Question 1

Heterophyllous development in response to environment is an example of which of the following phenomena ?

Accepted Answer

Plants follow different pathways in response to the environment or phases of life to form different kinds of structures. This ability is called plasticity. Heterophylly in cotton, coriander, and larkspur is an example of plasticity in response to phases of life, whereas heterophylly in buttercup is an example of plasticity in response to the environment. In buttercup, the leaves of juvenile plants and mature plants are different in shape, and similarly, the leaves of submerged plants are highly

Question 2

Length of the stem at time 0 is 20 cm. The arithmetic growth rate is 30 cm per day. What is the length of the stem at the end of the 7^ th day ?

Accepted Answer

The equation for arithmetic growth is given by: L_t = L_0 + rt Where: L_t is the length at time t L_0 is the initial length at time t = 0 r is the arithmetic growth rate t is the time Given: L_0 = 20 cm r = 30 cm/day t = 7 days Substituting the given values into the equation: L_7 = 20 + 30 7 L_7 = 20 + 210 L_7 = 230 cm

Question 3

Which of the following plant growth regulators promotes internode elongation prior to flowering in cabbage ?

Accepted Answer

Gibberellins promote internode elongation just prior to flowering in rosette plants like cabbage, beet, and many other plants with a rosette habit. This phenomenon is known as bolting. Ethephon is a source of ethylene, which promotes fruit ripening and abscission. Abscisic acid acts as a general plant growth inhibitor and stress hormone. Indole butyric acid is a synthetic auxin widely used to induce rooting in stem cuttings. Answer: Gibberellin

Question 4

Which one of the following is not a characteristic of plant cells in the phase of elongation ?

Accepted Answer

The period of growth is generally divided into three phases: meristematic, elongation, and maturation. The cells in the meristematic phase are rich in protoplasm and possess large conspicuous nuclei. Their cell walls are primary in nature, thin, and cellulosic with abundant plasmodesmatal connections. The cells in the phase of elongation are characterised by increased vacuolation, cell enlargement, and new cell wall deposition. Therefore, large conspicuous nuclei are a characteristic of meristem

Question 5

Match List I with List II : List I (Growth Regulator) List II (Function/Effect) A. 2,4-D I. Brewing industry B. GA _3 II. Stimulation of stomatal closure C. Kinetin III. Herbicide D. ABA IV. Nutrient

Accepted Answer

2,4-D is a synthetic auxin widely used as a herbicide to kill broad-leaved dicot weeds. GA _3 (Gibberellic acid) is used to speed up the malting process in the brewing industry. Kinetin is a cytokinin that promotes nutrient mobilisation, which helps in the delay of leaf senescence. ABA (Abscisic acid) acts as a stress hormone and stimulates the closure of stomata under conditions of water stress. Therefore, the correct matching is A-III, B-I, C-IV, D-II. Answer: A-III, B-I, C-IV, D-II

Question 6

Which of the following plant growth regulators is used as herbicide ?

Accepted Answer

Plant growth regulators have various physiological functions in plants. 2,4-D (2,4-Dichlorophenoxyacetic acid) is a synthetic auxin. It is widely used as a herbicide to kill broad-leaved dicotyledonous weeds in cereal crops and lawns, as it does not affect mature monocotyledonous plants. Gibberellins are used to promote stem elongation and seed germination. Kinetin is a cytokinin that promotes cell division. Abscisic acid is a stress hormone that inhibits growth and promotes seed dormancy.

Question 7

Which one of the following phytohormones promotes nutrient mobilization which helps in the delay of leaf senescence in plants?

Accepted Answer

Cytokinins help to overcome apical dominance. They promote nutrient mobilisation which helps in the delay of leaf senescence.

Question 8

Read the following statements on plant growth and development. (A) Parthenocarpy can be induced by auxins. (B) Plant growth regulators can be involved in promotion as well as inhibition of growth. (C)

Accepted Answer

ABA is a plant growth inhibitor and an inhibitor of plant metabolism. Apical dominance promotes growth of apical bud. Statements A, B and C are correct.

Question 9

Given below are some statements about plant growth regulators. A. All GAs are acidic in nature. B. Auxins are antagonists to GAs. C. Zeatin was isolated from coconut milk. D. Ethylene induces flowerin

Accepted Answer

Abscisic acid is antagonistic to Gibberellic acid. Auxins induce parthenocarpy in certain fruits, such as, tomatoes.

Question 10

Match List-I with List-II : array lll & List-I & & List-II \ .& Abscisic acid & I.& Promotes female flowers in cucumber \ .& Ethylene & II.& Helps seeds to withstand desiccation \ .& Gibberellin & III

Accepted Answer

Abscisic acid Helps seeds to withstand desiccation Ethylene Promotes female flowers in cucumber Gibberellin Promotes bolting in beet, cabbage etc. Cytokinin Helps in nutrient mobilisation Hence, the correct answer is option (3)

Question 11

F. Skoog observed that callus proliferated from the internodal segments of tobacco stem when auxin was supplied with one of the following except :

Accepted Answer

F. Skoog observed that from the internodal segments of tobacco stems the callus proliferated only if in addition to auxins the nutrient medium was supplied with the extracts of vascular tissues, yeast extract, coconut milk or DNA. Miller et al. later identified and crystallised the cytokinesis promoting active substance that they termed kinetin.

Question 12

Spraying sugarcane crop with which of the following plant growth regulators, increases the length of stem, thus, increasing the yield?

Accepted Answer

Sugarcanes store carbohydrate as sugar in their stems. Spraying sugarcane crop with gibberellins increases the length of the stem, thus increasing the yield.

Question 13

Auxin is used by gardeners to prepare weed-free lawns. But no damage is caused to grass as auxin

Accepted Answer

Auxin does not affect mature monocot plants. In monocots, especially grasses show limited translocation and cause rapid degradation of external auxin.

Plant - Growth and Development — Previous Year Questions & Solutions