Final answer:
Animal cells modify enzyme amounts through enzyme regulation, which includes mechanisms such as inhibition, activation, and feedback inhibition, in response to various cellular conditions and needs.
Step-by-step explanation:
The best understood way that animal cells modify the amounts of their enzymes is through enzyme regulation. Since enzymes lower and determine activation energies for chemical reactions, they play a critical role in determining the rates of biochemical reactions. This regulation ensures that enzymes function optimally under the specific conditions of different cell types. For example, digestive cells require different enzymes post-meal than many hours later. Factors such as pH and temperature can influence enzyme activity, but cells also utilize mechanisms such as enzyme inhibition or activation, and feedback inhibition to regulate enzyme levels and activity.