AQA AS Biology 2019 Paper 1 Unofficial Mark Scheme

There was the one with Chloroplast DNA and Nuclear DNA. I put - Chloroplast DNA didn't have histones, it was circular and it is smaller than nuclear DNA

Reply 3

CopyThat

Oooh!.. This could be used as an indication for the A-Level paper 1... What things came up? :biggrin:

Reply 4

Shivaay

To be honest, if you're looking for an indication for this years paper 1 you'd be better placed looking at the June 2018 AS papers which are on the AQA website.

Original post by CopyThat

Oooh!.. This could be used as an indication for the A-Level paper 1... What things came up? :biggrin:

Reply 5

Stuff about dna, a case study on cancer cells, Chloroplast. biurets test. asked about how dipeptides are similar and different. some dumb question about amino acids and them separating on a strip. required practical on effect of hydrogen peroxide on potato tubes. some question on conditions of the solution for the centrifuge; e.g. cold, buffered and isotonic

Original post by CopyThat

Oooh!.. This could be used as an indication for the A-Level paper 1... What things came up? :biggrin:

Reply 6

No 6 marker

Original post by gcsestudent26

was there a 6 marker? if so what was it about?

Reply 7

What did people write about how the enzymes active site leads to a high rate of reaction?

Reply 8

Original post by TNOD333

What did people write about how the enzymes active site leads to a high rate of reaction?

Active site is a specific shape due to the enyzme being a protein with a specific 3D tertiary structure, meaning only a substrate with a similar shape will fit the active site and form enzyme-substrate complexes and therefore the enzyme ignore/not react with anything but the subrate and that increase the rate of reaction.

(edited 4 years ago)

Reply 9

Original post by Kallum17

Active site is a specific shape due to the enyzme being a protein with a specific 3D tertiary structure, meaning only a substrate with a similar shape will fit the active site and form enzyme-substrate complexes and therefore the enzyme ignore/react with anything but the subrate and that increase the rate of reaction.

Pretty much what I wrote too 👍
What did people get for the rate of reaction values in the table and how did their graph look like?

Reply 10

Original post by TNOD333

Pretty much what I wrote too 👍
What did people get for the rate of reaction values in the table and how did their graph look like?

I messed that up, didn't know what arbitrary units meant and didnt see the limit of 1 unit. I thought i could just do 10/time for each. Im gutted because ive lost marks due to dumb units.

Reply 11

I’m not sure whether I got it right or not, but I did hydrogen peroxide concentration divided by the 10cm3 of oxygen value and plotted hydrogen peroxide concentration on X axis and rate of reaction of the Y axis and the curve was basically a standard positive correlation curve where, as the hydrogen peroxide concentration increases the rate of reaction increases. I rushed the curve due to limited time so it looked a little crappy and wishy washy

Original post by Kallum17

I messed that up, didn't know what arbitrary units meant and didnt see the limit of 1 unit. I thought i could just do 10/time for each. Im gutted because ive lost marks due to dumb units.

Reply 12

Original post by TNOD333

I think thats wrong, rate is volume of oxygen/ time it took. So 10/time for everything. Then you had to convert everything to arbitrary units as the maxium units was 1 (i didnt do this).

Reply 13

Yeah I think your right, I left the graph till near the end so I kind of rushed it and didn’t spend enough time on it
What you get for percentage error and the volume question
I got 7.5% and 7455 or something like that

Original post by Kallum17

I think thats wrong, rate is volume of oxygen/ time it took. So 10/time for everything. Then you had to convert everything to arbitrary units as the maxium units was 1 (i didnt do this).

Reply 14

Original post by TNOD333

1/15*100 + 0.5/5*100 = + or - 16.67 %

Reply 15

Yeah percentage uncertainty was 16.67% and the volume i got was 7455 or something

Original post by Kallum17

1/15*100 + 0.5/5*100 = + or - 16.67 %

Reply 16

Original post by Blizz Jr

Yeah percentage uncertainty was 16.67% and the volume i got was 7455 or something

I ****ed that up , i thought the chloroplast was 17500 and that the mitochondria was 200 something cm3 anf that the question wanted the volume of the original solution. I didn't have time to go back and check for mistakes. Im really gutted.
The actual way would be 17500 * 0.441 = 7717.5 - 200 = 7517.5 ( i dont remember the actual volume of mitochondria)

Reply 17

Original post by Kallum17

17500/100*44.1 = 7717.5
7717.5 - 262.5 = 7455

Reply 18

epooper

Does anyone have any idea what was going on with that’s amino acid filter paper question??? Absolutely no idea what it relates to ??

Reply 19