DP Biology (first assessment 2025)

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Question 23M.1A.SL.TZ2.9

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Date May 2023 Marks available [Maximum mark: 1] Reference code 23M.1A.SL.TZ2.9
Level SL Paper 1A Time zone TZ2
Command term Question number 9 Adapted from N/A
9.
[Maximum mark: 1]
23M.1A.SL.TZ2.9

In the grass plant Halopyrum mucronatum, the enzyme amylase breaks bonds in polysaccharides during germination. The graph shows how the activity of the enzyme varies with the concentration of polysaccharide.

[Source: Material from: Siddiqui, Z.S. and Khan, M.A., The role of enzyme amylase in two germinating seed morphs of
Halopyrum mucronatum (L.) Stapf. in saline and non-saline environment, published 2011, Acta Physiologiae
Plantarum, reproduced with permission of SNCSC.]

 

What is the reason for the curve levelling off?

A.  There is insufficient substrate for the enzyme to act on.

B.  The product acts as an enzyme inhibitor.

C.  The enzymes have all been consumed in the reaction.

D.  All the enzyme active sites are occupied by substrate.

[1]

Markscheme

D

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