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AQA A-Level Biology paper 2 11th June 2018 unofficial markscheme

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Yes it was in a glucose culture, glycolysis would only take place if anaerobic respiration happened and no gas would be produced

glycolysis doesnt produce gas but CO2 is released when pyruvate is converted to ethanol

Reply 41

mo08

Original post by eliza154

I put so the alkaline stuff had time to absorb the oxygen, I suppose we can't tell what's on the markscheme for those suggest questions

that's what i said too but now i'm not sure if i should've put that or rate of respiration to stabilise :/

Reply 42

sgsb0y

Original post by lucyv1234

Not 100% sure on this but I think it said the allele frequency was 0.1 which means you use p + q = 1 to get p and q and then put that in 2pq so the answer was 18?
I may be wrong though

No it gave you the percentage of people with the complete form of that eye disease, which is where you have two recessive alleles (homozygous), it didn’t give you the total frequency for all the recessive alleles in that population, just the frequency of homozygous recessive.

Reply 43

Mk1237

Why would expected ratio be different 2 actual ratio (2)

Reply 44

littlediddy

Original post by mo08

that's what i said too but now i'm not sure if i should've put that or rate of respiration to stabilise :/

They will allow both but likely the major reason is so that there was no oxygen left as you need the yeast to anaerobically respire.

Reply 45

eliza154

Original post by sgsb0y

No, I think you’re meant to do 84-1=83 and then 2^83. Just follow the pattern you’ve created, if the first division is 2^0 and the second is 2^1 therefore the 84th is 2^83.

don't understand how the first division is 2^0, that's before any divisions have taken place. the first time the cell divides you end up with 2 cells?

Reply 46

young122

Hardy Weinberg answer is 2^83

Reply 47

littlediddy

Original post by Mk1237

Why would expected ratio be different 2 actual ratio (2)

Should be 9:3:3:1 as it was a dihybrid cross

Reply 48

eliza154

Original post by mo08

that's what i said too but now i'm not sure if i should've put that or rate of respiration to stabilise :/

yeah hopefully we're all correct :biggrin:

I got 18% for hardy

Tumour Suppressor question?

Reply 51

Alice JP

Original post by JSC16

If anaerobic does not produce any gases how could the bubble possibly move to the right

In yeast it will

Reply 52

Helium2

Why is the expected ratio different to the observed?

i wrote random fertilisation of gamets and selective advantage

Reply 53

Daniortall

Original post by Helium2

Why is the expected ratio different to the observed?

i wrote random fertilisation of gamets and selective advantage

Isn’t it about the Autosomal linkage thing?

Reply 54

1234mmm

Original post by Xusor1

I put that CO2 increased pressure on the left of the liquid so It pushed it to the right .

I think you are right

Reply 55

CharlieEdl

Original post by pploveash

Yeah i got 18%

It was 43.2, it gave you the number of people who had the condition which is q squared because it was a recessive allele so you had to square root 0.1 to get q then do 1 take q to get p then do 2pq tofind heterozygotes.

Reply 56

ruadb0y

Grade boundaries gonna be as high as the number of cancer cells

Reply 57

Darkrai283

For the cell division question:

1 cell to begin with,
With first division -> 1x2^1
Therefore, with 84 divisions, it’s 1x2^84, which is the same as 2^84.