A-Level Science

January 2012 6BI05 Article Help

2012-01-01T17:39:00.000-04:00

I've been very busy with school, but I have made some important modifications to this blog. An update will be posted later. For now, I think that it is important to offer help with the January 2012 6BI05 scientific article.

Watch this space for an update that will include possible questions.

AS Biology - Carbohydrates!

2011-01-07T19:09:00.008-04:00

3 Distinguish between monosaccharides, disaccharides and polysaccharides (glycogen and starch — amylose and amylopectin) and relate their structures to their roles in providing and storing energy (β-glucose and cellulose are not required in this topic).

This website is your saviour for AS Biology biological molecules (carbohydrates, proteins, lipids and nucleic acids): http://www.mrothery.co.uk/biochm/biochmnotes.htm#CARBOHYDRATES

-Monosaccharides are the building blocks (monomers) are disaccharides and polysaccharides. These 'saccharides' are all carbohydrates.

-Two monosaccharides react = a disaccharide. The bond formed is called a glycosidic bond. It looks like this: [monosaccharide]---O---[monosaccharide]. Type of reaction: condensation reaction (water molecule given off!). One hydrogen from -OH group and one whole -OH group combine to give water. Therefore, the reverse of this reaction involves adding water to split the glycosidic bond (hydrolysis).

-Monosaccharides: glucose, fructose, galactose.

-Disaccharides: maltose (formed from 2 alpha glucose molecules), sucrose (formed from alpha glucose and fructose), lactose (formed from alpha glucose and galactose)

-KNOW THE STRUCTURE OF GLUCOSE (RING STRUCTURE FROM THAT WEBSITE). BE SURE TO BE ABLE TO DRAW HOW DISACCHARIDE FORMS FROM TWO MONOSACCHARIDES AND HOW THE WATER IS FORMED.

-KNOW WHAT ALPHA GLUCOSE IS (MIGHT AS WELL KNOW BETA AS WELL). The -OH on carbon one is BELOW the ring plane in alpha glucose. In beta glucose, the -OH on carbon one is ABOVE the ring plane. Please know this distinction. It is very important. Google it! Look at pictures to see the glucose rings and see how the -OH is arranged in the beta and alpha forms.

-Polysaccharides: poly=many; made up of many glucose (or other monosaccharides) bonded by glycosidic bonds. The polysaccharides you have to know are made up of only glucose: glycogen and starch.

-Glycogen: form of energy storage in ANIMAL CELLS. Made up of alpha glucose only! Glycosidic bonds are: 1-4 glycosidic bonds and 1-6 glycosidic bonds. 1-4 bonds are straight, 1-6 bonds are bent. So, the 1-6 bonds give glycogen a branched structure. Structure to function: the main function of glycogen is to act as an energy store in animal cells. Glucose is polymerised into glycogen (glycogenesis) and this glycogen is compacted into glycogen granules (this is great because it enables animals cells to store more glucose in a smaller space). Because glycogen is highly branched due to 1-6 links, it is easily hydrolysed into glucose (glycogenolysis). However, unlike glucose, glycogen is insoluble (this is good because it will not diffuse out of cells and it will have no osmotic effect on the cells).

-Starch: form of energy storage in PLANT CELLS. Starch is made up of alpha glucose only! Starch, like glycogen, contains both 1-4 and 1-6 links (know how these links are formed and how they look! Do your research, it's quick and easy!!!). HOWEVER, starch is made up of two forms of polysaccharides: amylopectin and amlyose. Amylose is a straight chain polymer and can form spirals; it is made up of ONLY 1-4 links hence it is straight chained. Amylopectin, on the other hand, is branched; it is made up of BOTH 1-4 AND 1-6 links (like glycogen). Because starch contains the highly branched amlyopectin, it can be easily hydrolysed into glucose. Additionally, the glucose can be formed into starch and compacted into starch grains/granules resulting in more glucose/energy being stored in smaller cell space. Starch, like glycogen, is insoluble meaning it will not have an osmotic effect in plant cells nor will it diffuse out of cells!

-Structure and function of monosaccharides and disaccharides: they're all a direct source of energy. Disaccharides can be quickly broken down into their respective monosaccharides. They're soluble and can exist in solution in living things. Glucose exists in blood and because it is soluble it can easily be transported around the body (it is small and can be trafficked into and out of cells). Sucrose in solution is used to transport glucose around plants.

-Remember: glucose = energy

4 Describe how monosaccharides join to form disaccharides (sucrose, lactose and maltose) and polysaccharides (glycogen and amylose) through condensation reactions forming glycosidic bonds, and how these can be split through hydrolysis reactions.

Check the website I sent above. Be able to draw how disaccharides are formed, how water is given off, know the formation of 1-4 and 1-6 links and how straight and branched chains come about. Know what a glycosidic bond is and know condesation/hydrolysis.

