due to haemorrhage or puncturing of the intestine.

Control

Antibiotics effective in enteric fever are

(a) Chloromycetiin

(b) Cotriomoxazole

(d) Chloramphenicol

Preventive measures

(1) Proper sanitation

(2) Personal cleanliness

(3) Sanitary disposal of human excreta

(4) Protection and purification of water

(5) Protection of food from microorganisms, flies and dust.

(6) Immunization against typhoid(TAB) vaccine

DRUG ADDICTION

noreply@blogger.com (Chayan Das) — Wed, 7 Dec 2011 07:25:00 -0800

SOCIALLY SIGNIFICANT HUMAN DISEASES(DRUG ADDICTION):

Disease- The term disease refers to ‘derangement of health or any bodily disorder” or disease is a condition of the body or its parts in which the functions are disturbed or deranged.

Socially Significant Diseases- These are abnormal changes that cause distress and suffering both, the person concerned and to the other people around him. These diseases cause mental illness due to smoking, drug, alcohol, etc. known as mental diseases or disorders.

DRUG ABUSE AND ADDICTION:

Drug is defined as any substance that, taken into living organism, may modify one or more of its function. Drug abuse is defined as the administration of drug for non-medical reasons, in quantities, frequencies which may impair with individuals ability to function effectively, and which may result in social, physical or emotional harms

Drug include those substances that work on the nervous system and act either as stimulants(to excite it) or as depressants(which slow down the activity of brain). Some may act as sedative and some others as hallucination.

Drug belonging to the third category are often used by the persons regularly. Their body becomes accustomed to them and may even become dependent. The addicts then feel an intense urge for them, and are physically ill and distressed when deprived of them. This condition of feeling compelled to take certain drugs is known as drug addiction.

SOME OF THE COMMON TYPES OF DRUGS USED:

(1) Tranquilizers and depressants

(2) Narcotics

(3) Stimulants or antidepressants

(4) Psychedelic or vision producing drugs

(5) LSD

EFFECT OF DRUG ABUSE ON HEALTH:

(1) Depresses brain activity and produce feelings of calmness and relaxation.

(2) Affects nervous system, alertness and restlessness.

(3) Affects nervous impulse, musculature relaxation, BP, heart beat.

(4) Lack of sleep, appetite and hallucination.

(5) Reduce respiratory and cardiovascular activities , cause nausea and vomiting

(6) Cause chronic psychosis and severe damage to Central Nervous System leading to suicide.

(7) Eye pupils dilate, blood sugar level raises, urination increases, anxiety

CONTROL MEASURES OF DRUG ADDICTION:

(1) Treatment and hospitalization of sick or addict persons.

(2) Rehabilitation for the addict person.

(3) Psychological treatment

(4) Banning illegal activities like buying and selling of drugs.

SMOKING

noreply@blogger.com (Chayan Das) — Wed, 7 Dec 2011 07:22:00 -0800

SMOKING

The regular consumption of tobacco in form of either cigarette, or chewing causes dependency on tobacco is called smoking. The prolonged use of tobacco may lead to the dependence of the body on them, called tobacco addiction. The regular consumption of nicotine causes addiction.

Tobacco is one of the most abused substances in the world. It is made from the leaves of tobacco plant (Nicotiana tobaccum and N.rustica).

Types of smoking:

There are many ways of using tobacco. These are in form of cigarette, chewing tobacco, cigar-pipes, hubble-bubble(hookah), etc.

Tobacco contains highly poisonous alkaloid drug called nicotine. Its smoke contains approx. 4000 different chemicals many of which are poisonous such as cyanide, formaldehyde, CO.

EFFECT OF SMOKING AND CHEWING TOBACCO ON HUMAN HEALTH:

(1) It stimulates adrenal medulla to secrete adrenaline hormone.

(2) It increases constriction of blood vessels.

(3) It paralyses the neurons and nerve conduction.

