1. Movement of leaves of Sensitive Plant, Mimosa pudica are due to
(a) thermonasty
(b) seismonasty
(c) hydrotropism
(d) chemonasty
2. Phytochrome is involved in
(a) phototropism
(b) photorespiration
(c) photoperiodism
(d) geotropism
3. Gibberellins promote
(a) seed germination
(b) seed dormancy
(c) leaf fall
(d) root elongation
4. Cut or excised leaves remain green for long if induced to root or dipped in
(a) gibberellins
(b) cytokinins
(c) auxins
(d) ethylene
5. Hormone primarily connected with cell division is
(a) IAA
(b) NAA
(c) cytokinin/Zeatin
(d) gibberellic acid
6. Leaves of many grasses are capable of folding and unfolding because they
(a) are very thin
(b) are isobilateral
(c) have specialised bulliform cells
(d) have parallel vascular bundles
7. Which one increases in the absence of light?
(a) Uptake of minerals
(b) Uptake of water
(c) Elongation of internodes
(d) Ascent of sap
8. Mowing grass lawn facilitates better maintenance because
(a) wounding stimulates regeneration
(b) removal of apical dominance and stimulation of intercalary meristem
(c) removal of apical dominance
(d) removal of apical dominance and promotion of lateral meristem
9. Leaf fall can be prevented with the help of
(a) abscisic acid
(b) auxins
(c) florigen
(d) cytokinins
10. Which of the following hormones can replace vernalisation?
(a) Auxin
(b) Cytokinin
(c) Gibberellins
(d) Ethylene
11. Which of the following movement is not related to auxin level
(a) Bending of shoot towards light
(b) Movement of root towards soil
(c) Nyctinastic leaf movements
(d) Movement of sunflower head tracking
12. Phototropic and geotropic movements are linked to:
(a) gibberellins
(b) enzymes
(c) auxin
(d) cytokinins
13. Abscisic acid controls
(a) cell division
(b) leaf fall and dormancy
(c) shoot elongation
(d) cell elongation and wall formation
14. Phytohormones are:
(a) chemicals regulating flowering
(b) chemicals regulating secondary growth
(c) hormones regulating growth from seed to adulthood
(d) regulators synthesised by plants and influencing physiological processes
15. Highest auxin concentration occurs
(a) in growing tips
(b) in leaves
(c) at base of plant organs
(d) in xylem and phloem
16. Tendrils exhibit/twining of tendrils s due to
(a) thigmotropism
(b) seismonasty
(c) heliotropism
(d) diageotropism
17. A chemical believed to be involved in
flowering is
(a) gibberellin
(b) kinetin
(c) florigen
(d) IBA
18. The hormone responsible for a pical dominance is
(a) IAA
(b) GA
(c) ABA
(d) florigen
19. Abscisic acid causes
(a) stomatal closure
(b) stem elongation
(c) leaf expansion
(d) root elongation
20. Which is employed for artificial ripening of banana fruits?
(a) Auxin
(b) Coumarin
(c) Ethylene
(d) Cytokinin
21. Cytokinins
(a) promote abscission
(b) influence water movement
(c) help retain chlorophyll
(d) inhibit protoplasmic streaming
22. In short day plants, flowering is induced by
(a) photoperiod less than 12 hours
(b) photoperiod below a critical length and uninterrupted long night
(c) long night
(d) short photoperiod and interrupted long night
23. Apical dominance is caused by
(a) abscisic acid in lateral bud
(b) cytokinin in leaf tip
(c) gibberellin in lateral buds
(d) auxin in shoot tip
24. Bananas can be prevented from overripening by
(a) maintaining them at room temperature
(b) refrigeration
(c) dipping in ascorbic acid solution
(d) storing in a freezer
25. Flowering dependent on cold treatment is
(a) cryotherapy
(b) cryogenics
(c) cryoscopy
(d) vernalisation
26. Dwarfness can be controlled by treating the plant with
(a) cytokinin
(b) gibberellic acid
(c) auxin
(d) antigibberellin.
