Edexcel A-level Biology B Paper 3 - 18th June 2025 [Exam Chat]

I think it wasn’t too bad but I had a hard time on some questions trying to get all the marks esp the 5 markers

Also what did people get for:
K for bacteria? (Can't remember what it was exactly)
Quadrat that was the best? (I got the 0.01 one as that showed 60 which was closest)
T? (-2.03 or something like that? Also what did people choose for degrees of freedom? Wasn't sure if it was 15, 16, or 30 lol. Not that it really makes a huge difference to the answering of that question tbh, it'd all be 10% significant for me.)
Magnification?

bro that quadrat one, how do u even do u even get the 4 marks, i was yapping on how she had to place 500 quadrats and it was an overestimate, i said it was the best but where are the 4m

You needed to calculate how many dandelions it predicted for the mean. The area was 5x10 so 50m² and it's calculated by taking how many dandelions were predicted per quadrat, then multiplying by however many times to represent 50m². For example, quadrat 0.01m² was best because it represented something like 6/500 (amount of dandelions divided by number of times used) and then you multiplied by 5000 to get 60, the closest value to 53

I had a gut feeling that serial dilution would come up and didn't have time to go over it, and there it was. Just had to skip over it but only 2 marks ig. What did people put down for the enzyme question on how to make sure that the colorimeter results were similar because I was stumped

You needed to calculate how many dandelions it predicted for the mean. The area was 5x10 so 50m² and it's calculated by taking how many dandelions were predicted per quadrat, then multiplying by however many times to represent 50m². For example, quadrat 0.01m² was best because it represented something like 6/500 (amount of dandelions divided by number of times used) and then you multiplied by 5000 to get 60, the closest value to 53

yea i said it was the closest i worked that out but i still said it was an overestimate but compared to 30 and 10 it’s nothing.

I had a gut feeling that serial dilution would come up and didn't have time to go over it, and there it was. Just had to skip over it but only 2 marks ig. What did people put down for the enzyme question on how to make sure that the colorimeter results were similar because I was stumped

are u talking about the student one with the extract? i just said collect all the extract and distribute it lol

I had a gut feeling that serial dilution would come up and didn't have time to go over it, and there it was. Just had to skip over it but only 2 marks ig. What did people put down for the enzyme question on how to make sure that the colorimeter results were similar because I was stumped

what did everyone get for the rate of pollen tube growth? i got 2.28 micrometres per minute

What did people say for 9 marker?
For value of seagrass I said:
1. Provides habitat for cod, increases biodiversity/species evenness and richness
1.1. Cod beneficial to UK economy, benefits human populace.
2. Prevents erosion of coastal areas thus protecting marine life and beach-based life from going extinct due to erosion of habitats.
2.1. Prevents further inland biodiversity loss from cascading extinctions.
3. Absorbs carbon.
3.1. Limits global warming which would increase sea life, see above for coastal talking points.
3.2. Prevents carbonic acid buildup in ocean leading to enzyme and protein denaturation.
For value of project:
1. Promotes biodegradeable methods.
1.1 Prevents further pollution as a result.
2. Preliminary test to see if it works.
2.1 If successful, can be replicated on larger scale in UK or other countries, new area to protect, would be feasible with benefits it brings to cod economy.
3. Helps act against global warming even during testing.
4. May lead to other hectares popping up due to seagrass reproduction.