Question

the term down - regulation refers to the process by which
multiple choice
a cell decreases the number of receptors it has for a hormone.
a carrier protein decreases the rate of degradation of the protein it ferries.
a large amount of hormone shuts down all metabolic activity in a target cell.
a endocrine cell decreases the amount of hormone it secretes

Explanation:

To determine the correct answer, we analyze the concept of down - regulation in the context of hormone - receptor interactions. Down - regulation in endocrinology is defined as the process where a target cell decreases the number of its receptors for a hormone.

• The second option is incorrect because down - regulation is not related to the rate of degradation of a protein by a carrier protein.
• The third option is incorrect as a large amount of hormone does not shut down all metabolic activity in a target cell; instead, down - regulation is about receptor number, not a complete shutdown of metabolism.

Answer:

A. a cell decreases the number of receptors it has for a hormone