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Date May 2022 Marks available 1 Reference code 22M.1.HL.TZ2.25
Level Higher level Paper Paper 1 Time zone Time zone 2
Command term Question number 25 Adapted from N/A

Question

Many blood-feeding insects inject an anticoagulant into their host in order to prevent blood from clotting. Female mosquitoes of the genus Anopheles inject the anticoagulant anophelin, which inhibits the action of the enzyme thrombin. Which statement explains how anophelin prevents blood clotting?

A. Platelets are no longer produced.

B. Platelets cannot produce fibrin.

C. Fibrinogen is not converted to fibrin.

D. Prothrombin is not converted to thrombin.

Markscheme

C

Examiners report

[N/A]

Syllabus sections

Core » Topic 6: Human physiology » 6.3 Defence against infectious disease
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