Question

how can the rate of a biochemical reaction be measured?
by measuring the amount of exercise done
by measuring the volume of the reaction mixture
by measuring the amount of evaporation
by measuring the depletion of the substrate

Explanation:

The rate of a biochemical reaction is related to how quickly reactants (substrates) are consumed or products are formed. Measuring the depletion of the substrate gives an indication of the reaction rate. Exercise amount, reaction - mixture volume, and evaporation amount are not direct measures of the reaction rate.

Answer:

by measuring the depletion of the substrate