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Question 1 of 126
1. Question
The given diagram shows different stages of seed germination. Identify A, B, C and D and select the correct option.
CorrectIncorrectHint
b
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Question 2 of 126
2. Question
Seeds which germinate only in the presence of light are called _____ seeds.
CorrectIncorrectHint
b
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Question 3 of 126
3. Question
The capacity of a seed to germinate and develop into a seedling is called
CorrectIncorrectHint
(b) The capacity of a seed to germinate and develop into seedling is called seed viability.
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Question 4 of 126
4. Question
During epigeal germination, the first thing that comes out of soil is
CorrectIncorrectHint
(b) In epigeal germination, seeds/cotyledons emerge out of the soil due to rapid elongation of hypocotyl. It is found in beans, castor, sunflower, pumpkin, etc.
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Question 5 of 126
5. Question
Hypogeal germination is found in
CorrectIncorrectHint
d
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Question 6 of 126
6. Question
Meristematic cells are characterised by
CorrectIncorrectHint
(d) A meristematic tissue is a group of similar and immature cells that are in continuous state of division. These tissues are found in growing regions of plants. The chief characteristics of these tissues are:
(i) The cells may be round, oval, polygonal or rectangular.
(ii) They have thin cellulosic cell walls.
(iii) They do not have intercellular spaces.
(iv) They have dense cytoplasm with prominent nuclei.
(v) Vacuoles are absent or many small vacuoles may be present.
(vi) The cells are in active state of metabolism. -
Question 7 of 126
7. Question
Increase in girth (diameter) of plant as a result of the activities of lateral meristems is called
CorrectIncorrectHint
(b) The lateral meristems, e.g., vascular cambium and cork cambium (in dicotyledons and gymnosperms) are the meristems that cause increase in the girth of the organs in which they are active. This is known as secondary growth of the plant.
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Question 8 of 126
8. Question
Secondary growth generally occurs in
CorrectIncorrectHint
(d) Secondary growth occurs in both dicots and gymnosperms due to the presence of lateral meristems.
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Question 9 of 126
9. Question
Growth at cellular level, is principally a consequence of increase in the amount of
CorrectIncorrectHint
a
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Question 10 of 126
10. Question
Growth is maximum in zone of
CorrectIncorrectHint
a
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Question 11 of 126
11. Question
Fastest phase of S-shaped growth curve is
CorrectIncorrectHint
(b) In the S-shaped growth curve, the log phase is the exponential phase, hence it is the fastest phase.
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Question 12 of 126
12. Question
Select the correct option regarding arithmetic growth.
CorrectIncorrectHint
(d) Increase in growth per unit time is called as growth rate. The growth rate may be arithmetic or geometrical. Arithmetic growth is a type of growth in which the rate of growth is constant and increase in growth occurs in arithmetic progression\(2,4,6,8,10,12\). Meristematic cells at the growing point divide in such a fashion that one daughter cell remains meristematic while the other grows and differentiates. The process continues. Mathematically, arithmetic growth is expressed as : \(L_t=L_0+rt\); where \(L_t=\) length after time \(t, L_0=\) length at the beginning, and \(r=\) growth rate. On plotting growth against time, a linear curve is obtained.
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Question 13 of 126
13. Question
Which one is the correct graph for arithmetic growth?
CorrectIncorrectHint
a
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Question 14 of 126
14. Question
Select the incorrect statement among the following.
CorrectIncorrectHint
(c) Geometric growth is quite common in unicellular organisms when grown in nutrient-rich medium. Here, every cell divides. The daughter cells grow and divide, the grand daughter cells repeat the process and so on. The number of cells is initially small so initial growth is slow. Later on, there is rapid growth at an exponential rate (log or exponential growth).
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Question 15 of 126
15. Question
The given figure shows the development of an embryo that undergoes two phases A and B. Select the correct option regarding it.
\(
\begin{array}{|l|l|l|}
\hline & \text { A } & \text { B } \\
\hline \text { (a) } & \text { Geometric phase } & \text { Arithmetic phase } \\
\hline \text { (b) } & \text { Arithmetic phase } & \text { Geometric phase } \\
\hline \text { (c) } & \text { Arithmetic phase } & \text { Exponential phase } \\
\hline \text { (d) } & \text { Exponential phase } & \text { Stationary phase } \\
\hline
\end{array}
\)CorrectIncorrectHint
(a) An embryo initially shows geometrical growth in cells but later it passes into arithmetic phase.
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Question 16 of 126
16. Question
The exponential growth can be mathematically expressed as
CorrectIncorrectHint
c
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Question 17 of 126
17. Question
Given graph is drawn on the parameters of growth versus time. Here A, B and C respectively represent
CorrectIncorrectHint
b
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Question 18 of 126
18. Question
The factors which influence growth are
CorrectIncorrectHint
(d) Growth involves the synthesis of more protoplasm, cell division, cell enlargement and cell differentiation. It is, therefore, influenced by all those factors which influence biosynthetic machinery such as the availability of water, oxygen, optimum temperature, optimum light, minerals, gravity, etc.
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Question 19 of 126
19. Question
The given figure shows growth of two leaves over the period of one day. If, \(A G=\) absolute growth and \(R G R=\) relative growth rate, then select the correct option.
\(
\begin{array}{|l|l|l|l|l|}
\hline & A G \text { for leaf } A & R G R \text { for leaf } A & A G \text { for leaf } B & R G R \text { for leaf } B \\
\hline \text { (a) } & 1 \% & 1 & 2 \% & 2 \\
\hline \text { (b) } & 100 \% & 5 & 10 \% & 5 \\
\hline \text { (c) } & 5 & 100 \% & 5 & 10 \% \\
\hline \text { (d) } & 5 & 100 \% & 5 & 100 \% \\
\hline
\end{array}
\)CorrectIncorrectHint
(c) Absolute growth rate (AGR): Absolute growth rate is the total growth per unit time.
Relative growth rate (RGR): It is growth per unit time per unit initial growth.
\(
R G R=\frac{\text { Growth in given time period }}{\text { Measurement at start of time period }}
\)
AG for leaf \(A=10 \mathrm{~cm}^2-5 \mathrm{~cm}^2=5 \mathrm{~cm}^2\)
RGR for leaf \(A=\frac{5}{5} \times 100=100 \%\)
AG for leaf \(B=55 \mathrm{~cm}^2-50 \mathrm{~cm}^2=5 \mathrm{~cm}^2\)
RGR for leaf \(B=\frac{5}{50} \times 100=10 \%\)
Though the absolute growth is same for both the leaves ( \(A[latex] and [latex]B\) ), relative growth rate is faster in leaf A because of its initial small size. -
Question 20 of 126
20. Question
A primary root grows from \(5 \mathrm{~cm}\) to \(19 \mathrm{~cm}\) in a week. Calculate the absolute growth rate (AGR) and relative growth rate (RGR) over the period.