27. Klinostat is employed in the study of
(a) osmosis
(b) growth movements
(c) photosynthesis
(d) respiration
28. What is a stress hormone? or The hormone produced during adverse environmental conditions is
(a) benzyl aminopurine
(b) dichlorophenoxy acetic acid
(c) ethylene
(d) abscisic acid
29. The regulator which retards ageing/ senescence of plant parts is:
(a) cytokinin
(b) auxin
(c) gibberellin
(d) abscisic acid
30. Removal of apical bud results in
(a) formation of new apical bud
(b) elongation of main stem
(c) death of plant
(d) formation of lateral branching
31. Movement of auxin is
(a) centripetal
(b) basipetal
(c) acropetal
(d) both B and C
32. The pigment, that absorbs red and
far red light in plants, is
(a) xanthophyll
(b) cytochrome
(c) phytochrome
(d) carotene
33. Ethylene gas is used for
(a) growth of plants
(b) delaying fruit‘s abscission
(c) ripening of fruits
(d) stopping the leaf abscission
34. Thigmotropic movement is best shown by
(a) movement in tendril
(b) insectivorous plants
(c) movement in roots
(d) movement in Mimosa pudica
35. What will be the effect on phytochrome in a plant subjected to continuous red light?
(a) Level of phytochromedecreases
(b) Phytochrome is destroyed
(c) Phytochrome synthesis increases
(d) Destruction and synthesis of phytochrome remain in equilibrium.
36. If a tree, flowers thrice in a year (Oct., Jan. and July) in Northern India, it is said to be
(a) photosensitive but thermoinsensitive
(b) thermosensitive but photoinsensitive
(c) photo and thermosensitive
(d) photo and thermoinsensitive
37. Which combination of gases is suitable for fruit ripening?
(a) 80% CO2 and 20% CH2
(b) 80% CH4 and 20% CO2
(c) 80% CO2 and 20% O2
(d) 80% C2H4 and 20% CO2
38. A plant hormone used for inducing morphogenesis in plant tissue culture is
(a) gibberellins
(b) cytokinins
(c) ethylene
(d) abscisic acid.
39. The response of different organisms to environmental rhythms of light and darkness is called
(a) phototaxis
(b) photoperiodism
(c) phototropism
(d) vernalization.
40. ABA is involved in
(a) dormancy of seeds
(b) root elongation
(c) shoot elongation
(d) increased cell division
41. The method that renders the seed coat permeable to water so that embryo expansion is not physically retarded is
(a) vernalization
(b) stratification
(c) denudation
(d) scarification
42. What reason will you assign for coconut milk used in tissue culture?
(a) Gibberellins
(b) Cytokinins
(c) Auxins
(d) Ethylene
43. Geocarpic fruits are produced by
(a) onion
(b) watermelon
(c) ground nut
(d) carrot
44. What breaks bud dormancy of potato tuber?
(a) Gibberellin
(b) IAA
(c) ABA
(d) Zeatin
45. Hormone responsible for senescence
(a) ABA
(b) auxin
(c) GA
(d) cytokinin
46. Which of the following prevents fall of fruits?
(a) GA3
(b) NAA
(c) Ethylene
(d) Zeatin
47. Which one is a long-day plant?
(a) Tobacco
(b) Glycine max
(c) Mirabilis jalapa
(d) Spinach
48. Glycolate induces opening of stomata in
(a) presence of oxygen
(b) low CO2 conc.
(c) high CO2 conc.
(d) absence of CO2
49. Proteinaceous pigment which control activities concerned with light
(a) phytochrome
(b) chlorophyll
(c) anthocyanin
(d) carotenoids
50. Seed dormancy is due to the
(a) ethylene
(b) abscisic acid
(c) IAA
(d) starch
51. Differentiation of shoot is controlled by
(a) high gibberellin: cytokinin ratio
(b) high auxin: cytokinin ratio
(c) high cytokinin: auxin ratio
(d) high gibberellin: auxin ratio
52. Plants deficient of element zinc, show its effect on the biosynthesis of plant growth hormone
(a) abscisic acid
(b) auxin
(c) cytokinin
(d) ethylene
53. Anthesis is a phenomenon which refers to
(a) reception of pollen by stigma
(b) formation of pollen
(c) development of anther
(d) opening of flower bud
54. One set of a plant was grown at 12 hours day and 12 hours night period cycles and it flowered while in the other s t night phase was interrupted by flash of light and it did not produce flower. Under which one of the following categories will you place this plant?
