20. Allosteric effectors: a. can cause large changes in enzymatic activity. b. can lead to a decrease in the availability of a protein. c. do not alter the sensitivity of a metabolic pathway. d. decrease the sensitivity of the enzyme at nearly all concentrations of substrate. e. alter enzyme activity by binding to the active site of an enzyme.

a. can cause large changes in enzymatic activity.

Explanation:

An enzyme refers to a biological catalyst that is typically used to speed up (accelerate) the rate of a chemical reaction by lowering the activation energy of its reactants.

When the activation energy of a reaction is low, the rate of the reaction would be faster. Therefore, an enzyme speeds or catalyzes the rate of a reaction by lowering its activation energy. Also, if the conditions are not optimal for an enzyme, it limits the ability of an enzyme to bind or be joined with its substrates. An increase in temperature increases or speeds up the rate of a reaction while low temperature limits or reduces the rate of a reaction. The optimal temperature for enzymes in the human body is around 37 degrees celsius.

An allosteric effector can be defined as an agent, organ or molecule that is being binded to an enzyme at a site, thereby causing a reduction (negative effect) or an increase (positive effect) in an enzyme activity.

Hence, an allosteric effector can cause large changes in enzymatic activity because it acts as an intermediary and mediates specific effect in a metabolic pathway.