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HORT 1047 Horticulture 1 > Quiz 7: Growth Hormones > Flashcards

Quiz 7: Growth Hormones Flashcards

1
Q

what are 2 ways cell can grow?

A
  1. enlargement

2. division

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2
Q

describe cell enlargement

A
  • softening of cell wall
  • cytoplasmic swelling due to water uptake
  • cells elongate in length
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3
Q

describe cell division

A
  • single parent cell forms 2 complete identical daughter cells- mitosis
  • occurs at meristems
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4
Q

what hormone is active during mitosis

A

cytokinin

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5
Q

requirements for growth

A
  1. water
  2. oxygen
  3. nutrients
  4. sunlight
  • location
  • temperature
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6
Q

what is a tropisms

A
  • growth or movement in response to external stimuli controlled by hormones
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7
Q

Phototropism

A
  • response to light
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8
Q

heliotropism

A

-diurnal response to sunlight

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9
Q

geotropism

A

response to earth or gravity

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10
Q

thigmotropism

A

response to touch ex vines

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11
Q

what characteristics will a plant in proper light have

A
  • full stems
  • short internodes
  • closely spaced leaves
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12
Q

what characteristics will plants have grown in too much shade

A
  • long internodes

- poorly developed leaves

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13
Q

what characteristics will plants have grown in complete darkness

A

-thin colourless stems with pale underdeveloped leaves (etiolation)

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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

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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
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16
Q

Diaheliotropism

A

-tracking sun (max amount if direct solar radiation leaf receive

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17
Q

Paraheliotropism

A

avoiding the sun

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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
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19
Q

geotropism

A

grow in same or opposite direction of gravity

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20
Q

negative geotropism

A

-opposite direction of gravity ex stems

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21
Q

positive geotropism

A
  • in direction of gravity

ex roots

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22
Q

diageotropism

A

-horizontal growth of rhizomes, stolons and some roots

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23
Q

what hormones affect geotropism

A
  • auxon and gibberelins
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24
Q

Thigmotropism

A

response to touch

ex tendrils grasp supportive objects

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25
Q

what hormones involved in thigmotropism

A

-uneven distribution of auxin

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26
Q

describe nastic movement

A
  • 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
Q

what does hormone mean in greek

A

to set in motion

28
Q

what do hormones do in plant

A
  • initiate biochem activities resulting in observable, physiological responses
29
Q

what is other word word for plant hormones

A
  • Plant Growth Regulators
30
Q

what are 5 principle hormones studied ( 3 growth, 2 decay)

A
  1. Auxin
  2. Gibberellins
  3. Cytokinin
  4. Abscisic acid
  5. ethylene
31
Q

what is greek word for auxin

A

to increase

32
Q

principle function of auxin

A
  • stimulate increase in cell length (esp near stem and root tips)
    cell elongation directly prop. to [auxin]
33
Q

what is IAA

A

-natural auxin in plants ;
-indole- 3- acetic acid
produced in apical meristem –> apical dominance
-moves downward, decreasing []

34
Q

t or f shade plant display lots of phototropism

A

false

35
Q

what hormone is responsible for adventitious root

A
  • auxin
36
Q

what is gibberellins

what is it related to

A

hormone controls growth of internodes

  • light intensity
  • high light = restrained
  • low light= active, increase internode length
37
Q

what are 4 functions of Gibberellins

A
  1. growth at internodes
  2. trigger seed germination
  3. breaking bud dormancy
  4. induce flowering
38
Q

t or f ; absence of gibberellins results in dwarfism

A

true

39
Q

what is bolting, what hormone involved

A
  • stimulation of flowering/ seed production in crops grown for leaves
  • gibberellins
40
Q

what is greek breakdown of cytokinin

A 
kytos= container/ cell
kinesis= movement
41
Q

what is primary role of cytokinin

A

promotion and regulation of cellular division

42
Q

what ratio promotes root formation

A

high ratio auxin and cytokinins

43
Q

what ratio promotes shoot formation

A

low ratio auxins to cytokinins

44
Q

what hormone promotes lateral bud growth in flowering plants

A
  • cytokinin
45
Q

what does senescence mean in latin

A

to grow old

46
Q

t or f once begun, senescence can be reversed

A

false

47
Q

what is senescence controlled by , what is it responsible for

A

hormones

  1. ripening of fruit
  2. ageing flowers
  3. leaf drop
48
Q

what hormones inhibit senescence

A
  • auxin, gibberellins, cytokinin
49
Q

what triggers production of abscisic acid and ethylene

A

environmental cues

50
Q

which hormone has the most control on leaf abscission

A

ethylene

51
Q

what is purpose of abscisic acid

A
  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
Q

what is syn of terminal buds and leaves stimulated by?

A

-stresses, water shortage, low temp

53
Q

describe leaf abscission

A
  • breakdown of chlorophyll
  • movement of sugars from leaf to body of plant
  • weakening of cell walls at base of petiole
54
Q

what cues abscission

A

low temp and short days cue reduction of auxin and increase production of ethylene

55
Q

what is ethylene

A

-gas hormone

56
Q

what characteristics does amount of ethylene vary in species

A
  • amount varies on species
  • tissue
  • stage of development
57
Q

what 5 things does ethylene stimulate

A
  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
Q

what is the triple response

A
  • stunting of growth
  • twisting of plants
  • abnormal thickening of stems
59
Q

what is the colour ripening in fruit a result of

A
  • chlorophyll breakdown
60
Q

what 3 things occur during fruit ripening

A
  • colour changes from chlorophyll breakdown
  • sugar content rises
  • cell walls and membranes soften
61
Q

describe apical dominance

A

controlled by growth hormones in apical meristem

62
Q

what does removal of meristem cause

A
  • reduction [ auxin]

- allows axillary buds to develop

63
Q

what are adventitious roots? how are they controlled ?

A
  • stimulation of root development on stems

- auxins

HORT 1047 Horticulture 1 (9 decks)

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