Question 1

Which of the following plant growth regulators is a gaseous hormone?

Accepted Answer

Ethylene is a gaseous plant growth regulator that plays a vital role in fruit ripening, transverse growth, and senescence in plants.

Question 2

Who discovered the plant hormone Gibberellin?

Accepted Answer

E. Kurosawa discovered Gibberellin in 1926 while studying the 'bakanae' (foolish seedling) disease of rice caused by the fungus Gibberella fujikuroi.

Question 3

What is the primary precursor of Indole-3-acetic acid (IAA)?

Accepted Answer

Tryptophan is the primary amino acid that acts as a precursor for the biosynthesis of the natural auxin, Indole-3-acetic acid (IAA), in plants.

Question 4

Removal of shoot tips (decapitation) results in:

Accepted Answer

Removal of shoot tips (decapitation) removes apical dominance and promotes the growth of lateral buds, leading to bushy growth.

Question 5

Which plant hormone is known as the 'stress hormone'?

Accepted Answer

Abscisic acid (ABA) is referred to as the stress hormone because it increases plant tolerance to various kinds of stresses, particularly water stress or drought.

Plant Growth and Development — MP Board Class 11 Biology Important Questions & Revision Notes