Plant Growth and Development

The wavelength of light absorbed by Pr form of phytochrome is

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

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

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

An enzyme that can stimulate germination of barley seeds is

1. invertase
2. -amylase
3. lipase
4. protease

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

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.

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

1. stratification
2. scarification
3. vernalization
4. chelation.

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.

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.

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

1. indole acetic acid
2. cytokinins
3. gibberellins
4. ethylene.