AQA GCSE B2 Biology Unofficial Mark Scheme - 9th June 2017 Watch

12johnsonA034
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So i made this from other people's posts combined, if parts aren't correct please let me know
If there's parts missing too!

1) Epithelial cells can be found in the skin or inside the body as lining around organs

[Labelling the parts]
-Cell membrane
-Cytoplasm

[Tickbox]
-Protein synthesis

[What is diffusion]
-Diffusion is the movement of particles from a high concentration to a low concentration to achieve equilibrium

2) [6 marker on the quadrat]
~Random sampling by standing and throwing
~Sample different areas
~Count twice to remove human error
~Repeat investigation to be more valid
~Count number of plants in quadrat and test the pH using the measure
~Repeat in different areas of pH

3) [Glucose sports drinks]
[Why are placebos important?]
To provide a control to compare it to and so that the cyclists don't know which they have so they don't act differently thinking that they are under the influence

[Evaluate the scientists' conclusion - Sports drinks make cyclists perform better] ??
Agree as the figure showed this, the placebo cyclists weren't able to carry on after 3 hours whereas when given sports drinks they were able to. The cyclists performance was generally much higher when given the glucose drink.
Disagree as it may not help performance because it was tested on a stationary bike at a constant speed which isn't realistic for a race. At around 2 (or 3) hours the glucose fuelled cyclists had a large drop in performance which would not help them in a race.

[Explain how the increased breathing rate, heart rate and concentration of glucose improve the athlete's performance]
~Increased breathing rate
= more oxygen to go into blood to be used for respiration, lets aerobic respiration happen which causes no lactic acid to build up so cyclist can continue to go
= more opportunity for carbon dioxide to be expelled

~Increased heart rate
= heart beats more so pumps more blood which takes more glucose and oxygen to cells for respiration to release energy so cyclist can be stronger

~Concentration of glucose
= Raise the amount of respiration that can be done with more glucose so more energy can be released which provides the cyclist with more energy

4) [What starch breaks down into]
Starch --> Sugars

[Control variables of starch experiment]
- Same volume of amylase
- Same volume of starch
- Same amount of time given for starch to break down

[Iodine colour]
4 minutes = Dark Blue
6 minutes = Light brown

[Improvements to the experiment]
- Repeat at the different pH levels
- Use smaller intervals of pH between 6-8 to get a more accurate result

[Suggest what happens to Amylase in pH 3]
It gets denatured so won't work in these conditions or (possibly) the reaction will show down even further

5) [Equation for photosynthesis]
Carbon dioxide + Water --> Glucose and Oxygen

[Arbitrary units at 0.04%]
16 arbitrary units

[Percentage increase in arbitrary units from 0.04% to 0.08%]
25%

[Why farmers shouldn't use more than 0.08%]
Causes more global warming, costs more, it's no more effective to use over 0.08% as everything above this has the same arbitrary units - therefore it would be a waste

[Changes the farmer could make to raise photosynthesis]
-Increase light
-Increase temperature

6) [What is an allele?]
Different forms of the same gene

[Type of cell division]
Mitosis

[How many chromosomes in a human cell?]
46 chromosomes

[Number of divisions to get to 16 cells]
4 divisions

[What does recessive mean?]
A non dominant allele that must have teo copies for it

[What does heterozygous mean?]
Two different alleles

[Ethical disadvantage of embryo screening]
Could harm the embryo or the mother

[Advantage of embryo screening]
Stop the suffering of the child, find out if the child had a genetic disorder

[Genetic cross diagram]
You should get NN, Nn, Nn and nn
- so the possibility of 25% or 1/4

7)[What is a species?]
A group of organisms that have common genes and can interbreed to produce fertile offspring

[How do we use fossils to see how species today have evolved from simple organisms?]
-Fossil record
-evidence of previous species
-can provide comparisons

[Different species question]
-Geographical isolation
-Speciation (can't interbreed)
-Adaptation and mutation
-Natural selection
- Similar characteristics due to few changes as there's reasonably similar environments
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cricinfo
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Would about 48ish in Paper 2, 50 in Paper 1 and about 50 in Paper 3 plus 50/50 in the ISA be enough to get an A star?
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12johnsonA034
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(Original post by cricinfo)
Would about 48ish in Paper 2, 50 in Paper 1 and about 50 in Paper 3 plus 50/50 in the ISA be enough to get an A star?
For sure it should be, normally on paper 3 around 47/48 out of 60 is equal to an A* and similar on the other papers
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emilygrace25
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isn't it 23 chromosomes
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Geekygirl07
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(Original post by cricinfo)
Would about 48ish in Paper 2, 50 in Paper 1 and about 50 in Paper 3 plus 50/50 in the ISA be enough to get an A star?
Should be. An A* is 360 UMS so you should get it!
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notcalleded
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(Original post by emilygrace25)
isn't it 23 chromosomes
Yeah. I thought it asked for the number of Chromozones in a Gamite.
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cricinfo
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(Original post by Geekygirl07)
Should be. An A* is 360 UMS so you should get it!
Thank you! Hope you do great
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ErinMobbs
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For question 3 - would "Glucose" be considered the correct answer??


Posted from TSR Mobile
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Emaemaema
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(Original post by emilygrace25)
isn't it 23 chromosomes
I put that too but it's 46 because it's 23 pairs, I'm so annoyed at myself
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sahir0113
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(Original post by cricinfo)
Would about 48ish in Paper 2, 50 in Paper 1 and about 50 in Paper 3 plus 50/50 in the ISA be enough to get an A star?
thats an easy a*
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Arezoo noori
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[QUOTE=ErinMobbs;72027548]For question 3 - would "Glucose" be considered the correct answer??

I also wrote glucose instead of sugars. 😳
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Arezoo noori
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That's annoying.
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Geekygirl07
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(Original post by cricinfo)
Thank you! Hope you do great
Thanks!! Me too, I'm dying for an A! I got 50/50 in isa, around 45 in B1, 50 in B2 and around 45 in b3.... hoping this secures it for me.. it should do!
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emilygrace25
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What mark do you think for an A*?
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tabby.m16
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(Original post by ErinMobbs)
For question 3 - would "Glucose" be considered the correct answer??


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i also put glucose, oh no
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ErinMobbs
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[QUOTE=Arezoo noori;72029274]
(Original post by ErinMobbs)
For question 3 - would "Glucose" be considered the correct answer??

I also wrote glucose instead of sugars. 😳
Me too but that was because I was sure that's what I was told! Hopefully it's considered the same
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Essi78654
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(Original post by emilygrace25)
isn't it 23 chromosomes
23 pairs = 46 overall, but I was a retard and put 46 and then added pairs at the end of the exam, thats 1 easy mark down the drain 🙃
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chocomonster101
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[QUOTE=ErinMobbs;72031946][QUOTE=Arezoo noori;72029274]

Me too but that was because I was sure that's what I was told! Hopefully it's considered the same[/QUO

DUDE ITS THE SAME!!!!
'In animals, during digestion, starch molecules are broken down in the body into small glucose molecules'

http://www.bbc.co.uk/bitesize/standa...es/revision/5/
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abdui080.304
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for the question about starch breakdown i wrote amino acids. would that be considered correct or not?
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s4b3rt00th
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can someone provide how many marks are provided for each question?
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