Which of the following is not true regarding enzymes?
a. enzymes are composed of amino acids.
b. enzymes have unique 3-dimensional shapes.
c. the substrate binds to the enzyme at the active site.
d. enzymes are used up in the reaction.

The answer is d.Enzymes are used up in the reaction.

Explanation:

Enzymes are never used in the reactions. As their function is to be a catalyst, therefore, they are not involved in any chemical reaction and they don't alter their composition. They do change, sometimes, their shape, in order to help properly with the catalysis, but that doesn't involve any other involvement of them.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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