Question

Auxin is mainly produced by
A. Apical root meristem
B. Root cambium
C. Apical stem meristem
D. Phloem in shoot tip

Answer 1

Auxin is a plant hormone which elongates the stem. They also promote active cell divisions and hence are produced in only those parts of plants that are alive and are constantly growing in length, girth, or width.

Step by step answer: Meristematic cells are the cells possessing the ability to divide and differentiating into different types of cells. The direction of stem growth of stem due to auxin is always influenced by sunlight and gravity. Shoots and stems tend to grow towards sunlight and gravity. Apical meristematic cells give rise to the primary body of the plant and are responsible for stem and root formation. There are many phytohormones that are nothing but signal molecules that regulate all the cellular activities in plants. Auxin is one such hormone that enables the increase in growth of stems. The word auxin is of Greek origin which means ‘to grow’. It is found in actively dividing parts of roots and stems. It promotes meristematic division. Mostly all the cells producing auxin are situated in the apical meristem in the stem. There, this hormone inhibits the growth of lateral buds, and this phenomenon is called ‘apical dominance’.
Thus the correct answer is option C. Apical stem meristem
Additional information: Auxins are also responsible for root growth, wilting of leaves, and fruit development. Indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid are some naturally occurring auxins. 1-naphthaleneacetic acid, 2,4-dichlorophenoxyacetic acid are few of the synthetically produced auxins.

Note: In laboratories during plant tissue culture experiments, artificial auxins are used to induce shoot formation. 1-naphthaleneacetic acid, 2,4-dichlorophenoxyacetic are the synthetic auxins.