(a) Long day
(b) Darkness neutral
(c) Day neutral
(d) Short day
55. Cell elongation in internodal regions of the green plants takes place due to
(a) indole acetic acid
(b) cytokinins
(c) gibberellins
(d) ethylene
56. An enzyme that can stimulate germination of barley seeds is
(a) lipase
(b) protease
(c) invertase
(d) a-amylase
57. Treatment of seed at low temperature under moist conditions to break its dormancy is called
(a) vernalization
(b) chelation
(c) stratification
(d) scarification
58. How does pruning help in making the hedge dense?
(a) It frees axillary buds from apical dominance
(b) The apical shoot grows faster after pruning
(c) It releases wound hormones
(d) It induces the differentiation of new shoots from the rootstock
59. Opening of floral buds into flowers, is a type of
(a) autonomic movement of variation
(b) paratonic movement of growth
(c) autonomic movement of growth
(d) autonomic movement of locomotion.
60. Which one of the following pairs, is not correctly matched?
(a) Gibberellic acid – Leaf fall
(b) Cytokinin – Cell wall elongation
(c) IAA – Cell wall elongation
(d) Abscissic acid – Stomatal closure.
61. ―Foolish seedling‘‘ disease of rice led to the discovery of
(a) ABA
(b) 2, 4-D
(c) IAA
(d) GA
62. Senescence as an active developmental cellular process in the growth and functioning of a flowering plant, is indicated in
(a) vessels and tracheid differentiation
(b) leaf abscission
(c) annual plants
(d) floral parts
63. One of the synthetic auxin is:
(a) IAA
(b) GA
(C) IBA
(d) NAA
64. Which one of the following acids is a derivative of carotenoids?
(a) Indole-3 -acetic acid
(b) Gibberellic acid
(c) Abscisic acid
(d) Indole butyric acid
65. Phototropic curvature is the result of uneven distribution of:
(a) gibberellin
(b) phytochrome
(c) cytokinins
(d) auxin
66. Coiling of garden pea tendrils around any support is an example of:
(a) thigmotaxis
(b) thigmonasty
(c) thigmotropism
(d) thermotaxis
67. Through their effect on plant growth regulators, what do the temperature and light control in the plants?
(a) Apical dominance
(b) Flowering
(c) Closure of stomata
(d) Fruit elongation
68. Which one of the following generally acts as an antagonist to gibberellins?
(a) Zeatin
(b) Ethylene
(c) ABA
(d) IAA
69. Vernalization stimulates flowering in
(a) zamikand
(b) turmeric
(c) carrot
(d) ginger
70. Which one of the following is not used for ex-situ plant conservation?
(a) Seed banks
(b) Shifting cultivation
(c) Botanical Gardens
(d) Field gene banks
71. During seed germination its stored food is mobilized
(a) Cytokinin
(b) ABA
(c) Gibberellin
(d) Ethylene
72. The pineapple which under natural conditions is difficult to blossom has been made to produce fruits throughout the year by application of
(a) IAA, IBA
(b) NAA, 2, 4-D
(c) Phenyl acetic acid
(d) Cytokinin
73. Typical growth curve in plants is
(a) Stair-steps shaped
(b) Parabolic
(c) Sigmoid
(d) Linear
74.Which of the following should be used for the control of weeds in farms ?
(a) Cytokinin
(b) Auxin
(c) Gibberrelin
(d) Ethylene
75. Study the following statements.
I. “X” hormone promotes root growth and root hair formation thus helping the plants to increase their absorption surface.
II. “Y” hormone induces flowering in mango and also promotes rapid internode/petiole elongation in deep plants and hence helping leaves or upper parts of shoot above water.
III. “Z” hormone inhibits the seed germination, increase the tolerance of plant to various stresses, play import in seed development, maturation and dormancy. Identify the correct names of hormones marked as ‘X’, ‘Y’ & ‘Z’.
(a) Y = ABA; X = Auxin; Z = GA
(b) Y = Auxin; X = C2H4 ; Z = GA
(c) Y = C2H4 ; X = C2H4 ; Z = ABA
(d) Z = GA; X = Auxin; Y = C2H4
76. The closure of lid of pitcher in pitcher plant, is due to
(a) paratonic movement
(b) autonomous movement
(c) turgor movement
(d) tropic movement
77. Which factor increases in plant in absence of light ?
(a) Availability of water, increases ascent of sap
(b) Availability of mineral ion, increases mineral nutrition
(c) Area of leaf-blade increase, rate of transpiration increases.
