Wild-Type Bacteria Can Synthesize Substance D, but Various Mutant Strains

question 79

Multiple Choice

Wild-type bacteria can synthesize substance D, but various mutant strains cannot.We know that substance D is synthesized from substance X in a pathway that involves three intermediate substances (A, B, and C) , but we do not know the order of the steps in the pathway.The table shows four different mutant strains that have been tested for their ability to grow on the various substances.A "+" means that the strain can grow on that substance; a "-" means that the strain cannot grow on that substance. Based on these data, what is the most likely order of the pathway? (A, B, C, D means that substance A is converted to substance B, which is converted to substance C, which is converted to substance D.)

• A) A, B, C, D
• B) A, C, B, D
• C) B, A, C, D
• D) C, B, A, D
• E) C, A, B, D

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Definitions:

Dendrites

Branch-like extensions of neurons that receive signals from other nerve cells and are integral for brain communication.

Neurotransmitters

Chemical substances in the nervous system that transmit signals across a synapse from one neuron to another, influencing mental states and behavior.

Alleles

Variants of a gene that occur at the same place on a chromosome, contributing to the diversity of traits in a population.

Dominant

Pertaining to a trait, allele, or characteristic that overrides or masks another in genetic expression.