AQA BIOL4 ~ 11th June 2013 ~ A2 Biology

For 1a) I put population change during the period and population number at the start of the period since the question asked for growth rate not just growth.

5c) I'm an idiot I put 61% by accident but I did the rest of it correctly would I get any marks haha?

Yeah thats what i though aswell...

you thought right

What was 8c again?

What was 8c again?

6 asked why is there high diversity in birds in amazon rain forest no? - I explained most of what you said but didn't the main thing want you to mention more habitats/niches, more food sources etc?

Yeah thats what i though aswell...

you thought right

What was the reason for concrete use as a surface being unreliable?


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What was the reason for concrete use as a surface being unreliable?


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What was the reason for concrete use as a surface being unreliable?

wohoo thought i lost 4 marks :/

What evidence from the pedigree chart shows that the condition is not X-linked?
- Affected daughter from unaffected father
- Daughter would have to have two copies of the recessive allele, one from each parent, therefore the father would have the recessive allele and as males only have one X chromosome would be affected.

Yeah sorry guys I missed those points out, you're quite right, I've now included them, thanks

1 a) What information is needed to calculate the growth rate of a population? (2)
- Birth and death rates
- Immigration and emmigration rate
OR
- Initial population
- Rate of population change
b) How does the graph show that it is in the early stages of a demographic transition? (2)
- Low life expectancy
- High death and birth rates

2 a) Which species is the pioneer? (1)
- U. Lactulana (something like that anyway)
b) 2b Explain how succession happens using examples.
- Colonization of Whatever
- Makes environment change
- Allows other whatever species to colonize
- Which change the environment to make it less hostile and more stable
- Which allows other species which are more adapted to colonize
- Climax

5 c) (?) The rate of the condition in a population was 1 in 1000. What would you expect the percentage of heterozygous individuals to be?
q^2 = 0.001, q = 0.0316, p= 0.9683, 2pq= 0.0612 = 6.12%


6 a) Explain how fragmentation of the Amazon rainforest in the past led to high species diversity in the current day (5)
- Initially there is variety
- Due to mutation
- Geographic isolation as forest fragments.
- Different selection pressures
- Different alleles selected for, differential reproductive success
- Frequency of different alleles increases in the different populations.
- When the areas become linked once again the species are genetically isolated and can no longer breed - they are different species
- More plant species
- More habitats/niches/food sources
- Therefore more species of bird

b) Why does speciation not occur as often now?
- As members of a population are not isolated they can read freely
- Same selection pressures affect whole population (wasn't as sure about this one, if anyone has any ideas please edit and re-post)


8 a) Describe the advantages of IPM (6)
- Minimises use of pesticides so minimises resistance
- Mechanical removal of pests minimises impact on non-pest species
- Biological aspect only requires one application and is specific
-Improved biodiversity
- Pesticides work instantly
- Biological agents slow
- Biological agents don't kill all of the pests
- Pesticides do
- Biological agents don't need to be continually applied
- Pesticides do
- Biological agents don't build up resistance
- Pesticides do


Anyone know any more points for this? I struggled a bit with this one


b) Describe how nitrates lead to the death of fish in ponds and lakes (5)
- High nitrate concentration causes and algal bloom
- Blocks light
- Plants at the bottom of the pond/lake can no longer photosynthesise and die.
- Saprobiontic organisms decompose the dead plants
- These respire aerobically
- Oxygen concentration of the water falls
- Fish require high oxygen concentration and so die

c) Describe how intensive farming methods increase the productivity of livestock (4)
- Selectively bred for maximum productivity
- Kept in a warm environment to minimise amount of energy required to maintain body temperature and minimise respiratory losses
- Movement may be restricted to minimise respiratory losses, maximising energy available for growth
-Fed concentrate diets which are easily digested so minimum energy is lost in the faeces


I can remember a couple of the other questions :
What is meant by phenotype? (2)
- Observable characteristics of an organism
- Resulting from both genotype and the effects of the environment

What evidence from the pedigree chart shows that the condition is recessive?
- Unaffected parents produce affected offspring
- Parents are therefore heterozygous

What evidence from the pedigree chart shows that the condition is not X-linked?
- Affected daughter from unaffected father
- Daughter would have to have two copies of the recessive allele, one from each parent, therefore the father would have the recessive allele and as males only have one X chromosome would be affected.

I can't remember what question numbers these were though, anyone?

you thought right

Does anybody remember what question 3 , 4 , first bit of question 5 and question 7 are??