Next post will deal with lipids!

6BI05 Article Help!

2010-12-25T03:08:00.010-04:00

I've been very busy lately and my ability to update regularly has been hindered. I will still try to post content for AS Biology and AS Chemistry by the May/June examinations but I am not making any promises.

I have decided to offer some help on the 6BI05 article because it can get difficult to study for the unit content AND work with the article. Here are some possible questions to get your brain ticking :)

Answers (and more questions) will be posted soon! Click HERE to download the PDF file.

UPDATE: Answers to first set of questions can be downloaded after clicking HERE.

6BI01 Introduction and Water!

2010-11-01T02:03:00.004-04:00

The 6BI01 unit, like all other main units, it worth 120 UMS points. The raw score, like all other main units, is 80 marks. Units 3(B) and 6(B) are worth 60 UMS. Unit 3B's raw score is 40 and 6B's is 50.

In AS, 6BI01 is worth 40% of the total grade earned! In the full A Level, this unit is worth 20%. So, it it clear that this unit is heavily weighted in the AS year so you should try you best to perform well. This is a fairly simple and straightforward unit. If you learn the concepts and familiarise yourself with previous questions and how they are answered you should earn yourself a nice, solid A. I scored 101/120 in this unit, but I had the potential to score 120/120. I underestimated the time factor and omitted lots of raw marks because time ran out. I knew the answers to to the questions I left out! I sat this unit in June 2009 and the time for this paper was 1 hour 15 minutes. The examiners realised that we were pressed for time so they increase the time for this paper to 1 hour 30 minutes. The raw marks remain unchanged.

This unit is called Lifestyle, Transport, Genes and Health. You will study important biological molecules, enzymes, cell membranes, transport, the cardiovascular system, protein synthesis and genetics. You will be asked to objective, short answer and extended response questions. You will have to pay attention to the quality of your written response in some questions. You can be asked to interpret and analyse graphs, draw and label diagrams and fill-in-the-blanks in paragraphs or tables. There's a systematic approach to answering these types of questions and I will cover them as I post content for this unit. Practical-based questions ALWAYS show up and so this is where your core practicals will be important. You may be asked to write out the entire method for a core practical or a practical similar to one you are required to know.

The list of core practicals that you will need to know for this unit:

1.Describe how the effect of caffeine on heart rate in Daphnia can be investigated practically, and discuss whether there are ethical issues in the use of invertebrates.

2.Describe how to investigate the vitamin C content of food and drink.

3.Describe how membrane structure can be investigated practically, eg by the effect of alcohol concentration or temperature on membrane permeability.

4.Describe how enzyme concentrations can affect the rates of reactions and how this can be investigated practically by measuring the initial rate of reaction.

You may want to take a look at this online resource for the core practicals. Keep in mind that I will be posting specific content for the core practicals on this website anyway.

6BI01 kicks off with water!

The importance of water as a solvent in transport, including its dipole nature.

Because it is charged, water is a very good solvent. Charged or polar molecules such as salts, sugars and amino acids dissolve readily in water and so are called hydrophilic ("water loving"). Uncharged or non-polar molecules such as lipids do not dissolve so well in water and are called hydrophobic ("water hating"). Because of water's dipole nature (and so, it's ability to dissolve a wide variety of substances), it is a very important biological solvent. Salts, sugars and amino acids can be dissolved in water and transported in blood around the body. Most of the body's cellular reactions take place in aqueous environments and a solvent (water) is needed to dissolve the reactants so that they can react. Because water molecules can hydrogen bond, they are very cohesive (water can flow). This cohesiveness makes water a good transport solvent.

To get a better understanding of how water's structure contributes to its function, you should do a bit more research on the internet and in your textbook and/or revision guide. Be sure to revise what hydrogen bonds are (with respect to water) and how they form. Here are a few websites which I used:

>http://www.s-cool.co.uk/alevel/biology/biological-molecules-and-enzymes/water.html

>http://www.worldofmolecules.com/solvents/water.htm Just read the part about water's dipole nature and it's ability to act as a sovlent

>http://www.mrothery.co.uk/biochm/biochmnotes.htm#WATER

BEWARE: You are NOT required to know about any other functions of water other than it's solvent abilities. You can learn other uses of water if you want, but you will not be tested on anything else other than water's importance as a solvent in transport.

>Here are a few questions that you should be able to answer:

+Water is the universal ________ in living organisms. [solvent]

+Why is water an important solvent in living organisms? [Because most biochemical reactions take place in aqueous solution]

+What is the chemical formula of water? [H20] *You should be able to draw the basic chemical structure of water and identify the partial charge on the atoms found in water.

+Why are water molecules described as polar? [Because they have a slight positive charge at one end of the molecule and a slight negative charge at the other end]

+Why can water molecules form hydrogen bonds with each other? [same answer as above]

Pretty simple beginning!

