Biological Timekeeping

Question 1

Biological clock

Answer 1

Timing mechanism using self-sustaining physiological pacemakers and/or environmental cues (daily, monthly, tidal, yearly); endogenous timing mechanism with a built-in schedule that acts independently of any cues from the animals surroundings

Question 2

Free-running cycle

Answer 2

Cycle of activity under constant environment; a cycle that occurs in the absence of environmental cues

Question 3

Circadian rhythm

Answer 3

Daily cycle independent of environmental cues; environment-independent internal clock (day/night cycles)

Question 4

Endogenous clock

Answer 4

Internal self-sustaining pacemaker

Question 5

Entrain

Answer 5

Set internal clock based on environmental cues; reset internal bodily clocks based on environment

Question 6

Zeitgerbers

Answer 6

Cues that provide information about the environment; clue that the body uses to entrain its circadian rhythms

Question 7

Endogenous clock hypothesis

Answer 7

Individuals might manage their priorities in response to a biological clock

Question 8

Environmental stimulus hypothesis

Answer 8

The relationship between command centers in an animal’s nervous system are altered largely on the basis of feedback information gathered by mechanisms that monitor the surrounding environment

Question 9

Circannual rhythm

Answer 9

Approximately a 365-day cycle; environment-independent timer capable of generating a circadian rhythm in conjugation with a mechanism that keeps the clock entrained to local conditions

Question 10

Photoperiod

Answer 10

Number of hours of light in a 24-hour period

Question 11

Photoperiodism

Answer 11

A response to seasonal changes in daylength

Question 12

Hypothalamic-pituitary-gonadal (HPG) axis

Answer 12

The cascade of reproductive hormones, which starts in the hypothalamus of the brain with the release of gonadalatropin-releasing hormone (GnRH)