TPO 13-2 Biological Clocks

The word consequently in the passage is closest in meaning to

• Nevertheless

• Moreover

• Additionally

• Therefore

In paragraph 1, the experiment on the fungus Neurospora is mentioned to illustrate

• The existence of weekly periods of activity as well as daily ones

• The finding of evidence that organisms have internal clocks

• The effect of space on the internal clock of organisms

• The isolation of one part of an organism’s cycle for study

According to paragraph 1, all the following are generally assumed to be true EXCEPT:

• Eukaryotes have internal clocks

• Animals’ daily rhythms are more dependent on external cues than on internal clocks

• The relationship between biological function and environmental cycle is a topic of intense research

• It is important for animals’ daily activities to be coordinated with recurring events in their environment

The word persistent in the passage is closest in meaning to

• Enduring

• Predicted

• Adjusted

• Strong

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?

• Stability, a feature of the biological clock’s period, depend on changeable factors such as temperature.

• A major feature of the biological clock is that its period does not change despite significant changes in the environment.

• A factor such as temperature is an important feature in the establishment of the biological clock’s period.

• Biological activity is not strongly affected by changes in temperature.

According to paragraph 2, which of the following is true about the circadian periods of animals deprived of environmental cues?

• They become longer over time.

• They can vary significantly from day to day

• They are not same for all members of a single species.

• They have the same length as the daily activity cycle of animal that are not deprived of such cues.

According to paragraph 2, what will an animal experience when its internal rhythms no longer correspond with the daily cycle of the environment?

• Change in period of the internal rhythms

• Increased sensitivity to environmental factors

• Reversal of day and night activity

• Disorientation

In paragraph 2, the author provides evidence for the role of biological clocks by

• Describing the process of establishing the period of a biological clock

• Listing the daily activities of an animal’s cycle: sleeping, feeding, moving, reproducing, metabolizing, and producing enzymes and hormones

• Contrasting animals whose daily schedules fluctuate with those of animals whose schedules are constant

• Presenting cases in which an animal’s daily schedule remained stable despite lack of environmental cues

The word duration in the passage is closest in meaning to

• Repetition

• Length

• Feature

• Process

In paragraph 2, why does the author mention that the period for different horseshoe crabs ranges from 22.2 to 25.5 hours?

• To illustrate that an animal’s internal clock seldom has a 24-hour cycle

• To argue that different horseshoe crabs will shift from daytime to nighttime vision at different times

• To illustrate the approximate range of the circadian rhythm of all animals

• To support the idea that external cues are the only factor affecting an animal’s periodic behavior