Chapter 31, Problem 3STP

Summary Introduction

Introduction:

Circadian rhythms are frequent shifts in the biology and actions of individuals occurring in 24-hour periods. The term circadian comes from a Latin word that means "about a day." Circadian rhythms exist in nearly every animal. In fact, it occurs in several living organisms

Answer to Problem 3STP

Correct answer:

The correct answer is Option (d) cycles of more than 24 h.

Explanation of Solution

Explanation/justification for the correct answer:

Option (d) cycles of more than 24h. When the squirrels were exposed to 24 hours of darkness, it maintained a sleep/wake cycle of 24h and 21 minutes, instead of 24h.

Explanation for incorrect answer:

Option (a) cycles of exactly 12 h. This is not possible because the experiment was done for a 24-hour cycle.

Option (b) Cycle of less than 12 h. This is not possible because the experiment was done for a 24-hour cycle.

Option (c) cycles of exactly 24 h. The experiment shows that squirrels maintained a sleep/wake cycle of 24h and 21 minutes, instead of 24h.

Conclusion

Squirrels that were exposed to 24 h of darkness displayed the cycle of more than 24 h circadian rhythm. Hence, the correct answer is Option (d).