Biological Rhythms

Question 1

When do biological rhythms occur?

Answer 1

When an animal’s physiological activities and behavior patterns can be directly related to environmental features that occur with regular frequency

Question 2

Types of rhythms

Answer 2

Circadian- day
Circannual- year; reproduction, migration
Circalunar- month
Tidal

Question 3

Circalunar rhythms (29.5 days)

Answer 3

Nocturnal predators increase activity around the time of a full noon

Question 4

Tidal rhythm (12.5 hours)

Answer 4

Daily rhythm superimposed on tidal rhythm

Question 5

How do animals synchronize their behavior and physiology to cyclic changes in the external environment

Answer 5

• direct response to changes in external environment
• biological clock synchronized to changes in external environment
• combination of both

Question 6

Evidence for existence of biological docks

Answer 6

• rhythm persists in constant conditions of light, temperature
• animals reared in isolation exhibit rhythms
• mutants with altered rhythm

Question 7

Characteristics of endogenous rhythms

Answer 7

• persist in absence of environmental cues
• period is not exactly that of environmental cycle
• rhythm is entrained by environmental cues
• temperature compensation

Question 8

Adaptiveness of biological clocks

Answer 8

• synchronize the activities of animals with conditions in their environments
• enabling them to prepare in advance for predictable events such as night, winter

Question 9

Location and functioning of circadian clock

Answer 9

Master clock located in the brain
Master clock is influenced by light

Question 10

Melatonin

Answer 10

Hormone produced by pineal gland, regulates circadian rhythm

Question 11

Circadian rhythms

Answer 11

• varies between individuals
• changes with age