Enzymes are described as biological catalysts because they
- A. are used up in the reactions they catalyse
- B. raise the activation energy of a reaction
- C. supply energy to drive unfavourable reactions
- D. speed up reactions by lowering the activation energy and are recovered unchanged
Explanation
An enzyme provides an alternative pathway with a smaller energy barrier, so a far larger proportion of collisions are effective at body temperature, and it emerges from each cycle ready to work again. It cannot make an energetically unfavourable reaction happen, only accelerate one that is already possible. A single enzyme molecule may convert thousands of substrate molecules per second.
Related questions
The high specificity of an enzyme for its substrate is due to
Enzyme activity is lost above about 45 degrees Celsius because
A competitive inhibitor reduces the rate of an enzyme catalysed reaction by
Heavy metal ions such as mercury and lead are poisonous partly because they
Each enzyme works fastest at a particular pH because a change in pH