Just as we humans possess chemical messengers in the form of hormones, plants also possess hormones. One of the largest and vast known classes of plant hormones – gibberellins are responsible to tune in different biological processes crucial in development of the plant right from germination, stem elongation, flowering, dormancy, development of flower, fruit and leaf senescence. Gibberellins or GAs are diterpenoid laying the foundation for molecules such as Vitamin A and E.
Gibberellin typically found in fungi and higher plants, gibberellic acid is available commercially for the purpose of gardening and horticultural benefits. Just some application of the same can change bush beans into dwarf corn into normal corn. The most extensive application of it is arguably in the production of grapes. As per evidence, gibberellins enhances stem-growth especially when put on to the whole plant. These are also responsible for elongation of rosette plants such as lettuce upon exposure to some environmental stimuli, for instance, long periods of exposure to daylight.
1. This is not a function of gibberellins
(a) promote dormancy
(b) promote cell elongation
(c) promote parthenocarpic fruit formation
(d) promote elongation of internodes
Answer: (a)
2. Elongation or lengthening of rosette plants is obtained by treating it with
(a) cytokinin
(b) gibberellin
(c) zeatin
(d) auxin
Answer: (b)
3. Generally, translocation of gibberellins is non-polar occurring through
(a) capillary rise
(b) phloem
(c) xylem
(d) both xylem and phloem
Answer: (b)
4. The gibberellin involved in flowering is
(a) GA1
(b) GA3
(c) GA4
(d) GA9
Answer: (d)
5. The earliest phases of synthesis of gibberellin occur in
(a) plastids
(b) mitochondria
(c) peroxisome
(d) cytoplasm
Answer: (a)
6. Nullification of genetic dwarfism is possible by spraying with
(a) zeatin
(b) auxin
(c) gibberellin
(d) cytokinin
Answer: (c)
7. The hormone involved in the regulation of florigen synthesis is
(a) zeatin
(b) gibberellin
(c) ethylene
(d) cytokinin
Answer: (b)
8. Gibberellins found in the aleurone layer of barley increases the transcription of
(a) lipase and cellulase
(b) protease and amylase
(c) protease and cellulase
(d) lipase and protease
Answer: (b)
9. This bioassay is used to test the presence of gibberellins
(a) dwarf pea elongation technique
(b) chlorophyll preservation test
(c) excised radish cotyledon enlargement test
(d) rice seedling growth inhibition test
Answer: (a)
10. Gibberellins were named after a fungus known as
(a) Gibberella acuminata
(b) Gibberella africana
(c) Gibberella fujikuroi
(d) Gibberella gaditijirrii
Answer: (c)
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