Process of Flowering
Multiple Choice Questions and Answers
1. The compound responsible for red and far-red reversible photoperiodic reaction is
(a) cytokinin
(b) phytochrome
(c) cytochrome
(d) anthocyanin
Answer: (b) phytochrome
2. Which of the following is necessary for flower formation in higher plants?
(a) Water and minerals
(b) Florigen
(c) Phyllocaline
(d) None
Answer: (b) Florigen
3. If a brief flash of light is provided during dark period to the plant that requires a short day then the plant is likely
(a) to flower
(b) not to flower
(c) to have no effect
(d) produces more flowers
Answer: (b) not to flower
4. In many plants, change over from vegetative phase to reproductive phase takes place in response to
(a) the length of the day
(b) the severity of temperature
(c) mainly the food material available in the soil
(d) the oxygen present in the air
Answer: (a) the length of the day
5. The pre-sowing low temperature treatment of seeds is known as
(a) scarification
(b) electrophoresis
(c) vernalization
(d) abscission
Answer: (c) vernalization
6. The short day winter annual ‘Pansy’ belongs to the genus
(a) Iberis
(b) Viola
(c) Malva
(d) Papaver
Answer: (b) Viola
7. The effect of length of the day on plant growth is called
(a) photoperiodism
(b) phototropism
(c) photosynthesis
(d) chemotropism
Answer: (a) photoperiodism
8. Induction of flowering by low temperature in plants is
(a) vernalization
(b) photoperiodism
(c) pruning
(d) cryobiology
Answer: (a) vernalization
9. The pigment that absorbs the red and far-red light in plant is
(a) cytochrome
(b) xanthophylls
(c) phytochrome
(d) carotene
Answer: (c) phytochrome
10. Which of the following is not a hormone?
(a) GA3
(b) Ethylene
(c) Phytochrome
(d) Auxin
Answer: (c) Phytochrome
11. The wavelength absorbed by Pr form of phytochrome is
(a) 640nm
(b) 660nm
(c) 720nm
(d) 740nm
Answer: (b) 660nm
12. Which of the following statements is correct?
(a) the two forms of the phytochrome are photochemically inconvertible
(b) the Pfr form converts to Pr form slowly in darkness
(c) the dark conversion of Pfr and Pr form appears to be restricted to the dicotyledons only
(d) all of the above
Answer: (d) all of the above
13. The Pfr (far-red form of phytochrome) is required for flowering in
(a) both long and short day plants
(b) long day plants only
(c) short day plants only
(d) day neutral plants only
Answer: (a) both long and short day plants
14. Which of the following are day neutral plants?
(a) Mirabilis, Lycopersicum esculentum and Pisum sativum
(b) Glycine max and Mirabilis
(c) Lycopersicum esculentum and Beta vulgaris
(d) Glycine max and Pisum sativum
Answer: (a) Mirabilis, Lycopersicum esculentum and Pisum sativum
15. Which of the following is more sensitive to photoperiodic induction?
(a) young leaves
(b) mature leaves
(c) young buds
(d) partially mature leaves
Answer: (d) partially mature leaves
16. Vernalization is
(a) growth curve related to light
(b) effect of photoperiod on plant growth
(c) speeding up the availability ability to flower by low temperature treatment
(d) diurnal photoperiodicity
Answer: (c) speeding up the availability ability to flower by low temperature treatment
