DP Chemistry (last assessment 2024)

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Question 18N.3.sl.TZ0.b.i

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Date November 2018 Marks available [Maximum mark: 3] Reference code 18N.3.sl.TZ0.b.i
Level sl Paper 3 Time zone TZ0
Command term Explain Question number b.i Adapted from N/A
b.i.
[Maximum mark: 3]
18N.3.sl.TZ0.b.i

Enzymes are mainly globular proteins.

Explain the action of an enzyme and state one of its limitations.

[3]

Markscheme

Enzyme action:

Any two of:

substrate binds to active site ✔

weakens bonds in substrate ✔

 

lowers activation energy

OR

provides alternate pathway ✔

 

increases rate of reaction

OR

acts as catalyst ✔

 

substrate specific ✔

 

Limitation:

Any one of:

temperature dependent ✔

pH dependent ✔

can be sensitive to heavy metal ions ✔

sensitive to denaturation ✔

can be inhibited ✔

substrate specific ✔

 

Accept “favourable orientation/conformation of the substrate «enforced by enzyme»” for M1.

Do not accept “substrate specific” as both an enzyme action and a limitation.

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