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Plant Growth and Development · Question 57

AIPMT 2007MCQMedium📈 Topic in 0% papers+4−1
1

The wavelength of light absorbed by Pr form of phytochrome is

  1. 680 nm
  2. 720 nm
  3. 620 nm
  4. 640 nm

Answer

(1) 680 nm

Solution

Phytochrome exists in two interconvertible forms, Pr and Pfr.

Pr (red-absorbing form) absorbs red light (about 660–680 nm) and changes into Pfr.

Pfr (far-red-absorbing form) absorbs far-red light (about 730 nm) and changes back into Pr.

∴ Among the given values, Pr absorbs 680 nm (red light); 720 nm lies in the far-red region absorbed by Pfr.

Answer: (1)

AIPMT 2007

Keep practising — Plant Growth and Development

2

Which one of the following pairs, is not correctly matched?

  1. Gibberellic acid - Leaf fall
  2. Cytokinin - Cell division
  3. IAA - Cell wall elongation
  4. Abscisic acid - Stomatal closure
AIPMT 2007
3

Opening of floral buds into flowers, is a type of

  1. autonomic movement of variation
  2. paratonic movement of growth
  3. autonomic movement of growth
  4. autonomic movement of locomotion
AIPMT 2007
4

An enzyme that can stimulate germination of barley seeds is

  1. invertase
  2. -amylase
  3. lipase
  4. protease
AIPMT 2006
5

Farmers in a particular region were concerned that premature yellowing of leaves of a pulse crop might cause decrease in the yield. Which treatment could be most beneficial to obtain maximum seed yield?

  1. Application of iron and magnesium to promote synthesis of chlorophyll
  2. Frequent irrigation of the crop
  3. Treatment of the plants with cytokinins along with a small dose of nitrogenous fertilizer
  4. Removal of all yellow leaves and spraying the remaining green leaves with 2,4,5-trichlorophenoxyacetic acid
AIPMT 2006
6

How does pruning help in making the hedge dense?

  1. It releases wound hormones.
  2. It induces the differentiation of new shoots from the rootstock.
  3. It frees axillary buds from apical dominance.
  4. The apical shoot grows faster after pruning.
AIPMT 2006
7

Treatment of seeds at low temperature under moist conditions to break its dormancy is called

  1. stratification
  2. scarification
  3. vernalization
  4. chelation.
AIPMT 2006
8

Parthenocarpic tomato fruits can be produced by

  1. treating the plants with phenylmercuric acetate
  2. removing androecium of flowers before pollen grains are released
  3. treating the plants with low concentrations of gibberellic acid and auxins
  4. raising the plants from vernalized seeds.
AIPMT 2006
9

Why is vivipary an undesirable character for annual crop plants?

  1. It reduces the vigour of the plant.
  2. It adversely affects the fertility of the plant.
  3. The seeds exhibit long dormancy.
  4. The seeds cannot be stored under normal conditions for the next season.
AIPMT 2005
10

Cell elongation in internodal regions of the green plants takes place due to

  1. indole acetic acid
  2. cytokinins
  3. gibberellins
  4. ethylene.
AIPMT 2004
11

One set of the plant was grown at 12 hours day and 12 hours night period cycles and it flowered while in the other set night phase was interrupted by flash of light and it did not produce flower. Under which one of the following categories will you place this plant?

  1. Long day
  2. Darkness neutral
  3. Day neutral
  4. Short day
AIPMT 2004

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