IGCSE Biology
2026 - 2028
Syllabus Checklist
Topic 5: Enzymes
Describe a catalyst
as a substance that increases the rate of a chemical reaction and is not changed by the reaction.
Describe enzymes
as proteins
that are involved in all metabolic reactions, functioning as biological catalysts
.
Describe why enzymes
are important in all living organisms in terms of maintaining reaction rates necessary to sustain life.
Describe enzyme action
with reference to the shape of the active site
being complementary
to its substrate
, leading to the formation of products
.
Investigate and describe the effect of changes in temperature
and pH
on enzyme activity, with reference to optimum temperature
and denaturation
.
Explain enzyme action
with reference to: active site
, enzyme-substrate complex
, substrate
, and product
.
Explain the specificity
of enzymes in terms of the complementary shape
and fit
of the active site
with the substrate.
Explain the effect of changes in temperature
on enzyme activity in terms of kinetic energy
, shape and fit
, collision frequency
, and denaturation
.
Explain the effect of changes in pH
on enzyme activity in terms of shape and fit
and denaturation
.
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