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Plant Physio FINALS > Plant Regulators > Flashcards

Plant Regulators Flashcards

1
Q
  • a photoreceptor that absorbs light and helps plants
    sense changes in light quality and duration.
A

Phytochrome

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2
Q

Two forms of phytochromes

A

Pr;
Pfr

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3
Q

Pr - absorbs _light with peak wavelength of __

A

red;
660nm

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4
Q

the inactive phytochrome form and does not initiate photomorphogenic response

A

Pr

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5
Q

Pfr - absorbs ____ light around ___nm

A

far-red;
700 to 750 nm

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5
Q

the active form and initiates responses such as seed germination.
flowering, and other growth processes
converts back to Pr after absorbing far-red light

A

Pfr

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6
Q
  • refers to plant growth influenced by light; changes in shape, structure, and function
A

Photomorphogenesis

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7
Q

Photomorphogenesis:

seedlings undergo ___through ____where plant stems
grow even in dark environments to quickly reach potential light source

A

etiolation;
skotomorphogenesis

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8
Q

Two stages of photomorphogenesis

A

Pattern Specification;
Pattern Realization

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9
Q
  • preparation of cells and tissues to
    become more responsive to light
A

Pattern Specification

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10
Q
  • occurs when the actual light-inducted
    responses are executed
A

Pattern Realization

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11
Q

Photomorphogenic responses: 4

A
  1. Leaf expansion
  2. Stem shortening and thickening
  3. Flowering timing - via photoperiodism
  4. Shade avoidance
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12
Q
  • the physiological response of plants to the length of day and night,
    influencing seasonal behaviors such as flowering, seed
    germination, and dormancy
A

Photoperiodism

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13
Q

refers to how plants use the length of day and night to determine the timing of
their flowering.

A

Photoperiodism in Flowering

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14
Q
  • specific length of darkness that a plant needs to start or prevent flowering
A

Critical night length

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15
Q

Types of Photoperiodic Plants:

A

Short-Day plants
Long-Day plants
Day-neutral plants

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16
Q
  • plants which require less exposure to light; need nights longer than their critical night length to flower.
A

Short-Day plants

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17
Q
  • plants which require more exposure to light
    need nights shorter than their critical night length to flower.
A

Long-Day plants

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18
Q
  • plants that are not sensitive to day length
A

Day-neutral plants

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19
Q

movement in plants is mostly seen as
__, __, __, or as__ of
plant parts

A

bending, turning, twisting or as elongation

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20
Q

movement of plants can be divided into:

A

Tropic Movements
Nastic Movement

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21
Q

Growth movements which occur in the direction of the stimulus; may be towards or away from the stimulus

A

tropic movement

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22
Q

Tropic movements are of various types (6)

A

Phototropism:
Chemotropism:
Hydrotropism:
Geotropism:
Thigmotropism:
Thermotropism:

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23
Q

Stimulus: Light
Description: This is the growth response of plants toward or away from
light.

A

Phototropism

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24
Q

___ is when a plant grows toward light (e.g., plant
stems and leaves), and __ is when a plant grows away
from light (e.g., roots).

A

Positive phototropism;
negative phototropism

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25
Q

In ___phototropism, plant cells on the __ side
elongate more than those on the ___ side, causing the plant to bend toward the light source. The hormone __plays a critical role in this
process.

A

positive;
shaded;
light-exposed;
auxin

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26
Q

Stimulus: Chemicals
Description: is the growth or movement of a plant part in response to chemicals.

A

Chemotropism

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27
Q

Pollen tube growth towards the ovule during fertilization, roots
growing toward nutrients like nitrogen, or avoidance of toxic substances is an example of

A

Chemotropism

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28
Q

Stimulus: Water
Description: refers to the plant’s growth in response to water

A

Hydrotropism

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29
Q

Roots exhibit ___ by
growing toward areas of higher moisture content in the soil to
optimize water uptake.

A

positive hydrotropism

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30
Q

Stimulus: Gravity
Description: is the directional growth of plant parts in
response to gravity.

A

Geotropism

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31
Q

____ is the growth of roots downward
(toward gravity), while ___ is the growth of stems and
shoots upward (away from gravity).

A

Positive geotropism;
negative geotropism

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32
Q

Geotropism response involves the plant’s gravity-sensing cells
(___) that detect the direction of gravity and help orient growth
accordingly

A

statocytes

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33
Q

Stimulus: Touch
Description: is the response of plants to physical contact or
touch

A

Thigmotropism

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34
Q

___ is exhibited by climbing plants or vines that
wrap around supports (e.g., tendrils or stems of climbing plants)

A

Positive thigmotropism

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35
Q

Stimulus: Temperature
Description: is the growth response of plants to temperature
gradients. It involves movement or growth toward warmer or cooler areas.

A

Thermotropism

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36
Q

These movements are non-directional responses to the stimuli;
independent of the direction of the stimulus; due to changes in
turgor or growth.

