Question

P, Q, R and S are four major types of phytohormones. P is a phytohormone which functions mainly as a growth inhibitor. It promotes the wilting and falling of leaves. Q, R and S are phytohormones which all promote growth of plants in various ways. Q is responsible for the phenomenon of phototropism in plants. R is involved mainly in shoot extensions. The phytohormone S helps in breaking the dormancy of seeds and buds. What are P, Q, R and S? Give one reason each for your choice.

Answer 1

P is abscisic acid because it is antagonistic to growth and inhibits it.
Q is auxin because it causes bending of shoots towards the light.
R is gibberellins because it increases the cell division in a plant shoot and increases its length.
S is cytokinin because it breaks the dormancy of buds and seeds.