photoperiodism

Question 1

photoperiod

Answer 1

regulation of seasonal activities by day length - when plants flower depending on the day length

Question 2

long day

Answer 2

only flower when day and light availability exceeds a critical threshold and day length - can only flower during summer

Question 3

short day

Answer 3

only flower when day length is less than its critical day length = short day = winter

Question 4

day neutral

Answer 4

can flower at any time of the year and is not affected by day length - affected by other factors such as soil and temp or heat or ph

Question 5

photoperiodism

Answer 5

response controlled by phytochrome which is a plant pigment which exists in two isomeric forms = Pr or Pfr

Question 6

pr

Answer 6

absorbs lot of red light and converts to far red - fast in red light and in daylight
- more red light in sunlight

Question 7

pfr

Answer 7

absorbs far red light and converts to red light - slow in darkness but fast in flash of far red light
- more far red light in darkness

Question 8

short day plants

Answer 8

winter = long nights needed and less amounts of pfr = there is less day light in winter so less pr is converted to pfr and longer nights = more pr and less pfr - pfr inhibits flowering

Question 9

long day plants

Answer 9

summer = short nights and long days so more pr during more daylight = more pfr and less pfr conversion to pr = needs more pfr - pfr stimulates flowering

Question 10

point of this?

Answer 10

plants want their seeds to germinate at the same time every year while chance of survival is at its highest eg rain or temp is right or eg if the plant relies on pollination then the plant will have to flower at the time pollinators are most active

Question 11

artificial plants

Answer 11

manipulate long day plants to grow during winter by providing flash of red light to convert fast to pfr and induce flowering