List of Recommended Books

2010-11-01T01:48:00.007-04:00

I will update this space with a list of recommended books and small book reviews of these books.

How Science Works

2010-07-21T15:39:00.012-04:00

The specifications for the new Edexcel science subjects state that How Science Works (HSW) is a newly introduced section of the GCE Science criteria, that builds on from the Key Stage 4 Programme of Study for science. The concept of HSW isn't quite new however, it's just that HSW now plays a major role in testing students' scientific knowledge.

I have found quite a nifty definition of what HSW means from this article. Here is the meaning:

So what does "how science works" actually mean? In addition to teaching the "facts" of science, teachers are now required to teach students things like "there are some questions that science cannot currently answer, and some that science cannot address", and that scientific and technological developments have their "benefits, drawbacks and risks".

I'd also like to add that many people seem to think that science is all about facts and figures. It is not. You don't wake up one day and suddenly hear about a major scientific breakthrough. You would have probably heard about scientific research, experiments and debates which led up to the breakthrough. So, science is a method and not a bundle of facts. As such, you will be doing more than just absorbing ideas about electrons and deoxyribonucleic acid (or DNA).

I suggest that you read the article I linked to above. The article (and subsequent user feedback) is quite thought-provoking.

HSW will be assessed in context of the various units you study during the course of your AS and A2 years. The learning outcomes of HSW are:

1. Use theories, models and ideas to develop and modify scientific explanations.

2. Use knowledge and understanding to pose scientific questions, define scientific problems, present scientific arguments and scientific ideas.

The two points above have to do with applying scientific knowledge/facts to explain various observations and investigating the science behind unfamiliar situations. We know that temperature usually increases the rate of a reaction, but why? How can we explain this observation?

3. Use appropriate methodology, including ICT, to answer scientific questions and solve scientific problems.

4. Carry out experimental and investigative activities, including appropriate risk management, in a range of contexts.

5. Analyse and interpret data to provide evidence, recognising correlations and causal relationships.

6. Evaluate methodology, evidence and data, and resolve conflicting evidence.

The four points above have to do with practical related work. We have to use appropriate and reliable apparatus to measure and record data in experiments. How do we determine which instruments are best suited to measure the rate of a chemical reaction in the human body? How do we ensure that the procedures used are very safe and reliable. What does the data tell us? Did we manage to control all other variables? Are our conclusions based on conflicting evidence?

7. Appreciate the tentative nature of scientific knowledge.

We didn't always know about the structure of the atom. Early scientists thought that the atom had a structure similar to a plum pudding. Today, we can speak of electron orbitals and subshells. We thought that our parents' fluids were drawn from various parts of the body to the semen and passed on to the offspring. Today, we now under how genes work (so much so that we are working on making banana vaccines). Science is constantly evolving. Theories have been disproved and new ones have been formulated. You must be able appreciate this tentative side of science.

8. Communicate information and ideas in appropriate ways using appropriate terminology.

This point isn't exactly 'new'. When you answer examination questions on particular topics, there will be terms that you will always have to use. When you talk about genetics you will find that you will frequently have to use terms like 'genes', 'monozygote', 'mutations' and 'chromosomes'. To communicate effectively, you will have to make sure you use appropriate words and ideas.

9. Consider applications and implications of science and appreciate their associated benefits and risks.

10. Consider ethical issues in the treatment of humans, other organisms and the environment.

We're not just doing science to write exams and show off our knowledge in front our lawyer and entrepreneur friends. The knowledge and understanding we gain from science is applied to everyday situations. That's why we can benefit from medicine and technology. However, everything has drawbacks. We must be stewards and citizens of the environment. We have to avoid polluting our environment and at the same time, realise that the world does not belong to humans alone. Working in ways that are not harmful to other species on Earth is a necessity. When we use animals in experiments we have to consider all the implications involved. It is clear that with all this scientific knowledge there comes great responsibility.

11. Appreciate the role of the scientific community in validating new knowledge and ensuring integrity.

12. Appreciate the ways in which society uses science to inform decision making.

We can't just do an experiment, make a conclusion and call it a day. Scientists have to present their work to other peers for review. The findings are also published in scientific journals and presented at scientific conferences. Specific steps must be taken to validate any conclusions or evidence obtained from experiments. The results we obtain from scientific investigations are used to make decisions which influence our everyday lives. However, we have to be careful with who is making the decisions. Scientific research may be in the best interest of humanity but the decisions made by the people in power are quite skewed. Scientists working for large oil companies may claim that global warming is not man-made. To satisfy non-scientist citizens, politicians may politicise the global warming debate whilst sidelining scientific methodology.

As you progress through the Biology and Chemistry specifications you will find many opportunities to develop the aforementioned skills. You don't have to exclusively study the HSW objectives, you have to integrate them in various topics of your syllabus.

