BIOL4 Biology Unit 4 Exam - 13th June 2011

I put 1:3 O_o This thread is depressing...

I wrote the same for the horses question!

for the decomposition one i wrote:

- decomoposers digest by extracellular digestion
- in doing so produce ammonium ions in soil
- these are converted into nitrates via nitrites by nitrifying bacteria
- nitrates used for protein synthesis, or nucleic acids
- microorganisms also respire aerobically releasing CO2
- CO2 can be taken in through stomata for photosynthesis
- products of photosynthesis, hexose sugars such as glucose which can be used in growth!

I also got 4% for hardy weinberg...

Overall, not a bad exam set by AQA. They have certainly learnt from their mistakes on previous exam papers. I thought this one covered the specification reasonably well, quite a lot on genetics though, where they could have added either predation, food chains or speciation.

What do you guys think?

i put 50:50 for the cats but i wasn't too sure

I wrote the same for the horses question!

for the decomposition one i wrote:

- decomoposers digest by extracellular digestion
- in doing so produce ammonium ions in soil
- these are converted into nitrates via nitrites by nitrifying bacteria
- nitrates used for protein synthesis, or nucleic acids
- microorganisms also respire aerobically releasing CO2
- CO2 can be taken in through stomata for photosynthesis
- products of photosynthesis, hexose sugars such as glucose which can be used in growth!

I also got 4% for hardy weinberg...

Stablising? Because by eliminating the recessive alleles, it is keeping the dominant. The dominant are the most common (due to previous equation, and that fact it is more often expressed in the phenotype), so is such the ''average'' phenotype, so the mean is being favoured?

That would be 1:1

but wasn't the question focused on nitrogen and not CO2? so I talked about ammonia, to nitrite, then to nitrate and (I should have put) taken up by the roots.. but I didn't haha.

That would be 1:1

How did you all work out 1:1

How did you all work out 1:1?

"What would the hardy weinburg principle suggest about allele freauenc"

I put that the allele frequency will not change from one generation to the next
I didnt mention anything about other factors
how many marks do you reckon i will get?

so would you get the marks for 50:50 or not??

becuase it said for THIS black male and a white cat....

THIS black male must = genotype Bb
and white cat must = genotype bb

so the crosses are 50% black, 50% white = 50:50 = 1:1 ....


ALSO


for the first question did people put: The two parents have black fur but produce cats with white fur. therefore the parents must be heterozygous dominant. (this proves that the allele for white fur is recessive) ...

im sure the question didn't solely specify nitrogen. i though it said how do decomposers make the products in dead matter available to plants for growth or something.

so i talked about digestion by microorganisms...the ammonium ions they produce which is converted into nitrogen, and then the fact they respire co2 which is also used. etc etc. obviously in much more detail than that though.