(4) It decreases the breathing capacity.

(5) Tobacco is carcinogenic. Smoking can result in lung cancer, oral cancer.

(6) It causes inflammation of bronchial tubes, particularly those leading to alveoli resulting in bronchitis.

(7) It causes emphysema.

(8) It has chances of causing heart diseases because of the constriction of the blood vessels.

(9) In women, smoking particularly affect the ovulation and menstrual cycle. In a pregnant women, it causes birth defects.

(10) It causes Pulmonary tuberculosis.

(11) Co reduces oxygen binding capacity of haemoglobin.

CONTROL OF SMOKING

(1) Treatment and hospitalization of sick person.

(2) Rehabilitation.

(3) Psychological treatment.

(4) Banning illegal activities like production and selling of tobacco, charas, bhang, hashis, etc that increase anti-social activities.

(5) Strict implementation of law against such anti social elements.

Strict prohibition on advertisement on use of tobacco and its product through any media such as television, newspaper, etc

AIDS

noreply@blogger.com (Chayan Das) — Wed, 7 Dec 2011 07:20:00 -0800

AIDS

AIDS (Acquired Immune Deficiency Syndrome) is a communicable disease caused by a virus. It affects the human defensive system. It makes a person unable to defend against any type of infection.

T4 lymphocytes are the cells that are responsible for development of immune system in human. AIDS is a disorder which impairs the body’s T4 lymphocytes cell’s immune system. The body’s immune system breaks down leaving the patient exposed to a variety of diseases. Hence, AIDS is considered as very dangerous and fatal diseases.

ORIGIN OF AIDS:

AIDS is thought to have originated in central Africa, possibly sharing an ancestor with a virus found in several species of African monkey. The virus then appears to have migrated to Haiti and then to USA and has subsequently been identified from almost all countries throughout the world. There are millions of people in the world having AIDS.

CAUSITIVE AGENT:

AIDS was first recognized in USA in 1981. In 1983, a French physician Dr. Luc Montagnier identified the virus in the lymph nodes of a male homosexual. He termed the virus Lymphadenopathy virus or LAV.

Shortly afterwards, Dr. Robert Gallo isolated an almost identical virus which he called “Human T cell Lymphotropathy Virus” or HTLV-3. These viruses are essentially the same, and now-a-days it is internationally called “Human Immunodeficiency Virus” i.e HIV.

MODE OF TRANSMISSION:

(1) Intimate sexual contact.

(2) Transfusion of virus containing blood in the body.

(3) Use of contaminated materials like needles, syringes, blades, etc.

(4) By women suffering from AIDS giving birth.

(5) IIt is also caused in drug addicts who share their needles.

PREVENTION METHODS:

(1) Sex education

(2) Screening before blood transfusion.

(3) Rehabilitation of drug addicts.

(4) Use of condoms

(5) Early diagnosis and treatment of other sexually transmitted diseases.

(6) Raising social awareness among the people about iAIDS.

ALCOHOL ADDICTION

noreply@blogger.com (Chayan Das) — Wed, 7 Dec 2011 07:17:00 -0800

SOCIALLY SIGNIFICANT HUMAN DISEASE (ALCOHOL ADDICTION)

Alcohol or ethyl alcohol is commonly consumed . It is obtained through the fermentation of various food articles (e.g. potato, molasses, grams, fruit juices) by organisms like yeast (Saccharomyces) and some fungi (Rhizopus).

There are two types of alcoholic beverages in the market. People consume both of these kind in large quantities

(a) In one kind concentration of alcohol is very low, Eg.s are beer, wine, etc.

(b) The other one is the kind in which the concentration of alcohol is very high. Egs. Whiskey, brandy, rum, gin, vodka, etc.

ALCOHOL ADDICTION

The regular consumption of alcohol either in large concentration or in high that causes dependence of the body on it is called alcohol addiction.

