Question

Select the correctly matched pair
(a) Darwin and Darwin- Gibberellic acid
(b) Went-Auxin
(c) Kurosawa- Ethylene
(d) Skoog and Miller- Abscisic acid
(e) Cousins- Cytokinin

Answer 1

Hint: Plant growth hormones or phytohormones are small organic molecules that are essential for their proper growth and functioning. The correctly matched pair is of that hormone which is synthesized by the growing apices of stems and roots and prevents the lateral buds from growing.

Complete answer:
Frits Went discovered the first plant hormone ‘Auxin’ in the tip of oat (Avena sativa) coleoptiles as a growth-promoting chemical. As it promoted growth, it was named auxin by Fris Went which is derived from a Greek word ‘auxein’ that means to increase. Dr. F. Went in 1928 collected the growth-stimulating substances in agar jelly. He did so by decapitating the coleoptile tips and placed them on the agar block for one hour so that the agar block absorbs the chemicals. The decapitated coleoptile tips along with the agar block were again placed over the freshly cut coleoptile stumps. This caused the bending of the freshly cut coleoptile stumps. He demonstrated the polar movement of auxins by discovering that the hormone traveled basipetal i.e from tip or apex to the base.

Additional Information: - Eiichi Kurosawa was a Japanese scientist who extracted gibberellin from the fungus Gibberella fujikuroi and reported that it causes extreme elongation of rice stems which eventually leads to their unbalancing and crops to get destroyed. This disease is known as bakanae or foolish seedling disease.
- Charles Darwin and his son Francis Darwin studied the effect of light on the bending of coleoptiles of canary grass and oats. They termed this phenomenon as phototropism.
-H.H Cousins in 1910 demonstrated that premature ripening of bananas when stored together with oranges due to the production of ethylene in oranges. Though later it was found out that it wasn’t the healthy oranges that were producing the ethylene but the fungus Penicillium growing over some of the oranges that led to enhanced production of ethylene. Later in 1934, ethylene was given the status of a phytohormone i.n. plant hormone.
-Skoog and Miller are identified with the study of morphogenesis of callus or mass of tissue into roots and shoots. They put forth the concept that a differential ratio of auxin-cytokinin concentration is required for organ differentiation and their relative concentration will decide whether rooting will take place or shooting.
So, the correct answer is ‘Went-Auxin.’

Note: -Auxin is a weakly acidic growth-promoting hormone that is produced by the growing apices of the stems and the roots which then migrate to the regions where they will perform their respective functions.
-It exhibits a phenomenon of apical dominance wherein auxin production by the apical buds in a plant prevents the growth of lateral branches.