Question

Which is not a phytohormone?
(a)Phytochrome
(b)Florigen
(c)GA
(d)IAA

Answer 1

Hint: They are also known as plant hormones. They play an important role in controlling various plant functions like growth, development, etc. Phytohormones are synthesized at an industrial scale(large scale manufacturing) using bioreactors and microorganisms.

Complete answer:
A class of photoreceptors present in multiple organisms such as plants, bacteria, and fungi, which they utilize to detect light is called phytochromes. Phytochrome is sensitive to light between the region of red and violet of the visible spectrum. It is divided into two categories Type I and Type II in which Type l are stimulated by the violet region and Type II is stimulated by the red light.
Phytohormones which are present naturally are auxins, gibberellic acid, kinin, dormin, florigen (flowering hormone), ethylene (gaseous hormone).

Additional Information: Florigen: Florigen is also known as the flowering hormone that is responsible for regulatory and activating flowering in plants. Florigen is synthesized in the leaves and performs in the stem tip meristem of buds or growing tips. It is known to be graft-communicable and even functions among species
IAA: Indole-3-acetic acid (IAA) is the most significant member of the auxin family. Auxin is a phytohormone synthesized at the tip of the stem (above the region of elongation) that endorses cell elongation. Auxin travels towards the shadier side of the plant making the cells in that region to grow longer than the other cells on the brighter side of the plant
GA: Gibberellic acid (GA) is one of the plant growth regulators that takes part in various physiological processes. It aids in the elongation of the stem, flowering, and germination of seeds in the plant.
So, the correct answer is ‘Phytohormones’.

Note: -Gibberellic acid is generally applied in the barley malting industry, where it is sprayed after the steeping process to create uniform growth. This provides cultivators right-sized kernels required for the industry.
-Five major types of auxins that are endogenous are indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid, and indole-3-propionic acid.
- When auxin comes into contact with plant cells, it creates drastic changes in the expression of genes. Active research is still going on to know the precise mechanisms by which this occurs, and two auxin signaling pathways are almost completely investigated.