\(
\begin{array}{|l|l|l|}
\hline & A G R & R G R \\
\hline \text { (a) } & 14 \mathrm{~cm} & 2.8 \\
\hline \text { (b) } & 14 \mathrm{~cm} & 3.8 \\
\hline \text { (c) } & 3.8 \mathrm{~cm} & 14 \% \\
\hline \text { (d) } & 24 \mathrm{~cm} & 2.8 \% \\
\hline
\end{array}
\)CorrectIncorrectHint
\(
\begin{aligned}
& \text { (a) } A G R=19-5=14 \mathrm{~cm} \\
& R G R=\frac{14}{5}=2.8 \mathrm{~cm}
\end{aligned}
\) -
Question 21 of 126
21. Question
Read the given statements and select the correct option.
(i) One maize root cell can give rise to more than 17,500 new cells per hour.
(ii) A cell in watermelon can increase in size upto 3,50,000 times.
(iii) The growth of pollen tube is measured in terms of length.
(iv) The growth of the leaf is measured in terms of surface area.CorrectIncorrectHint
d
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Question 22 of 126
22. Question
Cells of tracheary elements (tracheids and vessels) become dead at maturity and lose their protoplasm due to the deposition of lignocellulosic cell wall thickenings. This is an example of
CorrectIncorrectHint
(b)Â The cells derived from root apical and shoot apical meristems and cambium differentiate and mature to perform specific functions. This process leading to the maturation of cells is termed as differentiation. During differentiation, cells undergo few to major structural changes both in their cell walls and protoplasm, e.g., to form a tracheary element, the cells would lose their protoplasm, they also develop strong, elastic, lignocellulosic secondary cell walls, to carry water to long distances even under extreme tension.
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Question 23 of 126
23. Question
Which of the following is an example of differentiation?
CorrectIncorrectHint
d
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Question 24 of 126
24. Question
Living differentiated cells which have otherwise lost the capacity to divide, can regain the power of division under certain conditions. This phenomenon is termed as
CorrectIncorrectHint
(b) The living differentiated cells, that have lost the capacity to divide can regain the power of division under certain conditions, this phenomenon is termed as de-differentiation. E.g., the formation of meristems – interfascicular cambium (formed from medullary rays) and cork cambium (formed from outer layer of cortex) from fully differentiated parenchyma cells. While doing so, such meristems/ tissues are able to divide and produce cells that once again lose the capacity to divide but mature to perform specific functions, i.e., get redifferentiated. E.g., cells of secondary xylem, secondary phloem and periderm. Thus, redifferentiation can be defined as maturation or differentiation of dedifferentiated tissues.
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Question 25 of 126
25. Question
The dedifferentiated cells mature to form some specific cells to perform specific functions, this is referred to as
CorrectIncorrectHint
(c) The living differentiated cells, that have lost the capacity to divide can regain the power of division under certain conditions, this phenomenon is termed as de-differentiation. E.g., the formation of meristems – interfascicular cambium (formed from medullary rays) and cork cambium (formed from outer layer of cortex) from fully differentiated parenchyma cells. While doing so, such meristems/ tissues are able to divide and produce cells that once again lose the capacity to divide but mature to perform specific functions, i.e., get redifferentiated. E.g., cells of secondary xylem, secondary phloem and periderm. Thus, redifferentiation can be defined as maturation or differentiation of dedifferentiated tissues.
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Question 26 of 126
26. Question
_____ are examples of tissues, formed by dedifferentiation.
CorrectIncorrectHint
(c) Both interfascicular cambium and cork cambium are examples of tissues formed by dedifferentiation.
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Question 27 of 126
27. Question
Examples of tissues that are formed by redifferentiation are
CorrectIncorrectHint
d
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Question 28 of 126
28. Question
If a part of the pith from the stem of a plant is used as an explant and cultured on nutrient medium, which of the following processes is responsible for the formation of an undifferentiated mass of cells called callus?
CorrectIncorrectHint
(c) The portion of pith taken as an explant comprises of parenchymatous cells (j.e., simple permanent tissue which have lost the capacity to divide). When such cells are cultured on solid culture media, the parenchymatous cells of pith become meristematic and start dividing resulting in a mass of undifferentiated cells called callus. This is an example of dedifferentiation. These cells may be made to divide in different manners in order to produce different organs so that the meristematic cells of callus may become permanent tissues by the process of redifferentiation. For example, treatment of certain hormones may lead to the differentiation of shoot buds or roots.
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Question 29 of 126
29. Question
____ includes all the changes that an organism undergoes during its life cycle, from seed germination to senescence.
CorrectIncorrectHint
(d) Development is the sequence of events that occur in the life history of a plant which includes seed germination, growth, differentiation, maturation, flowering, seed formation and senescence. The process of development is considered as the sum of growth and differentiation controlled by several intrinsic factors (including genetic and hormonal) and extrinsic factors (including light, temperature, water, oxygen, nutrients, etc).
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Question 30 of 126
30. Question
Different kinds of structures develop in plants in different phases of growth or in response to the environment. This ability is called ____.
CorrectIncorrectHint
(a) Different structures develop in different phases of growth as well as in response to the environment. The ability to change under the influence of internal or external stimuli is called plasticity.
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Question 31 of 126
31. Question
In aquatic plant Ranunculus flabellaris (buttercup), submerged leaves are highly dissected whereas the emerged leaves are broad and lobed. This is an example of
CorrectIncorrectHint
(d) Heterophylly is the occurrence of different types of leaves on the same plant in different growth phases or under different environmental conditions. In case of environmental plasticity as shown by aquatic plant Ranunculus flabellaris (buttercup), the submerged leaves are highly dissected while the emerged leaves are broad and lobed.
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Question 32 of 126
32. Question
Intrinsic heterophylly is found in all except
CorrectIncorrectHint
(b) The plants such as cotton, coriander and larkspur exhibit intrinsic plasticity or heterophylly as the leaves of juvenile plants are quite different in shape from those of mature plants.
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Question 33 of 126
33. Question
Development in plants is influenced by both intrinsic and extrinsic factors. Which of the following is included under intrinsic factors?
CorrectIncorrectHint
(a) Development is the sequence of events that occur in the life history of a plant which includes seed germination, growth, differentiation, maturation, flowering, seed formation and senescence. The process of development is considered as the sum of growth and differentiation controlled by several intrinsic factors (including genetic and hormonal) and extrinsic factors (including light, temperature, water, oxygen, nutrients, etc.).
