Plant growth regulators: auxin, gibberellin, cytokinin, ethylene, ABA
- 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. Dedifferentiation is a pre-requisite for re-differentia… Answer: 1. A, B, C only Key idea: Check each statement. A true: auxins can induce parthenocarpy. B true: PGRs may promote or inhibit growth.... 1
- Which one of the following phytohormones promotes nutrient mobilization which helps in the delay of leaf senescence in plants? Answer: 4. Cytokinin Key idea: Cytokinins delay leaf senescence by promoting nutrient mobilisation. Ethylene and abscisic acid promote senes... 1
- Spraying sugarcane crop with which of the following plant growth regulators, increases the length of stem, thus, increasing the yield? Answer: 3. Gibberellin Key idea: gibberellins cause stem elongation. Spraying sugarcane with gibberellin increases internode length, so more... 1
- Auxin is used by gardeners to prepare weed-free lawns. But no damage is caused to grass as auxin Answer: 4. does not affect mature monocotyledonous plants. Key idea: synthetic auxins like 2,4-D kill dicot weeds but not monocot crops or g... 1
- Spraying of which of the following phytohormone on juvenile conifers helps in hastening the maturity period, that leads to early seed production? Answer: 3. Gibberellic Acid Key idea: Spraying gibberellic acid (GA) on juvenile conifers hastens maturity, so they produce seeds early. ABA... 1
- Which hormone promotes internode/petiole elongation in deep water rice? Answer: 4. Ethylene Key idea: In deep water rice, submergence raises ethylene levels, and ethylene promotes rapid elongation of internodes a... 1
- Production of Cucumber has increased manifold in recent years. Application of which of the following phytohormones has resulted in this increased yield as the hormone is known to produce female flowers in the plants : Answer: 4. Ethylene Ethylene promotes female flowers in cucumber, which increases fruit yield. Gibberellins in cucumber tend to promote male... 1
- The gaseous plant growth regulator is used in plants to : Answer: 3. promote root growth and roothair formation to increase the absorption surface The gaseous plant growth regulator is ethylene. It... 1
- Match List - I with List - II.List - I: (a) Manganese (b) Magnesium (c) Boron (d) IronList - II: (i) Activates the enzyme catalase (ii) Required for pollen germination (iii) Activates enzymes of respiration (iv) Functions in splitting of water during… Answer: 3. (a) - (iv), (b) - (iii), (c) - (ii), (d) - (i) Manganese functions in splitting of water in photosynthesis: (a)-(iv). Magnesium a... 1
- The plant hormone used to destroy weeds in a field is : Answer: 3. 2, 4-D 2,4-D is a synthetic auxin that kills dicot weeds without harming monocot crops such as wheat and maize. IAA, NAA and IBA... 1
- Name the plant growth regulator which upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop. Answer: 2. Gibberellin Gibberellin promotes stem elongation (internode length). Spraying it on sugarcane raises stem length and hence yield... 1
- Which of the following is not an inhibitory substance governing seed dormancy ? Answer: 1. Gibberellic acid Seed dormancy is maintained by inhibitors such as abscisic acid, phenolic acids and para-ascorbic acid. Gibberel... 1
- 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 ? Answer: 1. Auxin and Ethylene Key idea: Auxin and ethylene induce flowering in pineapple. Auxins (like NAA) and ethylene (ethephon) promote... 1
- What is the site of perception of photoperiod necessary for induction of flowering in plants ? Answer: 4. Leaves Key idea: Photoperiod is sensed by the leaves. Leaves perceive the light/dark duration and produce a flowering stimulus (f... 1
- Fruit and leaf drop at early stages can be prevented by the application of : Answer: 2. Auxins Auxins prevent early fruit and leaf drop (abscission) in plants. Ethylene promotes abscission and ripening, so it does the... 1
- You are given a tissue with its potential for differentiation in an artificial culture. Which of the following pairs of hormones would you add to the medium to secure shoots as well as roots? Answer: 1. Auxin and cytokinin In tissue culture, the ratio of auxin to cytokinin controls differentiation. A balanced supply gives both roo... 1
- Phytochrome is a Answer: 3. chromoprotein Phytochrome is a pigment protein with a light-absorbing non-protein part (a linear tetrapyrrole, phytochromobilin)... 1
- The *Avena* curvature is used for bioassay of : Answer: 3. IAA Key idea: The Avena (oat coleoptile) curvature test is a bioassay for the auxin IAA. Auxin placed on one side of a decapitate... 1