(d) Length of internode increases, growth of plant in longitudinal axis
78. Phototropic and geotropic movements are linked to
(a) gibberellins
(b) enzymes
(c) auxin
(d) cytokinins
79. Which is the correct sequence for different phases of growth?
(a) Cell formation of cell differentiation- cell elongation
(b) Cell formation – cell elongation- cell differentiation
(c) Cell differentiation- cell elongation- cell formation
(d) Cell differentiation- cell formation- cell elongation
80. One set of the plant was grown at 12 hours day and 12 hours night period cycles and it flowered while in the other set night phase was interrupted by flash of light and it did not produce flower. Under which one of the following categories will you place this plant?
(a) Long day
(b) Darkness neutral
(c) Day neutral
(d) Short day
81. Leaves of many grasses are capable of folding and unfolding because they
(a) are isobilateral
(b) have specialised bulliform cells
(c) are very thin
(d) have parallel vascular bundles
82. Which type of meristematic tissue is found in monocot plant for growth?
(a) Intercalary meristematic tissue
(b) Apical meristem tissue
(c) Lateral meristem tissue
(d) Meristematic tissue
83. The plant hormone controlling fruit ripening is
(a) IAA
(b) ABA
(c) GA
(d) Ethylene
84. Which of the following group show viviparous germination ?
(a) Rhizophora and Avicinnia
(b) Orchid and Rhizophora
(c) Maize and Bean
(d) Soyabean and Xanthium
85. Anthesis is a phenomenon which refers to
(a) reception of pollen by stigma
(b) development of anther
(c) opening of flower bud
(d) formation of pollen
87. Avena curvature test is a bioassay for examining the activity of
(a) auxins
(b) cytokinins
(c)ethylene
(d) gibberellins
88.If temporary light is made available for dark phase of long day plant, what is observed ?
(a) Flowering will not occur
(b) Increase in flowering
(c) Decreasing in flowering
(d) No change
89. What causes a green plant exposed to the light on only one side, to bend toward the source of light as it grows ?
(a) Green plants seek light because they are phototropic
(b) Light stimulates plant cells on the lighted side to grow faster
(c) Auxin accumulates on the shaded side, stimulating greater cell elongation there.
(d) Green plants need light to perform photosynthesis
90. What is indicated by any of the developing plant if it increase / hyperactivity in lateral buds ?
(a) It obtains more light
(b) Cytokinin decreases
(c) It stores more food
(d) Auxin decreases
91. A few normal seedlings of tomato were kept in a dark room. After a few days they were found to have become whitecoloured like albinos. Which of the following terms will you use to describe them?
(a) Mutated
(b) Embolised
(c) Etiolated
(d) Defoliated
92. If a tree, flowers thrice in a year (Oct., Jan. and July) in Northern India, it is said to be
(a) thermosensitive but photoin sensitive
(b) photosensitive but thermion sensitive
(c) photo and thermosensitive
(d) photo and thermoinsensitive
93.Induction of cell division and delay in senescence is done by
(a) Cytokinins
(b) Auxins
(c) Co
(d) GA
94. What is the site of perception of photoperiod necessary for induction of flowering in plants?
(1) Lateral buds
(2) Pulvinus
(3) Shoot apex
(4) Leaves
95. It takes very long time for pineapple plants to produce flowers. Which combination of hormones can be applied to artificially induce flowering in pineapple plants throughout the year to increase yield?
(1) Auxin and Ethylene
(2) Gibberellin and Cytokinin
(3) Gibberellin and Abscisic acid
(4) Cytokinin and Abscisic acid
96. Name the plant growth regulator which upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop.
(1) Ethylene
(2) Abscisic acid
(3) Cytokinin
(4) Gibberellin
97. Which of the following is not an inhibitory substance governing seed dormancy?
(1) Phenolic acid
(2) Para-ascorbic acid
(3) Gibberellic acid
(4) Abscisic acid
98. Plants follow different pathways in response to environment or phases of life to form different kinds of structures. This ability is called
(1) Maturity
(2) Elasticity
(3) Flexibility
(4) Plasticity
99. Which of the following plants is monoecious?
(1) Cycas circinalis
(2) Carica papaya
(3) Chara
(4) Marchantia polymorpha
Solutions :
1.Solution: (b)Mimosa pudica (touch me not) leaves show seismonastic movement in response to physical contact. The movement is due to
turgor changes due to ejection of water by cells of pulvinus (swollen leaf base) on touching it. It causes folding and drooping of leaves.
