# AQA Biology B2 - Unofficial Mark Scheme

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1. (Original post by jazz_xox_)
I read this as the number per quadrat, not per m2. for the third mark do you think they would credit it for your answer for part B?
If you got one calculation wrong but got the working out right for the rest of the question they will credit marks for your working, This is called and ECF (Error Carried Forward) mark.
2. (Original post by MotivateInspi)
I said that use a timer to time how long it takes 10 dm cubed of water to dissapear from the pondweed at each light intensity. Will that be okay?
This is a good point as photosynthesis uses water, but I don't think it would be a big enough change to measure it, you're supposed to count the oxygen bubbles you could still get 5 marks though
3. Do you mean the answer for how big is cell B (a gamete that had grown) is still 6.6 when that was the original size?
I got it was 13.2 when it grew and also 13.2 for a fertilised egg.

Havent looked through this thread yet but does anyone know the answer to the Bb phenotypes/genotypes question?
4. (Original post by CopyThat)
If you got one calculation wrong but got the working out right for the rest of the question they will credit marks for your working, This is called and ECF (Error Carried Forward) mark.
This makes me feel better then thank you! do you remember what the first calculation was?
5. (Original post by jazz_xox_)
This is a good point as photosynthesis uses water, but I don't think it would be a big enough change to measure it, you're supposed to count the oxygen bubbles you could still get 5 marks though
Lol! But it does not seem logical because you can easily miss bubbles or miss count that plus you have to see them to count them! AQA Bology needs to change its ways
Thanks btw!
6. (Original post by 11masanda002)
so was the answer to that question Meiosis because thats what i put but everyone is saying different things!!!!
It was mitosis as it was a FERTILISED egg cell dividing.
7. Does anyone know if there is a unit 3 unofficial mark scheme? If so please put a link
8. (Original post by jazz_xox_)
The parents both had Bb alles, as they both had brown hair, but both passed down a b allele to their daughter, who had red hair - caused by a recessive allele.

I used a punnet square to calculate the outcomes which turned out to be 3:1, brown:red.

Genotypes: BB, Bb, Bb, bb (actually think i wrote these down wrong)
Phenotypes: brown, brown, brown, red

so 25% chance of having red hair, which answers the question 'Show how this couple could produce a child with red hair)
oh my god is that how you were meant to write it down. I just wrote brown for some reason, started writing BB Bb Bb bb but didnt put it on the mothers side cause i didnt have a clue what i was doing.
9. 1ai)what is anaerobic? (1 mark)
1aii) how do we know they are? (1 mark)
1b) 1.5 mins (or whatever the graph answer really was) (1 mark)
1c) blood in body helps you run, how? (4 marks)

2)Pondweed question (6 marks)

3a) what is an enzyme? (2 marks)
3b)Where do they work? (1 mark)

4) total number of plantains in the 10 quads?
4b) total area of the 10 quads?
4bi) total area of the field?(4 marks total)
4bii) the mean plantain?
4c) 3 reasons (3 marks)

5)how do we know that he has it? ( 2 marks)
5ai) what are the chances of his kids getting it? (1 marks)
5aii) fill out the info (5 marks)
5b) what is a stem cell? (3 marks)
5bi) IVF and baby cord (2 marks)
5ii) why its good to use on same person? (1 mark)
5ii) also not good? (1 marks)

6)milk and catalase (2 marks)
7)Where are they found? (1 mark)
8) What are BCD? (3 marks)
9) mitosis (1 mark)

8a) fox fox fox (2 marks)
8b) Foxes why might this happen? (5 marks)
8c) fox no like other fox (1 mark)

9ai)digestive system (1 mark)
9a) glandular tissue (3 marks)
9b) epithelial tissue (1 mark)
9c) muscular tissue (2 marks)

Here is a draft guide on what each question equalled, obviously I was very vague with the questions name, but I hoped that would jog peoples memory on what i was talking about (also there is no q9, i just didnt know where to put the last few so i just added it) Also another disclaminer, these are only guesses and people could help by changing them them so its all adds to 60.
10. (Original post by mochias)
oh my god is that how you were meant to write it down. I just wrote brown for some reason, started writing BB Bb Bb bb but didnt put it on the mothers side cause i didnt have a clue what i was doing.
If you recognised any of the dominant/recessive alleles you should get something, don't dwell on it
11. Also since the glandular tissue was 3 marks and asked specifically about the stomach I think the marks will be: glandular tissue secretes hormones and enzymes (1st mark). These include protease which break down proteins (2nd mark) into amino acids (3rd mark). I only think this because it was specific to the stomach and protease is the only enzyme in the stomach?
12. (Original post by YAY GCSE)
Does anyone know if there is a unit 3 unofficial mark scheme? If so please put a link
http://www.thestudentroom.co.uk/show...4155883&page=3
13. (Original post by mochias)
Do you mean the answer for how big is cell B (a gamete that had grown) is still 6.6 when that was the original size?
I got it was 13.2 when it grew and also 13.2 for a fertilised egg.

Havent looked through this thread yet but does anyone know the answer to the Bb phenotypes/genotypes question?
The answer to the mass of DNA :
first was 13.2 as the chromosomes had copied
6.6 because of the first division
3.3 because of the second division

The phenotype question ended up to be 3:1, brown:red
Was there a question after the speciation one (the 5 marker)? I think I missed it -_-
There was. I missed it!

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15. (Original post by Miz9)
What did you get for that genetic diagram question? The red and brown hair allele??
1) 20 in total
3) 20/62.5=0.32 per metre
4) 0.32*5000=1600

For the allele question I got:
Brown hair, brown hair
Bb, Bb
XX, XY
16. (Original post by Actuvia)
The first question for the fox section was how can scientists find out if the foxes are part of the same species (or something along the lines of that)

My answer, which may not be correct:
I talked about comparing their DNA and to see if they could breed with one another
I just said see if they can breed and produce fertile offspring.
17. The first question for the fox section was how can scientists find out if the foxes are part of the same species (or something along the lines of that)

My answer, which may not be correct:I talked about comparing their DNA and to see if they could breed with one another
18. (Original post by YourVirginity)
anus xD
XD omg

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20. For the 5 mark question in b2 for the genotype and stuff what did everyone put for each one. The questions were like

Parents genotype
Parents phenotype
Gametes

Offspring genotypes
Offspring phenotypes

Think I got it all wrong 😂

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