Plant Growth and Development Flashcards

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1
Q

Development is the sum of the 2 processes

A

Growth and differentiation

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2
Q

Developmental processes are controlled by

A

Both internal and external factors

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3
Q

Plants have unlimited growth because of

A

Meristems

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4
Q

Lateral meristems, vascular cambium and cork cambium appear later in life in

A

Dicots and gymnosperms

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5
Q

1 maize root apical meristem can give rise to

A

> 17500 new cells/hour

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6
Q

Cells of watermelon may increase in size by upto

A

350000 times

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7
Q

3 phases of plant growth are

A

Meristematic, elongation, maturation

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8
Q

Meristematic cells have

A

Rich protoplasm and large conspicuous nuclei

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9
Q

Cells of elongation zone have

A

Increased vacuolation, cell enlargement, new cell wall deposition

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10
Q

Arithmetic growth example

A

Root elongating at constant rate

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11
Q

Arithmetic growth expression

A

Lt = Lo + rt [r = growth rate]

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12
Q

Geometric growth phases

A

Lag phase, log phase, stationary phase

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13
Q

Exponential growth equation

A

Wt = Wo*e^(rt) [r = relative growth rate/efficiency index]

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14
Q

Turgidity of cells helps in

A

Extension growth

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15
Q

Differentiation of cells into tracheids involves

A

Loss of cytoplasm, development of lignocellulosic, strong, elastic secondary cell wall

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16
Q

Interfascicular and cork cambium are formed from

A

Parenchyma cells by dedifferentiation

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17
Q

Growth and differentiation in plants is

A

Open type - determinate or indeterminate

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18
Q

Meristematic cell undergoes (diagram)

A

Plasmatic growth

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19
Q

Examples of plasticity

A

Heterophylly in cotton, coriander, larkspur [leaves of juvenile plant are different in shape from mature plant]
and buttercup [difference in shapes of leaves produced in air and water]

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20
Q

PGRs are

A

Small simple molecules of diverse chemical composition

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21
Q

Adenine derived PGRs are

A

N-furfurylamino purine, kinetin

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22
Q

Carotenoid derived PGRs are

A

Abscisic acid (ABA)

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23
Q

Terpenes derived PGRs are

A

Gibberelic acid GA3

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24
Q

PGRs are AKA

A

Plant hormones or phytohormones

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25
Q

PGR which is both a promoter and inhibitor

A

Ethylene (mostly inhibitor)

26
Q

Discovery of all 5 types of PGRs have been

A

Accidental

27
Q

Auxin was isolated by

A

F.W. Went from tips of coleoptiles of oat seedlings

28
Q

Auxin was discovered by

A

Charles and Francis Darwin from bending of coleoptiles of canary grass in response to light (avena curvature test)

29
Q

Bakane disease of rice seedlings was caused by

A

Fungus Gibberella fujikuroi

30
Q

PGR first isolated from human urine

A

Auxins

31
Q

Gibberellins were discovered by

A

E. Kurosawa in 1926

32
Q

Cytokinins were discovered by

A

F. Skoog and Miller in tobacco stem callus from vascular tissue extract, yeast extract, coconut milk and DNA

33
Q

Who crystallized cytokinins and named it kinetin

A

Miller et. al. in 1955

34
Q

3 different names for ABA

A

Inhibitor-B, Abscission 2, Dormin [3 independent researchers]

35
Q

Ethylene as a PGR was discovered by

A

H.H. Cousins in 1910 from ripened oranges

36
Q

Naturally found auxins

A

IAA, indole butyric acid

37
Q

Synthetic auxins

A

NAA, 2,4-dichlorophenoxyacetic

38
Q

Action of auxins

A

Initiate rooting in stem cuttings, promote flowering (pineapple), prevent premature fruit and leaf drop, promote abscission of older leaves and fruits, promote apical dominance, induce parthenocarpy (tomatoes), used as herbicides (kills dicot weeds, no effect on mature monocot plants), controls xylem differentiation, helps in cell division

39
Q

Number of types of gibberellins

A

> 100 [GA1, GA2, GA3, …]

40
Q

First gibberellin to be discovered

A

GA3

41
Q

Action of gibberellins

A

Increase length of axis, elongation and shape improvement of fruits (apples), delay senescence, speed up malting process, lessens maturity period, promotes bolting (in plants with rosette habit like cabbage, beet)

42
Q

Application of gibberellins to sugarcane increases yield by

A

20 tonnes/hectare

43
Q

Cytokinins were discovered from

A

Autoclaved herring sperm DNA

44
Q

Kinetin occurs naturally in plants - true/false

A

False

45
Q

Naturally occurring cytokinin

A

Zeatin from corn kernels and coconut milk

46
Q

Natural cytokinins are synthesised where

A

Rapid cell division occurs

47
Q

Action of cytokinins

A

Promotes production of new leaves, chloroplasts, lateral shoot growth, adventitious shoot formation, helps overcome apical dominance, promotes nutrient mobilization, delays leaf senescence

48
Q

Ethylene is synthesized in large amounts by

A

Tissues undergoing senescence and ripening fruits

49
Q

Action of ethylene

A

Promotes horizontal growth of seedlings, swelling of axis, apical hook formation in dicot seedlings, promotes senescence and abscission of leaves and flowers, promotes fruit ripening, enhances respiration rate of fruits during ripening [respiratory climactic], breaks seed and bud dormancy [germination in peanut seeds, sprouting of potato tubers], promotes internode elongation, promotes root growth and hair formation, initiates flowering and synchronizing fruit set in pineapple, mango

50
Q

Most widely used PGR

A

Ethylene

51
Q

Most widely used compound as source of ethylene

A

Ethephon

52
Q

Ethephon promotes

A

Fruit ripening in tomatoes and apples, accelerates abscission in flowers and fruits (thinning of cotton, cherry, walnut), promotes FEMALE FLOWERS in CUCUMBER thereby increasing yield

53
Q

Action of abscisic acid

A

Inhibits plant metabolism, seed germination, stimulates closure of stomata, increases tolerance towards stresses, plays role in seed development, maturation, dormancy (induces dormancy)

54
Q

PGR which acts as antagonist to GAs

A

Abscisic acid

55
Q

PGR which is AKA stress hormone

A

Abscisic acid

56
Q

Vernalisation prevents

A

Precocious reproductive development late in the growing season

57
Q

Examples of biennial plants

A

Sugarbeet, cabbages, carrots

58
Q

Winter variety of wheat is harvested in

A

Mid summer

59
Q

Dormancy

A

When a seed fails to germinate even when external conditions are favourable

60
Q

Dormancy is not controlled by external environmental factors - true/false

A

True - It is only under endogenous control

61
Q

Factors promoting seed dormancy

A

Hard seed coat, presence of abscissic acid, phenolic acid, para-ascorbic acid, immature embryos

62
Q

Effect of inhibitory substances can be removed by

A

Chilling, applying GAs and nitrates