Quiz 7: Growth Hormones Flashcards
(63 cards)
1
Q
what are 2 ways cell can grow?
A
- enlargement
2. division
2
Q
describe cell enlargement
A
- softening of cell wall
- cytoplasmic swelling due to water uptake
- cells elongate in length
3
Q
describe cell division
A
- single parent cell forms 2 complete identical daughter cells- mitosis
- occurs at meristems
4
Q
what hormone is active during mitosis
A
cytokinin
5
Q
requirements for growth
A
- water
- oxygen
- nutrients
- sunlight
- location
- temperature
6
Q
what is a tropisms
A
- growth or movement in response to external stimuli controlled by hormones
7
Q
Phototropism
A
- response to light
8
Q
heliotropism
A
-diurnal response to sunlight
9
Q
geotropism
A
response to earth or gravity
10
Q
thigmotropism
A
response to touch ex vines
11
Q
what characteristics will a plant in proper light have
A
- full stems
- short internodes
- closely spaced leaves
12
Q
what characteristics will plants have grown in too much shade
A
- long internodes
- poorly developed leaves
13
Q
what characteristics will plants have grown in complete darkness
A
-thin colourless stems with pale underdeveloped leaves (etiolation)
14
Q
give a common example of when phototropism - inside and outside
A
- inside: bend toward the windows
- outside: sun moves across sky , if blocked for part of the day plant appears one sided
15
Q
what is heliotropism
A
- diurnal movement of plant parts in response to the direction of the sun
- track the sun’s motion moves across sky
- reverts to neutral position
16
Q
Diaheliotropism
A
-tracking sun (max amount if direct solar radiation leaf receive
17
Q
Paraheliotropism
A
avoiding the sun
18
Q
t or f heliotropism is a growth movement
A
- false: rapid reversible movements in response to turgor changes in cells in an organ at base of leaf petiole
19
Q
geotropism
A
grow in same or opposite direction of gravity
20
Q
negative geotropism
A
-opposite direction of gravity ex stems
21
Q
positive geotropism
A
- in direction of gravity
ex roots
22
Q
diageotropism
A
-horizontal growth of rhizomes, stolons and some roots
23
Q
what hormones affect geotropism
A
- auxon and gibberelins
24
Q
Thigmotropism
A
response to touch
ex tendrils grasp supportive objects
25
what hormones involved in thigmotropism
-uneven distribution of auxin
26
describe nastic movement
- controlled by hormones but not in direct response to external stimuli
- non directional ex seed germination, flowers opening and closing
- combo hormones at various levels and []
27
what does hormone mean in greek
to set in motion
28
what do hormones do in plant
- initiate biochem activities resulting in observable, physiological responses
29
what is other word word for plant hormones
- Plant Growth Regulators
30
what are 5 principle hormones studied ( 3 growth, 2 decay)
1. Auxin
2. Gibberellins
3. Cytokinin
4. Abscisic acid
5. ethylene
31
what is greek word for auxin
to increase
32
principle function of auxin
- stimulate increase in cell length (esp near stem and root tips)
cell elongation directly prop. to [auxin]
33
what is IAA
-natural auxin in plants ;
-indole- 3- acetic acid
produced in apical meristem --> apical dominance
-moves downward, decreasing []
34
t or f shade plant display lots of phototropism
false
35
what hormone is responsible for adventitious root
- auxin
36
what is gibberellins
| what is it related to
hormone controls growth of internodes
- light intensity
- high light = restrained
- low light= active, increase internode length
37
what are 4 functions of Gibberellins
1. growth at internodes
2. trigger seed germination
3. breaking bud dormancy
4. induce flowering
38
t or f ; absence of gibberellins results in dwarfism
true
39
what is bolting, what hormone involved
- stimulation of flowering/ seed production in crops grown for leaves
- gibberellins
40
what is greek breakdown of cytokinin
```
kytos= container/ cell
kinesis= movement
```
41
what is primary role of cytokinin
promotion and regulation of cellular division
42
what ratio promotes root formation
high ratio auxin and cytokinins
43
what ratio promotes shoot formation
low ratio auxins to cytokinins
44
what hormone promotes lateral bud growth in flowering plants
- cytokinin
45
what does senescence mean in latin
to grow old
46
t or f once begun, senescence can be reversed
false
47
what is senescence controlled by , what is it responsible for
hormones
1. ripening of fruit
2. ageing flowers
3. leaf drop
48
what hormones inhibit senescence
- auxin, gibberellins, cytokinin
49
what triggers production of abscisic acid and ethylene
environmental cues
50
which hormone has the most control on leaf abscission
ethylene
51
what is purpose of abscisic acid
1. syn of terminal buds and leaves
2. suspend primary and secondary growth and trigger bud scale to protect bud over winter
3. stimulate closure of stomata
4. inhibits shoot growth (not roots)
5. induce seeds to syn storage proteins
6. inhibits gibberellins
7. induction and maintenance of dormancy
8. induces cell growth in response to wounding
52
what is syn of terminal buds and leaves stimulated by?
-stresses, water shortage, low temp
53
describe leaf abscission
- breakdown of chlorophyll
- movement of sugars from leaf to body of plant
- weakening of cell walls at base of petiole
54
what cues abscission
low temp and short days cue reduction of auxin and increase production of ethylene
55
what is ethylene
-gas hormone
56
what characteristics does amount of ethylene vary in species
- amount varies on species
- tissue
- stage of development
57
what 5 things does ethylene stimulate
1. release of dormancy
2. shoot and root growth differentiation --> triple response
3. stimulate leaf and fruit abscission
4. stimulates flower opening
5. stimulates flower and leaf senescence
6. stimulate fruit ripening
58
what is the triple response
- stunting of growth
- twisting of plants
- abnormal thickening of stems
59
what is the colour ripening in fruit a result of
- chlorophyll breakdown
60
what 3 things occur during fruit ripening
- colour changes from chlorophyll breakdown
- sugar content rises
- cell walls and membranes soften
61
describe apical dominance
controlled by growth hormones in apical meristem
62
what does removal of meristem cause
- reduction [ auxin]
| - allows axillary buds to develop
63
what are adventitious roots? how are they controlled ?
- stimulation of root development on stems
| - auxins
