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Factors Affecting Enzyme Activity

Part of Enzymes in Digestion · GCSE GCSE Biology revision

This deep dive covers Factors Affecting Enzyme Activity within Enzymes in Digestion for GCSE Biology. Enzyme structure and function, digestive enzymes, factors affecting enzyme activity, lock and key model, and practical investigations It is section 7 of 19 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 7 of 19

Practice

25 questions

Recall

25 flashcards

Factors Affecting Enzyme Activity

Painted enzyme activity illustration. Left panel: temperature graph with red bell curve peaking at 37°C. At the peak, a teal pac-man-shaped enzyme labelled 'active'. In the denatured zone above 50°C, the same teal enzyme is painted crumpled and twisted with no recognisable active site, labelled 'DENATURED — active site shape changed permanently'. Right panel: pH graph with green pepsin curve peaking at pH 2 (small painted stomach silhouette above) and blue most-enzymes curve peaking at pH 7 (small painted intestine silhouette above). Footer: 'Above ~50°C, hydrogen bonds break → active site shape changes → substrate no longer fits → ENZYME DENATURED (permanent).'

Figure: Both temperature and pH follow bell curves with optimum points. Above the optimum, enzymes denature.

1. Temperature

  • Low temperature: Enzymes work slowly (less kinetic energy)
  • Optimal temperature: Maximum enzyme activity (usually 37°C for human enzymes)
  • High temperature: Enzymes denature (active site changes shape permanently)
  • Q10 rule: Enzyme activity roughly doubles for every 10°C increase (until denaturation)

2. pH

  • Each enzyme has an optimal pH range
  • Wrong pH: Changes enzyme shape, reduces activity
  • Extreme pH: Permanent denaturation
  • Examples: Pepsin (pH 1.5), Amylase (pH 7), Trypsin (pH 8.5)

3. Enzyme Concentration

  • More enzymes: More active sites available
  • Rate increases until substrate becomes limiting factor
  • Plateau reached when all substrate is being used

4. Substrate Concentration

  • More substrate: More collisions with active sites
  • Rate increases until enzymes become limiting factor
  • Maximum rate: The rate levels off when all enzyme active sites are occupied (saturated) — adding more substrate beyond this point has no further effect

Keep building this topic

Read this section alongside the surrounding pages in Enzymes in Digestion. That gives you the full topic sequence instead of a single isolated revision point.

Bile: The Enzyme HelperRequired Practical 4: Food TestsThe Chemical Breakdown ChampionsEnzyme Structure and Function

Practice Questions for Enzymes in Digestion

What are enzymes?

  • A. Carbohydrates that provide energy for cells
  • B. Biological catalysts that speed up chemical reactions
  • C. Proteins that are used up during digestion
  • D. Molecules that store genetic information
1 markfoundation

Explain the effect of increasing temperature on enzyme activity.

3 marksstandard

Quick Recall Flashcards

What is an enzyme?
A biological catalyst that speeds up chemical reactions by lowering activation energy. Enzymes are proteins with specific 3D shapes.
What does lipase do?
Breaks down lipids (fats) into fatty acids and glycerol. Produced by pancreas, works in small intestine.

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Bile: The Enzyme Helper

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Required Practical 4: Food Tests