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Question 34 of 126
34. Question
Cytokinins are mostly
CorrectIncorrectHint
(c) Cytokinins are plant growth hormones which are basic in nature, either amino purine or phenyl urea derivatives, that promote cytokinesis (= cell division) either alone or in conjunction with auxin. Kinetin, a synthetic cytokinin, is 6 -furfuryl amino purine. Zeatin, a natural cytokinin, is 6-hydroxy 3-methyl trans 2-butenyl amino purine.
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Question 35 of 126
35. Question
Select the pair that consists of plant growth promoters only.
CorrectIncorrectHint
a
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Question 36 of 126
36. Question
Which of the following is both a growth promoter as well as a growth inhibitor?
CorrectIncorrectHint
d
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Question 37 of 126
37. Question
Functions of plant growth promoters and plant growth inhibitors are given here in a jumbled up manner. Select the option that correctly segregates these functions.
I. Cell division
II. Cell enlargement
III. Pattern formation
IV. Tropic growth
V. Flowering
VI. Fruiting
VII. Seed germination
VIII. Response to wound
IX. Response to stresses of biotic and abiotic origin
X. DormancyCorrectIncorrectHint
(c) Plant Growth Hormones (PGRs) or phytohormones are the organic substances which are synthesised in minute quantities in one part of the plant body and transported to another part where they influence specific physiological processes (Went and Thimann, 1937). PGRs are broadly divided into two groups – plant growth promoters and plant growth inhibitors. Plant growth promoters perform growth-promoting activities like cell division, cell enlargement, pattern formation, tropic growth, flowering, fruiting and seed formation. They are three in number viz., auxins, gibberellins and cytokinins. Plant growth inhibitors have important functions in inducing plant responses to wounding, biotic and abiotic stresses, dormancy and abscission. Abscisic acid is known as plant growth inhibitor. Ethylene is largely plant growth inhibitor but is also involved in some growth promotion activities.
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Question 38 of 126
38. Question
Hormone involved in phototropism is
CorrectIncorrectHint
(a) Phototropic curvature is the result of uneven distribution of auxin. Darwin and Darwin observed that the coleoptiles of canary grass responded to unilateral illumination by growing toward the light source (phototropism). After a series of experiments, it was concluded that the tip of the coleoptile contains auxin that caused the bending of the entire coleoptile in relation to the direction of light.Â
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Question 39 of 126
39. Question
Which plant hormone induces the phenomenon of phototropism in plants?
CorrectIncorrectHint
(a) Auxins play a very important role in certain tropic movements shown by plants, e.g., phototropism in shoots and geotropism in roots.
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Question 40 of 126
40. Question
Avena curvature test is a bioassay for examining the activity of
CorrectIncorrectHint
a
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Question 41 of 126
41. Question
Gibberellin was first extracted from
CorrectIncorrectHint
(a)Â In Japan (in early \(1800^{\prime}\) ‘s), certain rice plants suffered from bakanae (foolish seedling) disease. Such rice plants were thin, pale green, spindle-shaped, longer by \(50 \%\) than the healthy plants and were sterile. The disease was found by Hori and Kurosawa to be caused by a fungus, Gibberella fujikuroi. The fungus is the perfect stage of Fusarium moniliforme. The active substance which caused the disease was extracted and named gibberellin by Yabuta (1935).
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Question 42 of 126
42. Question
Which one is paired incorrectly?
CorrectIncorrectHint
(d) Kogl et al. (1931) isolated auxin from human urine called heteroauxin which was identified as indole-3-acetic acid (IAA). Zeatin is a cytokinin-like substance isolated and crystallised by Letham (1963-65) from milky endosperm of corn (Zea mays). It also occurs in coconut milk. Yabuta and Sumiki (1938) isolated a chemical substance from the cultural filtrate of fungus Gibberella fujikuroi in crystalline form and named it gibberellic acid. Cousins (1910) found that ripe oranges produced a volatile substance that hastened the ripening of unriped bananas nearby. With the help of gas chromatography, R. Gane (1934) found that the ripening-causing volatile substance was ethylene. Abscisic acid was isolated by Addicott et al (1963) from cotton bolls.
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Question 43 of 126
43. Question
Who isolated auxins from tips of coleoptiles of oat seedlings?
CorrectIncorrectHint
(b) Isolation of auxins from tips of coleoptiles of oat seedlings is based upon Avena coleoptile curvature test. This experiment was devised by F.W. Went (1926). It is based on the quick polar transport of auxin, downwards in Avena coleoptile. The result will be differential growth and formation of curvature. The degree of curvature is almost proportional to the concentration of auxin.
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Question 44 of 126
44. Question
High concentration of auxin is present in
CorrectIncorrectHint
b
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Question 45 of 126
45. Question
Which of the following effects of auxins on plants is the basis for their commercial application in tissue culture?
CorrectIncorrectHint
c
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Question 46 of 126
46. Question
Which of the following hormones is used in root formation on stem cutting?
CorrectIncorrectHint
(d) Auxins, e.g., IBA, NAA stimulate root formation on the stem cuttings. NAA is synthetic auxin while IBA is considered as both natural and synthetic auxin.
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Question 47 of 126
47. Question
Select the correct statement regarding auxins.
CorrectIncorrectHint
d
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Question 48 of 126
48. Question
Apical dominance in dicot plants is due to the presence of more _____ in the apical bud than in the lateral ones.
CorrectIncorrectHint
(a)Â Apical dominance is the phenomenon by which presence of apical bud does not allow the nearby lateral buds to grow. Apical bud inhibits the growth of lateral buds by releasing auxins. When a plant is decapitated, i.e., its apical bud is removed then the lateral buds sprout, resulting in dense bushy growth. This phenomenon is widely used in the tea plucking and hedge making.
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Question 49 of 126
49. Question
The term ‘auxin precursor’ refers to
CorrectIncorrectHint
a
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Question 50 of 126
50. Question
Read the given statements and select the correct option.
(i) Darwin and Darwin (1880) found that the sensation of unilateral illumination was perceived by the coleoptile tip of canary grass.
(ii) IAA is universal natural auxin discovered by Kogl et al.
(iii) IBA is both natural and synthetic auxin.
(iv) Auxins promote the growth of lateral shoots.CorrectIncorrectHint
(c) Auxins promote the growth of apical buds and suppress the growth of lateral buds/lateral shoots.
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Question 51 of 126
51. Question
In the process of apical dominance, lateral buds are unable to grow in the presence of apical bud. This is due to
CorrectIncorrectHint
b
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Question 52 of 126
52. Question
Decapitation, i.e. removal of shoot tips in a plant usually results in
CorrectIncorrectHint
(b) Apical dominance is the phenomenon by which presence of apical bud does not allow the nearby lateral buds to grow. Apical bud inhibits the growth of lateral buds by releasing auxins. When a plant is decapitated, i.e., its apical bud is removed then the lateral buds sprout, resulting in dense bushy growth. This phenomenon is widely used in the tea plucking and hedge making.
