AQA A2 Biol4 January 2012 pre- exam discussion

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Reply 1980

It did say show your working, \:

crapp.. but I didnt think of it to be scaled? So I just counted the blocks and it was proportional so.. \:

I'm not sure, maybe you will though, at least you got the right answer so you definitely got 1 mark :smile:

I really need to get off here and revise for chem 4 tomorrow haha...

Reply 1981

ILikeToEat

I see no reason why counting the blocks would be a problem at all. Anyway, usually its 2 marks for correct answer, so not worried about this.

Reply 1982

joker12345

Original post by EffKayy

It did say show your working, \:

crapp.. but I didnt think of it to be scaled? So I just counted the blocks and it was proportional so.. \:

Did you write your calculation? Because that should count as working ...

Reply 1983

ashleyp

Original post by joeyloeykins

It was sex linked :frown:

they told you in the information at the start of the question, something like:
"The gene is carried on the X chromosome"

Which means it's not carried on the Y chromosome

Okay, but both male and female have the X chromosme? So both could potentially have the hairless allele?

Reply 1984

SoftMusk

-myocardial infarction LOOOL -.- how much for a C/D do u guys think?

Reply 1985

joker12345

Original post by izzwizz

shall i attempt an unofficial mark scheme?

YES!

Reply 1986

EffKayy

Original post by joeyloeykins

I'm not sure, maybe you will though, at least you got the right answer so you definitely got 1 mark :smile:

I really need to get off here and revise for chem 4 tomorrow haha...

Lmaooo I knowwwwww Ive got chem4 tommorow but ive been on here for hours discussing!

Reply 1987

Drex

1a) Community - all organisms of all populations in same habitat 1
b) Mark release recapture - capture them, mark them, release them giving time to distribute evenly among population and recapture them. do the calculation: total captured in 1st sample x total 2nd sample/ total marked recaptured. 3
c) cant remmber
d) adaption to niche due to large mouth - can eat prey more easily etc 2

2a) name all primary consumers 1
b) effect on mayfly population after fall in secondary consumer population - deacrease becasue there will now be more shrimps to compete with it for the primary consumer 3
c) calculation - 17.8%? 2
d) more efficent than 10% - higher SA:V ratio, less heat lost to surroundings, cold blooded. 2
e) solar energy in dead plants - not all solar energy transferred, so when it dies the solar energy is still there 2

3a) marram grass - line/belt transect with quadrats and % cover? 3
b) why adding more marram grass helps sand dunes - less hostile environment so other organisms can establish there 2

4a)main abiotic factor - temperature 1
b) other than temperature - soil pH 1
c) CO2 fluctuations - day/ night etc 4
d) selection question - confers advantage, more likely to reproduce and pass on the advantageous allele blah blah 3

5)a) recessive allele - both parents have hair phenotype but produce hairless offspring. allele for hairless must be present in both but the hairless phenotype isnt displayed in either so they must be heteroygous, recessive allele only displayed in homozygous recessive 2
b) Proof of it being on X chromosome 1
c) 25%? i put 50% forgetting it said male :/

6a) nitrifying 1
b) o2 in air used for active transport in respiration 2
c) i put too fast so ammonia wont have been nitrifyed - probs something to do with denitrifying bacteria when waterlooged? dont know 2
d) effect on N on fish - eutrophication? algal bloom, aerobic die out so fish die 3

7a) why same breed - i put so they use the food in same way, some breeds may be more efficient with food. its probably to do with SA:V ratio staying consant so only temperature is having the effect. 2
b) some animals allowed to eat more, why not reliable - means some animals will grow faster because they have more food, so it cant test the effect of temperature only 2
c) describe relationship - growth rate rises then falls with temperature rise. 1
d) conclusion - was it me or was that really obvious? cant remember what i put though just remember it was easy
e) why they didnt go above 35 - already seen that increase in temp will cause fall in growth after a certain point. waste of time and money. also they know enzymes will denature 2
f) why more efficient at 20 degrees than 0? - cant remember 2
g) evaluate conclusion - yes becasue it is highest on graph BUT overlap so not significant (p>0.05)
other factors etc 4

8a) ATP - immediate source, simple reaction, soluble so good for transport, small manageable amounts so none wasted 4
b) ATP in mitochondria - i forgot about krebs and just talked of Oxidative Phosphorylation 6
reduced NAD and FAD are oxidised, electron joins transport chain, protons actively transported into intermembrane space, electrons lose energy to make ATP, protons back by chemiosmosis and O2 final acceptor
c) i got this wring but i think its because the ATP made in LDR is used in Calvin cycle 5

I just added the marks on as someone requested some marks mising if someone wants to correct

ORIGINALLY POSTED BY TheBigDog ( I just added the marks - i don't want to seem like th one taking credit for the mark scheme )

(edited 12 years ago)

Reply 1988

joker12345

On the genetic diagram, if you ignored the fact that it was X linked and went for normal dominant/recessive but still got 25% probability, do you think that'll be one mark, or do you lose all marks?

Reply 1989

izzwizz

Original post by joker12345

On the genetic diagram, if you ignored the fact that it was X linked and went for normal dominant/recessive but still got 25% probability, do you think that'll be one mark, or do you lose all marks?

probably lose all the marks, i hope not though.

Reply 1990

joeyloeykins

Original post by joker12345

On the genetic diagram, if you ignored the fact that it was X linked and went for normal dominant/recessive but still got 25% probability, do you think that'll be one mark, or do you lose all marks?

I think you would get it all wrong, I did that in one of the mocks at school but ended up with the correct answer (by luck) and it was all marked wrong, but they may have just been horrible teachers

Reply 1991

NutterFrutter

Original post by joker12345

On the genetic diagram, if you ignored the fact that it was X linked and went for normal dominant/recessive but still got 25% probability, do you think that'll be one mark, or do you lose all marks?

You'll probably only lose 1 mark.

Reply 1992

ashleyp

is aspect an abiotic factor anyone??

Reply 1993

EffKayy

Original post by ashleyp

is aspect an abiotic factor anyone??

o_O ?

Reply 1994

joker12345

Original post by EffKayy

Lmaooo I knowwwwww Ive got chem4 tommorow but ive been on here for hours discussing!

Me too, this is such a total and utter waste of time!

Reply 1995

liviaaa

Original post by Drex

2a) name all primary consumers 1
b) effect on mayfly population after fall in secondary consumer population - deacrease becasue there will now be more shrimps to compete with it for the primary consumer 3
c) calculation - 17.8%? 2
d) more efficent than 10% - higher SA:V ratio, less heat lost to surroundings, cold blooded. 2

That doesn't make sense does it... surely a higher SA:V means more heat loss? I think the answer was something to do with it being single celled anyway.

Reply 1996

FruitTwist

The ATP question about it in biological processes - what was the EXACT question? Did it ask for why or how????? Please reply :frown:

Reply 1997

Drex

Original post by liviaaa

That doesn't make sense does it... surely a higher SA:V means more heat loss? I think the answer was something to do with it being single celled anyway.