Test: ACT Science

Sleep plays a vital role in defining the daily activities of virtually all animals. During periods of sleep, the parasympathetic nervous system becomes active and induces a relaxed state in response to increased levels of the hormone melatonin. Despite its ubiquity in the animal kingdom, the purpose of sleep and its role in our daily lives has been disputed by scientists. Two scientists discuss their theories about the purpose of sleep.

Scientist 1

During periods of sleep, animals are able to conserve energy that they would otherwise be spending on unnecessary activity. If an animal’s primary food source is most abundant during daylight, it is a waste of precious energy to be moving about at night. For example, many herbivores, such as squirrels, are diurnal (asleep during the night) because their food source is available during the day, while many insectivores, such as bats, are nocturnal (asleep during the day) because their food source is available during the night. Food sources, as an animal’s most valuable resource, dictate their sleep cycles. Many animal traits observable today evolved as a result of the supply and demand of food in their natural habitat.

Scientist 2

During waking hours, it is true that the body utilizes large amounts of energy; however, the role of sleep is to restore biological products that were utilized during periods of wakefulness, rather than simply to avoid utilizing energy in the first place. Many types of biological molecules, such as hormones, are released throughout the body while an animal is active. Sleep serves as a period of inactivity during which the body can manufacture and store a supply of these molecules, for future use during the next period of activity; furthermore, sleep allows the body to repair cellular damage that has accumulated during waking hours. Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase. Sleep is necessary for animals to prevent accumulation of damage and to regenerate crucial biomolecules for daily life.

1.

Which of the following is likely true of melatonin?

Melatonin causes animals to seek food sources.

Melatonin causes animals to use more energy.

Diurnal animals will express high levels during the day.

Nocturnal animals will express high levels at night.

Diurnal animals will express high levels at night.

1/40 questions

0%

Access results and powerful study features!

Take 15 seconds to create an account.
Start now! Create your free account and get access to features like:
  • Full length diagnostic tests
  • Invite your friends
  • Access hundreds of practice tests
  • Monitor your progress over time
  • Manage your tests and results
  • Monitor the progress of your class & students
By clicking Create Account you agree that you are at least 13 years old and you agree to the Varsity Tutors LLC Terms of Use and Privacy Policy.
Learning Tools by Varsity Tutors