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4.3 Biological Rhythms & Navigation — Test 1
Q1. In mammals, the primary (master) circadian clock is located in the:✓ Suprachiasmatic nucleus (SCN)
Q2. If a bird is kept in a closed cage with all external time cues blocked, its biological clock will:✓ Run free (free-running rhythm)
Q3. The photoreceptor commonly involved in light entrainment of the biological clock in flies, fungi and plants is:✓ Cryptochrome
Q4. Environmental cues that synchronise (entrain) biological rhythms are called:✓ Zeitgebers
Q5. Which description does NOT apply to circadian rhythmicity?✓ It is rhythmic only in the presence of a 24-hour light/dark cycle
Q6. Human biological rhythms can be classified as: (a) the REM/non-REM sleep cycle; (b) the menstrual cycle; (c) the sleep-wake cycle. These are respectively:✓ Ultradian; infradian; circadian
Q7. The major environmental cue triggering bird migration is:✓ Day length (photoperiod)
Q8. Starlings normally orient by the sun during migration. If kept in captivity with an artificial light source fixed in one direction, they will:✓ Re-orient about 15° per hour relative to the artificial light
Q9. The mechanism by which ants find their way back to the nest after foraging, by continuously integrating distance and direction travelled, is called:✓ Path integration
Q10. The estimation of distance by counting steps or the number of visual features passed is called:✓ Odometry
Q11. The extraordinary sensory ability that elephants possess for long-distance communication is the:✓ Emission and detection of ultra-low-frequency (infrasonic) sounds
Q12. Homing pigeons can use the sun or the Earth's magnetic field. In one experiment, a test group wears Helmholtz coils (disrupting magnetic sensing) and a control group does not. The expected result is that:✓ On a sunny day both groups orient correctly, but on a cloudy day only the control group does
Q13. Which of the following is NOT a function of dispersal behaviour (moving away from the natal home)?✓ Preventing species extinction directly
Q14. Unsynchronised, low-amplitude (desynchronised) EEG activity is generated when an animal is:✓ Awake, active and alert
Q15. A free-running rhythm in constant darkness demonstrates that the biological clock is:✓ Endogenous (internally generated)
Q16. A biological rhythm with a period much longer than 24 hours (such as an annual or monthly cycle) is termed:✓ Infradian
Q17. A rhythm with a period much shorter than 24 hours (such as the ~90-minute sleep cycle) is termed:✓ Ultradian
Q18. Melatonin, the hormone that signals darkness and helps regulate sleep, is secreted by the:✓ Pineal gland
Q19. The use of familiar landmarks to navigate a known route (as a person uses shops to find their way) is called:✓ Piloting
Q20. Match each term with its description and select the correct option.✓ A-ii, B-i, C-iii, D-iv