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Life Processes at the Cellular Level · Part 2 of 5
6 exam-style questions with model answers, plus 8 quick multi-choice questions — every question on this part of the standard, grouped by the 2 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
Define the term enzyme, and describe what is meant by the active site.
Explain why boiling an enzyme stops it from working, but cooling it to 5 °C does not.
A mutation changes one amino acid in an enzyme. The enzyme still folds, but the reaction it catalyses now runs at only 5% of its normal rate. The cell's overall respiration rate falls sharply. Discuss how a single amino acid change can have this effect.
Describe what happens to the rate of an enzyme-controlled reaction as the substrate concentration is increased from zero, and state what the rate depends on once the graph has levelled off.
Explain why the rate of an enzyme-controlled reaction increases between 10 °C and 35 °C, but decreases between 45 °C and 60 °C.
A cell is treated with a substance that binds to the active site of one enzyme in the respiration pathway. Researchers find that adding a very large excess of that enzyme's substrate partly restores the reaction rate. Discuss what this tells us about the inhibitor and about the enzyme, and explain the consequences for the cell.