92) In the fungus Neurospora, a metabolic pathway synthesizes the amino acid Z (which is essential for its survival) from the precursor W. The intermediates X and Y are also produced in this pathway. The enzymes E1, E2, and E3 catalyze three reactions in the process, as follows:
E1 E2 E3
W ? X ? Y ? Z
X- ray radiation can be used to create a mutant strain of Neurospora that has a defective gene sequence for E2.
Based on this scenario, the mutant strain will survive on media that contain
A) W, X, Y, or Z.
B) only Y or Z.
C) only X.
D) only Z.
E) only W or X.

Question

92)	In the fungus Neurospora, a metabolic pathway synthesizes the amino acid Z (which is essential for its survival) from the precursor W. The intermediates X and Y are also produced in this pathway. The enzymes E1, E2, and E3 catalyze three reactions in the process, as follows:
E1 E2 E3
W ? X ? Y ? Z
X-	ray radiation can be used to create a mutant strain of Neurospora that has a defective gene sequence for E2.
Based on this scenario, the mutant strain will survive on media that contain
A) W, X, Y, or Z.
B) only Y or Z.
C) only X.
D) only Z.
E) only W or X.

Quizplus · Accepted Answer

The mutant strain has a defective E2 enzyme, so it cannot convert X to Y. Therefore, it needs Y or Z in the media to survive, as it cannot produce Y on its own.

92) in the Fungus Neurospora, a Metabolic Pathway Synthesizes the Amino