Q49.1-2ITD - Campbell Biology

Question

For the wild-type hamsters that received 𝛕 SCN transplants, what would have been an appropriate experimental control?

Step-by-Step Solution

Answer

Scientists established that the SCN is essential for circadian rhythms in laboratory mice by surgically removing it. An appropriate experimental control for the wild-type hamsters that received 𝛕 SCN transplants will be transplanting one wild-type hamster to another wild-type hamster.

Step 1: SCN (suprachiasmatic nucleus)

A structure located in the anterior part of the hypothalamus is the suprachiasmatic nucleus. It is known as the brain's pacemaker because it regulates the body's circadian rhythm.

It is a tiny region in the brain that controls the sleep-wake cycle and the circadian rhythms, located just above the optic chiasm and regulates many other body functions for 24 hours.

Step 2: SCN of a hamster

The suprachiasmatic nucleus (SCN) of the hamster is morphologically and functionally heterogeneous. Many behavioral and physiological responses in mammals are controlled by the suprachiasmatic nucleus (SCN), which synchronizes these rhythms to daily environmental cycles.

Step 3: Experimental control for the τ SCN transplants

In the absence of external stimuli, wild-type hamsters have a circadian cycle that lasts around 24 hours; hamsters homozygous for the (tau) mutation have a cycle that lasts only about 20 hours.

The SCN was surgically removed from wild-type hamsters by the researchers. Each of these hamsters received an SCN transplant from a hamster of the opposite genotype many weeks later.

Thus, transplanting one wild-type hamster into another wild-type would be the appropriate control in this experiment.