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jl., , , , nat would be expected to happen if:, , wh, , @ GA, is applied to rice seedlings, , ) dividing cells stop differentiating, , (c) arotten fruit gets mixed with unripe, fruits, , (@) you forget to add cytokinin to the, , culture medium, [HOTS], , SOLVED QUESTION BANK, , very Short Answer Type Questions [1 Mark], , ie, , Ans., , Ans., , , , Who first observed phototropic curvature, in plants?, , Charles Danwin and his son, Francis Darwin., What was Darwin’s conclusion after the, experiments on canary grass?, , Darwin concluded that the tip of the, coleoptile was the site of transmittable, influence that caused the bending of the, coleoptile towards light., , . Where was the first auxin isolated from?, , The first auxin was isolated from human, urine., , In most plants, the terminal bud suppresses, the development of lateral buds into, branches. What is this phenomenon, known as? Name the phytohormone, that can promote this phenomenon,, , . — Apical dominance is the phenomenon., , — Auxin can promote it., Name the causative agent of ‘bakane’, disease in rice seedlings., , . Gibberella fujikuroi, . Name the most extensively studied form, , of gibberellin., , s. Gibberellic acid — GA,, , Which property of gibberellins is, responsible to the foolish seedling disease, in rice plants?, , Ans., , Ans,, , Ans., . What is meant by ‘bolting’ in plants?, , Ans., , 10., , Ans., . Name the phytohormone used to, , Ans., 12., , Ans., , Ans., , Plant Growth and Development 89, , (a) The rice seedlings will show internodal, elongation and grow taller., , (b) A callus will be formed., , (c) The other fruits will ripen, as ethylene, is given out by the rotten fruit., , (d) Cell division will not take place., , Their ability to cause an increase in the, length of the axis/internodes., , . In a wheat field, some broad-leaved, , weeds were seen by a farmer. Which plant, hormone would you suggest to get rid of, a them?, , 2, 4-dichlorophenoxy acetic acid (2, 4D)., , The sudden elongation of internodes prior to, flowering in rosette plants, is called bolting., How does spraying of sugarcane plants, with gibberellins increase the yield of, sugar? [HOTS], By increasing the length of internodes., , develop seedless/parthenocarpic fruits in, , (a) grapes and (5) tomato, respectively., , (a) Gibberellin (b) Auxin, , Name the source from which the first, , Kinetin was isolated. What is it chemically?, , — Autoclaved herring sperm., , — Itis a modified form of adenine, a purine, base., , . Name the growth regulator which was, , isolated from corn kernels. What is its, main biological activity?, , Zeatin; it promotes cytokinesis of cell, division.
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Ags., , , , Tractor eek? Biology—Ul, , . Whe identified and crystallised kinetin, , fos?, Skoog and Miller, , 5. Meation two sources of Zeatin,, , Cem kemels and coconat milk., , Which hormone can be used fo overcome, , the effect of apical dominance in plants?, INCT 2011], , Cywkinin, , Name the plant growth regulator (PGR), , that can fit into both growth promoters, , and growth inhibitors, but is largely an, , imbibitor., , Exhyieae, , Who coafirmed the release of 3 volatile, , sabstance from ripening oranges that, , could hasten ripening of bananas? What, , is that substance named as?, , Cousins: it is ethyfene., , How does ethylene help plants to absorb, , more water and minerals?, , By promoting root growth snd root hair, , formation and thereby increasing the area, , of sbsorpaon., , Define climacteric., , Climacteric refers to the increased rate of, , respiration Gung Fipening of fruits., , 4 farmer grows cucumber plants in his, , ficld. He wants to increase the number, , of female flowers in them. Which plant, , growth regulator can be applied to, , achieve this? INCT 2013], , . Ethylene., , Name the widely used compound in, agricultere, which releases ethylene., , , , Ethephon., , _ Which hormone is known as stress, bormone in plants? {NCT 2012], Abscisic acid., , a4. Name the phytohormone to which ABA, , is antagonistic., Ans. Gibberellins, 25. ABA induces dormancy in seeds. How is, it helpful to the plants?, It helps the seeds to withstand desiccation, , Ans., and other factors unfavourable for growth., , Short Answer Type Questions [2 Marks], , 36. Mention the role of the plant growth, , regulators grouped as inhibitors in plants,, , Ans. They play important role in:, (i) plant responses to biotic and abiotic, , stresses., Gi) pl, (iii) promoting abscission., (i) inducing dormancy., 27, March Column I with Column Tl., , ant responses to wounds., , , , , , , , , , ~~ Column | Column, OR WWent SL Bihylene, B. Skoogand | 2. Gibberellins, | Miller |, 'C. Cousins | 3. Auxin |, D. Kurosawa | 4. ABA |, { | 5. Cytokinin —, , Ans. (c) A-3, B-5, C-1, D-2, 28. Where are auxins generally produced?, Name two auxins that occur naturally, in plants., ‘Ans. — Auxins are produced in shoot apices and, root apices., — Indole acetic acid (IAA) and indole, butyric acid occur naturally in plants., 29. Name two each, of (a) Natural auxins and, (6) Synthetic auxins?, Ans. (a) Indole-acetic acid (IAA) and Ind, , butyric acid (IBA)., , jole
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(6) Naphthalene acetic acid (NAA) and, 2,4-dichloro phenoxy acetic acid, (2.4-D)., , 30, Mention four functions that auxins, , perform in plants., , Ans. (i) Auxins promote apical dominance in, plants, i.e., they inhibit the growth of, lateral buds into branches., , (i) They are involved in xylem, differentiation., , (ii) Auxins promote abscission of mature, leaves and fruits., , (iv) Auxins control phototropic curvature, in plants,, , 31. How are auxins useful in agriculture/, , horticulture?, , Ans. (i) Auxins are used to initiate rooting in, stem cuttings for plant propagation., , (i) Auxins are used to promote flowering, in pineapple., , (ii) Auxins are used to induce, parthenocarpy in tomato., , (iv) Auxins are used as herbicides/, weedicides to kill dicotyledonous, weeds in wheat fields and in preparing, weed-free lawns., , 32. Write any four functions of cytokinins in, , plants,, , Ans. (i) Cytokinins promote nutrient, mobilisation that helps to delay, senescence of leaves., , (ii) They help in the formation of, chloroplasts in leaves., , (iii) They promote formation of leaves., , (iv) They help in lateral shoot growth and, adventitious shoot formation., , 33. (a) During mid 1960s, three researchers, independently reported purification, and chemical characterisation of, three different kinds of plant growth, inhibitors. Name them., , , , Plant Growth and Development 91, , (6) Later they were found to be, chemically identical. What common, name was given to them?, , Ans. (a) The plant growth inhibition were called:, , (1) Inhibitor-B, (ii) Abscission, (ii) Dormin, (b) They are all now called abscissic acid., , 34. There are a number of events in the life of, , plants, where two or more PGRs interact, to effect that event. Name any four such, events., , Ans. (i) Dormancy of seeds/buds, , (ii) Senescence, (iii) Apical dominance, (iv) Abscission of leaves, flowers and, , fruits., 35. Match the following sets:, Set A Set B, (a) 24D (i) Delay of leaf, senescence, , (4) Abscisic acid (ii) Weed-free lawns, (c) Ethylene, (d) Cytokinin, , (iii) Stomatal closure, (iv) Ripening of fruit, INCT 2016], , Ans. (a)-(ii), (b)-(iii), (c)-(iv), (@)-(i), , 36. Mention any six types of functions,, , influenced or controlled by plant growth, promoters., , Ans. Plant growth promoters control activities like, , (i) cell division, (7i) cell enlargement,, (iii) pattern formation, (iv) tropic movements,, (v) flowering, and (vi) seed formation., , 37. Give the chemical name of one example, , of each of the following and mention one, function of each of them:, , (a) Natural auxins, (5) Synthetic auxins, , (c) Gaseous plant hormones.
