DP Biology (first assessment 2025)

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Question 21N.1A.HL.TZ1.38

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Date November 2021 Marks available [Maximum mark: 1] Reference code 21N.1A.HL.TZ1.38
Level HL Paper 1A Time zone TZ1
Command term Question number 38 Adapted from N/A
38.
[Maximum mark: 1]
21N.1A.HL.TZ1.38

The image shows part of a myofibril from a relaxed muscle fibre.

[Source: Sarcomere. Sameerb. Available at https://commons.wikimedia.org/wiki/File:Sarcomere.gif
[Accessed 30 November 2021].]

 

What occurs during muscle contraction?

A. Myosin binding sites are blocked.

B. The bands labelled Y get shorter.

C. The bands labelled X get shorter.

D. Calcium ions bind to myosin.

[1]

Markscheme

C

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