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AQA A-level Biology 7402 - Paper 3 - 17th June 2019 Unofficial Markscheme

Q1.
Ultrafiltration describe process...
Tick Box
Thicker medulla

Q2)
Heart dissection
LEFT atroventricular valve
LEFT ventricle
Precautions...
Scapel (sharp etc)
Gloves (sanitory purposes etc)
Uni directional flow
Describe valves opening and closing
Describe pressure changes and flow of blood

Q3)
Samples of water
Make up KNOWN solutions of water
Measure absorbance of each sample... use colorimeter
Calibration Curve
Use graph to determine cloudiness

Nutrient cycle role of sparobionts
decompose , ammonification etc

Q4)
Caffeine --> Why it increase HR
Mention increase nerve impuleses to medulla oblangata
Increase nerve impulse frequency through sympathetic NS
More Noradrenaline released
More SAN/AVN excitation
More contraction of cardiac muscle

Control:
NO caffeine but sugar
Effect: See whether sugar actually has an affect on increasing HR

Q5)
Anti cancer drug (3marks)
Trexall has a similiar hape/structure to folic acid
Acts as an COMPETITIVE inhibitor
Less E-S complexes formed
Less nucleotides available for DNA replication
Less division by mitosis

Other than age:
Ethnicity?
Metabolism?
Same progression of their disease?

V02 graph and CS activity
mention each effect both had positive increase
One more than other

Use all graph
No correlation/overlap

Age of cancer cell 4.4-4.8

STARFISH question...
Choice chamber ... two things kept the same so that they show normal behaviour
PH
Temperature
Coral reef etc
Explain whether either light can be used(3 marks)
Comment on BOTH SD
Effect on each

comment on vo2/cs graph and evaluate conclusion of that retarded graph both 3 marks each so 6 marks
then 2 marker for mitrochondrial rna or something, was the last question

I think there are a few more marks for that mitrochondria question but I cant rmemeber them lemme know if you remember

Edit got them:

1 mark for mutation - substitution
2 marks for comment on the effect of VO2/CS question after 8 weeks of exercise

Maths questions...
17.4
Volume of blood (70-78 range)
Sphere question
Hours for starfish... 3 Hours
30030mm^3

Essay (25marks)
Bonding and bonds in organisms
DNA and its use in tech

Help me with questions @evilhomer

(edited 4 years ago)

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What a hero

Hi all

I couldn't find anyone making an unofficial markscheme and thought there must be a few people wanting to find out what the answers were!

I will update this when people start agreeing on answers and keep this updated.

Put what you got below

EH :evil:

Reply 3

wajopdsjf

evil homer , i have the start of a marksheme up look on my profile, but idk how to tag it

Original post by Evil Homer

Hi all

Reply 4

wetti

Heart: Left ventricle, left atrio-ventricular valve.

Reply 5

CopyThat

**** i thought it was the semi-lunar valve.. it looked quite high up :frown:

Reply 6

trollface54

https://i.pinimg.com/originals/e5/6c/40/e56c4095f50b7b019a952042756f4807.jpgIn this diagram it looks like it was semi lunar valve

Looks like it was semi lunar valve

Reply 9

wajopdsjf

they wouldve made it clearer if it was semi lunar eg by labelling the aorta
but the fact that they labelled left ventricle gave it away....

Original post by trollface54

Looks like it was semi lunar valve

Reply 10

JF2000

There was a question about the anti-cancer drug and how it helps slow cell devision can't quite remember it though

Reply 11

CopyThat

Pretty sure that was just competetive inhibition?

Original post by JF2000

There was a question about the anti-cancer drug and how it helps slow cell devision can't quite remember it though

Reply 12

wajopdsjf

yes ive added it

Original post by CopyThat

Pretty sure that was just competetive inhibition?

Reply 13

Vfdvf-%

Will I get the mark for just saying it was an inhibitor, I’m scared

Reply 14

wajopdsjf

Im afraid it was 3 marks so you may needed to add more detail

Original post by Vfdvf-%

Will I get the mark for just saying it was an inhibitor, I’m scared

Reply 15

Danielle D

did u just write 'it is an inhibitor' in that question?

Original post by Vfdvf-%

Will I get the mark for just saying it was an inhibitor, I’m scared

Reply 16

Vfdvf-%

Yes

Original post by Danielle D

did u just write 'it is an inhibitor' in that question?

Reply 17

hobicorn

You’d probably have to be more specific and say what kind of inhibitor as there are two types and mark schemes are usually specific with that

Reply 18

Vfdvf-%

I said less enzyme-substrate complexes formed so I’ll probably get 1 mark

Original post by hobicorn

You’d probably have to be more specific and say what kind of inhibitor as there are two types and mark schemes are usually specific with that

Reply 19

Alifiahus

I think you’d have to be more specific, I don’t even think competitive inhibition would be accepted? (Unless this is an example of competitive inhibition I’m not sure) There was a methyl group (-CH3) on the diagram, so I wrote that the drug slows down cell division my methylation, the methyl group binds to the promoter region on the DNA molecule, which prevents RNA polymerase from binding, therefore preventing transcription