NEET BIOLOGY

Detailed explanation-1: -Based on several lines of evidence, including the rapid growth response during gravitropism and phototropism, auxin is also a major factor controlling internode elongation (Cleland, 2010).

Detailed explanation-2: -Gibberellin is a growth promoter hormone which is produced by the mevalonic acid as the precursor. It helps in the elongation of the internode and breaks the dormancy of seed.

Detailed explanation-3: -The gibberellins have many physiological effects, depending on the GA type and plant species. They are known to stimulate dramatically cell proliferation and elongation at the intercalary meristem level, thus leading to internodal growth.

Detailed explanation-4: -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.