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Biology (NCERT) - Class XI > XI Chap 15 Plant Growth Development > Flashcards

XI Chap 15 Plant Growth Development Flashcards

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1
Q

Plant development is the sum of 2 processes: _______ and ________

A

growth and differentiation

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2
Q

The first step in plant growth is ____________

A

seed germination

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3
Q

_______ is regarded as one of the most fundamental and conspicuous characteristics of a living being

A

growth

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4
Q

Define growth

A

irreversible permanent increase in size of an organ / organ parts / individual cell

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5
Q

Growth is accompanied by _________ processes that occur at the expense of energy

A

metabolic (anabolic and catabolic)

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6
Q

Why is plant growth unique?

A

retain the capacity for unlimited growth throughout their life due to presence of meristems

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7
Q

Plant form of growth wherein new cells are always being added by activity of the meristem is called ___________

A

open form of growth

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8
Q

In ________________, the lateral meristems, vascular cambium and cork-cambium appear later in life.

A

dicotyledonous plants and gymnosperms

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9
Q

What are the meristems that cause increase in girth of organs?

A

lateral meristems, vascular cambium, cork-cambium

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10
Q

What is secondary growth of plant?

A

increase in girth of organs, later in life

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11
Q

Growth at cellular level is consequence of increase in amount of _________

A

cytoplasm

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12
Q

Increase in protoplasm is easy to measure directly. T or F?

A

False

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13
Q

Growth can be measured by increase in ? (6)

A 
fresh weight, 
dry weight, 
length, 
area, 
volume, 
cell number
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14
Q

A single maize root apical meristem can give rise to _____ new cells per hour

A

17,500

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15
Q

Cells in watermelon may increase in size by upto ____________ times per hour

A

3,50,000

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16
Q

Growth of pollen tube is measured in terms of its ___________

A

length

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17
Q

What measure indicates growth in a dorsiventral leaf?

A

increase in surface area

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18
Q

Plant growth is divided into how many phases? What are they?

A

3

meristematic, elongation and maturation

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19
Q

The constantly dividing cells at the root and shoot apex represent the ________ phase of growth

A

meristematic

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20
Q

The cells in the meristematic region are rich in _______ and possess ______ nuclei

A

cytoplasm, large conspicuous

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21
Q

Describe cell walls of meristematic region cells

A

primary in nature,
thin,
cellulosic,
abundant plasmodesmatal connections

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22
Q

Cells next to the meristematic zone, away from the tip represent the phase of __________

A

elongation

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23
Q

What are characteristics of cells in elongation phase?

A
  1. increase vacuolation
  2. cell enlargement
  3. new cell wall deposition
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24
Q

Furthest away from the apex are the cells undergoing phase of __________

A

maturation

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25
Q

Cells of maturation zone attain their maximal size in terms of _____ and _______

A

wall thickening, protoplasmic modifications

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26
Q

What is growth rate?

A

increased growth per unit time,

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27
Q

What are the 2 types of growth rates?

A

arithmetic or geometrical

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28
Q

Arithmetic vs. geometric growth

A

Arithmetic - only one daughter cell of mitosis divides, other differentiates and matures; linear curve; Lt = L0 + rt

Geometric - both daughter cells continue to divide; starts with lag phase and eventually leads to a stationary phase due to limited nutrients; sigmoid/S-curve; W1 = W0 * e^rt

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29
Q

Relative growth rate is represented by the letter ____

A

r

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30
Q

Relative growth rate is the measure of the ability of the plant to ______

A

produce new plant material

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31
Q

Relative growth rate is aka ________

A

efficiency index

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32
Q

Final size of W1 depends on W0 wrt plant growth. T or F?

A

True

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33
Q

Quantitative comparisons between growth of living systems can be made in 2 ways:

A

absolute and relative

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34
Q

Plant cells grow in size by cell enlargement which in turn requires _______

A

water

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35
Q

_________ of cells helps in extension growth

A

Turgidity

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36
Q

Water also provides the medium for enzymatic activities needed for plant growth. T or F?

A

True

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37
Q

How do oxygen and nutrients help in plant growth?

A

Oxygen - releasing metabolic energy

Nutrients - synthesis of protoplasm and source of energy

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38
Q

Environmental signals such as light and gravity can affect plant growth. T or F?

