Netrin Was First Discovered in a Biochemical Assay for the Attraction

question 14

Multiple Choice

Netrin was first discovered in a biochemical assay for the attraction of vertebral commissural axons to floor plate. In mutants for the worm netrin homologue Unc6, sensory axons failed to project ventrally and motor neurons fail to project dorsally. This result suggested that:

• A) Unc6 can repel neurons as well as attract them.
• B) Unc6 and netrin have conserved roles as well as sequences.
• C) sensory neurons and motor neurons somehow interpret the Unc6 signal differently.
• D) All of the above
• E) None of the above

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Definitions:

Operant Stimulus

A stimulus that follows a behavior and increases or decreases the likelihood of that behavior occurring again; used in operant conditioning.

CS

Conditioning Stimulus; in conditioning, it's the stimulus that, when paired with an unconditioned stimulus, can elicit a conditioned response.

Unconditioned Stimulus

In classical conditioning, a stimulus that naturally triggers a reflexive or unlearned response.

Salivation

The secretion of saliva, often in response to the sight, smell, or taste of food, which is part of the digestive process.