DP Biology (first assessment 2025)

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Question 20N.2.SL.TZ0.c

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.2.SL.TZ0.c
Level SL Paper 2 Time zone TZ0
Command term Discuss Question number c Adapted from N/A
c.
[Maximum mark: 2]
20N.2.SL.TZ0.c

Discuss whether the data supports the hypothesis that the gradient in cyanogenesis is due to its benefits against herbivory in rural areas.

[2]

Markscheme

a. (hypothesis) not supported;

b. large overlap/little difference between cyanogenic and non-cyanogenic (in herbivory);

c. smaller difference between cyanogenic and non-cyanogenic in rural areas;

d. both show negative correlation between herbivory and distance from city center/same trend;

e. some support/hypothesis partly supported by lower herbivory in cyanogenic (at all distances).

Do not accept ‘No’ unqualified as an answer.

Do not award mpe if the answer states that the hypothesis is supported without doubt/fully.

Examiners report

This was possibly the hardest part of the data-based question. Candidates were spread approximately equally between 0, 1 and 2 marks. Many candidates did not realise that the differences between herbivory in cyanogenic and non-cyanogenic plants were unlikely to be significant, especially in the rural areas that were furthest from the city. The hypothesis stated in the question was therefore not supported. Candidates should be encouraged to consider both the closeness of means and also the spread, when analysing data.

Syllabus sections