2.Solution: (c) Borthwick& Hendricks (1952) gave the concept of phytochrome. Phytochrome is a coloured protein pigment located in plasma
membrane to perceive the photoperiodic stimulus in leaves. It may exist in two interconvertable forms Pr and Pfr (red and far red light absorbing forms)
3.Solution: (a) Some light sensitive seeds like Lectuca sativa (Lettuce) germinate in complete darkness with the help of Gibberellins
which otherwise require specific light conditions.
4.Solution: (b) Because cytokinins help cells in retaining chlorophyll for longer time. Cytokinin delay the senescence (ageing) of leaves and other
organs.
5.Solution: (c) The most important function of cytokinins (zeatin is one of the cytokinins present in Zea mays – the corn) is the promotion of
cell division. These are now established as true cell division factors.
6.Solution: (c) Monocot leaves have some specialized cells in the epidermal cells of their leaves called bulliform cells (motor cells) which lose or
gain turgidity due to which their leaves show coiling and uncoiling.
7.Solution: (c) In the absence of light stem become excessive long due to the development of ‗etiolin‘ which causes ‗etiolation‘. Cell of internodes get enlarged.
8.Solution: (b) Apical dominance is a common observation in vascular plants. If apical meristem is intact & growing, the lateral tips growth is suppressed. According to Thimann& Skoog the Auxin, synthesized in apical meristem, in translocated downwards & inhibits the growth of lateral
tips. That is why mowing grass lawns facilitates better maintenance.
9.Solution: (d) It is due to Richmond-Lang effect. Cytokinins prevent degeneration of chlorophyll, proteins and nucleic acids.They increase of inflow of auxin and amino acids. It reactivates leaf metabolism.
10.Solution: (c) Vernalization is the low temperature treatment for flowering in plants. Plants are treated (seeds and seedlings) with very low
temperature to promote germination. A Lang & co-workers demonstrated that the application of gibberellins can replace the cold treatment or vernalization in many plants.
11.Solution: (c) All except nyctinastic movement are related to auxin. Nyctinastic (sleeping) movement of leaves are due to diurnal changes. (changes in day and night).
12.Solution: (c) Phototropic movements are the plant responses towards light. Generally plant shoot and flower show positive phototropism while geotropism is the plant response to the gravity of earth. Generally roots are positively geotropic. All these movements are linked to Auxin.
13.Solution: (b) Abscisic acid as the name suggests cause abscission due to which leaves fall. It also inhibitor & induce bud
dormancy in various plants.
14.Solution: (d) Phytohormones are plant hormones which are synthesized by the plants and act as regulators and influence physiological
process like growth, movements etc. auxins, gibberellins etc. are the phytohormones.
15.Solution: (a) Highest concentration of auxins occurs at the growing tips was proved by Went in 1928 by his experiment on Avena coleoptile. It was demonstrated that auxins are synthesized at the tips and then translocated downwards where they cause growth.
16.Solution: (a) Twining of tendrils is due to thigmotropism i.e. movement due to the contact with a foreign body (touch).
17.Solution: (c) Chailakhyan (1936) a Russian investigator who researched on photoperiodism proposed the term ‗florigen‘. According to
him ‗Florigen Complex‘, the true flowering hormone includes two group of substances formed in leaves (i) Gibberellins which are necessary for the formation and growth of stem and (ii) Anthesins which are necessary for flower formation. Acting together they form the substance named
‗florigen‘.
18.Solution: (a) Apical dominance is caused by the action of auxins & IAA (Indole-3-acetic acid) is a naturally occurring auxin.
19.Solution: (a) Abscisic acid is a stress hormone. During desication abscisic acid is synthesized which reduces transpiration by closure of
stomata. It conserves water.
20.Solution: (c) Ethylene is a plant hormone which has the most remarkable effect of stimulation of fruit ripening.
21.Solution: (c) Cytokinins cause delay in senescence (Richmond-Lang effect). Senescence is the phenomenon in which the mature leaves
lose chlorophyll, turn yellow and fall off.
22.Solution: (b) A short day plant is one that flowers on photoperiods shorter than the critical day length. It generally flowers when treated by
a short day and uninterrupted long night (more than 12 hrs.)
23.Solution: (d) Apical dominance is the phenomenon by which presence of apical bud does not allow lateral buds to grow. Apical dominance is due to auxin. When shoot tip is cut; then lateral buds start growing.
