This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Growth Regulators in Plants – 1”.
1. Who isolated the hormone auxin?
Explanation: F.W. Went isolated hormone auxin. Charles and Francis Darwin had discovered auxin. Skoog and Miller identified and crystallized cytokinesis promoting substance and named it kinetin.
2. Movement of auxin is centripetal.
Explanation: Auxin is a hormone which is produced by growing apices of the plant. It is transported to other growing region in both acropetal as well as basipetal succession.
3. The hormone responsible for apical dominance is________
Explanation: Indole-3-acetic acid (IAA) is the hormone responsible for apical dominance. ABA promotes abscission of older parts. GA delays senescence. Kinetin helps in removing apical dominance and aiding lateral growth.
4. Phototropic and geotropic movements are linked to________
Explanation: Auxin is associated with different movement of plant stem including phototropic and geotropic movements. GA promotes early maturity of plants. ABA prevents death of plant in stressful conditions. Ethylene increases respiratory rate of plants.
5. The concentration of auxin is highest in _______
c) growing tips
d) vascular bundles
Explanation: The concentration of auxin is found to be highest in growing tips as they are the source of the hormone. It further spreads to leaves & stem. Vascular bundles have no role in the activity of PGRs.
6. The hormone which can replace vernalization is _______
Explanation: Gibberellic acid is the hormone which can be function similar to vernalisation treatment. IAA initiates rooting in stem cuttings. ABA is functional in unfavorable conditions. Kinetin is responsible for formation of new leaves, lateral shoot growth and adventitious shoot formation.
7. Foolish seeding disease of rice led to discovery of Cytokinins.
Explanation: Foolish seeding disease of rice was found to be caused by a fungal pathogen Gibberalla fujikori. It was reported in 1926 by Japanese scientist Eiichi Kurosawa after observing symptoms in uninfected seedlings of rice after treatment with sterile filtrates of the fungus which resulted in the discovery of Gibberellic acid (GA3).
8. Which of the following is a terpene derivative?
Explanation: GA is a terpene derivative. Ethylene is a volatile gaseous hormone. ABA is a derivative of carotenoids. Auxin is an indole compound.
9. Which of the following hormone promotes bolting?
Explanation: Bolting is the elongation of internode just prior to flowering. It is seen in plants with rosette habit. GA promotes the action of bolting. Ethylene helps rapid internode elongation in deep-water seedlings of rice. Auxin promotes rooting in stems. Kinetin promotes shooting in stems.
10. The hormone responsible for speeding up of malting process in brewing industry is ________
Explanation: GA3 is the hormone responsible for speeding up of malting process in brewing industry. Auxin is useful to prepare weed free lawns. Ethylene is responsible for quick initiation of flowering in fruit plants. Kinetin is naturally present in meristematic regions of the plant.
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