Question

Which of the following auxins are widely used as herbicides?
(A)2, 4-D and 2, 4, 5-T
(B)2, 4-D and cytokinin
(C)2, 4-D and 2, 4-T
(D)2, 4, 5-T and GA

Answer 1

Hint: The auxins which are widely used as herbicides is an organic compound with the chemical formula ${ C }_{ 8 }{ H }_{ 6 }{ Cl }_{ 2 }{ O }_{ 3 }$ and another one which is a is a chlorophenoxy acetic acid which is used to defoliate broad-leafed plants.

Complete solution:
The auxins which are widely used as herbicides are 2, 4-D and 2, 4, 5-T. Auxins like indole-3-acetic acid (IAA) and indole butyric acid (IBA) are isolated from plants. NAA whose full form is naphthalene acetic acid and 2, 4-D (2, 4-dichlorophenoxyacetic acid) are synthetic auxins. all these auxins are used extensively in agricultural and horticultural practices. Auxins are widely used as herbicides. 2, 4-D, and 2,4,5-T are commonly wanted to kill dicotyledonous weeds, it doesn't affect mature monocotyledonous plants. It's used to prepare weed-free lawns by gardeners.

Additional Information:
2,4-D is known to be the one among the oldest and also the most generally available herbicides and defoliants within the world, having been commercially available since 1945, and is now produced by many chemical companies since the patent thereon has long ago expired. It was often found in the numerous commercial lawn herbicide mixtures and is mostly used as a weedkiller on cereal crops, pastures, and orchards. Over 1,500 herbicide products contain 2,4-D as a lively ingredient. 2,4,5-T was known to develop within the late 1940s and was widely utilized in the agricultural industry until being phased out, starting within the late 1970s because of toxicity concerns. Agent Orange, a defoliant employed by the British within the Malayan Emergency and therefore the U.S. within the Vietnam War, was made up of equal parts 2,4,5-T and 2,4-D (2,4-dichlorophenoxyacetic acid).

So, the correct answer is ‘2, 4-D and 2, 4, 5-T’.

Note: Auxin is a phytohormone produced within the stem tip that promotes cell elongation. Auxin will move to the darker side of the plant i.e part receiving less sunlight, causing the cells there to grow larger than corresponding cells on the lighter side of the plant.