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Biology 102 > Ch. 39 B > Flashcards

Ch. 39 B Flashcards

(58 cards)

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1
Q

What are the effects of gibberellins (5)

A

1) Stem Elongation
2) Fruit Growth
3) Seed Germination
4) Flowering
5) Leaf Expansion

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2
Q

How do Gibberellins stimulate growth?

A

Enhancing cell division and elongation

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3
Q

Where are Gibberellins produced?

A

Young roots and shoots

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4
Q

What is bolting?

A

Rapid growth of floral stalk

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5
Q

What is required for fruit development?

A

Auxin and Gibberellin

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6
Q

What does the release of gibberellins indicate to the embryo?

A

The germination of the seed (after imbibition)

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7
Q

What is the function of Amylase?

A

Breaks down amylose

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8
Q

What does Abscisic acid do? What does it affect?

A

1) It slows growth by stopping the actions of growth hormones
2) Causes seed dormancy and drought tolerance

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9
Q

What does the ratio of ABA to gibberellins indicate?

A

Affects whether the seeds will break dormancy

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10
Q

What causes early germination?

A

Low levels of ABA

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11
Q

What is the primary signal that enables plants to withstand a drought

A

ABA

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12
Q

ABA accumulation causes what for drought tolerance

A

Stomata to close rapidly (wilting of leaves)

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13
Q

What does the transport of ABA from water-stressed root system to leaves indicate?

A

Early warning system

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14
Q

Abiotic Stress (Plant Development)

A

Primary Metabolites
Heat, cold, drought, salt, metals, flooding

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15
Q

Biotic Stress (Plant Defense)

A

Phytohormones
Herbivore attack, Insect attack, Pathogen attack

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16
Q

When do plants produce ethylene?

A

Response to stress: Drought, flooding, mechanical pressure, injury and infection

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17
Q

What are the effects of ethylene? (3)

A

Senescence: Loss of cell division and growth
Leaf abscission: less leaves
Fruit Ripening

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18
Q

What is the triple response to mechanical stress?

A

1) Triple response: Elongation slowed, thickened stem, and horizontal stem growth
2) Happens when seedling tips is pressed against obstacle ethylene is produced
3) Absence of ethylene causes normal growth

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19
Q

What is senescence? When does it happen?

A

Programmed death of certain cells or organs or entire plant
Burst of ethylene is associated with apoptosis

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20
Q

What is Leaf Abscission?

A

Change in balance of auxin and ethylene causes leaves to fall and DIE

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21
Q

What triggers ripening?

A

Release of more ethylene

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22
Q

Change in shape due to a response to light

A

Photomorphogenesis

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23
Q

What can plants detect?

A

Light: presence, direction, intensity, and color

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24
Q

Two major classes of light receptors?

Study These Flashcards
A

1) Blue light photoreceptors
2) Phytochromes

25
What does blue light initiate?
1) Hypocotyl elongation 2) Stomatal opening 3) phototropism
26
What is phototropin?
Protein kinase involved in mediating plant responses to blue light
27
What do phytochromes do? (3)
Pigments that regulate plant response to light De-etiolation, seed germination (red light), and shade avoidance
28
What does red light cause
Induced germination
29
What inhibits germination?
Far-red light
30
Are the effects of red and far-red light reversible?
Yes
31
What does final light exposure do?
Determines the response (for seed germination)
32
What are the two photoreversible states
Pr and PFr
33
What triggers the conversion of Pr to Pfr
Red light (faster than the reverse reaction)
34
What triggers the conversion of PFr to Pr
Far-red light
35
What contains both red and far red light thus causing germination?
Sunlight
36
Red light nm?
600-700
37
Far red light nm?
700-750
38
Explain the interaction of canopy leaves and red and far-red light
they absorb red light and allow far-red light to pass through to shaded leaves
39
what does Pr induce?
vertical growth
40
plant processes and circadian rhythms
1) some processes affected by light and temperature 2) others under frequency of 24 hr even under constant conditions
41
photoperiod
lengths of night and day environmental stimulus to detect time of year
42
Photoperiodism
physiological response to photoperiod
43
Short-day plants
light period is shorter than a critical length governed by minimum hours of consecutive darkness (if maximum consecutive darkness is exceeded= flowering)
44
Long-day plants
light period longer than a certain number of hours governed by maximum hours of darkness (if maximum consecutive darkness is exceeded= no flowering)
45
Day-neutral plants
controlled by plant maturity not photoperiod
46
photoperiods are controlled by what?
critical night length
47
gravitropism
response to gravity
48
How are roots and shoots affected by gravitropism?
roots show positive shoots show negative
49
what are statoliths?
cytoplasmic components that help plants detect gravity
50
Thigmomorphogenesis
changes in form from mechanical disturbance ex) rubbing stems
51
Thigmotropism
growth in response to touch
52
what are Action potentials?
touch response from electrical impulses
53
How do plants reduce transpiration? (3)
1) closing stomata 2) reducing exposed surface area 3) shedding leaves
54
How do plants survive flooding?
1) enzymatic destruction of root cortex 2) aerial roots
55
How do plants respond to salt stress?
producing solutes that tolerate high concentration
56
How do plants respond to heat stress? (2)
1) transpiration 2) heat-shock proteins
57
How do plants respond to cold stress? (3)
1) alter lipid composition in membranes 2) increase solute concentration in cytosol to reduce water loss 3) antifreeze proteins
58
describe plant response to attacks by pathogens and herbivores
use defense systems

Biology 102 (38 decks)

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