ConceptConceptDocsDocuments

CAIE A-Level Biology 3.1 Enzyme Mode of Action Question Bank

Practise enzyme mode-of-action questions by explaining active-site fit, activation energy and colorimeter evidence from reaction investigations.

Syllabus
2028–2030
Course
Biology 9700
Level
AS

Exam points

  • explain active-site specificity using complementary substrates and enzyme-substrate complexes
  • compare lock-and-key with induced fit, including conformational change and product release
  • interpret activation-energy diagrams or colorimeter data from enzyme reaction progress

Covered syllabus points

3.1.1—Enzymes as globular proteins3.1.2—Enzyme mode of action3.1.3—Enzyme action hypotheses3.1.4—Enzyme reaction investigations3.1.5—Colorimetry in enzyme reactions

3.1 Mode of Action question 1

[Maximum number: 3]

Prostaglandins are small lipids produced in many tissues of the body. One role of prostaglandins is to cause inflammation at the site of an injury or infection. Inflammation is the normal first response of the immune system to injury or infection.

Cyclooxygenase (COX) is an enzyme that catalyses one of the steps in the reaction pathway for the formation of prostaglandins from phospholipids. The reaction pathway occurs in the smooth endoplasmic reticulum (SER) of cells. Part of the reaction pathway is shown in Fig. 1.3.

Fig. 1.3

Fig. 1.3

Sometimes inflammation can have side-effects, such as pain. Aspirin is a drug that can be used to reduce these side-effects.

Aspirin reduces the catalytic activity of the COX enzyme by modifying the R-group of one of the amino acids.

Suggest how modifying the R-group of an amino acid in the COX enzyme can reduce the catalytic activity of the enzyme.

All question bank results loaded