A

True

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39
Q

Differentiation, dedifferentiation vs. redifferentiation

A

Differentiation - structural changes to cell wall and protoplasm

Dedifferentiation - cell that have lost ability to differentiate can regain it

Redifferentiation - dedifferentiated cells can once again lose the capacity to divide to perform other specific functions

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40
Q

To form a tracheary element, how do cells differentiate?

A

lose their protoplasm

develop strong, elastic, lignocellulosic secondary cell walls

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41
Q

Formation of meristems from fully differentiated parenchyma cells is an example of __________

A

dedifferentiation

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42
Q

Differentiation in plants, like growth, is open. T or F?

A

True, because cells/tissues arising out of meristem have different structures

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43
Q

Final structure at maturity of a cell/tissue is partly determined by the location of the cell within. T or F?

A

True

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44
Q

Cells positioned away from root apical meristems differentiate as __________ while those pushed to the periphery mature as _______

A

root-cap cells, epidermis

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45
Q

_________ includes all changes that an organism goes through during its life cycle from germination of the seed to senescence.

A

Development

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46
Q

Describe the sequence of developmental processes in plant cell/tissue/organ

A

meristematic cell
-> plasmatic growth -> differentiation
-> expansion/elongation -> maturation
=> mature cell -> senescence -> death

some cells in plasmatic growth phase divide again to join back meristematic cell

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47
Q

What is plasticity? Examples

A

ability of plants to follow different pathways in response to environment/phases of life to form different kinds of structures

e.g. heterophylly in cotton, corianer and larkspur

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48
Q

In __________ plant, different shapes of leaves in terrestrial vs aquatic habitats is an example of ____________ development

A

buttercup

heterophyllous

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49
Q

Plant growth regulators (PGR) are ______ molecules of _______ chemical composition

A

small, simple

diverse

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50
Q

Plant regulators could be?

A 
indole compounds
adenine derivative
derivatives of carotenoids
terpenes
or gases
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51
Q

PGRs can be divided into 2 groups based on _______. The groups are?

A

functions;

promoters and inhibitors

52
Q 
Specify if these are promoters or inhibitors:
auxins
abscisic acid
gibberellins
cytokinins
ethylene
A 
auxins - promoter
abscisic acid - inhibitor
gibberellins - promoter
cytokinins - promoter
ethylene - can be either, mostly inhibitor
53
Q

________ types of PGRs play an important role in plant responses to wounds and biotic/abiotic stresses.

A

Inhibitors

54
Q

Pattern formation, seed formation and dormancy are growth promoting activities in plants. T or F?

A

False, first two are correct but dormancy is growth inhibiting

55
Q

Discovery of each of the five PGRs were the result of years of concerted efforts of scientists across the world. T or F?

A

False, accidental discoveries

56
Q

Charles Darwin and his son Francis Darwin observed that ____________ responded to unilateral illumination by growing towards the light source aka _____________

A

coleoptiles of canary grass, phototropism

57
Q

______ of the coleoptile is the site of transmittable influence causing the bending of the plant.

A

Tip

58
Q

Auxin was isolated by ____________ from tips of coleoptiles of _________

A

F. W. Went,

oat seedlings

59
Q

The bakanae (foolish seedling) disease of rice seedlings was caused by _______ type of pathogen ___________ (scientific name)

A

fungal, Gibberella fujikuroi

60
Q

_________ reported the symptoms of bakanae disease when treated with sterile filtrates of fungus Gibberella fujikuroi in the year ______

A

E. Kurosawa, 1926

61
Q

The active substance in the pathogen causing bakanae is _________

A

gibberelic acid

62
Q

___________ observed that from internodal segments of tobacco stems, the _______ proliferated only if in addition to auxins the nutrient medium was supplemented with one of the following:

A

F Skoog et al;
callus;
extracts of vascular tissues, yeast extract, coconut milk or DNA

63
Q

___________ observed that from internodal segments of tobacco stems, the _______ proliferated only if in addition to auxins the nutrient medium was supplemented with one of the following:

A

F Skoog et al;
callus;
extracts of vascular tissues, yeast extract, coconut milk or DNA

64
Q

In the year _____, ___________ identified the cytokinesis promoting active substance observed by F Skoog et al, and termed it __________

A

1965, Miller et al, kinetin

65
Q

During mid-19__s, three independent researches reported purification and chemical characterisation of 3 inhibitors: ______

A

1960s;

inhibitor-B, abscission II and dormin

66
Q

_____________ (3) are all chemically identical and are named abscisic acid (ABA)

A

Inhibitor-B, abscission II and dormin

67
Q

In 1910, _________ confirmed release of volatile substance from ripened _______ that hastened the ripening of stored bananas. Later this substance was identified as ________

A

H. H. Cousins,
oranges,
ethylene

68
Q

What are the five categories of PGRs?

