Midterm 1 Practice Exam Flashcards
Bright daylight can influence:
a. Amount of melatonin secreted in humans
b. Phase of onset of melatonin secreted in humans
c. Phase of onset of activity in hamsters
d. All of the above
d.
All of the above
If free running hamsters in constant lighting conditions are given a light pulse during the middle of the subjective day, this will:
a. Phase advance the activity rhythm
b. Phase delay the activity rhythm
c. Have little or no effect on the activity rhythm
d. Cause the activity rhythm to be disrupted for 24 hours
c.
Have little or no effect on the activity rhythm
- Evidence from hamsters suggests that the activity-rest circadian rhythm can be entrained to any period within:
a. 10-50 hours
b. 18-26 hours
c. 23-25 hours
e. 16-36 hours
f. Any period is entrainable, if the light is bright enough.
b.
18-26 hours
Biological rhythms observed in constant environmental conditions are said to be __________(4).
If an appropriate ___________(5) is given, the rhythm is said to become ___________ (6) to environmental conditions.
Biological rhythms observed in constant environmental conditions are said to be *Free-running (4).
If an appropriate *Zeitgeber (5) is given, the rhythm is said to become *Entrained (6) to environmental conditions.
cdsc
cdsCd
cds
cdscds
In an early experiment by de Mairan, a mimosa plant was placed in a dark cabinet and temperature was held approximately constant.
The plant continued to show a daily rhythm of leaf movements, with leaves open during the day and folded at night.
This result indicates most conclusively that:
a. the natural daily rhythms of light and temperature are not required for rhythmic leaf movements.
b. chlorophyll is not involved in the mechanism of leaf movements.
c. the plant must be capable of using some environmental cue other than light or temperature to regulate its leaf movements.
d. leaf movements do not have any adaptive value to the plant.
a.
The natural daily rhythms of light and temperature are not required for rhythmic leaf movements.
An experiment by de Candolle showed that the rhythmic leaf movements of the mimosa plant continued in constant darkness with a period length that was not exactly 24h.
This type of observation helped to convince biologists that:
a. plants have less accurate biological clocks than animals
b. biological clocks cannot continue to express consistent oscillations in the absence of time cues from the environment
c. the leaf movements of mimosa are fundamentally different from those of most plants
d. some daily rhythms are driven by internal, self-sustained oscillators
e. none of the above
d.
Some daily rhythms are driven by internal, self-sustained oscillators.
A common feature of circadian, circannual, circatidal, and circalunar rhythms is that all of them:
a. are related to the period of the earth’s rotation about its own axis
b. are related to geophysical rhythms that may have some importance to organisms
c. have period lengths that usually vary in some regular relationship to an organism’s body size
d. have period lengths that are always shorter than the corresponding geophysical rhythm
e. all the above
b.
Are related to geophysical rhythms that may have some importance to organisms
As compared to homeostatic processes, biological rhythms seem to be much less dependent on:
a. internal negative feedback mechanisms
b. genetically transmitted information
c. coordination between many cells
d. timekeeping mechanisms
e. the nervous system
a.
Internal negative feedback mechanisms
For a nocturnal animal that is freerunning under constant conditions, the beginning of the active phase (locomotor activity) corresponds approximately to:
a. beginning of subjective day
b. beginning of subjective night
c. alpha
d. rho
e. mid-point of subjective day
b.
beginning of subjective night
The term “temperature compensation” is most clearly illustrated by the observation that:
a. organisms are unable to entrain to daily cycles of environmental temperature
b. organisms are able to entrain to daily cycles of environmental temperature
c. mean environmental temperature has little effect on taudd
d. the phase angle of entrainment is not affected by environmental temperature
e. none of the above
mean environmental temperature has little effect on taudd
Differences between individuals of a species with respect to tau:
a. may result from genetic differences
b. may be a result of different photoperiod histories of the individuals
c. may be related to age
d. do not exist
e. “a” , “b”, and “c”
e.
“a” , “b”, and “c”
a. may result from genetic differences
b. may be a result of different photoperiod histories of the individuals
c. may be related to age
Rodents are most likely to become arrhythmic (non-rhythmic) when exposed to:
a. continuous darkness (DD)
b. continuous light (LL)
c. a 24h light/dark cycle
d. constant (unvarying) temperature
b.
continuous light (LL)
If you wanted to estimate the limits of entrainment to light/dark cycles for a particular species, which of the following would provide helpful information:
a. the degree of temperature compensation of its circadian clock
b. the phase response curve and tau
c. the phase angle of entrainment to a 12L:12D cycle (12h light and 12h dark)
d. all the above
e. none of the above
b.
The phase response curve and tau
For people on a normal day-night schedule, cortisol levels peak in the______________ and are lowest in_________________.
a. Early afternoon; late evening
b. Early morning; early evening
c. Early evening; early morning
d. Middle of the night; late afternoon
b. Early morning; early evening