Alcohol is rapidly absorbed by the wall of the stomach. It enters the blood stream within minutes of ingestion. Alcohol is not a stimulant, as people commonly believe, instead, it is a depressant. If taken in limited or modest amount alcohol reduces feeling of tension. The dependence on alcohl may be physical, physiological or social.

EFFECTS OF ALCOHOLIC DRINKS:

(1) Alcohol causes anesthetic effect (loss of sensation) on nervous system.

(2) Loss of emotional control

(3) Leads to neuritis due to inflammation of axons.

(4) High concentration of alcohol causes increased secretion of gastric juices which causes ultimately gastritis.

(5) Liver is mostly affected by high concentration of alcohol.

(6) Alcoholic fats are deposited on the walls of the blood vessels and thus increase the BP and affect the functions of heart.

(7) It affects the normal function of nephrons of kidney.

CONTROL OF ALCOHOLISM

(1) Treatment and hospitalization

(2) Rehabilitation

(3) Psychological treatment

(4) Strict implementation of laws against anti-social elements.

(5) Banning production and selling of alcohol.

GENETIC MATERIAL( DNA)

noreply@blogger.com (Chayan Das) — Mon, 5 Dec 2011 05:48:00 -0800

GENETIC MATERIALS(DNA)

Gene is a part of DNA that encodes for a particular character. Genes are located in the DNA which is situated in 23 pairs of chromosomes. In humans there are about 3 billion base pairs of DNA in their chromosomes.

Basically, a gene determines a character. For a character , a gene is responsible.

DNA AS THE HEREDITARY MATERIAL

The DNA is defined as the information tape which encodes the messages for all the vital activities and transmits it from one generation to the next.. This fact has been proved evidentially by the Bacterial transformation experiment.

DNA (deoxyribo-nucleic acid)

Location: DNA is found in nucleus, mitochondria and plastids.

Structure: Watson and Crick(1953) proposed a model of DNA molecule for which they were awarded the Nobel Prize..A DNA consists of following structures:

(1) DNA molecule consists of two antiparallel chains of polynucleotides fprming a double helical structure

(2) These strands are spirally coiled (helical structure).

(3) Among the two strands, One strand is in 3’ to 5’ direction and the other strand in 5’ to 3’ direction.

(4) The DNA strand has sugar-phosphate chain on the outside and purines and pyrimidine bases on the inner side of the helix.

(5) Both strands are joined by weak hydrogen bonds.

(6) The distance between two strands is 20 armstrong.

(7) There are 10 base pairs on a complete turn.

(8) A purine is attached to specific pyrimidine base.

(9) A DNA molecule contains 28% adenine, 24% guanine, 20% cytosine and 28% thymine.

(10)Nucleotides in a helix are joined together by phosphor-diester bonds.

SIGNIFICANCES OF DNA:

(1) It is the carrier of genetic information from one generation to another.

(2) It controls all biological activities of cell.

It synthesizes( DNA- RNA)., the process is called transcription

PLANT MOVEMENT

noreply@blogger.com (Chayan Das) — Fri, 2 Dec 2011 23:07:00 -0800

PLANT MOVEMENT

Simple unicellular motile green alga, chalymydomonas and its flagellated zoospores move from place to place but the movement of firmly rooted higher plants is of different nature. The movement is not of the entire plant body but only a curvature of some of its organs. The basis of all such movements is the irritability of the sensitive protoplasm in response to a variety of stimuli.

Plant movements can be grouped into two major parts:

1. Growth movements and

2. Turgor movements

Growth movements;

This type of movement is accompanied by growth and the curvature is rather permanent. These movements are associated with the unequal growth of the part of the plant. It can be grouped under two types;

A. Autonomic movements: the movements which occur without the effect of external stimuli. it is again divided into four groups:

1.Epinasty

2.Hyponasty

3.Nutation

4.circum nutation

B. Paratonic movements: Growth movements which are induced by external stimuli. It is also classified into two types:

1.Tropic movements or tropism

2.Nastic movements

Turgor movements :these are known as curvature movements. These are caused by turgor changes (swelling or shrinkage of living cells due to change in osmotic potential)

Difference between phototropism and photoperiodism

phototropism	photoperiodism
1.It is the growth response to light	1.It is the developmental response to the light
2.plants respond to direction of light	2.plants respond to the duration of light in the diurnal cycle.
3.it operates through the photo oxidation of auxins.	4.it operates through the interplay of photosynthesis.

