2016 OCR Biology A Breadth - Unofficial Mark Scheme

Last page letters were: C, then ADF (4marks)

Deffo put AF for the last one so idk if I'd get a mark there

Please post any questions you remember! If you are confident in the correct answer, please also give what you wrote and any other acceptable answers you may think were available; please also correct me if I am wrong anywhere here
Assigned question number and answer
== SECTION A - ALL MULTIPLE CHOICE [1 mark] ==
| 1) Microscope (correct row)
| (LM 1,500x mag, 2 micrometers; TEM 500,000x mag, 0.2nm; SEM 100,000x mag, 0.2nm)
| C

| 2) Monomers of disaccharides join by what bond?
| Glycosidic
| Think it was C

2)

Questions without assigned number
POTATO TUBER QUESTION
Which two steps in the procedure should be taken to produce valid results?
- I put that different concentrations were used and the mass change was recorded.

How can the student use the results to calculate water potential?
- I put 'plot a graph of mass change against concentration, find x intercept, use calibration curve'

Label the parts of the cell. [3 marks]
- I think on this one there was cell wall, plasma membrane, and tonoplast.

What would be found in the gap between the membrane and cell wall in the plasmolysed cell? [1 mark]
- (LABEL W) Sucrose Solution @DaVinciGirl


TRANSPORT QUESTION
State the name of the name of the shift in the oxygen dissociation curve to the right: [1 mark]
- Bohr Effect

BLOOD VOLUMES QUESTION
Percentage change in volume of O2 in saturated blood and saturated plasma? [2 marks]
- My solution:
-where x = plasma value, y = blood value:
-$100\times\frac{y-x}{x}=6600$

Erythrocytes have no organelles. Advantages/disadvantages? [2 marks]
- My solution:
- Advantages: More space for Haemoglobin.
- Disadvantages: Short lifespan.

Viruses do not use erythrocytes as host cells; plasmodium does - suggest why? [2 marks]
- My solution:
- Plasmodium is a protoctist.
- It invades the erythrocyte and acts as a parasite.
- As it has no organelles, the virus cannot use this as a host to reproduce.

Volume of oxygen per minute? [2 marks]
- 1005 cm^3 @htrowslec

I think i put B,C and ADF, can't even remember what they were now xD

I had that exactly but crossed out B because it was 4 marks not 5

I'm just waiting for someone to respond, but I believe the first tuber question would be about controlling variable, like keeping the inital mass of potato disc the same and using the same volume of sucrose solution?

I did that in once of the mocks but they sometimes have more letters you need than the number of marks

B was the temperature one, so the rate increases until 25 degrees then decreases at high temp. This did confuse me slightly so i didn't put it down. How is this proof of translocation? (i think part (a) was translocation and (b) proof of source to sink?)

It relies on active transport, which requires carrier proteins that would denature at high temperatures, bc i think it was asking for proof that it was an active process

B was the temperature one, so the rate increases until 25 degrees then decreases at high temp. This did confuse me slightly so i didn't put it down. How is this proof of translocation? (i think part (a) was translocation and (b) proof of source to sink?)

It was asking for proof that it was an active process and the only appropriate answer was C because it mentioned that translocation would stop with a drug that inhibits respiration

It was asking for proof that it was an active process and the only appropriate answer was C because it mentioned that translocation would stop with a drug that inhibits respiration

Surely B's also acceptable then, as the sucrose is actively loaded into the phloem, and these proteins would denature at high temperatures?

the one for percentage increase was 98.05% i think. bonding of two nucleotides was condensation reaction, obviously water given out. the multiple choice question about potometers, was that the tap didn't need to be open, the table for the rhino was something like, animalia, phylum, class, genus and sumatrasomething cant remember. Would i be correct if i put permanent Vacuole instead of tonoplast?

My logic is that the heat is another seperate thing because it denatures the proteins that load the sucrose, C specifically mentions energy being stopped therefore it is proof.
I'm in the same boat as you I have no idea

I think W was sucrose solution

Posted from TSR Mobile

I thought W was air spaces :/

I think W was sucrose solution

Posted from TSR Mobile

The percentage increase was definitely 6600%
Nucleotide bonding was condensation releasing water, yes
Potometers tap not open, yes
I wrote vacuolar membrane, completely forgot the word tonoplast. There was another label to the middle of the vacuole so I think they'd accept vacuolar membrane as well as tonoplast