This HSW message marks the end of my introductory posts. I plan to provide a bit of help with Physics and Mathematics but most of what I post from now on will be content relating the Edexcel Biology and Chemistry specifications. Note that I do not intend to post any coursework or essays on this blog. My only intention is to offer guidance with the specification. You are responsible for studies and examination performance.

Thank you and welcome aboard!

Written Alternative Papers

2010-07-12T17:23:00.020-04:00

As mentioned quite a few times before, two out of the six units you take in A Level sciences will involve practical work. Practical knowledge will be assessed in all six units. So, you can be asked about experiments and procedures in your Unit 1, 2, 4 and 5 tests. Unit 3 and 6 are specifically focused on practical skills and knowledge. International students will not be able to take the actual practical assessments and so the alternative is the practical written paper which replaces practical units (Unit 3 and 6).

The written alternative to internal practical assessment have the unit codes:
Unit 3B: 6BI07 + 6CH07
Unit 6B: 6BI08 + 6CH08

The unit titles are listed below. Click each title pair to download the respective specification.

Biology Unit 3B: Practical Biology and Research Skills
Biology Unit 6B: Practical Biology and Investigative Skills
>Specification here.

Chemistry Unit 3B: Chemistry Laboratory Skills I Alternative
Chemistry Unit 6B: Chemistry Laboratory Skills II Alternative

>Specification here.

Biology Unit 3B: Practical Biology and Research Skills

Students are expected to develop experimental skills, and a knowledge and understanding of experimental techniques, by carrying out a range of practical experiments and investigations covered in Units 1 and 2.

The paper will contain two questions. Question One will definitely test you on the core practicals listed in the AS Biology Unit 1 + 2 specification. Question Two will test your reporting skills. In the original coursework unit for Unit 3, you would have had to complete a report so this is why you are being tested as such. Check page 80 of the original specification for more information on the report.

Biology Unit 6B: Practical Biology and Investigative Skills

Students are expected to develop a wide knowledge and understanding of experimental procedures and techniques throughout the whole of their Advanced Level course. They are expected to become aware of how these techniques might be used to investigate interesting biological questions. This unit will assess students’ knowledge and understanding of experimental procedures and techniques and their ability to plan whole investigations, analyse data and to evaluate their results and experimental methodology.

This paper is a step up from the AS paper. You will have to answer three questions. Question One tests knowledge and understanding of the experimental principles and applications of the practical work they have undertaken in Units 1, 2, 4 and 5. Yes, ALL units need to be studied for this paper. Core practicals from any given unit may turn up. The specification did not explicitly state that only core practicals will show up in question one. You may be provided with the procedure of an unfamiliar experiment which relates to a topic in your specification.

Question Two tests your data handling skills. This question will test students’ ability to tabulate and manipulate raw data and to recognise anomalous results and explain how they may be dealt with appropriately. They will be expected to be able to suggest suitable statistical tests and interpret their results.

Question Three will test students’ ability to plan a safe scientific investigation, suggest ways in which the data collected might be analysed and evaluate the limitations of their planned methodology. Note: the nature of the investigation will most likely not reflect any familiar examples of practical experiments mentioned in the specification. As such, you will have to carefully think about how you approach this question.

Here's a list of the core practicals (taken directly from the specification):

>Unit 1

1. Describe how the effect of caffeine on heart rate in Daphnia can be investigated practically, and discuss whether there are ethical issues in the use of invertebrates.

2. Describe how to investigate the vitamin C content of food and drink.

3. Describe how membrane structure can be investigated practically, eg by the effect of alcohol concentration or temperature on membrane permeability.

4. Describe how enzyme concentrations can affect the rates of reactions and how this can be investigated practically by measuring the initial rate of reaction.

>Unit 2

5. Describe the stages of mitosis and how to prepare and stain a root tip squash in order to observe them practically.

6. Describe how totipotency can be demonstrated practically using plant tissue culture techniques.

7. Describe how to determine the tensile strength of plant fibres practically.

8. Describe how to investigate plant mineral deficiencies practically.

9. Describe how to investigate the antimicrobial properties of plants.

>Unit 4

10. Describe how to carry out a study on the ecology of a habitat to produce valid and reliable data (including the use of quadrats and transects to assess abundance and distribution of organisms and the measurement of abiotic factors, eg solar energy input, climate, topography, oxygen availability and edaphic factors).

11. Describe how to investigate the effects of temperature on the development of organisms (eg seedling growth rate, brine shrimp hatch rates).

12. Describe how DNA can be amplified using the polymerase chain reaction (PCR).

13. Describe how gel electrophoresis can be used to separate DNA fragments of different length.

14. Describe how to investigate the effect of different antibiotics on bacteria.

>Unit 5

15. Describe how to investigate rate of respiration practically.

16. Describe how to investigate the effects of exercise on tidal volume and breathing rate using data from spirometer traces.

