Biological timing

Question 1

Circa-annual

Answer 1

yearly cycles

Question 2

Circadian

Answer 2

Daily cycles

Question 3

Circa-lunar

Answer 3

Responses related to the moon/monthly

Question 4

Biorhythm

Answer 4

A cycle of events that is controlled endogenously (genetically)

Question 5

Benefits of biological clocks

Answer 5

• Allow prediction of events necessary for a build-up of food or reserves
• Synchronization of internal physiological processes
• Synchronization of social activities
• Allow for growth and development

Question 6

Photoperiodism

Answer 6

Response to changes in day length by making appropriate physiological changes - in plants

Question 7

Advantages of photoperiodism

Answer 7

Synchronises with ideal season for flowering, leaf fall and germination

Question 8

Pr

Answer 8

Phytochrome red absorbs sunlight (mostly red light)

Question 9

Pfr

Answer 9

Phytochrome far red absorbs night light (far red light)

Question 10

Short day plants

Answer 10

• Require a short day and a long night
• Produce flowers only if the photoperiod (day length) is less than a critical length
• Flower in winter

Question 11

Long day plants

Answer 11

-Require a long day and a short night
- Produce flowers only if the photo period that exceeds a certain critical length
- Flower in summer

Question 12

When Pr absorbs red light

Answer 12

Quickly changed to Pfr

Question 13

Endogenous

Answer 13

Something that is controlled internally/genetically

Question 14

Exogenous

Answer 14

Controlled externally by zeitgebers or environmental cues

Question 15

Zeitgebers

Answer 15

• ‘Time giver’
• Environmental cue which can change/train the internal clock, prompts us

Question 16

Entrainment

Answer 16

Use of zeitgebers to change your internal clock, by resetting it to match environmental cues

Question 17

Zeitgebers that control circaannual

Answer 17

Seasons, photoperiod

Question 18

Zeitgebers that control circadian

Answer 18

Temperature, humidity, light, sound

Question 19

Zeitgebers that control circatidal

Answer 19

Ocean movements

Question 20

Pfr is unstable in night, what happens

Answer 20

Slowly reverts back to Pr

Question 21

Lots of Pr means

Answer 21

Night is long

Question 22

Not much of Pr means

Answer 22

Night is short

Question 23

When there is a flash in the night what happens

Answer 23

Pfr is quickly converted as mistaken for short night, resets the plants counter of how long night is - short day plants won’t flower

Question 24

Period of a rhythm

Answer 24

Time it takes to complete one entire wake/sleep cycle - generally 24 hours

Question 25

Photoperiod rhythms are controlled by-

Answer 25

Pienal gland behind the eye and the suprachiasmatic nuclei (SCN)

Question 26

Phase shift

Answer 26

When onset of the period of the rhythm is changed - normally due to removal of zeitgebers

Question 27

Biological clock is made up of

Answer 27

Suprachiasmatic nuclei (SCN) at the base of the brain

Question 28

When light intensity is low/high (biological clock)

Answer 28

eye detects less/more light and send messages to SCN which triggers the pineal gland to release more/less melatonin - controls the circadian rhythm

Question 29

Diurnal

Answer 29

Active during the day

Question 30

Nocturnal

Answer 30

Active during the night