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Question 53 of 126
53. Question
In tea plantations and hedge making, gardeners trim the plants regularly so that they remain bushy. Scientific explanation behind this is
CorrectIncorrectHint
(d) Apical dominance is the phenomenon by which presence of apical bud does not allow the nearby lateral buds to grow. Apical bud inhibits the growth of lateral buds by releasing auxins. When a plant is decapitated, i.e., its apical bud is removed then the lateral buds sprout, resulting in dense bushy growth. This phenomenon is widely used in the tea plucking and hedge making.
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Question 54 of 126
54. Question
Removal of auxin source demonstrates that leaf abscission is _____ by auxin and apical dominance is _____ by auxin.
CorrectIncorrectHint
(d)Â Shedding of mature leaves from the stem or ripe fruits from the stem is called abscission. Generally, a layer of tissue is formed at the base of the organ. This layer of tissue is called abscission zone. Abscission zone does not occur when the concentration of auxin is high, particularly when the gradient of auxin is steep, i.e., more auxin on distal side and less auxin on proximal side. The abscission zone formation occurs rapidly when the auxin gradient becomes slight or neutral. Moreover, the plant hormone ethylene is found to promote the abscission. Thus, a high concentration of auxin prevents the formation of abscission layer and the phenomenon is controlled by the concentrations of auxin and ethylene. Apical dominance is promoted by auxin.
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Question 55 of 126
55. Question
The hormone responsible for the given phenomenon is
CorrectIncorrectHint
(a) The given figure represents apical dominance. Auxins are mainly responsible for apical dominance. IAA is a natural auxin.
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Question 56 of 126
56. Question
Functions of auxins include
CorrectIncorrectHint
(d) NAA and 2, 4-D are often employed for inducing flowering in litchi and pineapple. Application of auxins (e.g., IAA, IBA) and conjugate auxins (e.g., IBA-alanine) to unpollinated pistils make them develop into seedless fruits (or parthenocarps) which carry a better market price than the normal fruits having seeds. 2 , 4-D and 2, 4, 5-T are used as weedicides (herbicides) which destroy broad leaved weeds in cereal crops and lawns.
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Question 57 of 126
57. Question
To get a carpet like grass, lawns are mowed regularly, this is done to
CorrectIncorrectHint
a
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Question 58 of 126
58. Question
Artificial application of auxins like IAA, IBA and NAA to unpollinated pistils can form
CorrectIncorrectHint
(d) NAA and 2, 4-D are often employed for inducing flowering in litchi and pineapple. Application of auxins (e.g., IAA, IBA) and conjugate auxins (e.g., IBA-alanine) to unpollinated pistils make them develop into seedless fruits (or parthenocarps) which carry a better market price than the normal fruits having seeds. 2, 4-D and 2, 4, 5-T are used as weedicides (herbicides) which destroy broad leaved weeds in cereal crops and lawns.
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Question 59 of 126
59. Question
The term ‘antiauxin’ refers to
CorrectIncorrectHint
(b) The compounds which inhibit the action of auxins are called as antiauxins, e.g., p-chlorophenoxy isobutyric acid (PCIB).
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Question 60 of 126
60. Question
Which of the following statements regarding gibberellins is incorrect?
CorrectIncorrectHint
(d)Â Gibberellins are weak acidic growth hormones having gibbane ring structure which cause cell elongation of intact plants in general and increased internodal length of genetically dwarfed plants (e.g., pea, corn) in particular. \(\mathrm{GA}_3\) was one of the first gibberellins to be discovered and remains the most intensively studied form.
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Question 61 of 126
61. Question
The fruits can be left on the tree longer using GA so as to extend the market period. This is due to which function of GA?
CorrectIncorrectHint
(b) Some of the gibberellins are commercially used in delaying ripening of fruits. \(\mathrm{GA}_7\) delays senescence 50 that fruit can be left on the tree for longer period. It extends period of marketing. Ripening of Citrus fruits can be delayed with the help of gibberellins. This is useful in storing the fruits.
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Question 62 of 126
62. Question
To speed up the malting process in brewing industry the growth hormone used is
CorrectIncorrectHint
(b) Gibberellins are used to speed up the malting process in brewing industry. They increase the yield of malt from barley grains.
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Question 63 of 126
63. Question
Read the given statements and select the correct option.
Statement 1: Elongation of reduced stem is possible due to application of gibberellin hormone.
Statement 2 : Gibberellin stimulates cell division and cell elongation.CorrectIncorrectHint
a
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Question 64 of 126
64. Question
Spraying sugarcane with gibberellins increases the yield by as much as 20 tonnes per acre. GA performs it by
CorrectIncorrectHint
(c) Sugarcane stores carbohydrate as sugar in their stems. Spraying sugarcane crop with gibberellins increases the length of the stem, thus increasing the yield by as much as 20 tonnes per acre.
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Question 65 of 126
65. Question
Dwarfness can be controlled by treating the plant with
CorrectIncorrectHint
b
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Question 66 of 126
66. Question
Bolting, i.e., internode elongation just prior to flowering in beet, cabbage and many rosette plants, is promoted by
CorrectIncorrectHint
(b) Certain plants show profuse leaf development but reduced internode growth. Such form of growth is called rosette, where a large number of broad leaves remain attached to a very short axis. Stimulation in the internode growth just before reproduction is called bolting. If plants are treated with gibberellins during conditions of rosette growth, the plants bolt and flower. Normally, bolting is favoured in nature by either cold nights or long days.
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Question 67 of 126
67. Question
Internodal elongation is stimulated by
CorrectIncorrectHint
d
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Question 68 of 126
68. Question
Which phytohormone would you use if you are asked to ‘bolt’a rosette plant?
CorrectIncorrectHint
(b) Certain plants show profuse leaf development but reduced internode growth. Such form of growth is called rosette, where a large number of broad leaves remain attached to a very short axis. Stimulation in the internode growth just before reproduction is called bolting. If plants are treated with gibberellins during conditions of rosette growth, the plants bolt and flower. Normally, bolting is favoured in nature by either cold nights or long days.
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Question 69 of 126
69. Question
Which of the following physiological effects is caused in plants by gibberellic acid?
CorrectIncorrectHint
(b) One of the most striking effects of the gibberellins is the reversal of dwarfism in many genetically dwarf plants. Rosette plant of sugar beet, when treated with \(\mathrm{GA}_3\), undergoes marked longitudinal growth of the axis. Similarly, dwarf pea and dwarf corn attain almost normal size when treated with gibberellins. The dwarf plants have very low GA level which appears to account for the dwarfing habit. Thus, the external supply of GA to such plants causes rapid elongation.
