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Edexcel IAL Biology 2.7 Enzyme action and specificity

Identify the active-site or inhibitor evidence, connect R-group bonding to three-dimensional shape and trace how the change affects substrate binding and rate.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
AS

Exam points

  • Explain specificity through active-site shape, R groups and substrate complementarity.
  • Compare competitive and non-competitive inhibition using diagrams or rate data.
  • Explain denaturation through disrupted bonds, tertiary structure and active-site change.

2.7—Enzyme action and specificity question 1

[Maximum number: 1]

The photograph shows a species of fungus growing on a dead tree in a woodland habitat.

Figure for Question 2.7—Enzyme action and specificity question 1 — Edexcel A-Level Biology AS

© www.pqpictures.co.uk / Alamy Stock Photo Wood contains a high proportion of lignin and cellulose. Fungi can break down molecules in wood by releasing extracellular enzymes.

Different species of fungus can break down different molecules in wood. The effect of two species of fungus on the percentage loss in mass of wooden blocks was investigated. Species A was grown on one set of wood blocks and species B was grown on another set of wood blocks. The percentage loss in mass of the blocks was recorded every four weeks. The graph shows the results of the investigation.

Figure for Question 2.7—Enzyme action and specificity question 1 — Edexcel A-Level Biology AS

Suggest one reason for the difference in breakdown of the wood by species A and species B.

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