What is the best explanation for the fish surviving gradual temperature change but not a rapid temperature change? (A) It takes time for each gene to be expressed - HSC - SSCE Biology - Question 19 - 2014 - Paper 1

The best explanation for the fish surviving gradual temperature changes lies in the biochemical capacity of their enzymes. Enzymes are proteins that catalyze biochemical reactions, and their activity can be highly sensitive to temperature.

In the case of gradual temperature changes, the fish have the ability to acclimate to these changes. They can slowly adjust their enzyme activity, allowing for efficient metabolic processes even as the temperature shifts. On the other hand, rapid temperature changes can lead to the denaturation of enzymes, which occurs when the protein structure unfolds due to abrupt changes in temperature. It takes time for enzymatic adaptations to take place, making gradual changes more manageable for the fish.

Therefore, option (D) 'Some enzymes will not denature if the temperature change is gradual' accurately captures this explanation.