NEET Biology: Plant Hormones questions with solutions

Q1. Hormone responsible for ageing is

1. GA
2. IAA
3. Ethylene
4. Cytokinin

Answer: Ethylene

Ethylene is the plant hormone best known for promoting senescence, abscission, and fruit ripening, so it is associated with ageing in plants. The other options mainly support growth and cell division rather than aging.

Q2. A high concentration of synthetic auxin is generally used for

1. control of cell enlargement
2. Weed control
3. Prevention of the growth of lateral buds
4. Enhancing root initiation

Answer: Weed control

High concentrations of synthetic auxins overstimulate growth pathways, causing abnormal growth and death in susceptible weeds. That is why they are commonly used as selective herbicides rather than for normal growth promotion.

Q3. Coconut water is rich in

1. Auxins
2. Gibberellin
3. Abscisic acid
4. Cytokinin

Answer: Cytokinin

Coconut water contains high levels of cytokinins, especially compounds that stimulate cell division and shoot formation. This is why it is often used in plant tissue culture media to promote growth.

Q4. Growth hormones connected with bolting are

1. Cytokinins
2. Auxins
3. coumarins
4. Gibberellins

Answer: Gibberellins

Gibberellins stimulate stem elongation and can induce bolting, the rapid vertical growth seen before flowering. The other options are involved in cell division, tropic responses, or secondary metabolites, not classic bolting.