# AQA Biology B2 - Unofficial Mark Scheme

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1. (Original post by Roquebrune2014)
Don't know the question number, but it was the question about why a donor organ would be rejected, you need to say there are different antigens on the surface for a solid 3/3

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Was this the advantage of using stem cells from an umbilical cord in comparison to a donor question?

Are you sure you are talking about b2 and not b3?
2. the gametes would be B and b for both because i dont think its asking about x and y
3. (Original post by GCSE_core)
Was this the advantage of using stem cells from an umbilical cord in comparison to a donor question?

Are you sure you are talking about b2 and not b3?
No it was definitely an organ question, I was replying to this:

Maybe it was B3, it's all a blur now anyway...

For the advantage of stem cells one I put that it was quicker to treat them as there was no donor waiting list

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4. Foundation mark scheme?
5. For the measurements ones...
there were 20 planktons
the quadrat was 25cm by 25 cm soooo... 625 cm^2... divide by 100 to get to meters to get 6.25m^2
And then so every m^2 there would be 3.2 planktons...
The total area of the field was i thibk 500m by 100m...or it could have been something else i cant remember so it came to 50000m^2
So the estimated number of plankons was 50000 X 3.2 = 160000
or it could have been 50000/3.2 to get 15625 (im not sure)
6. Hey guys i created a question paper thread with the relevant information required for the questions i think. Hopefully it will trig ur memories and help out the answers. Some questions are incomplete and would appreciate your help.
http://www.thestudentroom.co.uk/show...9#post65655309
7. (Original post by Roquebrune2014)
No it was definitely an organ question, I was replying to this:

Maybe it was B3, it's all a blur now anyway...

For the advantage of stem cells one I put that it was quicker to treat them as there was no donor waiting list

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I honestly don't remember this on B2, there's not much/nothing on antigens and organs.
I also put it was quicker as you wouldn't need a donor
8. (Original post by GCSE_core)
The question last year was still an investigation question but measuring the distribution of organisms. No way would a quadrat be used for photosynthesis because there are plans/organisms to measure and you throw a quadrat on the floor. I'm afraid your teacher is wrong-hope you've done well though.

omg i give up i don't want to fight with you so i hope u did well aswell
but then what did u write about?
9. (Original post by GCSE_core)
I honestly don't remember this on B2, there's not much/nothing on antigens and organs.
I also put it was quicker as you wouldn't need a donor
Yeah it probably was, sat them back to back so it's hard to remember, plus when I was revising I was basically treating B2+3 as one massive biology exam

Yay someone put it was quicker too!

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10. (Original post by hansa123)
omg i give up i don't want to fight with you so i hope u did well aswell
but then what did u write about?
To make it a fairer/more accurate test to keep the starting amount of water in the beaker the same, leave the plant in the water for the same time, same light bulb intensity etc
11. (Original post by GCSE_core)
To make it a fairer/more accurate test to keep the starting amount of water in the beaker the same, leave the plant in the water for the same time, same light bulb intensity etc
This is the correct approach to the experiment question👍

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12. (Original post by Roquebrune2014)
This is the correct approach to the experiment question👍

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Thankyou so much! Hope you get the grade you're after😄
13. There was a question In the stem cell part that asked something like: "why is it better to use stem cells from the umbilical chord rather than the embryos in IVF?" And then the one after was "Why can't you treat someone's genetic disorder with their own individual stem cells?"
14. (Original post by GCSE_core)
To make it a fairer/more accurate test to keep the starting amount of water in the beaker the same, leave the plant in the water for the same time, same light bulb intensity etc
oh
15. (Original post by Cakes717)
I agree
would you say the genotype was heterozygous or homozygous and the gametes was Bb or bb
16. (Original post by afghan-superman)
Nope sorry, the gametes were the offspring, it was (BB Bb Bb bb) meaning only 25% chance of red hair
I put BB Bb Bb bb for the genotypes, but gametes are the sex cells, X Y for males and XX for females
17. (Original post by GCSE_core)
Thankyou so much! Hope you get the grade you're after😄
You're welcome! You too😀

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18. For the 6 mark question I wrote about iodine solution testing for starch and turning the leaves dark blue to see if photosynthesis has taken place. I said that I put the leaves in different light intensitys and then put them in beakers to see how long the solution took to turn blue and then recorded it. Does anyone know if they would accept this method?
19. Is there any chance you could put the number of marks next to each question so we can could, thanks.
20. (Original post by Blahblahblah7)
The pictograms thing said that A is a cell then B is double its size then it spilits (C) so back to same size as A then that splits again

And D,E,F,G are sperm cells

So A = 6.6
B = 13.2
C = 6.6
And D onwards are 3.3 I think???
There wasnt a D, it just asked how many pictograms would be in a fertilised embryo, which was 6.6

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