Question

Which of the following is a dicot weedicide?
A) 2,4-D
B) NAA
C) IBA
D) IAA

Answer 1

Hint: Some chemicals which are spread in the field for getting rid of several weeds is called weedicide. It affects the dicots mostly.

Complete Answer:
1) The full form of 2,4-D is 2,4-dichlorophenoxyacetic acid. It is auxin which is produced synthetically. It affects mostly the leaf of a plant and used extensively in treating weeds. It is affected in killing dicot plant tissues. Though it is effective in leaves but it does not work in case of monocot plants such as rice, corn,grasses etc.
2) The full form of NAA is Naphthalene acetic acid that is a synthesized plant hormone used in the growth of plantlets in plants like sugarcane and others. It bears a carboxymethyl group in its first position. It is used in the plant growth horticulture section.
3) The full form of IBA is indole-3-butyric acid (IBA) that is also a synthetically produced hormone used in the plant growth system. It is used as auxin hormone precursor. It is light yellow in colour and is crystalline solid in nature.
4) The full form of IAA is Indole-3-Acetic Acid which is the another name of the plant hormone Auxin. It is produced in the apical portion of plants i.e. apical buds and used for inducing cell division or elongation.

Hence Option A: 2,4-D is the correct answer.

Note: Excluding 2,4-D others are synthetically produced hormones which are effective in plants. 2,4-D is also extensively used as herbicide.