17. Describe how to investigate habituation to a stimulus.

Chemistry Unit 3B: Chemistry Laboratory Skills I Alternative

This unit contains a practical written examination that covers the content of Units 1 and 2. There is no specific content for this unit.

Students are expected to develop experimental skills, and a knowledge and understanding of the necessary techniques, by carrying out a range of practicals while they study Units 1 and 2.

The practical written examination covers the areas of physical, organic and inorganic chemistry and the following types of practicals:

-qualitative observations

-quantitative measurements

-preparations.

Chemistry Unit 6B: Chemistry Laboratory Skills II Alternative
This unit contains a practical written examination that covers the content of Units 4 and 5. There is no specific content for this unit.

Students are expected to develop experimental skills, and a knowledge and understanding of the necessary techniques, by carrying out a range of practicals while they study Units 4 and 5.

The practical written examination covers the areas of physical, organic and inorganic chemistry and the following types of practicals:

-qualitative observations

-quantitative measurements

-preparations.

*Both of these exams test qualitative (descriptions, things you can see and place into categories but not measure using numbers) observations, quantitative measurements (numbers and calculations involved!) and preparations. Be sure to look at the document I mention below. You will have a clear idea of the practical work that you must be aware of for your Chemistry exams.

* Qualitative observations include things such as flame colour tests, colours of familiar compounds/elements, overall physical properties of compounds (both organic and inorganic), things you see from reactions (both organic and inorganic), smells etc.

*Quantitative measurements include things such as calculating moles/masses/volumes using titration information, finding the empirical formula of an organic compound, finding enthalpy changes and rates of reactions etc.

*Preparations include performing experiments to obtain a desired product which may be both organic and inorganic. You will need to know why certain things are done in various steps of the preparations.

Click here to download the document which maps out all the practical related work in the Chemistry specification. This will be very very helpful when you are studying for all your unit tests.

If you have any questions or doubts and you need advice you are always welcome to contact me :)

Grades!

2010-07-05T22:04:00.010-04:00

Right-o! This post will address marks/grades and UMS.

Marks/Grades

Your AS grades count for 50% of your total A Level grade. The same holds true for your A2 grades. For the science subjects (and maybe most other subjects), you will be graded out of 600 UMS marks. UMS marks are the marks you obtain AFTER your paper has been marked. Your raw score is converted to a corresponding UMS score. Your grade depends on what UMS score you get.

You will always need the follow percentage UMS scores to get the matching grade:

80% - A

70% - B

60% - C

50% - D

40% - E

Your AS course is graded out of 300 marks and your A2 course is graded out of 300 marks (hence total of 600). You receive an AS grade based on what you get out of 300. Your 'A2' grade is really your grade out of 600 and not just the second 300.

Going by the above fixed percentages, you will always need the following marks (out of 300 and 600) to get the matching grade:

80% - A ==> 240/300 , 480/600

70% - B ==> 210/300 , 420/600

60% - C ==> 180/300 , 360/600

50% - D ==> 150/300 , 300/600

40% - E ==> 120/300 , 240/600

You get a U grade when your UMS marks ranges from 0% to 39%. A grade of A, B, C, D or E indicates a 'pass'.

I want to focus on getting As and Bs (and maybe Cs) only :)

So much for overall grades. You also get individual grades for each unit you sit. You will sit a total of six units for Biology and Chemistry. The 'main' units are each worth 120 marks. These units are: 1, 2, 3 and 4. So we have a total of 480 marks. Your practical units are each worth 60 marks (units 3B and 6B). This takes the total up to, yep you guessed it, 600 marks. The same percentage 'rule' applies to your unit grades. Hence you need the follow marks out of 120 or 60 to get the matching grades:

80% - A ==> 96/120 , 48/60

70% - B ==> 84/120 , 42/60

60% - C ==> 72/120 , 36/60

50% - D ==> 60/120 , 30/60

40% - E ==> 48/120 , 24/60

UMS

You should have noticed that I mentioned raw marks and UMS marks. Edexcel A Levels (and I guess this applies to other boards as well) are curved. This means that you DO NOT need a particular raw mark in a paper to get a certain grade.

Let's say that Biology Unit 1 is worth 80 raw marks (and it really is!). 80% of 80 is 64. You would think that you need 64/80 in a Biology Unit 1 paper to get an A grade (since As are 80%). WRONG. Your raw mark DOES NOT directly determine your final grade. Your UMS mark does.

You raw marks are scaled (up or down, mostly up) according to how the population of candidates performed on a given test (that is, whether it was an easy, average or hard paper). If the paper was generally hard, then you will need less raw marks to get an A grade. If the paper was generally easy, then you will need more raw marks to get an A grade.