But there is slight difference in between the terms growth and development. Growth is irreversible increase in size, volume and weight of an organism whereas development is a sequential series of changes taking place in the life of an organism.

Growth generally proceeds development whereas development generally takes place after growth.

OSMOREGULATION

noreply@blogger.com (Chayan Das) — Fri, 2 Dec 2011 22:25:00 -0800

OSMOREGULATION:

Osmoregulation is the process by which water content and ion concentrations are regulated in the cells. Kidney plays an important role in maintaining water and osmotic concentration in the body. This phenomenon is called osmoregulation.

In aquatic animals like fishes or the animals living in water, the urine excreted is more dilute than the plasma of the blood so as to remove excess of water. Thus animals excrete hypotonic urine.

In case of man, hypertonic urine is excreted which is more concentrated than their blood plasma.

ADH AND REGULATION OF WATER ABSORPTION

Body maintains the solute potential of the blood at an approximately steady state by balancing the water uptake from the diet with water lost in evaporation, sweating, egestion and urine. The precise control of solute potential is achieved by the effect of ADH.

Antidiuretic hormone(ADH) or vasopressin is the hormone released by posterior part of pituitary gland. The main function of ADH is to increase the permeability of distal convoluted tubule and collecting duct due to which reabsorption of water increases from tubules to the blood stream.

Kidney functions as a osmoregulatory organ due to following functions:

1. Regulation of fluid balance or maintenance of osmotic pressure.

2. Regulation of electrolytes concentration

3. Maintenance of acid base balance

4. Removal of other substances like mineral salts, iodides, drugs, arsenic and even bacteria

Liver also acts as a osmoregulatory organ. It is an extremely active organ. It functions as :

1. Carbohydrate metabolism

2. Fat metabolism

3. Protein metabolism

4. Detoxification of drugs

5. Production of heat

6. Secretion of bile

7. Storage of vitamins

8. Breakdown of erythrocytes and defense

Regulation of body temperature: This phenomenon maintains the body temperature in two ways:

1. Heat production

2. Loss of heat

When the amount of heat gained by the body becomes very low, body compensates the heat from various organs of body like muscles, liver, digestive organs . And when there is excessive heat in the body, it loses the amount of heat through skin, expired air, urine and faeces.

NERVOUS CO-ORDINATION

noreply@blogger.com (Chayan Das) — Fri, 2 Dec 2011 21:47:00 -0800

NERVOUS COCRDINATION

There are various organ systems functioning in the body. These functions are regulated, controlled and co-ordinated for proper functioning by a system called nervous system. Functional unit of nervous system is the neuron.

FUNCTIONS OF NERVOUS SYSTEM:

(1) The impulses or stimuli are carried from the tissues and organs to the nerve centres. After being interpreted and analysed, messages are carried from the nerve centres to the desired tissues and organs.

(2) It links various organs and systems and co-ordinates all their activities.

(3) It stimulates and inhibits the activities of various muscles, glands and visceral organs according to the kind of information received.

(4) It helps to maintain steady state of the body (homeostatic condition) by coordinating various activities.

Parts of nervous system;

A. Central nervous system*(CNS)

B. Peripheral nervous system(PNS)

C. Autonomic nervous system(ANS)

CNS includes brain and spinal cord.

PNS includes the nerves arising from brain and spinal cord such as cranial nerves and spinal nerves.

ANS consists sympathetic and parasympathetic nervous system. It includes nerves and ganglia. It controls and co-ordinates such organs which are under the involuntary control.

