Scientists Have Found That the Lifetimes of MRNAs Coding for Pair-Rule

question 27

Multiple Choice

Scientists have found that the lifetimes of mRNAs coding for pair-rule regulatory elements in Drosophila embryos may last only a few minutes. What does this suggest about the overall developmental plan of an animal body?

• A) The role of mRNAs is less important than the position of genes in chromosomes.
• B) Homeotic genes have greater impact in forming an embryo than mRNA from pair-rule genes.
• C) Building an animal body requires a sequence of precisely timed steps.
• D) Timing of pair-rule sequence determination is not as important as spatial signaling.

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Definitions:

Fixed Interval

A schedule in operant conditioning where the first response is rewarded only after a specified amount of time has elapsed.

Variable Ratio

A schedule of reinforcement where a response is reinforced after an unpredictable number of responses, making it highly effective in maintaining behavior.

Fixed-ratio Schedule

A type of reinforcement schedule in operant conditioning where a response is reinforced only after a specified number of responses, leading to high and steady response rates.

Reinforcement

In psychology, a process in which a behavior is made more likely to occur in the future by its consequences.