AQA BIOL4 ~ 11th June 2013 ~ A2 Biology

can some1 link me the unofficial mark scheme please

What was the answer to the P <0.01 question?

Answers from top of my head:

Pioneer species: - Ulva Lactuna (whatever it was)

Blocks: - blocks may prevent growth of algae? (Not sure)

Describe and explain succession:
- pioneers species change environment
- allows other species to colonise
- other species outcompete existing ones
- environment less hostile
- then just talk about what's happening in graph between different types of algae

Define phenotype: (this is what's in the spec)
- expression of the genetic constitution
- and it's interaction with the environment

Tach-says caused by recessive allele: (can't remember what the actual numbers were on pedigree diagram)
- offspring has condition
- parents don't so must be carriers/heterozygous

Hardy Weinberg calc:
- 6%
- but I'm sure you can get 1/2 marks for identifying q^2 and working out 2pq?

Why the number of heterozygotes may be different?
- random fusion of gametes
The question mentioned that due to the Tach-says genetic disease, most individuals with the disease do not survive after childhood; therefore don't reach the age to reproduce and pass on the allele, hence overtime this decreases the % of heterozygote alleles overall.

Tick box for respiration: (Y represents Yes)
- occurs in mitochondria X Y Y
- co2 produced X Y Y
- reduced NAD Y Y Y

Why glucose not used as respiratory substrate:
- glucose broken down into pyruvate
- glycolysis only occurs in the cytoplasm

How does methanfate (whatever it was) inhibit reaction:
- competitive inhibition/ binds to active site of enzyme
- preventing an enzyme substrate complex to form

Why oxygen concentration decrease:
- oxygen is a terminal electron acceptor
- oxygen combines with protons and electrons to form a molecule of water

In dark:
- so no photosynthesis can take place

I ron deficiency - TP:
- less GP produced
- less TP produced
- less electrons excited in chlorophyll
- less ATP produced
Etc (??? No idea??)^

Take lizards from many sites, why:
- so that investigation is 'representative of the whole sample'

Random:
- uses a random number generator (calculator)
- produce numbers to use as co-ordinates on a grid

% used:
- allow a comparison to be made
- as into atlas starting numbers were different

- questions on interpreting etc...

Speciation: (in a nut shell)
- populations become isolated
- 2 populations separate thus no interbreeding between them
- variation
- such as mutations exist
- advantageous allele
- successfully reproduce
- leads to a change in allele frequency

Increase in nitrates in river: (in a nut shell)
- eutrophication occurs
- algal bloom occurs
- dense later of algae, absorb light
- increased competition of algae, death too
- decomposed by saprobionts whose populations increase
- increased aerobic respiration by the above ^ uses up oxygen
- water becomes depleted, hence fish die

Integrated Pest Management: (this question did not ask advantages of bio control and pesticides):
- reduces amount of pesticides that need to be sprayed
- minimizes risk to both humans and environment
- reduces risk of pests developing resistance
- increase crop productivity
- limits economic damage to agricultural system
- cheap to use - requires one application

Intensive rearing of domestic live feedstock to increase net productivity:
- kept inside so loss energy lost as heat
- controlled diet and fed on high proportion of carbohydrates so less is in farces
- restricted movement so less energy wasted in movement
- genetically selected for high productivity
- antibiotics added to reduce any risk of disease

there is less than 0.01 probability that the correlation (between whatever was mentioned) occurred due to chance.

What did people get for the tick questions on respiration?

What did people get for the tick questions on respiration?

not quiet sure, but i think i didnt tick anything in the first row. ? or maybe only ticked the last box of the first row. Can't remember the headings

I'm glad to see this, but check the correction to that one question, everyone in my college talked about that.

I can't remember the titles and details, but i remember the order i placed them;

- - [tick]
- [tick][tick]
[tick][tick][tick]

The grade boundaries for an A for the last 5 Bio4 papers:

52 - January 2013
50 - June 2012
50 - January 2012
53 - June 2011
47 - January 2011

The highest raw mark needed for an A was 53, I am expecting about 55 for an A this time.

I can't remember the titles and details, but i remember the order i placed them;

- - [tick]
- [tick][tick]
[tick][tick][tick]

I dont think we have much to worry about with the grade boundaries. People are on about them being in the 60's, but ive just checked every grade boundary from Jan 2013 to Jan 2010 and an A* has never been higher than 57/75, its lowest being 39/75. Here are the boundaries:

Jan 2010: A 41 B 37 C 33 D 29 E 26
Jun 2010: A* 39 A 35 B 31 C 27 D 23 E 19
Jan 2011: A* 52 A 47 B 42 C 38 D 34 E 30
Jun 2011: A* 57 A 53 B 49 C 45 D 41 E 37
Jan 2012: A* 54 A 50 B 46 C 42 D 38 E 34
Jun 2012: A* 54 A 50 B 46 C 42 D 38 E 35
Jan 2013: A* 57 A 52 B 47 C 43 D 39 E 35

I disliked your comment by accident how do i undo the dislike??

Shouldn't it be:

- [tick] [tick]
- [tick] [tick]
[tick] [tick] [tick]

As the link reaction does take place in the mitochondria.