Question 35: Name the plant hormones responsible for the following
(a) elongation of cells
(b) growth of stem
(c) promotion of cell division
(d) falling of senescent leaves.
Answer:
a) Elongation of cells:- Auxin
b) Growth of stem:- Gibberellins
c) Promotion of cell division:- Cytokinin
d) Falling of senescent leaves:- Abscisic acid
Auxin, Gibberellins, Cytokinin, Abscisic acid all are the plant growth hormones which influences the specific physiological role or processes. Auxin promotes cell elongation, apical dominance, prevention of abscission layer and regulates the plant growth movement like phototropism and geotropism. Gibberellins enhance the longitudinal growth of stem when applied to intact plants; stimulate the pollen germination and growth of pollen tubes in some species. Cytokinin main function is to promote the cell division and also show some other physiological effects like cell enlargement, provides resistance to plant under high temperature, cold or diseases. And, Abscisic acid inhibits gibberellins stimulated growth and promotes senescence in leaves by causing the loss of chlorophyll pigment, decreasing rate of photosynthesis and change the metabolism of proteins and nucleic acid.
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