17. The response of different organisms to environmental rhythms of light and darkness is called
(a) vernalization
(b) phototaxis
(c) photoperiodism
(d) phototropism
Answer: (c) photoperiodism
18. Photoperiodic stimulus is perceived by
(a) leaves
(b) flowers
(c) buds
(d) meristems
Answer: (a) leaves
19. Which of the following plants is LDP?
(a) tobacco
(b) Glycine max
(c) Mirabilis jalapa
(d) Spinach
Answer: (d) Spinach
20. Phytochrome was discovered by
(a) FW Went
(b) Borthwick and Hendricks
(c) F.F Blackman
(d) R Hills
Answer: (b) Borthwick and Hendricks
21. A pigment connected with both floral induction and seed germination is
(a) florigen
(b) chlorophyll
(c) plastocyanin
(d) phytochrome
Answer: (d) phytochrome
22. Phytochrome is found in
(a) algae
(b) fungi
(c) vascular cryptogams
(d) flowering plants
Answer: (d) flowering plants
23. When the dark period of short day plant is interrupted by a brief exposure of light the plant?
(a) will not flower at all
(b) flowers immediately
(c) gives more flowers
(d) turns into a long day plant
Answer: (a) will not flower at all
24. A chemical believed to be involved in flowering is
(a) gibberellins
(b) kinetin
(c) florigen
(d) IBA
Answer: (c) florigen
25. Which one shows red-far red interconversions?
(a) carotenoids
(b) cytochromes
(c) chlorophylls
(d) phytochrome
Answer: (d) phytochrome
26. Flowering is induced by
(a) soil water content
(b) soil acidity
(c) photoperiod
(d) content of green pigment
Answer: (c) photoperiod
27. Pigment involved in regulation/ photomorphogenetic response is
(a) phytochrome
(b) cytochrome
(c) xanthophylls
(d) chlorophyll b
Answer: (a) phytochrome
28. Who discovered photoperiodism?
(a) Darwin
(b) Lysenko
(c) Arnon
(d) Gardner and Allard
Answer: (d) Gardner and Allard
29. Which ones are long day plants?
(a) wheat, poppy, soyabean
(b) wheat, poppy beat
(c) wheat, oats soyabean
(d) wheat, xanthium, paddy
Answer: (b) wheat, poppy beat
30. Pr state of phytochrome absorbs light wavelength of
(a) 660 nm
(b) 640nm
(c) 620nm
(d) 720nm
Answer: (b) 640nm
31. Importance of day length in flowering of plants/ photoperiodism was first discovered in
(a) cotton
(b) tobacco
(c) Lemna
(d) Petunia
Answer: (b) tobacco
32. Photoperiodic stimulus is perceived by
(a) shoot apex
(b) leaf
(c) flower
(d) young stem.
Answer: (a) shoot apex
33. Wheat is a……. day plant
(a) long
(b) shot
(c) only b
(d) none
Answer: (a) long
34. Phytochrome exists in…… forms
(a) 2
(b) 3
(c) 4
(d) none
Answer: (a) 2
35. When Pfr pigment absorbs…… wavelength, it is converted to Pr form.
(a) 660nm
(b) 740nm
(c) 640
(d) 620
Answer: (a) 660nm
36. The optimum range of temperature for vernalization is
(a) 1-7 degree centigrade
(b) 1-2 degree centigrade
(c) 1-3 degree centigrade
(d) none
Answer: (a) 1-7 degree centigrade
37. Low temperature treatment produces a hypothetical hormone called
(a) vernalin
(b) florigen
(c) auxin
(d) none
Answer: (a) vernalin
38. Which of the following is a long day plant?
(a) barley
(b) sorghum
(c) tobacco
(d) soybean
Answer: (a) barley
39. Which of the following is not a day neutral plant?
(a) roses
(b) pea
(c) tobacco
(d) tomatoes
Answer: (c) tobacco
40. Which of the following is a short night plant?
(a) barley
(b) larkspur
(c) sugar beet
(d) all the above
Answer: (d) all the above
41. Which of the following hormones can replace vernalisation?
(a) gibberelins
(b) auxin
(c) florigen
(d) all the above
Answer: (a) gibberelins
42. Maximum growth takes place in
(a) green light
(b) blue light
(c) ultraviolet
(d) red light
Answer: (d) red light
43. Florigen is synthesized in
(a) Stems
(b) leaves
(c) roots
(d) fruits
Answer: (b) leaves
44. A pigment responsible for light sensitivity in plants is
(a) Chlorophyll
(b) phytochrome
(c) carotene
(d) cytochrome
Answer: (b) phytochrome
45. Which of the following pigment is present in two forms?
(a)Cytochrome
(b) Florigen
(c) Phytochrome
(d) Venalin
Answer: (c) Phytochrome
46. Most of the plants are seasonal due to
(a) Photoperiodism
(b) phototropism
(c) photosynthesis
(d) photolysis
Answer: (a) Photoperiodism
47. Generally the internode of a plant elongates most in
(a) ultraviolet light
(b) infrared light
(c) blue wavelength of light
(d) complete spectrum of visible light
Answer: (c) blue wavelength of light
48. For germination of seed, which light is necessary?
(a) red light
(b) green light
(c) far red light
(d) blue light
Answer: (a) red light
49. Vernalization is done at
(a) Low temperature
(b) Low light intensity
(c) High temperature
(d) High light intensity
Answer: (a) Low temperature
50. The movement of organs in response to light is called
(a) Hydrotropism
(b) Thigmotropism
(c) Phototropism
(d) Geotropism
Answer: (c) Phototropism