A
  1. Auxins
  2. Gibberellins
  3. Cytokinins
  4. Ethylene
  5. Abscisic acid (ABA)
69
Q

Auxins comes from Greek meaning _____

A

to grow

70
Q

Auxin was first isolated from _________

A

human urine

71
Q

The term auxin is applied to _______ acid and other compounds having growth regulating properties.

A

indole-3-acetic acid (IAA)

72
Q

Auxins are generally produced by _______ in plants

A

growing apices of stem and roots

73
Q

Auxins like ____ and ____ have been isolated from plants

A

Indole-3-acetic acid (IAA)

indole butyric acid (IBA)

74
Q

_______ and _____ are synthetic auxins

A

Naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic (2,4-D)

75
Q

Auxins help in what plant processes?

A
  • initiate rooting in stem cuttings
  • promote flowering (e.g. pineapple)
  • prevent fruit and leaf drop at early stage
  • promote abscission of older mature leaves and fruits
  • induce parthenocarpy (e.g. tomatoes)
  • controls xylem differentiation
  • cell division
76
Q

What is apical dominance?

A

The growing apical bud inhibits growth of lateral axillary buds

77
Q

___________ usually results in the growth of lateral buds

A

Decapitation, removal of shoot tips

78
Q

________ is used to prepare a weed-free lawn by gardeners

A

Auxin

79
Q

Auxins are also widely used as herbicides. T or F?

A

True

80
Q

2,4-D is widely used to kill _________ as it does not affect ___________

A

weeds, mature monocot plants

81
Q

Gibberellins is a promotory or inhibitory PGR?

A

promotory

82
Q

There are more than _________ gibberellins reported from ____ and _______

A

100, fungi, higher plants

83
Q

_________ was one of the first gibberellins to be discovered and is the most intensively studied form.

A

GA3

84
Q

All GAs are alkaline. T or F?

A

False, acidic

85
Q

What roles do gibberellins play in plants?

A
  • increase length of axis (e.g. grape stalks, sugarcane)
  • cause fruits to elongate and improve shape (e.g. apple)
  • delay senescence (fruits left longer on tree, extended market period)
  • early seed production (by hastening the maturity period e.g. juvenile conifers)
  • promotes bolting i.e. internode elongation prior to flowering (e.g. beet, cabbages and rosette plants)
86
Q

In the brewing industry, GA3 is used to ________

A

speed up the malting process

87
Q

Spraying sugarcane crop with ___________ can increase yield by as much as _______ per acre

A

gibberellins,

20 tonnes

88
Q

Cytokinins were discovered as a kinetin (modified form of _____) from the _________

A

adenine, autoclaved herring sperm DNA

89
Q

Kinetin is naturally occurring in fungi and higher plants. T or F?

A

False, does not occur naturally in plants

90
Q

Search for natural substances with cytokinin-like activities led to isolation of _____ from _____

A

zeatin;

corn-kernels and coconut milk

91
Q

Natural cytokinins are synthesised in regions where ___________

A

rapid cell division occurs

92
Q

Cytokinins help plants in what ways?

A
  • produce new leaves
  • produce chloroplasts in leaves
  • lateral shoot growth
  • adventitious shoot formation
  • overcome apical dominance
  • nutrient mobilisation => delay of leaf senescence
93
Q

__________ is a gaseous PGR

A

Ethylene

94
Q

Ethylene is synthesised in large amounts by _______

A

tissues undergoing senescence and ripening fruits

95
Q

Influence of ethylene on plants?