I'll use an example of Biology Unit 2. This unit was first tested in January 2009. In the January 2009 sitting, the paper was considered to be fairly difficult. As a result you needed only 52/80 (65%) for an A grade. This means that a raw mark of 65% was scaled up to a UMS mark of 80%. In June 2009, however, the Biology Unit 2 paper came relatively easy. What happened as a result? You needed 61/80 (76%) for an A grade. I hope you understand this concept better now :)

The ramifications of the UMS 'factor' means that you actually don't need full raw marks to get 100% in a paper. In the June 2009 sitting of Biology Unit 2, you needed 71/80 raw to obtain 120/120 UMS! Any mark above 71 would still be 120/120. So 71/80 is the cap for maximum UMS.

UMS calculations aren't too complicated either. There's a pretty useful post on TSR which explains the process of UMS calculation.

The shiny A* Grade!

The implementation of the new specifications for A Level subjects also saw the addition of a new grade, the A* grade. You may have noticed that I did not mention this grade above. To obtain this grade, you need to fulfill some things:

-You need to obtain an overall A grade at the A Level. This means that you must obtain 480/600 UMS or above at the end of your course.

-You need to obtain at least 90% AVERAGE at the A2 level. This means that you must obtain 270/300 UMS or above in your A2 units.

This is a bit different for Maths. You must obtain 90% AVERAGE in C3 and C4 only (in addition to obtaining an A overall). Getting at least 90% average in C3 and C4 corresponds to obtaining at least 180/200 total for C3 + C4.

I will give three scenarios to help you better understand the A* system.

Scenario One: The student obtains 265/300 in his AS year and 271/300 in his A2 year. His total out of 600 is 536. This means he obtained an A overall by exceeding the 480 threshold. He also obtained 90%+ at the A2 level. So, he WILL be awarded an A*.

Scenario Two: The student obtains 210/300 in her AS year and 270/300 in her A2 year. Her total out of 600 is 480. This is an A overall. Additionally, she also obtained 90% at the A2 level so she WILL be awarded an A*.

Scenario Three: The student obtains 300/300 in his AS year and 269/300 in his A2 year. His total out of 600 is 569. This is an A overall. However, the student did not obtain at least 90% in his A2 year so he WILL NOT be awarded an A*.

Even though Student Three obtained the highest overall mark, he will be awarded a simple A. This is why I do not fully support the A* system as is the case with many others. I guess the people in charge are trying to tell us that we must work hard in our A2 year. It really is harder to get high marks at the A2 level. Keep in mind that lots of people take subjects at the AS level but the ones who continue with any given subjects are more likely to want to excel in the subject. This raises the 'competition' and therefore you might need higher raw marks for a certain grade. This is illustrated in the Maths course. The AS units usually have lower grade boundaries than the A2 units.

My next posts will touch on the written alternative papers and a brief description of the 'How Science Works' concept.

If you have any questions or doubts and you need advice you are always welcome to contact me :)

Course structure for Edexcel Biology and Chemistry - Part Two

2010-07-05T21:21:00.022-04:00

In my previous post, I explained the units tested in the Biology specification. I have yet to explain: the units tested in the Chemistry specification, grades/marks/UMS and the written alternative to practicals/coursework. After these introductory posts, I plan to start posting resources for each subject. I will occasionally post updates for Physics and Mathematics (w/ Mechanics) so keep an eye out for those posts as well.

Details about a particular unit will be posted when I begin to post content on a given unit. Such details include: number of questions in the paper, the time allotted for the paper, number of sections in the paper and the synoptic factor of each paper (at the A2 level).

EDEXCEL CHEMISTRY

The official specification can be downloaded here.

The international extension to this specification is here.

The specification code for AS Chemistry is: 8CH01

The specification code for A2 Chemistry is: 9CH01

You will have to take a total of six units in the entire course. Units 1, 2, 4 and 5 include the actual content which you must learn. Units 3, 3B, 6 and 6B examine practical aspects to the course. I will focus more on Units 3B and 6B since these are the written alternatives to coursework and they often test content taken directly from the specification. The codes for Unit 3 and 6 are: 6CH03 & 6CH06. The codes for 3B and 6B are: 6CH07 & 6CH08.

Each of the 'main' units is divided into several topics.

Unit 1: The Core Principles of Chemistry, 6CH01

-Formulae, equations and amounts of substance

Energetics

Atomic structure and the periodic table

Bonding

Introductory organic chemistry: Alkanes + Alkenes

Unit 2: Application of Core Principles of Chemistry, 6CH02

-Shapes of molecules and ions

Intermediate bonding and bond polarity

Intermolecular forces

Redox

The periodic table — groups 2 and 7

Kinetics

Chemical equilibria

Organic chemistry: Alcohols, Halogenoalkanes

Mechanisms

Mass spectra and IR

Green Chemistry

Unit 4: General Principles of Chemistry I – Rates,Equilibria and Further Organic Chemistry, 6CH04

-How fast? – rates

How far? – entropy

Equilibria

Application of rates and equilibrium

Acid/base equilibria

Further organic chemistry: Chirality, Carbonyls, Carboxylic acids + derivatives

Spectroscopy and chromatography

Unit 5: General Principles of Chemistry II – Transition Metals and Organic Nitrogen Chemistry, 6CH05

-Redox and the chemistry of the transition metals

Organic chemistry – arenes, nitrogen compounds and synthesis

The A2 units seem to have less content than the AS ones. Do NOT be fooled. You will be required to use AS knowledge in your entire A2 course. In addition, the topics in Unit 2 (redox, kinetics and equilibria) are only introductory. You go much more in depth at the A2 level.