A

Nastic Movements

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37
Q

Types of Nastic movement (4)

A

Photonasty
Nyctinasty
Thermonasty
Seismonasty or Thigmonasty

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38
Q

Stimulus: Light
Description: is the nastic movement of plant parts in response
to light, but the movement is not necessarily towards or away from the light
source (like in phototropism).

A

Photonasty

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39
Q

It often involves the opening or closing of
flowers or leaves in response to changes in light intensity.

A

Photonasty

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40
Q

Stimulus: Darkness (or changes in the light cycle)
Description: is the movement of plant parts in response to
the onset of darkness or changes in the photoperiod (day-night
cycle).

A

Nyctinasty

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41
Q

often seen in flowers or leaves that open during the day and close at night

A

Nyctinasty

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42
Q

Stimulus: Temperature
Description: is the response of plants to temperature changes.
This can involve the opening or closing of flowers, leaves, or other plant
structures in response to temperature variations.

A

Thermonasty

43
Q

Stimulus: Mechanical stimulus (touch or vibration)
Description: , is the movement of plant parts
in response to mechanical stimuli such as touch, vibration, or even
shaking. This is typically a rapid, non-directional response to external
physical disturbances.

A

Seismonasty, or thigmonasty

44
Q

Environmental and Genetic Factors on control of flowering:

A

Influence of light, temperature, and plant genetics

45
Q

: The duration of light and dark periods affects flowering

A

Photoperiodism

46
Q

: these plants Flower when daylight exceeds a critical length (e.g., __ and ___).

A

Long-Day Plants;
spinach, lettuce

47
Q

these plants Flower when daylight is shorter than a critical length (e.g., __ and ___)

A

Short-Day Plants;
chrysanthemums,
poinsettias

48
Q

these plants Flowering is not affected by day length (e.g., __ and __)

A

Day-Neutral Plants;
tomatoes, corn

49
Q

Environmental and Genetic Factors: Influence of Temperature (2)

A

Vernalization;
Thermoperiodism

50
Q

: Some plants require a period of cold temperature to flower (e.g., winter wheat,
biennial plants like carrots)

A

Vernalization;

51
Q

: Daily temperature fluctuations can influence flowering, with some plants
requiring specific day/night temperature patterns

A

Thermoperiodism

52
Q

Environmental and Genetic Factors: Influence of plant genetics (2)

A

Genetic Regulation;
Genetic Mutations

53
Q

Flowering genes control the transition from vegetative to reproductive growth.

A

Genetic Regulation:

54
Q

Key flowering genes (4)

A

FLOWERING LOCUS T (FT):
CONSTANS (CO):
LEAFY (LFY):;
APETALA1 (AP1):

55
Q

Genetic mutations can alter flowering __ and __s, impacting
the adaptability and reproduction of plants

A

time and pattern

56
Q

is a hypothetical hormone or signal produced in leaves under favorable
conditions, inducing flowering

A

Florigen

57
Q

Florigen Moves from the __to the___ where it triggers floral development.

A

leaves ;
shoot apical meristem

58
Q

In many plants, the ___ has been identified as a component of
florigen.

A

FT protein

59
Q

Acts as a mobile signal promoting flowering.

A

FLOWERING LOCUS T (FT):

60
Q

: Regulates FT expression in response to photoperiod.

A

CONSTANS (CO)

61
Q

Integrates signals and promotes floral meristem identity

A

LEAFY (LFY):

62
Q

Initiates flower development and determines floral organ identity

A

APETALA1 (AP1):

63
Q

Influence of External Cues (2)

A

Light (Photoperiod);
Temperature (Thermoperiod)

64
Q

:
Plants perceive changes in day
length through photoreceptors
like phytochromes and
cryptochromes.

A

Photoperiodic Response

65
Q

: CO
protein levels and activity are regulated by __, influencing FT
expression and thus flowering.

A

Signal Transduction; light

66
Q

High or low
temperatures can accelerate or delay
flowering

A

Temperature Sensitivity:

67
Q

: Extended exposure to cold
temperatures leads to changes in gene
expression that promote flowering once
favorable conditions return.

A

Vernalization

68
Q

High temperatures can
negatively impact flowering and fruit set,
particularly in sensitive crops.

A

Heat Stress:

69
Q

is the process by which prolonged exposure to cold
temperatures induces flowering in some plants

A

Vernalization

70
Q

Flowering Pathways (3)

A

Vernalization
Photoperiodism
Autonomous pathways

71
Q

Cold temperatures promote the expression of flowering genes
(e.g., ____ in wheat) while repressing flowering
inhibitors (e.g., ____ in Arabidopsis).

A

VERNALIZATION1 (VRN1);
FLOWERING LOCUS C (FLC)

72
Q

is the response of plants to the relative lengths of light and dark periods,
influencing flowering.

A

Photoperiodism

73
Q

: Require longer daylight periods to flower. The CONSTANS (CO) gene
promotes the expression of FT under long-day conditions.

