BIOMOLECULES AND ENZYMES

BIOLOGY

HORMONES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which plant hormone helps elongate the stem between nodes?
A
cytokinins
B
ethylene
C
gibberellins
D
abscisic acid
Explanation: 

Detailed explanation-1: -Auxins function primarily in stem elongation by promoting cell growth. Indole-3-acetic acid (IAA) is the major naturally occurring auxin and one of the major growth factors in plants. They were the first group of plant growth hormones discovered.

Detailed explanation-2: -Physiological studies and phenotypic characterization of mutants impaired GA biosynthesis. It revealed that GA plays an important role in stem or internode elongation. It stimulates cell division and expansion in response to light or dark.

Detailed explanation-3: -Gibberellins stimulate cell elongation by altering the rheological properties of the cell wall; as a consequence, the water potential of the cell is lowered allowing for water uptake and therefore an increase in cell volume.

Detailed explanation-4: -The plant hormone gibberellin (GA) controls major aspects of plant growth such as germination, elongation growth, flower development, and flowering time. In recent years, a number of studies have revealed less apparent roles for GA in a surprisingly broad set of developmental as well as cell biological processes.

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