DP Biology (first assessment 2025)

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Question 21N.2.SL.TZ0.a

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Date November 2021 Marks available [Maximum mark: 2] Reference code 21N.2.SL.TZ0.a
Level SL Paper 2 Time zone TZ0
Command term Describe Question number a Adapted from N/A
a.
[Maximum mark: 2]
21N.2.SL.TZ0.a

Describe the effect of temperature on the total biomass.

[2]

Markscheme

a. negative correlation/decrease (in biomass) as temperature rises in added-nutrients (mesocosms);
b. little/no (significant) change in biomass as temperature increases in control (mesocosms);

Examiners report

The word ‘total’ confused some candidates who tried to write about both the control and added-nutrients without distinguishing between them. Of those candidates who realised that ‘total’ must mean the total biomass within a mesocosm, almost all got the decrease in ‘with nutrients’ mesocosms as temperature increased, but many were not discerning enough with the control mesocosms. The differences were less than the error bars, so were clearly insignificant and should have been ignored Question 2.

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