F ... 25 - External Factors and Plant Growth

Question 1

external factors?

Answer 1

gravity
light
touch

Question 2

tropism

Answer 2

directional growth in response to external stimulus

Question 3

gravitropism

Answer 3

directional growth due to gravity… bending

[ plant’s knocked over ]

Question 4

thigmotropism

Answer 4

directional growth due to touch… tendrils
[ plant touches object ]
can inhibit growth - elongation

Question 5

phototropism

Answer 5

directional growth due to light

Question 6

morphogenesis

Answer 6

change in dev or growth in response to stimulus

Question 7

gravity perception in plants

Answer 7

starch statoliths settle, redistributes auxin, change in growth

Question 8

how is light perceived as a signal?

Answer 8

phytochromes
phototropisms
photomorphogenesis
circadian rhythms

Question 9

phytochrome

Answer 9

photoreceptor… red / far red light

Question 10

phototropism

Answer 10

shoots + (towards light)

roots - (away from light)

Question 11

photomorphogenesis

Answer 11

development affected by light

Question 12

circadian rhythms

Answer 12

cyclic responses to enviro stimuli (~24 hours)

leaf rises / lowers

Question 13

photoperiodism

Answer 13

flowering time

physiological resp to photoperiod (day/night lengths)

Question 14

short day plant

Answer 14

req light period shorter than critical daylength to flower

Question 15

long day plant

Answer 15

req light period longer than # hours to flower

Question 16

day-neutral plant

Answer 16

unaffeted by photoperiodism… flowers at maturity

Question 17

heliotropism

Answer 17

solar tracking [sunflowers]

NOT asymmetric growth, mvt of connective tissue at organ base