Edexcel Biology (Unofficial) B2 Mark Scheme. Watch

keepyourapology
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How did that exam go? Will be posting a mark scheme based on answers soon!

Special thanks to niichola!
Spoiler:
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Question 1 (Bacterial/Yeast Cell) :
Part (a):
(yeast cell)
• has a nucleus (1)
• does not have a flagellum(1)
• does not have a plasmid(1)
• has a vacuole(1)
(bacterial cell)
• has chromosomal DNA /circular DNA (1)
• has a capsule (1)
• has a slime coat (1)
• does not have mitochondria (1)
Part(b):
Mitochondria. (1)
Part(c):
Question about how anaerobic respiration breaks down to form alcohol and carbon dioxide. Compare anaerobic and aerobic respiration of a yeast cell.
Part (?):
The values for the table go from 300 -> 400 -> 200. This shows that the Enzyme activity is reduced below or above the optimum temperature/pH.
This applies to all enzymes, hence most of their graphs have an upside down U-shape.
So the value for the sucrose/lactose (can't remember which) will not increase as the values go from 28 -> 35 ->
It will rather decrease to around (28 -7) = 21. It could be from around 17-21, hence it is that is the correct answer.
(thanks to TheMasterofLife!)


Question 2 (Digestion):
Part (a):
Peristalsis
Part(b):
Disadvantages of using the tube as a model : No villi
Part (c):
The amylase in the saliva will break down the starch present in the bread to form sucrose.

Fossils Question :
Part(a) :D
Part (b):
Human Intervention
Loss of habitat
Climate Change
Predators (correlate to increase in group B&C)
Part(c):
  • The mammals have a humerus;
  • an ulna
  • wrist bones
  • and 5 fingers/digits. There is more to write, but that should be enough. The other answers are:
  • a radius
  • The wrist bones are called carpals
DNA Extraction:
Part(a):
Part(b):Break up proteins in cell membrane.
Part(c):
Part(d):
Differences between mitosis & meiosis:
Haploid cells vs Diploid Cells (1)
Genetically Varied vs Genetically Identical (1)
4 Daughter Cells vs 2 Daughter Cells (1)

Circulatory System:

Part(a):Pulmonary Vein
Part(b):De-oxygenated blood moves into the right atrium via the vena cava, moves to the right ventricle through the valves, and goes to the lungs via the pulmonary artery.
Part(c):
Part(d):Six marker on how the narrowing of coronary arteries affect the functioning of the heart and surrounding body cells.
  • The narrower artery is on the left ventricle. By it being narrow, the muscles receive less oxygen and glucose, and will be worker weaker.
  • The ventricle will not be able to contract as strongly as before, causing less heart pressure
  • This will cause a weaker heart, and decrease the cardiac output
  • This means that the less blood will be going throughout the body, meaning more anaerobic respiration when exercising
  • There will be more lactic acid left over
  • There will be a longer excess post-exercise oxygen consumption (EPOC) (didn't actually write it, just realized it now)
Leaves:

Part(a):
Part(b):
Part(c):
Light is no longer the limiting factor, and hence, increasing the amount of light intensity will not affect rate of reaction, as some other factor is in shorter supply and is controlling the rate.
Part (d):
Six marker on movement of water in a plant.
Last edited by keepyourapology; 2 years ago
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Asfand786
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not bad actually, just stumbled a little at the fossils topic
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keepyourapology
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What was the answer for that test tube sucrose/lactose question?
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roshna00
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the chloroplast question threw me a bit
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Asfand786
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(Original post by keepyourapology)
What was the answer for that test tube sucrose/lactose question?
I put down 17, but idk if its right, some people put 18 and some put 15 but it was about an estimate so idk
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roshna00
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(Original post by Asfand786)
I put down 17, but idk if its right, some people put 18 and some put 15 but it was about an estimate so idk
Yeah i put 17. I think its okay as long as its lower than the other 2
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Asfand786
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(Original post by keepyourapology)
How did that exam go? Will be posting a mark scheme based on answers soon!