A
  • horizontal growth of seedlings
  • swelling of axis
  • apical hook formation in dicot seedlings
  • senescence and abscission of plant organs (esp. leaves and flowers)
  • fruit ripening (enhances respiration rate)
  • flowering and synchronising fruit-set (pineapples and mango)
  • breaks seed and bud dormancy i.e. initiates germination (e.g. peanut seeds, potato tubers)
  • rapid internode/petiole elongation (e.g. deep water rice plants)
  • helps leaves / upper shoot to reman above water
  • promote root growth and root hair formation => increased SA for absorption
96
Q

___________ is one of the most widely used PGRs and ____ is the most widely used source of it.

A

ethylene, ethephon

97
Q

Ethephon in an aqueous solution is readily absorbed and transported within the plants and releases ethylene rapidly. T or F?

A

False, releases slowly, everything else is correct.

98
Q

Ethephon effects on plants?

A
  • fruit ripening in tomatoes / apples
  • abscission in flower and fruits (cotton, cherry, walnut - thinning)
  • female flowers in cucumber => higher yield
99
Q

____________ was discovered for its role in regulating abscission and dormancy

A

Abscisic acid - ABA

100
Q

Effects of ABA on plants:

A
  • general plant growth inhibitor
  • inhibits metabolism
  • inhibits seed germination
  • stimulates closure of stomata
  • increases tolerance to stresses
  • withstand seed desiccation
101
Q

What is respiratory climactic?

A

rise in rate of respiration during ripening of fruits as a result of ethylene

102
Q

________ PGR is also called the stress hormone

A

ABA

103
Q

In most situations, ABAs act as an antagonist to ____________

A

GAs

104
Q

______ PGR plays an important role in seed development, maturation and dormancy.

A

ABA

105
Q

PGR roles could be complimentary or __________, individualistic or ___________

A

antagonistic, synergistic

106
Q

The role of PGR is of only one kind of intrinsic control. T or F?

A

True

107
Q

Many extrinsic factors control plant growth and development via PGRs during events like vernalisation or plant movements. T or F?

A

True

108
Q

Long day, short day vs. day neutral plants?

A

LD - for a period exceeding a critical duration
SD - for a period less than critical duration
Day-neutral - no correlation between light exposure duration and flowering response

109
Q

What is photoperiodism?

A

response of plants to periods of day and night

110
Q

Not only duration of light but also duration of dark is of equal importance to plant growth. T or F?

A

True

111
Q

Shoot apices (the precursor to flowering apices) can perceive photoperiods just like flowering apices. T or F?

A

False, they cannot

112
Q

It has been experimentally shown that a hormonal substance is responsible for flowering; it migrates from leaves to shoot apices to induce flowering after exposure to necessary photoperiod. T or F?

A

False, it’s a hypothesis (not proven) but described accurately

113
Q

What is vernalisation?

A

When plant flowering is quantitatively or qualitatively dependent on exposure to low temperature

114
Q

What is the function of vernalisation?

A
  • prevents precocious reproductive development late into growing season
  • enables plant to have sufficient time to reach maturity
115
Q

What are the 2 varieties related to vernalisation?

A

Winter - planted in autumn, germinate, small seedlings in winter, resume growth in spring, harvested around mid-summer

spring - planted in spring, flower and produce grain by summer

116
Q

Some examples of food plants that have winter and spring varieties?

A

wheat, barley, rye

117
Q

What are biennial plants?

A

biennial = monocarpic plants that normally flower and die in second season

118
Q

Examples of biennial plants?

A

Sugarbeet, cabbages and carrots

119
Q

How is vernalisation seen in biennial plants?

A

subjecting growth to a cold treatment => subsequent photoperiodic flowering response

120
Q

What happens in a seed which fails to germinate even when external conditions are favourable?

A

period of dormancy under endogenous control (not controlled by external factors)

121
Q

What are some reasons for seed dormancy?

A
  • impermeable and hard seed coat
  • presence of chemical inhibitors (e.g. ABA, phenolic acids, para-ascorbic acid)
  • immature embryos
122
Q

Seed dormancy can be overcome through natural and man-made measures. T or F?

A

True

123
Q

Root and shoot apical meristems sometimes along with __________ contribute to the elongation growth of plant axes.

A

Intercalary meristem

124
Q

General principles for differentiation for cell, tissues and organs are similar. T or F?

A

True

125
Q

Intercellular intrinsic factors are the chemical substances called PGRs. T or F?

A

True

126
Q

Any PGR has diverse physiological effects on plants. T or F?

A

True

127
Q

Diverse PGRs manifest uniquely different effects. T or F?

A

False, can be similar effects

Biology (NCERT) - Class XI (23 decks)

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