AQA BIOL2~3rd June 2013~AS Biology (Now Closed)

What was the UMS mark for an A?

Here is the link to the paper:

http://issuu.com/aidn2/docs/biology_2013_january_paper

You have to sign up, but its fast!

Here is the mark scheme:

http://www.thestudentroom.co.uk/attachment.php?attachmentid=201318


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What was the UMS mark for an A?

Goood 2/2 marks...don't think the first is relevant, it's just about the co2 rise
There are 3 sub-units, there is a 5 carbon deoxyribose sugar, an organic base and a phosphate group. The bases are in two's, each base is complementary to the one it bonds with. Adenine pairs with Thymine, Cytosine pairs with Guanine. 2 hydrogen bonds form between A and T, and 3 form between C and G. These bases also form the triplet code, 3 bases code for one amino acid. Single rings are T and C, double ring bases are G and A.

Why is it advantageous for the oxygen dissociation curve being more to the right for a mouse? Explain. (3 marks)

You would get 6 out of 6, But just to help you out you don't need to know about how many hydrogen bonds till A2, but it's intersting fact however, simply to get the mark all you had to state was.

Deoxyribose sugar
Phosphate group
Organic bases to include: Cytosine, Thymine, Adenine and Guanine
(6/6)

I think it's because a mouse is a smaller organism so it would therefore have a large surface area to volume ratio.Therefore they will have higher rates or Aerobic respiration. so they are more likely to loose heat very fast and so there would need to be a lower saturation of Haemglobin with Oxygen so it can be released rapidly to maintain body temeperature of the mouse.

Describe and explain the events in the tissue and the blood when the Co2 levels in the blood go from Low to high concentrations. (Include the word Haemoglobin and affinity) 6 Marks.

oh okay
released rapidly is okay, it's better I think to put released more readily because then you're comparing it to the other side, being released less readily which would happen if the curve was more to the left.

When the blood has low partial pressures of CO2 haemoglobin has a higher affinity for oxygen. This is in the lungs, there is a high saturation of Hb with oxygen. These red blood cells move to the cells/tissues. When they get there there's higher partial pressures of CO2. This lowers the PH, changes the shape of the molecule to one that more readily releases oxygen. It now has a lower affinity, and releases oxygen more easily, and faster. The cells need the CO2 for respiration to fuel the cells with energy. The red blood cells go back to the lungs and the Hb changes shape again to a molecule that readily associates with oxygen. It goes round in a cycle.

Compare and contrast the structures of glycogen and cellulose, showing how each molecules structure is linked to its function. [6 marks]

Error:
Cells do not need CO2 for respiration but give it off as a bi-product.

(4/6)

Glycogen major carbohydrate storage for animals made up of sub units of alpha glucose monosacchrides. It's stored as small granules and found at energy dependent parts of the body such as Muscles which need a high demand of energy. It is made up of smaller chains so it can be hydrolysed a lot more easily and so produce energy more readily.
Cellulose made up of beta-glucose monosacchrides the Beta-glucose is inverted in comparison to Alpha-glucose molecules. It occurs in layers of straight chains parallel to one another which are joined together by hydrogen bonds which create cross-links between parallel chains. These chains make an overall structure known as Microfibrils.This structure and number of microfibrils provides great overall strength and is appropriate for it's role to support the cell and prevent damage of the cell by Osmosis.

Name and Explain the types of genetic Differences. (6 marks)

Has anyone got the Jan paper and MS?

If so, please attach!

Post 123

Oh I see, meant oxygen
6/6
I haven't gone over that yet but i'll have a go..do you mean genetic differences as in meiosis, mutations, and fusion of gametes?

yes I do, you already have 3/6 marks

Mutation is when DNA is mutated to produce different alleles...Fusion of gametes is when a sperm and an egg fertilise to increase genetic variation. The paternal and maternal chromosomes join.

Outline two ways by which genetic diversity is increased [2 marks]

Hey guys, do we need to know about inspiration and expiration in fish as it is not really explained in the Nelson Thrones Book, but my teacher taught us it, what do you guys think?


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