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Question 70 of 126
70. Question
The activity of \(\alpha\)-amylase in the endosperm of a germinating seed of barley is induced by
CorrectIncorrectHint
(d) Gibberellic acid induces de novo (a new) synthesis of various hydrolytic enzymes, such as, \(\alpha\)-amylase, ribonuclease, \(\alpha-1\), 3 -glucanase and protease in aleurone cells of barley grains. This has been experimentally shown by isolating the aleurone layer and treating it with gibberellin solution. These enzymes are mobilised to endosperm during germination and hydrolyse the storage reserve.
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Question 71 of 126
71. Question
Kinetin, a modified form of adenine was discovered from
CorrectIncorrectHint
a
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Question 72 of 126
72. Question
Hormone primarily concerned with cell division is
CorrectIncorrectHint
(c) Cytokinins are growth hormones that promote cytokinesis (= cell division)
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Question 73 of 126
73. Question
Match column I with column II and select the correct option from the codes given below.
\(
\begin{array}{|c|l|l|l|}
\hline & \text { Column I } & & \text { Column II } \\
\hline \text { A. } & \text { Natural auxin } & \text { (i) } & \text { NAA } \\
\hline \text { B. } & \text { Synthetic auxin } & \text { (ii) } & \text { Zeatin } \\
\hline \text { C. } & \text { Bakane disease of rice } & \text { (iii) } & \text { IAA } \\
\hline \text { D. } & \text { Natural cytokinin } & \text { (iv) } & \text { GA } \\
\hline & & \text { (v) } & \text { Kinetin } \\
\hline
\end{array}
\)CorrectIncorrectHint
a
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Question 74 of 126
74. Question
Natural cytokinins are synthesised in regions where rapid cell division occurs. Such regions are
CorrectIncorrectHint
(d) About 18 types of cytokinins have been discovered till now. Some of them are constituents of $t$ RNAs. Roots are considered as the major source of cytokinin synthesis; from roots, the cytokinins pass upwardly through xylem. Cytokinin synthesis also occurs in the areas where cell division takes place, e.g., growing embryos and developing seeds, endosperm of seeds, young fruits, developing shoot buds, etc.
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Question 75 of 126
75. Question
What would happen if you forget to add cytokinin to the culture medium?
CorrectIncorrectHint
a
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Question 76 of 126
76. Question
In addition to auxins, _____ must be supplied to culture medium to obtain a good callus in plant tissue culture.
CorrectIncorrectHint
(b) Callus is an unorganised, undifferentiated mass of dividing cells formed during tissue culture which requires both auxins and cytokinins for its growth and differentiation. In callus, shoot regeneration is promoted by a cytokinin, such as BAP (Benzylaminopurine) and root regeneration is promoted by an auxin, such as NAA (Naphthalene acetic acid). Thus, shoot and root regenerations in callus are controlled by auxin-cytokinin balance. Usually, an excess of auxins promote root regeneration and that of cytokinins promote shoot regeneration.
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Question 77 of 126
77. Question
In plant tissue culture experiments, high auxin to cytokinin ratio favours _____ development and high cytokinin to auxin ratio favours ______ development.
CorrectIncorrectHint
(a) Callus is an unorganised, undifferentiated mass of dividing cells formed during tissue culture which requires both auxins and cytokinins for its growth and differentiation. In callus, shoot regeneration is promoted by a cytokinin, such as BAP (Benzylaminopurine) and root regeneration is promoted by an auxin, such as NAA (Naphthalene acetic acid). Thus, shoot and root regenerations in callus are controlled by auxin-cytokinin balance. Usually, an excess of auxins promote root regeneration and that of cytokinins promote shoot regeneration.
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Question 78 of 126
78. Question
A plant hormone used for inducing morphogenesis in plant tissue culture is
CorrectIncorrectHint
(c) Cytokinins play a vital role in morphogenesis in plants. They oppose initiation of roots in stem cuttings treated with auxin and result in the formation of callus at the cut end. It is now well known that kinetin-auxin interaction controls the morphogenetic differentiation of shoot and root meristems.
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Question 79 of 126
79. Question
The phenomenon of apical dominance can be overcome by exogenous application of
CorrectIncorrectHint
(c) Presence of cytokinin in an area causes preferential movement of nutrients towards it. When applied to lateral buds, they help in their growth despite the presence of apical bud. They thus act antagonistically to auxin which promotes apical dominance. Therefore, cytokinin can overcome apical dominance, caused by auxins.
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Question 80 of 126
80. Question
Phytohormone A causes apical dominance while phytohormone B overcomes the same. Select the option that correctly identifies A and B.
\(
\begin{array}{|l|l|l|}
\hline & A & B \\
\hline \text { (a) } & \text { Auxin } & \text { Cytokinin } \\
\hline \text { (b) } & \text { Cytokinin } & \text { Auxin } \\
\hline \text { (c) } & \text { Gibberellin } & \text { Cytokinin } \\
\hline \text { (d) } & \text { Auxin } & \text { Gibberellin } \\
\hline
\end{array}
\)CorrectIncorrectHint
(a) Presence of cytokinin in an area causes preferential movement of nutrients towards it. When applied to lateral buds, they help in their growth despite the presence of apical bud. They thus act antagonistically to auxin which promotes apical dominance. Therefore, cytokinin can overcome apical dominance, caused by auxins.
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Question 81 of 126
81. Question
Hormone that promotes growth of lateral buds and has negative effect on apical dominance is
CorrectIncorrectHint
a
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Question 82 of 126
82. Question
Auxin and cytokinin are antagonistic in which of the following functions?
CorrectIncorrectHint
(c) Presence of cytokinin in an area causes preferential movement of nutrients towards it. When applied to lateral buds, they help in their growth despite the presence of apical bud. They thus act antagonistically to auxin which promotes apical dominance. Therefore, cytokinin can overcome apical dominance, caused by auxins.
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Question 83 of 126
83. Question
Induction of cell division activity and delay in senescence is caused by
CorrectIncorrectHint
(c) The most important function of cytokinins is the promotion of cell division. The varying amounts of cytokinins, alongwith sufficient auxins is required for the growth of callus in tissue culture experiments. Cytokinins delay the senescence of leaves and other organs by mobilisation of nutrients. It is known as Richmond-Lang effect.
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Question 84 of 126
84. Question
Cytokinins help to produce all except
CorrectIncorrectHint
(d) Rooting on cut stem is a function of auxin not cytokinin.
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Question 85 of 126
85. Question
Which among the following is not a function of cytokinins?
CorrectIncorrect -
Question 86 of 126
86. Question
Match column I with column II and select the correct option from the codes given below.