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Ans., , (a) Indole acetic acid ist, , (b) 2,4 dichlorophenoxy, {e) Ethylene promotes ripe, . How are gibberellins useful iv, , to improve product, points in suppo!, , Fesether weré® Biology iW, , esponsible, for apical dominance, well division, in vascular eambium and xylem, differentiation,, , etic acid is used, , , , as a weedicide to get a weed-free lawn, , ning of fruits, , and root growth and formation of root, , hairs., pagriculture, , ivity? Give three, rt of your answer., , of gibberellins increases, d thereby, rin, , () Application, the length of the stem ant, increase the yield of suga, sugarcane., , (ii) Gibberellins delay senescence and, , the fruits can be left on the trees for, , longer duration, so as to increase the, market period., , Gibberellins cause fruits like apple to, , elongate and improve in shape., , e conifers hastens the, , ly seed, , (iii), , (iv) Spraying juvenil, maturity period, leading to ear!, , production., , 39, What would be expected to happen, if:, , (a) GA, is applied to rice seedlings, (6) Arotten fruit gets mixed with unripe, , fruits., , (c) You forget to add cytokinin to the, , culture medium. [NCT 2019, 2014], , Ans. (a) The rice seedlings would grow tall due, , to elongation of internodes., , (b) The ripening of fruits will be hastened, , due to release of ethylene by the rotten, fruit., , (c) Roots will be initiated from the callus., , 10, Aus, , (a), (b), (©), Ans. (d), , (b), , (c), , 41. (a), , (b), , Ans. (a), , 42. (a), , , , or the following:, , Name the stress hormone found tn, , plants., Whiat cases, why do Jateral buds start developing, , info branches, when apical buds are, INCT 20145, , épakane’ disease Of rice?, , removed?, , Abscisic acid is the stress hormone,, , The ‘hakane’ disease is caused by, , Gibberella fugjikurol., When the apical buds are removed,, the synthesis of auxin decreases,, — Auxins are responsible for apical, dominance, a phenomenon in which, the lateral buds are suppressed to, grow into branches., In the absence of auxins (apical, buds), there is no apical dominance, and hence, the lateral buds develop, into branches., Which phytohormone is also called, a stress hormone? How does this, hormone overcome stress conditions?, Name the phytohormone, which is, , widely used to kill the dicotyledonous, [NCT 2011], , weeds?, , Abscisic acid is the stress hormone., , It causes closure of stomata and, , increases the tolerance of plant to, , water stress., , — It induces dormancy in seeds and, thereby helps the plant to withstand, dessication and other unfavourable, factors that affect plant growth., , 2,4 dichlorophenoxyaceitic acid, , (2,4 D)., , What is meant by apic:, , Name the phytohormone w, , controls it., , al dominance?, hich, , Sie RN ei ae cae acca
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() How docs abscisic acid act as a stress, hormone in drought condition?, INCT 2012), ) Apical dominance is the phenomenon, ans * in which the presence of apical buds, suppresses the growth of lateral buds, into branches., Auxin is responsible for this,, (0) During drought, abscisic acid signals, closure of stomata and thereby checks, the loss of water and increases the, tolerance of plants to water stress,, , Long Answer Type [II] Questions [5 Marks], 43, The plant growth regulators (PGRs), are small, simple molecules of diverse, chemical composition. Mention any five, types, with an example of each., Ans. (i) Indole compounds ~ e.g. Indole acetic, acid (IAA) and Indole butyric acid, (IBA)., (ii) Adenine derivatives — e.g. N-furfuryl, amino purine/kinetin., (iii) Carotenoid-derivatives — e.g. abscisic, acid., (iv) Terpenes — e.g. gibberellins, (v) Gases — e.g. ethylene, , Competency/Case-based Question, , 44. The gaseous plant growth regulator,, ethylene could fit into either of two groups, of PGRs - promoters and inhibitors,, though largely it is an inhibitor,, (4) Name twosites in plants where ethylene, , is synthesised in large amounts., , (5) How does ethylene help in, , , , (@ increasing the absorptive, surface in plants?, , , , Plant Growth and Development 93, , (i) keeping the leaves and upper, parts of the shoot to remain, above water in deep water rice, plants?, , {e) Na, as a source of ethylene in agriculture., Mention any three of its functions., , , , the most widely used compound, , (d) Name the most widely used compound, as a source of ethylene in agriculture., Mention any three of its functions., , Ans. (a) (i) Tissues undergoing senescence, , (ii) Ripening fruits, (b) (i) Ethylene promotes root growth, , and formation of root hair; hence,, , it increases absorptive surface in, plants., , (ii) Ethylene promotes rapid, elongation of internodes and, petiole in deep water rice plants;, hence, leaves and upper parts of, the shoot can remain above the, level of water., , (c) Ethephon is the most widely used, compound as a source of ethylene., Functions:, , (i) Ithastens fruit ripening in tomatoes, and apples., , (ii) It accelerates abscission of flowers, and fruits, i.e., thinning of flowers, in cotton, cherry, walnut, etc., , (ii) It promotes formation of female, flowers in cucumber and thereby, , increases productivity.