CNS consist of two parts:

A. Brain

B. Spinal cord

PNS constitutes two types of nerves:

A. Cranial nerves

B. Spinal nerves

ANS consists of two antagonistic systems:

A. Sympathetic nervous system

B. Parasympathetic nervous system

NERVE

NUTRITION

noreply@blogger.com (Chayan Das) — Fri, 2 Dec 2011 20:50:00 -0800

The sum total processes of taking in digestion, absorption and assimilation of food are known as nutrition. It is important because:

(1)It provides energy to the body to perform various activities.

(2)It provides essential materials for growth.

(3)It maintains the body temperature.

TYPES OF NUTRITION:

There are two main types of nutrition:

(a)Autotrophic or holophytic nutrition

(b)Heterotropic nutrition

(a) Autotropic or holophytic nutrition:It is the process by which the organisms can synthesize their food by the process of photosynthesis.

(b) Heterotropic nutrition: It is the process by which organisms cannot synthesize their food by themselves. There are three types of heterotropic nutrition:

(a) Holozoic nutrition

(b) Saprozoic nutrition

FOOD AND NUTRIENT: Food can be defined as any essential substance that when absorbed into the body tissues, yields materials for the production of energy, growth, repair of tissues and regulation of life processes.

COMPONENTS OF FOOD:

1.Carbohydrates 2.Proteins

3.Fat 4.vitamins

5.Minerals 6.water

BALANCED DIET:

Proper quality and quantity of food is most significant basis of health, proper growth, normal activity, vigour

and longevity. Human food should contain the various nutrients in such proportions as can satisfy all the various nutrients in such proportions as can satisfy all the various needs of body. Such a food is called balanced diet.

food		Recommended amounts in gm/day
	Adult man		Adult woman
cereals	520		440
Meat/fish	30		30
Sugar/molasses	35		20
Roots and tubers	60		50
vegetables	70		40

VARIATIONS

noreply@blogger.com (Chayan Das) — Wed, 30 Nov 2011 20:29:00 -0800

VARIATIONS

In nature, it is difficult to find out two individuals similar. Even the progeny of the same parents differs not only in itself but also with the parents. These differences are called variations. Variations may be useful, useless and harmful. Harmful or useless variations make individuals unfit for struggle for existence, where as the useful variations are quite significant and make organisms fit in the nature. Such variations are transmitted(inherited) to the next generation so that the progenies are more suited.

Significances of variations:

Variations form Types of variation:

A. variation types of based on the types of cells:

(1) somatic or acquired variations

(2) germinal variations`

(1)Somatic variations: The variation that effects only the somatic cells are called somatic variations. The causes of such variations are not inherited from parents to offsprings. Such variations are also called acquired variations. The possible causes of such variations are:

A. Environmental factors

B. Use and disuse of organs

C. Conscious efforts

(2)Germinal variations: The variations that affect the germinal or reproductive cells only are called germinal variations. These are inherited from parents to offsprings. The possible cases of such variations are mainly due to:

(1) Recombination

(2) Mutations

B. Based on the degree of differences produced:

(1) Continuous variation

(1) (2)discontinuous variation the basis of heredity

(2) They constitute the raw material for evolution

(3) It help in adaptation of organisms to the change in environment

(4) Useful variants of plants and animals can be created

(5) It makes individuals better suited for their survival in nature

Antibiotics and vaccines

noreply@blogger.com (Chayan Das) — Tue, 29 Nov 2011 04:05:00 -0800

Antibiotics:
Antibiotics are the chemical substances produced synthetically by microorganisms. They can inhibit the growth of bacteria and other microorganisms and even destroy them. The first antibiotic is penicillin which was discovered by a british bacteriologist, Alexander Flemming in 1928. It was in fact a coincidence. Fleming was working on Staphylococcus and it happened that some spores of a mould floated into his laboratory. He threw these spores out of the window and luckily one of his Staphylococcus colonies. he observed that the bacteria were quickly destroyed. Later this mould was identified as Penicillium notatum. Due to this reason, the active substance which killed the bacteria was known as Penicilliun.