24.Solution: (c) Ascorbic acid is an organic acid with antioxidant properties. Its appearance is white to light yellow crystals or powder. It is water soluble. The L-enantiomer of ascorbic acid is commonly known as Vitamin C. Ascorbic acid is easily oxidized and so is used as a reductant in
photographic developer solutions and as a preservative.
25.Solution: (d) Vernalization is the method of inducing early flowering in plants by pretreatment of their seeds at low temperature.
26.Solution: (b) One of the most important effects of gibberellins is the reversal of dwarfism (even in genetically dwarf plants). Dwarf pea & dwarf corn attain almost normal size when treated with gibberellins. It has been proved that dwarf plants have lower level of GA which causes the dwarfism. Thus the external supply causes rapid elongation of internodes. GA does not have any effect of elongation on normal (non dwarf or tall)
plant.
27.Solution: (b) Klinostat = Clinostat is an apparatus used to nullify the effect of geotropism. It has a clock to the main axis of which is attached
to a rod. Top of the rod is attached to a flower pot. The klinostat is kept in horizontal position and allowed to rotate (to nullify the geotropism) and plant growth is observed.
28. Solution: (d) Abscisic Acid (ABA) is called stress hormone which works in adverse environmental condition when there is low water content in atmosphere or in drought conditions. ABA causes the stomatal closure of leaves due to which the water loss by the plant is minimized.
29.Solution: (a) Cytokinin help in retaining chlorophyll, hence delay senescense.
30.Solution: (d) Apical buds inhibit lateral branching due to apical dominance. Removal of apical bud promotes lateral branching.
31.Solution: (d) Auxins are synthesized at the tip of shoot & then transported towards the base i.e. basipetal. In all segments of root at all temperatures, the movement of Auxin is polarised acroketalles.
32.Solution: (c) The pigment phytochrome is involved in flowering and many other light-mediated processes. It absorbs red and far red light
in plants for photosynthesis.
33.Solution: (c) Ethylene is a gaseous plant hormone which plays an important role in fruit ripening. In the presence of ethylene there is an increase in the rate of respiration.
34.Solution: (a) The phenomenon of thigmotropism is a response to contact with a solid object. It is exhibited by tendrils of climbing plants that
grow around a pole or the stem of another plant.
35.Solution: (a) Continuous exposure to red light causes • Conversion of Pr to Pfr which is rapidly destroyed. • Inhibition of synthesis of Pr. •
Total amount of phytochrome decreases.
36.Solution: (d) In northern India, during these months there is observed maximum variation in light intensity and duration and temperature. Hence only plants that are photo-and thermoinsensitive can flower during these months.
37.Solution: (d) Ethylene acts physiologically as a hormone in plants. It stimulates the ripening of fruit, the opening of flower , and the abscission
(or shedding) of leaves. Its biosynthesis starts from methionine with 1- aminocyclopropane-1-carboxylic acid (ACC) as a key intermediate.
38.Solution: (b) Cytokinins are used in tissue culture to induce shooting of the cultural callus.
39.Solution: (b) Photoperiodism is the effect of duration of light and darkness on the growth, development and behaviour of an organism.
40.Solution: (a) Gibberellins are involved in shoot elongation. Auxins are important in root elongation and cell division
41.Solution: (d) Scarification is the breaking of the seed coat barriers which can be done by mechanical or chemical methods.
42.Solution: (b) The medium in tissue culture provides all the essential nutrients required for growth and division of callus. Coconut milk
contains cytokinins which is useful in tissue culture.
43.Solution: (c) Geocarpic fruits are those which develop underground. Groundnut is the fruit which develops underground, onion and carrot
also occur within the soil but onion is modified stem while carrot is modified root.
44.Solution: (a) IAA promotes apical dominance. ABA induces dormancy in buds.
45.Solution: (a) ABA or Abscisic acid is responsible for leaf fall or senescence.
46.Solution: (b)NAA or Naphthalene Acetic Acid is synthetic auxin. It is used to check fruit fall specially in tomato.
47.Solution: (d) Long day plants undergo flowering after receiving light above a critical day length. e.g. Spinach, sugarbeet. Short day plants
flower only when they receive light below a critical day length. e.g. Glycine max, Tobacco.
48.Solution: (b) During day time, due to photosynthesis CO2 concentration is low.