\(
\begin{array}{|l|l|r|l|}
\hline & \begin{array}{l}
\text { Column I } \\
\text { (Phytohormone) }
\end{array} & & \begin{array}{l}
\text { Column II } \\
\text { (Plant part where } \\
\text { it is synthesised) }
\end{array} \\
\hline \text { A. } & \text { IAA } & \text { (i) } & \begin{array}{l}
\text { Tissues undergoing } \\
\text { senescence }
\end{array} \\
\hline \text { B. } & \text { Cytokinins } & \text { (ii) } & \text { Shoot apices } \\
\hline \text { C. } & \text { Ethylene } & \text { (iii) } & \text { Root apices } \\
\hline
\end{array}
\)Â
CorrectIncorrectHint
a
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Question 87 of 126
87. Question
Read the given statements and select the correct option.
Statement 1: Ethylene is a gaseous hormone.
Statement 2 : Ethylene causes climacteric ripening of fruits.CorrectIncorrectHint
(a) Ethylene is a gaseous hormone. It aids in ripening of climacteric fruits and dehiscence of dry fruits. Climacteric fruits are the fleshy fruits which show a sudden sharp rise of respiration rate at the time of ripening (respiratory climacteric). They are usually transported in green or unripe stage. Ethylene is used to induce artificial ripening of these fruits, e.g., apple, mango, banana, etc.
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Question 88 of 126
88. Question
Artificial ripening of fruits is caused by the treatment of
CorrectIncorrectHint
c
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Question 89 of 126
89. Question
If a fully ripen fruit gets mixed with unripe fruits, the unripe fruits will
CorrectIncorrectHint
(b) Ethylene production by plants is autocatalytic, i.e., a small amount of ethylene will stimulate production of its larger amounts. Thus, a few ripe fruits will initiate ripening of nearby fruits. It is, therefore, a common practice to keep few ripe bananas with unripe bananas to hasten ripening.
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Question 90 of 126
90. Question
The most widely used compound as a source of \(\mathrm{C}_2 \mathrm{H}_4\) is
CorrectIncorrectHint
(d) Ethephon, i.e., 2-chloroethyl phosphonic acid is a source of ethylene used commercially. It is used in aqueous solution and releases ethylene slowly.
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Question 91 of 126
91. Question
Read the given statements to identify the phytohormone that performs these functions.
(i) Horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings
(ii) Promoting senescence and abscission of leaves and flowers
(iii) Breaking seed and bud dormancy
(iv) Initiating germination in peanut seeds
(v) Sprouting of potato tubersCorrectIncorrectHint
b
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Question 92 of 126
92. Question
Gibberellins promote the formation of A flowers on genetically B plants in Cannabis while ethylene promotes formation of C flowers on genetically D Cannabis plants.
\(
\begin{array}{|l|l|l|l|l|}
\hline & A & B & C & D \\
\hline \text { (a) } & \text { male } & \text { female } & \text { femalel } & \text { male } \\
\hline \text { (b) } & \text { male } & \text { male } & \text { female } & \text { female } \\
\hline \text { (c) } & \text { female } & \text { male } & \text { male } & \text { female } \\
\hline \text { (d) } & \text { female } & \text { female } & \text { male } & \text { male } \\
\hline
\end{array}
\)CorrectIncorrectHint
a
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Question 93 of 126
93. Question
A farmer grows cucumber plants in his field. He wants to increase the number of female flowers in them. Which plant growth regulator can be applied to achieve this?
CorrectIncorrectHint
(b) Ethylene has a feminising effect on sex expression. The genetically male plants of cucumber can be induced to produce female flowers in the presence of ethylene. The number of female flowers and hence fruit is enhanced in these plants.
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Question 94 of 126
94. Question
Seed dormancy is caused by
CorrectIncorrectHint
(b) Seed dormancy is mainly caused by ABA. Dormancy allows seeds to tolerate desiccation and extremes of temperature better. Due to its action of inducing dormancy in seeds, buds, etc, ABA is also called as dormin.
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Question 95 of 126
95. Question
Select the mismatched pair.
CorrectIncorrectHint
(b) Gibberellic acid increases the yield of sugarcane crop. Cytokinins inhibit apical dominance and act antagonistically to auxins which promote apical dominance. Rhizomes, corms, tubers, seeds (e.g., peanut) and other storage organs can be made to sprout early by exposing them to ethylene. Abscisic acid is a plant growth inhibitor which inhibits seed germination.
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Question 96 of 126
96. Question
Read the given statements and identify the plant hormones X, Y and Z.
(i) Hormone Y induces flowering in mango and also promotes rapid internode/petiole elongation in deep water rice plants and hence helping leaves or upper part of shoot to remain above water.
(ii) Hormone X promotes apical dominance.
(iii) Hormone Z inhibits the seed germination, increases the tolerance of plant to various stresses, play important role in seed development, maturation and dormancy.CorrectIncorrectHint
d
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Question 97 of 126
97. Question
The hormone ‘ \(X\) ‘ does the following functions :
(i) Induces seed dormancy
(ii) Inhibits seed germination
(iii) Prepares plants to cope with stress
(iv) Stimulates closure of stomata
The hormone ‘ \(X\) ‘ should beCorrectIncorrectHint
a
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Question 98 of 126
98. Question
The hormone which reduces transpiration rate by inducing stomatal closure is
CorrectIncorrectHint
(a) ABA (Abscisic acid) is a stress hormone which is synthesised by the plant during drought or other stress conditions. It causes rapid movement of \(\mathrm{K}^{+}\)ions out of the guard cells, closes stomatal pores and thus reduces the transpiration rate.
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Question 99 of 126
99. Question
Bud dormancy is induced by
CorrectIncorrectHint
(c) ABA is known as dormin as it induces dormancy, in buds, underground stems and seeds in a variety of plants, e.g. ABA induces winter bud dormancy in duckweed plant.
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Question 100 of 126
100. Question
Hormone responsible for ageing is
CorrectIncorrectHint
(c) ABA is a plant growth inhibitor. It promotes senescence and ageing in plant parts.
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Question 101 of 126
101. Question
Read the given statements and select the option that correctly identifies the incorrect ones.
(i) Cytokinin is primarily concerned with cell division.
(ii) \(\mathrm{C}_2 \mathrm{H}_4\) breaks seed and bud dormancy.
(iii) \(\mathrm{ABA}\) stimulates the opening of stomata.
(iv) \(\mathrm{C}_2 \mathrm{H}_4\) initiates germination in peanut seeds, sprouting of potato tubers.
(v) ABA is synergistic to GA.CorrectIncorrectHint
(c) ABA causes stomatal closure. ABA is antagonistic to GA.
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Question 102 of 126
102. Question
Match column I with column II and select the correct option from the codes given below.
