Question

The secretion of of hormone A causes an increase in activity X in an organism. If this mechanism works by positive feedback, which of the following statements represents that fact?
A. An increase in X produces an increase in A
B. An increase in X produces a decrease in A
C. A increase in A produces an increase in X.
D. A decrease in A produces an increase in X.
E. Both A and C are correct.

Answer 1

Answer:

E. is the correct answer

Explanation:

C. An increase in A produces an increase in X.

This statement can be directly concluded from the description of the effects of hormone A on the activity of X in the problem.

A. An increase in X produces an increase in A

This statement can be concluded from the fact that A and X work in a positive feedback mechanism.

In a positive feedback mechanism, a stimulus produces a response (secretion of hormone A) which has an effect (increase in X) that increases the original stimulus. A cycle is created, in which secretion of A causes an increase of X, and the increase of X causes an increased secretion of A.

To shut off the positive feedback cycle, an outside factor is required.