Question

6-furfurylaminopurine, 2,4-dichlorophenoxy acetic acid, and, indole-3-acetic acid are examples respectively for-
A. Synthetic Auxin, Kinetin and Natural Auxin
B. Gibberellin, Kinetin and Natural Auxin
C. Natural Auxin, Kinetin and Synthetic Auxin
D. Kinetin, Synthetic Auxin and Natural Auxin
E. Natural auxin, Gibberellin and Kinetin

Answer 1

Option D- Kinetin, Synthetic Auxin and Natural Auxin
Hint: All these are examples of PGRs (Plant Growth Regulators). These are chemicals (hormones) that regulate various functions of growth. The 5 most important growth regulator hormones are auxin, gibberellin, cytokinin, ethylene, and abscisic acid. Now these growth hormones are naturally present in every plant but can also be synthesized artificially in the laboratory to use it in fields to promote better yields. Thus, these hormones are of two types- natural and artificial.

Complete answer:
The first compound is 6-furfurylamino purine, which is a type of cytokinin. Natural cytokinin is also known as kinetin. Cytokinin occurs in regions where rapid cell division occurs such as root apices, developing shoot buds, young fruits, etc. They are involved in some marked physiological functions, namely, counteracting apical dominance, promoting cell division, delaying senescence, etc.
The compound 2,4-dichlorophenoxy acetic acid is a type of synthetic auxin. Auxin is a very important PGR which has many physiological roles along with a widespread application in the agricultural industry and a PGR, weedicide, etc. It promotes apical dominance, cell division, cell differentiation (mainly vascular tissue differentiation), promotes parthenocarpy, used as a flowering and rooting agent.
The compound indole-3-acetic acid is a type of naturally occurring auxin.

Note:
All the types of PGRs have some special/relevant functionally active members, due to which it is decided whether the particular compound taken into consideration is an auxin, or a gibberellin or a cytokinin or any other PGR.
Like, ‘indole’ and ‘phenoxy’ groups are the major structural and functional groups of auxins. IAA (Indole-3-acetic acid), IBA (Indole-3-butyric acid), 2,4-D, 2,4,5-T, all are auxins.
Similarly, cytokinins are derivatives of purine.