\(
\begin{array}{|l|l|r|l|}
\hline & \text { Column I } & & \text { Column II } \\
\hline \text { A. } & \text { Auxin } & \text { (i) } & \text { Fruit ripening } \\
\hline \text { B. } & \text { Cytokinins } & \text { (ii) } & \text { Phototropism } \\
\hline \text { C. } & \text { Abscisic acid } & \text { (iii) } & \text { Antagonist to GAs } \\
\hline \text { D. } & \text { Ethylene } & \text { (iv) } & \text { Growth of lateral buds } \\
\hline
\end{array}
\)CorrectIncorrectHint
b
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Question 103 of 126
103. Question
Select the correct match.
CorrectIncorrectHint
a
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Question 104 of 126
104. Question
Plants which require an exposure to light for a period greater than critical day length are
CorrectIncorrectHint
(a) Long day plants (LDPs) flower when they receive long photoperiods or light hours which are above a critical length, e.g., henbane (Hyoscyamus niger), wheat, oat, sugarbeet, spinach (Spinacea oleracea), radish, barley, larkspur, lettuce, etc.
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Question 105 of 126
105. Question
The given figure shows the flowering responses of three plants A, B and C to the photoperiod. Select the correct option regarding this.
\(
\begin{array}{|l|l|l|l|}
\hline & A & B & C \\
\hline \text { (a) } & \text { Long day plant } & \text { Day neutral plant } & \text { Short day plant } \\
\hline \text { (b) } & \text { Short day plant } & \text { Day neutral plant } & \text { Long day plant } \\
\hline \text { (c) } & \text { Long day plant } & \text { Short day plant } & \text { Day neutral plant } \\
\hline \text { (d) } & \text { Short day plant } & \text { Long day plant } & \text { Day neutral plant } \\
\hline
\end{array}
\)CorrectIncorrectHint
c
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Question 106 of 126
106. Question
Maryland mammoth tabacco is a short day plant. Its critical duration of darkness is 10 hours. Under which of the following conditons will it not flower?
CorrectIncorrectHint
(a) A short day plant is the one that flowers on photoperiods shorter than the critical day length. As the critical duration of darkness in the Maryland mammoth tobacco is 10 hours, i.e., it requires a minimum period of darkness of 10 hours to flower. Thus under the condition shown in option (a), the plant will not flower.
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Question 107 of 126
107. Question
Four potted plants (I, II, III and IV) of a short day plant, which has the critical period of 14 hours; are taken and exposed to light for different time periods. The light periods given are listed in the table.
\(
\begin{array}{|c|c|}
\hline \text { Potted plant } & \text { Photoperiod } \\
\hline \text { I } & 10 \mathrm{hrs} \\
\hline \text { II } & 15 \mathrm{hrs} \\
\hline \text { III } & 16 \mathrm{hrs} \\
\hline \text { IV } & 20 \mathrm{hrs} \\
\hline
\end{array}
\)Which potted plant will show flowering after exposure to light?
CorrectIncorrectHint
(a) A short day plant (SDP), which has a critical period of 14 hours, will flower only if it is provided a continuous period of darkness of 14 hours; which has been given to the potted plant-I only. In rest of the potted plants, more amounts of light periods are being given and thus the dark periods have been reduced to below 14 hours.
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Question 108 of 126
108. Question
Sedum is a long day plant. Its critical duration of light is 13 hours. Under which of the following conditions would it flower?
CorrectIncorrectHint
A long day plant (LDP) is the one that flowers on photoperiods longer than critical day length. As the critical duration of light in Sedum is given to be 13 hours i.e., it requires a minimum period of light of 13 hours to flower. Thus, the plant will flower-only under the conditions shown in option (c). So, the correct answer is ‘option c’
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Question 109 of 126
109. Question
Phenomenon of photoperiodism was first discovered by ________ in the “Maryland mammoth” variety of _________.
CorrectIncorrectHint
(a) The effect of photoperiods or daily duration of light hours (and dark periods) on the growth and development of plants, especially flowering, is called photoperiodism. Photoperiodism was first studied by Gamer and Allard (1920) in ‘Maryland mammoth’ a variety of Tobacco.
Long Day Plants (LDP) flower when they receive long photoperiods or light hours which are above a critical length, e.g., henbane (Hyoscyamus Nget), wheat oat sugar beet, spinach (Spinacia oleracea), radish, barley, larkspur, lettuce.
So the correct answer is ‘Garner and Allard, tobacco’. -
Question 110 of 126
110. Question
The effect of daily duration of light and dark periods on the growth and development of plants, especially flowering, is called
CorrectIncorrectHint
(d) Photoperiodism determines the amount of growth, dormancy and flowering. Flowering occurs in response to absorption of light by Cyt red and cytochrome farred, period of exposure to light that is, greater than or less than the critical value, accordingly the plants are termed long day plant, short day plant and day neutral plant. With the exposure to right amount of light the flower formation is stimulated by hormone florigen.
So, the correct answer is ‘Photoperiodism’ -
Question 111 of 126
111. Question
Photoperiod stimulus is perceived by ______ pigment.
CorrectIncorrectHint
(c) Experimental evidences have indicated that the photoperiodic stimulus in plants is perceived by pigment phytochrome. Phytochrome is a photoreversible pigment that absorbs light and the flowering is a phytochrome-mediated process.
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Question 112 of 126
112. Question
Low temperature treatment to speed up the process of flowering is referred to as
CorrectIncorrectHint
(b) Vernalisation is the process of shortening of the juvenile or vegetative phase and hastening flowering by a previous cold treatment. In vernalization by cold treatment, winter varieties are transferred into spring or summer varieties. The site of vernalization is apical meristem or all the meristematic cells e.g., shoot tip, embryo tips, root apex etc. The low temperature required for vernalization is usually $0^{\circ}-5^{\circ} \mathrm{C}$. As a result of vernalization, a flowering hormone called vernalin is formed (reported by Melchers), but vernalin has never been isolated.
So the correct option is ‘vernalization’. -
Question 113 of 126
113. Question
The stimulus of cold treatment (vernalisation) is perceived by
CorrectIncorrectHint
(d) Vernalisation is the conversion of winter variety into spring variety by chilling treatment or low temperature. Treatment with low temperature \(\left(\mathrm{O}-4^{\circ} \mathrm{C}\right)\) leads to shortening of vegetative phase and initiation of reproductive phase. The stimulus of cold treatment is perceived by shoot tips, embryo tips and other meristematic regions pf the plant.
So, the correct answer is ‘Shoot apices’. -
Question 114 of 126
114. Question
Cabbage is a biennial plant which produces flowers in second year of growth. In an attempt to make it flower in a single year, four potted plants (I, II, III, and IV) of cabbage were subjected to different temperatures for several days as given in the table.
