Aqa a-level biology 7402 - paper 2 - unofficial mark scheme 13th June 2019

Yes it did because the overall DNA strand length will be shorter

I put so it wouldn't evaporate so IAA conc the same in each dish

I put the same amount of oxygen for respiration for each one...

I put that too, as different oxygen may effect how much they can respire and therefore would affect growth

I also got 0.608 for my Rf value. I also got 177 something similar for the kJ for the energy question about the zebras.

I think I got 3.24 micro
metres for the dna bases. I can’t really remember this question but I think they told you it was 9.513 kilobases long ( I can’t remember if it was 9.531 or 9.513 ) so I multiplied by 1000 to get 9531 or 9513 whichever. Then divided by ten because 10 base pairs were equivalent to a set measurement ( cannot remember exactly ) then I multiplied my answer by the set measurement.

Aren’t they in the same room though anyway so the conc of o2 would just be the same regardless idk

i wrote about transects and quadrats for the 5 marker would i get 0?

the electrophoresis question, which volunteers did people get for the last question?

the electrophoresis question, which volunteers did people get for the last question?

I had no clue what the hell that was about I just said 2 and 5

Could be right I was thinking that too but then before the DNA winds into a helix the bases arent paired so I was thinking they may be talking about if the bases were placed side by side the actual length of the whole dna since theres 2 strands, and the first bit mentioned kilobases which is each singular bases and the DNA consists of double strands so maybe might have wanted you to notice it otherwise I doubt they wouldve said 10 base pairs instead of just 10 bases but who knows

the electrophoresis question, which volunteers did people get for the last question?

What was the reason for the lid on the Petri dish? I put so Iaa doesn’t evaporate and contaminate the other dishes/ would alter its concerntration therefore conc not controlled but wasn’t sure

I put 5 and 3...

No, quadrats is the correct answer! Transects, however, is not. So depends how much you talked about quadrats.

Oh god I think I misinterpreted this because I put about the lid being for darkness so the IAA would remain evenly distributed instead of going to the shaded areas only (so the elongations a straight line so easier to see change)