49.Solution: (a) Refer ans. 2
50.Solution: (b) Ethylene breaks dormancy of different plants. Abscisic acid induces dormancy in seeds. Buds and underground storage organs.
51.Solution: (c) Differentiation of root is controlled by high auxin concentration. While in tissue culture auxin concentration is made high to promote rooting.
52.Solution: (b) Zinc is one of the component of Auxin.
53.Solution: (d) Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period.
54.Solution: (d) Short day plants require long uninterrupted dark period for flowering. They will not produce flower if night was interrupted by flash of light.
55.Solution: (c) Gibberellins induces eleongation of internodes.
56.Solution: (d) a-amylase enzyme stimulates the germination of barley seed.
57.Solution: (c) Treatment of seed at low temperature under moist conditions to break dormancy is called stratification.
58.Solution: (a) When an apical bud is present on a plant, it suppresses the growth of axillary buds, this is called apical dominance. When in
pruning apical bud is cut off the axillary buds start growing & hedge become dense.
59.Solution: (c) Opening of floral buds into flowers, is a type of autonomic movement of water which is due to epinasty.
60.Solution: (a) Gibberllic acid stimulates cell growth of leaves and stem causing their expansion, elongation respectively and leaf fall is
controlled by ABA.
61.Solution: (d) The effect of gibberellins had been known in Japan since early 1800 where certain rice plants were found to suffer from
bakane or bakanae (foolish seedling) disease. Such rice plants were thin, pale green, spindle-shaped, longer by 50% than the healthy plants, and were sterile.
62.Solution: (b) Senescence as an active developmental cellular process in the growth and functioning of a flowering plant, is indicated in lead abscission. Senescence is the changes that occur in an organism between maturity and death, i.e., ageing. Characteristically there is a deterioration in functioning as the cells become less efficient in maintaining and replacing vital cells components.
63.Solution: (d) NAA is a synthetic auxins. Some of the most widely used weed killers are synthetic auxins. Synthetic auxin analogs include 1–
naphthaleneacetic acid (NAA), 2, 4- dichlorophenoxy acetic acid (2,4-D) and 2,4,5-trichlorophenoxy acetic acid (2,4,5- T).
64.Solution: (c) Abscisic acid (ABA), also known as abscisin II and dormin, is a plant hormone. It functions in many plant developmental
processes, includsing bud dormancy. Abscisic acid is a derivative of carotenoids. It was called ―abscisin II‖ originally because it was thought to play a major role in abscission of fruits. At about the same time another group was calling it ―dormin‖ because they thought it had a major role in
bud dormancy. The name abscisic acid (ABA) was coined by a compromise between the two groups.
65.Solution: (d) Phototrophic curvature is the result of uneven distribution of auxin. The experiments conducted by Charles Darwin concluded that the tip of coleoptile of canary grass contain auxin that causes the bending of the entire coleoptile towards the light source.
66.Solution: (c) The coiling of garden pea tendrils around any support is an example of thigmotropism. Thigmotropism is the growth movement in response to touch. The stems and tendrils of the climbers are positively thigmotrophic in their response.
67.Solution: (b) Flowering is induced by light and temperature.
68.Solution: (c) Gibberellins & ABA are antagonistic with each other. ABA counteracts many effects of gibberellins like induction of hydrolases
and alpha- amylases in barley seedlings.
69.Solution: (c) Carrot is a biennial plant which flowers in the second season. Vernalization is the subection of seeds or seedlings to low
temperature in order to hasten plant development and flowering. Vernalization is commonly used for crop plants such as winter rye and is possible because the seeds and buds of many plants require cold in order to break dormancy. Winter cereals are therefore sown in the autumn for
flowering the following year. However, if germinating seeds are artificially vernalized they can be sown in the spring for flowering the same year. Biennial plants, such as carrot (Daucuscarota), will remain in their non – flowering rosette form until subjected to cold treatment.
70. Solution: (b) Shifting or Jhum cultivation contributes to deforestation. Ex-situ conservation is a biodiversity conservation method in which
threatened animals and plants are taken out of their natural habitat and placed in protected and carring environment zoological parks, botanical gardens, wildlife safari parks, seed banks and gene banks.
71.Solution: (c) Gibberellins stimulate the synthesis of α- amylase and proteases enzyme in germinating grains of cereals. They are involved in the conversion of starch into sugar. The proteases convert an inactive β- amylase to the active form. The active β- amylase and α-amylase together digest starch to glucose which is mobilized to meet the metabolic demands of embryo.
