AQA AS Biology Unit 1 Unofficial Mark Scheme

Hey everyone. Hope you did well on your tests.

As I haven't seen one being made, I've made a start to one and will add more answers when more people contribute to it. This is obviously unofficial, so the real mark scheme could be pretty different. a ; denotes a different point for each mark.

1)

a) Golgi Appartus (1 mark)

b) Nucleus or Nuclear envelope or Nucleolus; lysomomes; Mitochondria;ER
(2 points for 2 marks)

c) What's the function of the mitochondria?
Produce ATP (for energy)

d) Resolution is highest/greatest; due to shorter wavelength of electrons; can see detailed structures; amoeba are thin so TEM works (2 marks)

2)
Describe investigation A
a) 2 drinks decrease the risk of heart disease; then increase it (as you drink more) (2 marks)
b) 0.2. The y-axis said concentration remaining, so you had to do 10 - 4 which is 6. Then divide that by 30 to get 0.2
c) Evaluate the claim 'Alcohol is good for you'

Yes - in low consumption;
No - correlation does not mean causation;
may be another factor involved;
drinking more than 2/3 increases the risk of heart disease;
didn't specify what alcohols were so can't be sure on the quantity;

3)

4) a) What is a pathogen? A micro-organism that causes disease. (1 mark)
b) Phagocytes may destroy bacteria. Explain how.

Phagocytes attracted by chemicals/recognise the antigens;
Engulf/ingest bacteria;
Remain in vacuole/vesicles/phagosome;
Lyosomoes release (hydrolytic) enzymes/fused with vacuoles;
Pathogen digested/hydrolysed/broken down;

c)

5)

6) Starch/amylase question
a)
b)
c)

7) a) Hydrolysis (1 mark)
b) Proteins too large
c) Villi become damaged; reduced surface area; less diffusion;
membrane bound enzymes; reduced breakdown of proteins; less absorption (Once only for less absorption) (3 marks)

d) Factors to consider: Body mass; Side effects; Age; Gender; (2 marks)

8) a) How does the heart co-ordinate contraction of the atria and ventricles?

SAN sends out electrical activity/wave of impulses;
Stimulates contraction of atria/initiates heart beat/acts as pacemaker;
AVN delays (electrical impulses);
Allowing atria to fill before ventricles contract/ventricles to fill before
contract;
AVN sends of wave of electrical activity down Bundle of His/Purkyne fibres;
Causing ventricles to contract (from base up) / ventricular systole;

b) How does a diet increase the risk of heart disease?

High consumption of fat/cholestrol accumulate in artery wall/ under lining / endothelium of artery;
Atheroma;
Can cause blood clots/thrombus
May break off;
and get lodged in the coronary artery;
Reduces blood supply;
(so) reduces oxygen supply;
Heart muscle can't respire without oxygen and so dies;
Salt/ions;
can causes high blood pressures;

Bit short at the moment - so I'd appreciate if people told the order of the questions (if they remember)!

Question about tube A and B, explain why solution in tube B was higher. (3 marks) Then student concluded that ph8 is optimum. Evaulate this claim. (2 marks)

Reply 21

sconter

11

also bendict+ heat was an answer.

Reply 22

The Assassin

OP

18

Was that tube question question 5 or 6? Don't remember.

Reply 23

MediterraneanX

16

Original post by billybobs

Part c) on question 2 asked to evaluate the newspaper claim of "Alcohol is good for you".

For: Between 1-3 drinks of alcohol is shown to decrease the risk of heart disease by the diagram

Against: States "good for you" - not to do with heart disease as shown by the diagram

Correlation does not show causation - could be due to another factor

The increase of intake after 3 drinks shows to increase the risk of heart disease

I think :3

I basically said three out of the above, but then worried and turned it into a bit of a creative writing sesh and ended up mentioning that we're told investigation C's participants are 40-50 but the ages of the other participants are unclear so it could be if they're all within a fairly limited age span the results wouldn't translate to other age groups? No idea if thats right but it was worth a try!

Reply 24

Blob2491

12

Predicted grade boundaries anyone?

Reply 25

mulac1

wasnt the lung q only about the diaphragm and not the ribcage...

Reply 26

Chicken Bacon

16

Original post by The Assassin

Was that tube question question 5 or 6? Don't remember.

6, bro =]

Reply 27

Scienceisgood

21

Original post by billybobs

Part c) on question 2 asked to evaluate the newspaper claim of "Alcohol is good for you".

For: Between 1-3 drinks of alcohol is shown to decrease the risk of heart disease by the diagram

Against: States "good for you" - not to do with heart disease as shown by the diagram

Correlation does not show causation - could be due to another factor

The increase of intake after 3 drinks shows to increase the risk of heart disease

I think :3

It NEVER said that it causes anything, so, you can't say corrolation doesn't cause the disease because it never said it caused one in the first place.
It merely said "Alcohol is good for you".

Reply 28

britash

2

Original post by Blob2491

Predicted grade boundaries anyone?

47/48 out of 50 for the A
43/44 for the B
36/37 for the C..?

Reply 29

dhillon1

10

does anyone know the answers to the starch/amylase question???

Reply 30

Chicken Bacon

16

Original post by britash

47/48 out of 50 for the A
43/44 for the B
36/37 for the C..?

lower than 48 for an A, but higher than 40 for an A, I'd say 45 seems right

Reply 31

mulac1

a) benedicts test
b) why higher in B than A
c) can't remember...

Reply 32

Blob2491

12

Original post by iAre Teh Lejend

lower than 48 for an A, but higher than 40 for an A, I'd say 45 seems right

I'd say 48 for an A, seemed easier than the January paper

Reply 33

billybobs

5

Original post by Scienceisgood

It NEVER said that it causes anything, so, you can't say corrolation doesn't cause the disease because it never said it caused one in the first place.
It merely said "Alcohol is good for you".

I meant that the alcohol correlation in decreasing the risk of heart disease doesnt mean that this is the causation of decreasing heart disease - it may have been due to the fact that all the participants in the investigation had been exercising or eating a good diet when they were on a low amount of alcohol.

Reply 34

Chicken Bacon

16

Original post by dhillon1

does anyone know the answers to the starch/amylase question???

ph8 tube, enzyme breaks down starch into amylase reducing water potential in tube, water moves in, so tube B solution is higher

Reply 35

totw

I wrote about the atria and ventricles contracting as well as the SAN and everything, so will i get the marks for writing about the cardiac cycle as well as the SAN stuff

Reply 36

britash

2

Original post by iAre Teh Lejend

lower than 48 for an A, but higher than 40 for an A, I'd say 45 seems right

Lets hope so. I got 45/60 in January and that was a B.. I want an A :smile:

Reply 37

Chicken Bacon

16

Original post by Blob2491

I'd say 48 for an A, seemed easier than the January paper

Really ? a lot of people said they lost a LOT of marks. I found the paper fairly straight forward, but meh, the boundaries based on overall performance of students.