A

Long-Day Plants

74
Q

Flower when the day length is shorter. The CO gene’s activity is inhibited
during long days, preventing FT expression.

A

Short-Day Plants:

75
Q

control flowering based on internal developmental cues,
independent of external environmental factors.

A

Autonomous pathways

76
Q

pathway involves the regulation of flowering genes by the plant’s
developmental state and internal signals

A

Autonomous pathways

77
Q

Integration of Signals (4)

A

Signal Convergence;
Gene Interaction:
Hormonal Regulation
Environmental Cues:

78
Q

Flowering is controlled by the integration of multiple pathways
(vernalization, photoperiodic, autonomous) to ensure optimal timing.

A

Signal Convergence:

79
Q

Key regulatory genes (e.g., FT, CO, FLC) interact to integrate
signals from different pathways

A

Gene Interaction:

80
Q

Hormones such as ___ can interact with flowering
pathways to modulate the timing and development of flowers

A

Hormonal Regulation: ;
gibberellins

81
Q

External factors like light, temperature, and nutrient availability
provide additional layers of regulation to fine-tune the flowering process

A

Environmental Cues:

82
Q

Before death, plants undergo deteriorative processes that end
their functional life, known as ___.

A

senescence

83
Q

The death of a plant or plant
parts as a direct consequence of senescence

A

Programmed Cell Death (PCD):

84
Q

types of senescence

A

Overall Senescence;
Top Senescence;
Deciduous Senescence;
Progressive Senescence

85
Q

Description: Occurs in annual plants, where the entire plant undergoes
aging and eventually dies.;
Process: Triggered after flowering and seed production; the whole
plant begins a rapid decline, leading to death

A

Overall Senescence

86
Q

Description: Observed in perennials; senescence affects only
the parts above ground.
Characteristics: Roots remain alive and viable, allowing for
regrowth in the following season

A

Top Senescence

87
Q

Description: Occurs in woody plants; less drastic as it mainly affects
leaves.
Characteristics: All leaves age and shed, typically in the fall,
allowing the plant to conserve energy and resources during
unfavorable seasons

A

Deciduous Senescence

88
Q

Description: A gradual process seen in plants where leaf senescence
progresses from the base upwards as the plant grows.
Characteristics: This pattern allows the plant to redistribute nutrients
from older leaves to new growth

A

Progressive Senescence

89
Q

Importance of Senescence in Plants

A

Resource Redistribution:
Adaptation and Survival:
Hormonal Regulation

90
Q

Controlled by hormones like __ and ___, which signal the onset of senescence.

A

ethylene and
abscisic acid

91
Q

Biochemical Changes During Ripening:

A

Color change, softening, and sweetness increase

92
Q

Color Change (2)
Softening: (2)
Sweetness Increase (2)

A

Color Change: Chlorophyll Degradation, Carotenoids and Anthocyanins
Softening: Cell Wall Breakdown, Water Movement
Sweetness Increase: Starch Conversion, Acid Reduction

93
Q

As fruits ripen, the green pigment chlorophyll breaks down

A

Chlorophyll Degradation:

94
Q

These
pigments become more
prominent, resulting in yellow,
orange, and red hues in the
fruit

A

Carotenoids and
Anthocyanins:

95
Q

Cell Wall Breakdown:
Enzymes like __ and __break down the cell wall components, leading to softer texture

A

pectinases and cellulases

96
Q

as the key hormone in fruit ripening, along with other hormones that influence the process.

A

Ethylene

97
Q

Ethylene triggers a cascade
of biochemical events, including __, __, and ___

A

enzyme activation
for cell wall breakdown, chlorophyll degradation,
and starch conversion

98
Q

is often used to
artificially induce ripening in harvested fruits

A

Ethylene gas

99
Q

: Help in maintaining fruit firmness and delaying
ripening until the fruit is ready

A

Auxins

100
Q

: Influence the size and quality of the fruit,
and may delay ripening in some cases

A

Gibberellins

101
Q

Plays a role in the onset of fruit
ripening and senescence, contributing to color change
and sugar accumulation.

A

Abscisic Acid (ABA):

102
Q

A natural process by which a plan intentionally sheds parts of itself, such as
leaves, flowers, fruits, or seeds due to developmental or environmental signals

A

abscission

103
Q

Purpose of Abscission (3)

A

Seasonal Leaf Drop ;
Fruit and seed Release;
Defense mechanism

104
Q

Phases of Abscission:
___ - Leaf is healthy and auxin
gradient flows from leaf blade to stem

A

Phase I

105
Q

Phases of Abscission:
- auxin gradient is reversed
or reduced causing cells in the zone
of abscission to react to ethylene

A

Phase II

106
Q

Phases of Abscission:

  • hydrolytic enzymes break
    down cell walls and plant organ
    detache
A

Phase III

Plant Physio FINALS (13 decks)

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