Question 1 (Bacterial/Yeast Cell) :
Part (a):
(yeast cell)• has a nucleus (1)• does not have a flagellum(1)• does not have a plasmid(1)
(bacterial cell)• has chromosomal DNA /circular DNA (1)• has a capsule (1)• has a slime coat (1)• does not havemitochondria (1)

Fossils Question :

MCQ Answer : D
what about Vacuole?
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keepyourapology
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(Original post by Asfand786)
what about Vacuole?
Yes that too! This is a copy of the mark scheme from the 2013(?) paper because the same question came up! And the vacuole answer was in the 'accept' section.
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caitlinford3
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(Original post by roshna00)
Yeah i put 17. I think its okay as long as its lower than the other 2
(Original post by Asfand786)
I put down 17, but idk if its right, some people put 18 and some put 15 but it was about an estimate so idk
17? where did you get that from? wasn't it 42?
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keepyourapology
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(Original post by caitlinford3)
17? where did you get that from? wasn't it 42?
17, cuz it should have been less than the other two. I put 20 but Idk who's right.
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caitlinford3
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(Original post by keepyourapology)
17, cuz it should have been less than the other two. I put 20 but Idk who's right.
Are we talking GCSE or iGCSE? From what I remember there was pH 9 = 28 mg/cm^3 ; pH 7 = 35mg/cm^3 and then you would notice the pattern and add 7 again for pH 5 to get 42mg/cm^3?
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keepyourapology
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(Original post by caitlinford3)
Are we talking GCSE or iGCSE? From what I remember there was pH 9 = 28 mg/cm^3 ; pH 7 = 35mg/cm^3 and then you would notice the pattern and add 7 again for pH 5 to get 42mg/cm^3?
GCSE, but as I said, idk it's right because I was just following the pattern from the sucrose solution, because it said 369, 455 and 225, indicating that the middle value at pH 7 would be the highest.
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bue34 c
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What did you guys think of this exam?
ill post my answers
q1 bacteria has not got mitochondria, bacteria has not got nucleus
next part is organelle in yeast that allows it to respire? mitochondria
equation for yeast to anaerobically respire is gulocose - alcohol + carbon dioxide
write the differences between aerobic and anaerobic in yeast? I said when yeast aerobically respire they don't just use glucose put also use oxygen.( I think thats right)
next part ...
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keepyourapology
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What did y'all put for the question about different number of chloroplasts in the last question?
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caitlinford3
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(Original post by keepyourapology)
GCSE, but as I said, idk it's right because I was just following the pattern from the sucrose solution, because it said 369, 455 and 225, indicating that the middle value at pH 7 would be the highest.
The bottom 3 in the table weren't sucrose they were lactose, and it was following the lactose? Sucrose + lactose would perform differently
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caitlinford3
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(Original post by keepyourapology)
What did y'all put for the question about different number of chloroplasts in the last question?
I said something like it's an adaption which would maximize photosynthesis because light intensity is a limiting factor and so having chloroplasts on every site will make sure that they capture every site of light intensity, something like that, I didn't like that Q
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keepyourapology
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(Original post by caitlinford3)
The bottom 3 in the table weren't sucrose they were lactose, and it was following the lactose? Sucrose + lactose would perform differently
Yeah, lots of people said that, but then, why would they put that sucrose table if it didn't show the pattern? Maybe it was to throw us off, but I'm not very sure. I'll ask my Biology teacher. What did other people in your year put?

(Original post by caitlinford3)
I said something like it's an adaption which would maximize photosynthesis because light intensity is a limiting factor and so having chloroplasts on every site will make sure that they capture every site of light intensity, something like that, I didn't like that Q
That's a really good answer, ngl, I put a dumb one, like there's more chloroplasts at the top because that's where most of the sun is absorbed so the plant can start producing glucose right away. Wow, I feel stupid now. xP I hope I didn't lose enough marks to lose an A*..I don't know how the grade boundaries will be.
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htkta
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I said something along those lines too. I mentioned that more photosynthesis means more glucose for respiration but I don't know whether that has any relevance? The heart diagram Q messed me up. I always get those wrong :/
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bue34 c
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(Original post by caitlinford3)
I said something like it's an adaption which would maximize photosynthesis because light intensity is a limiting factor and so having chloroplasts on every site will make sure that they capture every site of light intensity, something like that, I didn't like that Q

Yh i put something similar I said more chloroplast will increase the rate of photosynthesis and chloroplast at different places like leaf palisade cells will mean photosynthesis can occur quicker because it is closer to the stomata hence it can get carbon dioxide and oxygen at a faster rate through diffusion - so less diffusion pathway through the spoons Mesophyll layer
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keepyourapology
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(Original post by htkta)
I said something along those lines too. I mentioned that more photosynthesis means more glucose for respiration but I don't know whether that has any relevance? The heart diagram Q messed me up. I always get those wrong :/
What were the heart questions? I completely forgot..And don't worry, I'm sure you did okay. The paper was a bit messed up.
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