Botany MCQs for NEET — Practice Questions with Answers

Growth regulators, also known as plant hormones, are organic chemicals. They play a crucial role in regulating various physiological processes in plants, including growth, development, and responses to stimuli.

Auxin was first isolated from human urine. The discovery was made by F. W. Went in the 1920s. He identified the growth-promoting substance in the tips of oat coleoptiles and later found that the same substance was present in human urine.

Auxins are commonly used as herbicides to control weed growth. Synthetic auxins like 2,4-D and MCPA mimic the natural auxin hormone in plants, which disrupts the normal growth processes in weeds, leading to their death.

Abscisic acid (ABA) is an organic substance known to act as a growth inhibitor. It plays a crucial role in processes such as seed dormancy and stomatal closure under stress conditions like drought.

Indole-3-acetic acid (IAA), a type of auxin, was first isolated from human urine. This discovery was significant as it identified a natural plant hormone in a biological sample, highlighting its role in plant growth and development.

Cytokinins are a class of plant hormones that promote cell division (cytokinesis) in plant roots and shoots. They are primarily found in regions of active cell division, such as meristematic tissues.

The drooping of fruit after maturation is typically due to a decrease in the amount of auxin. Auxins are hormones that promote cell elongation and growth; a reduction in their levels can lead to the weakening of cell walls and subsequent drooping.