WJEC A-Level Biology Unit 3 (A2) [7th June 2023] Exam Chat

There was a small question asking about the marking used on frogs. They mentioned cutting off a toe or something. How did you say that it may affect the validity of the results?

i said something very similar but less detailed. i said when ph rises, the protons flow down the electrochemical gradient, through atp synthase, into stroma or whatever i mentioned. energy releases is used to synthesis ATP from adp and pi

i also found it funny how they used trucks in question 1.

strange. i found the enzyme question in the beginging hard to remember, but i ended up writing nad and fad. there was a part that asked for you to describe why the yeild of atp is different and i think my answer was silly, but i talked about the how there is 10 nad molucules but only 2 fad produced. i worded it weirdly too. ugh

i assumed they meant actually chopping off a toe. i said they might lose blood, effecting survival. id rather they have used marker with ink because my answer seems silly.

I found the paper ok but so time consuming as every question seemed to be an application style question. The 9 marker was very kind though. What did you put for density dependent factors limiting population? I put disease then went onto say because it was a continuous decline. if it was density independent then there would have been more peaks and troughs?

Then there was one about a chemical affecting the ascending loop of Henle I think? Vaguely remember putting something about the co-transporter protein active site changing shape so no substrate enzyme complex formed and glucose remained in the filtrate instead of being reabsorbed in the ascending limb.

The section on action and absorption spectrum seemed pretty straightforward

What did you all put for the enzyme on the first page and the planetary boundary one with the enzyme and products??

I put decarboxylase as the enzyme and the planetary boundary one, if i am thinking of the same one about the carbon fixation, put RuBP and CO2 as the reactants and RuBisCo as the enzyme

I got so confused with that one bc dehydrogenation happens between TP and pyruvate but then it asked what happens to the carbons 😭😭ugh idk

i said that there was an increased competition for food because pond 1 had 5000 tadpoles per meter and pond 2 had 1000. i calculated the rate of decline for pond 2 and then said it was smaller than pond 1 due to the fact it had more competition

I found the paper ok but so time consuming as every question seemed to be an application style question. The 9 marker was very kind though. What did you put for density dependent factors limiting population? I put disease then went onto say because it was a continuous decline. if it was density independent then there would have been more peaks and troughs?

Then there was one about a chemical affecting the ascending loop of Henle I think? Vaguely remember putting something about the co-transporter protein active site changing shape so no substrate enzyme complex formed and glucose remained in the filtrate instead of being reabsorbed in the ascending limb.

The section on action and absorption spectrum seemed pretty straightforward

Wait did they purposely increase the pH? I thought it happened naturally over a short amount of time.

for that i said we exhale it! i looked at previous mark scheme that asked about what happens to the co2 and it usually says about breathing out but the wording of it made me a bit stumped. hopefully we did alright!

Where was the question on the frog markings?? Was it a single one marker at the bottom of the page or something because i never saw it and looked over the entire paper at the end!

yes it was only a 1 mark question so and was on the page at the top after the table of numbers of frogs.