In each of these unit tests, you will be present with objective questions (choosing answers from given options), structured questions and short answer questions. Short answer questions require you to write a phrase or a word. Structure questions will require you to carefully think about your answer and arrange your ideas in a logical manner. Questions denoted with an asterisk (*) will test your quality of written communication (QWC). Your answers to QWC questions must use correct grammar and appropriate language. You must avoid spelling key terms incorrectly. It is usually best to write your QWC answers in prose format but I do think that answers in bullet or point form can score full marks provided that you fulfill the stated QWC requirements and you include relevant points.

If you have any questions or doubts and you need advice you are always welcome to contact me :)

Course structure for Edexcel Biology and Chemistry - Part One

2010-07-05T20:58:00.017-04:00

If you're from the UK and you are taking Edexcel Biology and Chemistry at the Advanced Level, you will have to take four written examinations. If you're an international student, you will have to take two additional exams which serve as the written alternative to practicals/coursework.

EDEXCEL BIOLOGY

The official specification can be downloaded here.

The international extension to this specification is here.

The specification code for AS Biology is: 8BI01

The specification code for A2 Biology is: 9BI01

You will have to take a total of six units in the entire course. Units 1, 2, 4 and 5 include the actual content which you must learn. Units 3, 3B, 6 and 6B examine practical aspects to the course. I will focus more on Units 3B and 6B since these are the written alternatives to coursework and they often test content taken directly from the specification. The codes for Unit 3 and 6 are: 6BI03 & 6BI06. The codes for 3B and 6B are: 6BI07 & 6BI08.

Each of the 'main' units is divided into two topics.

Unit 1: Lifestyle, Transport, Genes and Health, 6BI01

-Topic 1: Lifestyle, health and risk

This topic begins with a consideration of the structure and functions of a number of molecules, including water, carbohydrates and triglycerides. The structure and function of the cardiovascular system is also included as an introduction to the ways in which diet and lifestyle factors may affect the heart and circulatory system. Ideas about correlation, causation and the concept of risks to health are covered.

-Topic 2: Genes and health

This topic begins with a consideration of the structure and functions of the cell membrane and gas exchange surfaces. The structure and properties of proteins, enzyme and nucleic acids lead to the genetic code and protein synthesis. Principles of inheritance, gene therapy and genetic screening are included, giving opportunities for discussion of the social and ethical issues surrounding genetic screening for genetic conditions.

Unit 2: Development, Plants and the Environment, 6BI02

-Topic 3: The voice of the genome

This topic begins with an overview of cell structure and considers how cell ultrastructure is related to function. Cell division and cell aggregation to form tissues and organs are also included. The topic then considers meiosis, the formation of gametes, fertilisation, stem cells, gene expression and cell differentiation. The role of the genotype and effect of the environment on phenotype is also stressed.

-Topic 4: Biodiversity and natural resources

This topic begins with a comparison of the structure of a typical plant cell with that of an animal cell, and the structure and roles of cellulose and starch. The relationship between plant tissues, xylem and sclerenchyma, is also included. The topic continues with a consideration of the importance of plant products to humans, species diversity, and how diversity arises through natural selection and evolutionary change. The role of zoos in the conservation of endangered species is also described.

Unit 4: The Natural Environment and Species Survival, 6BI04

-Topic 5: On the wild side

This topic builds an appreciation that photosynthesis is the primary process that underpins the majority of ecosystems, and provides students with an understanding of how ecosystems work. The topic continues by looking at whether climate change will lead to extinction of species or evolution by natural selection, and looks at the evidence for global warming and its effects on plants and animals. By the end of the topic students should appreciate how scientific understanding can make us aware of our responsibilities as stewards of the environment.

-Topic 6: Infection, immunity and forensics

This topic starts by looking at how forensic pathologists use a wide variety of analytical techniques to determine the identity of a person or other animal, and to establish the time and cause of death of an organism, including humans. It then considers how bacteria and viruses use a variety of routes into their hosts and how hosts have evolved barriers and internal mechanisms to combat infections. These protections are not always successful and many people in the world still die from infectious diseases. This topic also investigates the evolutionary battles that take place between invading pathogens and their hosts.

