DP Biology (first assessment 2025)

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Question 19M.1A.SL.TZ1.9

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.1A.SL.TZ1.9
Level SL Paper 1A Time zone TZ1
Command term Identify Question number 9 Adapted from N/A
9.
[Maximum mark: 1]
19M.1A.SL.TZ1.9

Which wavelength of electromagnetic radiation is absorbed efficiently by chlorophyll for photosynthesis?

A. 45 nm

B. 45 μm

C. 450 nm

D. 450 μm

[1]

Markscheme

C

Examiners report

This was another question that was criticised for testing what was considered by some to be pointless factual recall. Only 40 % of candidates correctly identified the wavelength of light that chlorophyll absorbs but the discrimination index was very high. Two of the answers could have been eliminated if candidates knew that the wavelengths of light are measured in nanometres not micrometres. The two answers remaining were 45 nm and 450 nm. Any candidate who remembered that the spectrum of visible light and also of absorption by chlorophyll is from 400 to 700 nm could easily have chosen the correct answer. In the examiners’ view the spectrum of visible light and the units used to measure light wavelengths are useful pieces of information and not pointless facts.

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