Question

The most efficient precursor of ethylene is
(a) Adenine
(b) Thiocarbamate
(c) Zeation
(d) Methionine

Answer 1

Hint: The most efficient precursor of ethylene is also a compound that is the only sulfur containing amino acid essential for mammals. In plants and microorganisms, this compound belongs to the aspartate family along with threonine and lysine.

Complete answer:
The most efficient precursor of ethylene is methionine. Let's begin the explanation by understanding about plant growth regulators. For the plants to grow and reproduce they need sun, water, minerals, oxygen, and other nutrients. Apart from these external demands, plants also rely on certain organic compounds to signal, regulate, and monitor their growth. Such compounds are commonly referred to as ‘plant growth regulators’ or hormones of plant growth. Examples of plant growth regulators are kinetin, ethylene, and ascorbic acid among others.
Now let's study briefly about ethylene.
Ethylene is a plant hormone that is found in gaseous form in nature. The breakdown of methionine gives rise to ethylene. It is primarily found in all the dividing cells. Ethylene when sprayed on fruits helps in early ripening and maturation. There are two pathways for ethylene biosynthesis postulated in higher plants. The first one represents the dissolution of oxidized linolenic acid while the second one includes methionine degradation.

So, the correct answer is, ‘Methionine.’

Note:
- Adenine is a nucleic acid precursor. It is found in the intestinal cells since they cannot synthesize purines on their own.
- Thiocarbamate is an efficient herbicide, fungicide, and pesticides.
- To assess the possible routes, the apple tissue was treated with radioactive linolenic acid and the concerned radioactive methionine analogs. From the results, it was inferred that none of the proposed ethylene precursors converted as successfully to ethylene as methionine.