Unit 5: Energy, Exercise and Coordination, 6BI05

-Topic 7: Run for your life

This topic begins with a study of muscle structure and function, and the ways in which energy is provided by means of aerobic and anaerobic respiration. The responses of the heart and respiratory system to exercise are included, with the concept of homeostasis and its importance in both the regulation of body temperature and at the molecular level with a reference to gene switching. The topic ends by considering the effects of both too much and too little exercise on the body, how medical technology is used in relation to sports, and the ethical positions with respect to the use of performance-enhancing substances by athletes.

-Topic 8: Grey matter

This topic begins by considering how plants detect and respondto changes in their environment. This is followed by details of the structure and function of the mammalian nervous system, including imaging techniques to investigate the brain. This is developed into an enquiry into how imbalances in brain chemicals may result in conditions such as Parkinson’s disease and its treatment with drugs. The topic requires students to discuss the ethics of the Human Genome Project and to consider the risks and benefits associated with the use of genetically modified organisms.

In each of these unit tests, you will be presented with objective questions (choosing answers from given options), structured questions and short answer questions. Short answer questions require you to write a phrase or a word. Structure questions will require you to carefully think about your answer and arrange your ideas in a logical manner. Questions denoted with an asterisk (*) will test your quality of written communication (QWC). Your answers to QWC questions must use correct grammar and appropriate language. You must avoid spelling key terms incorrectly. It is usually best to write your QWC answers in prose format but I do think that answers in bullet or point form can score full marks provided that you fulfill the stated QWC requirements and you include relevant points.

In my next post, I will outline the Chemistry specification.

If you have any questions or doubts and you need advice you are always welcome to contact me :)

The beginning...

2010-07-04T22:04:00.017-04:00

Hi! Welcome to my blog.

I have just finished my two-year Advanced Level course and I have decided to make a blog to help others who will be doing A Levels. I have a passion for science and most of the help I intend to give will be based on science subjects (specifically Biology and Chemistry). I do not like Mathematics or Physics and so I do not feel confident in giving advice in these fields. I'm no expert either. I am going to start university this fall and I really hope that I have a wonderful time there!

All my subjects were taken through the Edexcel examining body and so most of the content I post here will reflect that. I am in no way affiliated with Edexcel. I do not own anything that is of the 'Edexcel name'. I am simply a 'tutor' who intends to share information on two specifications created by said exam board.

There are many resources on the internet for A Level subjects. I particular find The Student Room to be very helpful. As time progresses, I will post links to more useful websites. The A Level section of 'TSR' will be of most interest to you if you wish to primarily utilise the website for academic reasons. I do suggest that you create an account there as you will gain access to a plethora of resources! You will find many helpful notes and recent past papers and markschemes there. I will keep you posted with what's relevant to your Biology and Chemistry specifications.

Enough about that. You probably just finished your GCSE or O Level subjects and you are now planning to take the big A Levels! You will be thinking about which Sixth Form Colleges you may want to attend and which and how many subjects you want to study. Do not be overwhelmed! It's all a simple process. Most people take A Levels before going to university. Many will use their A Level grades to gain entrance in universities in the UK and Europe. Keep in mind that you can still study at the Advanced Level and then attend college/university in the USA.

Which Sixth Form College you decide to attend is primarily up to you! Think about location, social scene (if it applies to you), work load and of course finances. Most people would not have a problem in picking a college.

Subjects! The usual number of subjects taken is four at the Advanced Subsidiary (AS) Level. I've seen people take more subjects. I've never really seen anyone taking two AS subjects, but I'm sure the possibility exists. People may opt to 'drop' one of their AS subjects when they reach the A2 (2nd year) Level. I did Biology, Chemistry, Mathematics with Mechanics and Physics at the AS and A2 levels. You will decide if you want to drop anything after or during the course of your AS studies.

It is best to think carefully about which subjects you want to do and why you want to do those subjects. You should definitely NOT do subjects to impress anyone or to 'look smart'. It's A Levels! Do subjects that you need and want to do. Most people continue with subjects they took at GCSE and some pick up new ones. Science A Levels build on previous GCSE knowledge. You may not like Physics but you might need it to get into the university program of your choice. Plan ahead! Think about what you want to do after A Levels. Don't pressure yourself too much though.

A Levels are a big jump from GCSE. The subjects have more depth and the questions are more demanding. At GCSE Biology you would have learnt about cell organelles and their basic functions. At AS Biology you study these organelles in some bit of detail. The practical aspect of the science subjects is more emphasized at the A Level. International students taking Edexcel science subjects are required to take written alternative to coursework/practicals. I will expand on this at a later date.

A Level Biology is notorious for the amount of content included in the specifications. Chemistry has a lot of content as well but it's less memorising and more application of basic principles.

In the next post, I will focus on the structure of the Biology and Chemistry specifications. I will explain the various units involved.

If you have any questions or doubts and you need advice you are always welcome to contact me :)

Good luck!