72.Solution: (b) Plants which are difficult to flower can be made to do so by spraying them with 2, 4, – D (2, 4 – dichlorophenoxy acetic acid) and
NAA (napthalene acetic acid) which are synthetic auxins, e.g., litchi, pineapple Apical dominance is a common observation in vascular plants. If apical meristem is intact & growing, the lateral tips growth is suppressed. According to Thimann& Skoog the Auxin, synthesized in apical meristem, in translocated downwards & inhibits the growth of lateral tips. That is why mowing grass lawns facilitates better maintenance.
73.(b) If we plot the increase in cell number (growth rate) against time, a typical S-shaped curve is obtained. This is called growth curve or sigmoid growth curve.
74.(b) Auxin
75.(d) Z = GA; X = Auxin; Y = C2H4
76. (b) Plants have the capacity of changing their position, in response to external or internal stimuli which are known as plant movements. The movements which occur due to internal stimuli are called autonomic movements and those that occur due to external stimuli are called paratonic movements. Nepenthes (pitcher plant) is an insectivorous plant. In this the leaf lamina is modified to form a pitcher and leaf apex forms a coloured lid. When the insect enter the pitcher it is an external stimuli, so the closure of the lid is paratonic movement.
77. (d) Absence of light reduces the overall growth, photosynthesis, uptake of minerals and ascent of sap. However, the elongation of internodes is seen to occur in the absence of light.
78. (a) Auxin regulates some of the important plant growth movements like photoropism and geotropism. Phototropism means growth of plants in response to light and geotropism means growth of plants towards gravity.
79. (b) Cell formation – cell elongation- cell differentiation
80. (b) Plants require a day length or light period for flowering, this light period is called as photoperiod. It was first studied by Garner and Allard. Short day plants (SDP’s) flower in photoperiods less than critical day length, e.g., Nicotiana tabacum, Glycine max (Soybean), Xanthium strumarium. Further these plants require long uninterrupted dark period and hence are called long night plants. Long day plants (LDP’s) flower in photoperiod more than critical day length, e.g., Hyocyamus niger (Henbane), radish, Beta, spinach, Plantago, etc. Day neutral plants flower in any photoperiod, e.g., tomato, maize, cucumber, etc.
81.(b) Leaves of many grasses are capable of folding and unfolding because they have specialised bulliform cells.
82. (a) Intercalary meristems occur only in monocots, at the bases of leaf blades and at nodes ,the areas where leaves attach to a stem. This tissue enables the monocot leaf blade to increase in length from the leaf base.
83.(d) Ethylene is known to be a key player of plant aging, including fruit ripening, and flower and leaf senescence
84. (a) Rhizophora and Avicinnia
85. (c) Anthesis refers to opening of a flower bud. It is the duration of life of a flower from the opening of the bud to setting of the fruit.
86. (a)The Avena geo-curvature test is a bioassay for auxin-type growth regulators.
87. (a) Flowering will not occur
88. (c) Auxins induce cell elongation. In a differentially illuminated plant, they accumulate in the shaded part, causing elongation of the cells in the shaded part. This unequal elongation on two sides causes the plant to curve or bend towards the light source i.e., phototropic curvature.
89. (d) Auxin decreases
90. (c) In seismonastic movement. response is made to mechanical shocks such as blows, shaking or pressure. In Mimosa, turgor changes occur in thin walled cells of pulvinus (lower side) and pulvinnules (upper side), causing folding of pinnules, drooping of compound leaves.
91. (c) photo and thermosensitive
92. (a) Cytokinins (CK) are a class of plant growth substances (phytohormones) that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. Cytokinins (CK) are a class of plant growth substances (phytohormones) that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.
93(4) Leaves
94 (1) Plant hormone auxin induces flowering in pineapple. Ethylene also helps in synchronization of flowering and fruit set up in pineapple.
95(4)Gibberellin upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop by 20 tonnes per acre.
96(3) Effect of inhibitory substance can be removed by application of certain chemicals like gibberellic acid and nitrates.
97(4) Plasticity
98(3) Chara is an alga with monoecious condition. It has male sex organ antheridium and female sex organ oogonium at the same node. Cycas circinalis, Carica papaya and Marchantia polymorpha are dioecious