Most commonly used antibiotics:
1. PENICILLIN
2. STREPTOMYCIN
3. TETRACYCLINE
Depending upon their effect, antibiotics are divided into two categories:
1. Broad spectrum of antibiotics
2.specific antibiotics

Vaccines:
vaccines are the preparation of killed or living microorganisms which produce immunity when administered into the body. Immunity is defined as the ability of body to resist with diseases.When a pathogen enters into a human body, it releases a toxic chemical to destroy the human defense system called antigen. Human body also defends themselves against and defends and destroys that antigen by releasing antibody.
Types of immunity
1.Natural or in born immunity
2.Acquired immunity

Introduction to biotechnology

noreply@blogger.com (Chayan Das) — Tue, 29 Nov 2011 03:37:00 -0800

Biotechnology is the application of scientific and engineering principles to the processing of materials using biological agents to provide goods and services. it is more broadly defined as "any technique that uses living organisms to make or modify products to improve plants and animals or to develop microorganisms for specific uses."
Branches of biotechnology:
l.Plant tissue culture: it is the technique of growing plant cells,tissues or organs in an artificially prepared nutrient medium under aseptic condition.In this technique, a growing tissue is excised from plant and kept in a callus inducing artificial medium to produce calli. These calli can regenerate green plants after putting them into a regeneration medium

TISSUE-CALLUS-PLANT REGENERATION

2. Protoplast culture: protoplast is a cell without cell wall. It can be obtained,cultured and fused. A complete plant can be obtained from a single protoplast culture.
3.Gene transfer: Gene is a part of a DNA segment with a particular character. In this technique a foreign gene can be inserted into other plants by the direct gene transfer and agrobacterium mediated DNA transfer technology

Introduction

noreply@blogger.com (Chayan Das) — Mon, 28 Nov 2011 23:14:00 -0800

A biological adaptation is any structural (morphological or anatomical), physiological, or behavioral characteristics of an organism or group of organisms (such as species) that make it better suited in its environment and consequently improves its chances of survival and reproductive success. Due to individual phenotypic plasticity (variability), individuals will be more or less successful. Some adaptations may improve reproductive success of the population, but not a particular individual, such as seen in altruistic behavior in social insects.

Organisms that are adapted to their environment are able to :

    * secure food, water, and nutrients
    * obtain air, warmth, and spaces
    * cope with physical conditions such as temperature, light, and heat
    * defend themselves from their natural enemies
    * reproduce and rear offspring
    * respond to changes around them

Adaptation occurs in response to changes in the environment, life style, or relationship to other organisms. Environmental dynamicity, voluntary or compelled shifting of habitat, and human activities may put organisms in a new niche or in environmental stresses or pressures. In such circumstances, the organisms require characteristics suitable to the new situation. Organisms that are not suitably adapted to their environment will either have to move out of the habitat or die out. The term die out in the context of adaptation means that the death rate over the entire population of the species exceeds the birth rate for a long enough period for the species to disappear.

While adaptations provide for the individual purpose of the organism—survival, reproduction, development, maintenance—these same characteristics provide diversity and add to human fascination with, and enjoyment of, nature. Furthermore, while adaptations often are seen as a static set of suitable characteristics, in reality the process of developing adaptations is a dynamic process. Whether envisioned as the product of design or natural selection, or natural selection on the microevolutionary level and design for macroevolutionary changes, the reality is that new adaptations are needed when organisms encounter new environments, and such have arisen for millions of years.

In some extreme conditions, it is possible for the previous adaptation to be poorly selected, the advantage it confers over generations decreasing, up to and including the adaptation becoming a hindrance to the species' long–term survival. This is known as maladaptation.