DP Biology (first assessment 2025)

Test builder »

Question 23M.2.HL.TZ1.6b

Select a Test
Date May 2023 Marks available [Maximum mark: 4] Reference code 23M.2.HL.TZ1.6b
Level HL Paper 2 Time zone TZ1
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 4]
23M.2.HL.TZ1.6b
(b)

Explain the regulation of metabolic pathways by end-product inhibition.

[4]

Markscheme
  1. final product in pathway acts as an inhibitor/blocks (reaction)/slows (reaction);
  2. first/early/earlier enzyme (in pathway is inhibited);
  3. non-competitive / binds at allosteric site / causes active site to change;
  4. production of end-product reduced/paused when there is an excess;
  5. isoleucine inhibits enzyme using threonine as substrate at start of pathway to isoleucine;
  6. negative feedback / production restarts when end-product used up/concentration drops;

For mpe accept other examples of end-product inhibition if verified. Please add a note in such cases.

Syllabus sections