Figure 15.3

Multiple Choice

Figure 15.3
Above is a metabolic pathway for the synthesis of an amino acid (E) , without which an organism could not live. Enzymes are represented by numbers, and substrates by letters. Use this figure for the next two questions.
-According to the figure above,if enzyme 3 was nonfunctional in an organism,which of the following outcomes would you predict?

A) The cell would die because of a lack of the essential amino acid.
B) Another enzyme would be able to catalyze the reaction and the pathway would proceed.
C) Substrate C would accumulate,and there would be no substrate D formed.
D) Lack of enzyme 3 would result in a cessation (halt) of the entire metabolic pathway.