\(
\begin{array}{|c|c|}
\hline \text { Potted plant } & \text { Temperature } \\
\hline \text { I } & 5^{\circ} \mathrm{C} \\
\hline \text { II } & 20^{\circ} \mathrm{C} \\
\hline \text { III } & 30^{\circ} \mathrm{C} \\
\hline \text { IV } & 25^{\circ} \mathrm{C} \\
\hline
\end{array}
\)Which potted plant will show flowering?
CorrectIncorrectHint
(a) In plants, flowering is either quantitatively or qualitatively dependent on exposure to low temperature which is known as vernalisation. The biennials plants complete their life cycle in two years as in cabbage, carrot, etc. They germinate and grow vegetative in first year and produce flowers in the second year of growth. These plants fulfill their cold requirement during winters. However, such biennial plants can be made to flower in one growing season by providing low temperature treatment (i.e., \(0-5^{\circ} \mathrm{C}\) temperature) to young plants or moistened seeds. The low temperature required for vernalization is usually \(0-5^{\circ} \mathrm{C}\). So the correct answer is ‘ \(\mathrm{I}\) ‘.
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Question 115 of 126
115. Question
Vernalisation can often be replaced by
CorrectIncorrectHint
(c) Vernalization is exposure of plants to a certain degree of cold conditions so as to make them flower, or break seed dormancy.
For example, in Hyoscyamus niger a cold requiring long day plant when treated with GA, produced flowers in long day condition with out cold treatment. The exposure to GA made the plant produce hormone vernalin which induced flowering in the plant. So, the correct answer is ‘Gibberellins’ -
Question 116 of 126
116. Question
Which of the following inhibitors causes seed dormancy?
CorrectIncorrectHint
d
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Question 117 of 126
117. Question
Select the incorrect statement.
CorrectIncorrectHint
d
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Question 118 of 126
118. Question
Dormancy of seeds is broken by red light in
CorrectIncorrectHint
(c) Many viable seeds germinae immediately after harvest if provided with suitable conditions of germination i.e., water, oxygen and suitable temperature. Some plants like lettuce need light also.
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Question 119 of 126
119. Question
In Xanthium and many grasses, seed dormancy occurs due to
CorrectIncorrectHint
(a) Impermeability of seed coats to oxygen.
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Question 120 of 126
120. Question
Weakening of hard seed coat with pieces of glass is
CorrectIncorrectHint
a
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Question 121 of 126
121. Question
A young dicot seedling (e.g., soybean) is laid horizontally on a surface and is subjected to gravity stimulus. The shoot bends in upward direction and the root bends in downward direction. Which out of the following is the possible reason for this movement?
CorrectIncorrectHint
(a) Auxins play a prominent role in the various tropic movements shown by plants such as phototropism and gravitropism. Phototropism is the movement in response to light. The shoot tip is responsible for the directional movement in response to sunlight, as tip is the area where auxins are synthesised. The part of the shoot tip which receives direct sunlight will have the least amount of auxin. More auxin present on the shaded side promotes more cell division and elongation, causing the plant to bend towards sunlight. Gravitropism is the movement in response to gravity. Roots bend downwards in response to gravity due to the regulated transport of auxins called as polar auxin transport.
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Question 122 of 126
122. Question
Seed germination is the sprouting of a seed and growth of the embryo present inside the seed into a seedling or young plant capable of independent existence. Refer the given figure showing seed germination and mark the incorrect option.
CorrectIncorrectHint
(c) Given figure illustrates epigeal seed germination which occurs in bean seeds. In this type of seed germination, cotyledons are pushed out of the soil by greater growth of hypocotyl. Hypocotyl grows actively and becomes curved to protect the plumule and cotyledons from friction of soil. After coming out of the soil surface, the hypocotyl straightens. The loosened seed coats fall down, cotyledons turn green and become photosynthetic to function as first leaves of the seedling.
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Question 123 of 126
123. Question
A farmer while growing grape plants in his garden, observes the following:
(i) Fruit size normally remained small.
(ii) Natural seed abortion.
(iii) Reduced stem and leaf growth.
Which problems could be solved by application of gibberellic acid during the development of fruits?CorrectIncorrectHint
(b) Application of gibberellins increases the number and size of several fruits, e.g., grape, tomato, etc. The hormone creates more room by increasing the size of stalks so that fruits can grow in size.
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Question 124 of 126
124. Question
Select the correct option regarding the phytohormone to which the given molecular structure belongs.
CorrectIncorrectHint
(d) Given molecular structure belongs to hormone gibberellic acid (GA). Gibberellic acid (GA) breaks the dormancy of several types of seeds. One biochemical reaction known to be enhanced by \(G A\) is the synthesis of hydrolase enzymes (especially- \(\alpha\)-amylase) in the endosperm of cereal grains, e.g., barley.
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Question 125 of 126
125. Question
Consider the following statements and select the correct option stating which one is true \((T)\) and which one is false (F).
(i) Cotton plants do not depend on photoperiod.
(ii) Phytochrome is a pigment-protein complex which exists in two inter-convertible forms- \(P_r\) and \(P_{f r}\).
(iii) Tobacco produces flowers after getting the inductive cycles of long dark periods and short photoperiods.
(iv) 2,4-D acts as weedicide to remove broad-leaved weeds.
(v) Auxins promote the growth of lateral buds whereas cytokinins inhibit it.\(
\begin{array}{cccccc}
& \text { (i) } & \text { (ii) } & \text { (iii) } & \text { (iv) } & \text { (v) } \\
\text { (a) } & \mathrm{T} & \mathrm{T} & \mathrm{F} & \mathrm{F} & \mathrm{T} \\
\text { (b) } & \mathrm{T} & \mathrm{T} & \mathrm{T} & \mathrm{T} & \mathrm{F} \\
\text { (c) } & \mathrm{F} & \mathrm{F} & \mathrm{T} & \mathrm{F} & \mathrm{T} \\
\text { (d) } & \mathrm{T} & \mathrm{T} & \mathrm{F} & \mathrm{T} & \mathrm{F}
\end{array}
\)CorrectIncorrectHint
(b) Auxins promote growth of apical buds whereas cytokinins promote growth of lateral buds.
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Question 126 of 126
126. Question
\(X\) and \(Y\) are antagonistic plant growth regulators. \(X\) is growth inhibitor whereas \(Y\) is growth promotor. \(X\) helps the plant to cope with stresses whereas \(Y\) helps the plant to overcome dormancy after stress is over. Identify hormones \(X\) and \(Y\) and select the incorrect option regarding them.
CorrectIncorrectHint
(c) In the given paragraph, \(X\) refers to abscisic acid (ABA) which is a plant growth inhibitor and is also known as stress hormone whereas \(Y\) refers to gibberellic acid which is a plant growth promotor. Both these plant growth regulators or phytohormones work antagonistically to each other. ABA causes seed dormancy by preventing amylase activity whereas \(Y\) leads to seed germination by promoting amylase activity.