Fill in the places with appropriate word/ words. a. A phase of growth which is maximum and fastest is __________. b. Apical dominance as expressed in dicotyledonous plants is due to the presence of more ________ in the apical bud than in the lateral ones. c. In addition to auxin, a ________ must be supplied to culture medium to obtain a good callus in plant tissue culture. d. ________ of a vegetative plants are the sites of photoperiodic perception.

Question

Philoid · Accepted Answer

a) A phase of growth which is maximum and fastest is the log phase or exponential phase.

In this phase, the cells are not dormant. Here cell numbers increase in a logarithmic pattern. It is a period characterized by cell doubling.

b) Apical dominance as expressed in dicotyledonous plants is due to the presence of more auxins in the apical bud than in the lateral ones.

Explanation: Auxins are responsible for apical dominance. In most plants, the growing apical bud inhibits the growth of the lateral buds. This is called apical dominance.

c) Cytokinin- kinetin, zeatin, and 6-benzylaminopurine

Explanation: Auxin helps cells elongate, but it doesn't work alone. Cytokinins promote cell division (cytokinesis) and are produced in roots, embryos and fruits, or wherever there is actively growing tissue. However, cytokinins need auxin to induce cell division.

d) Leaves of a vegetative plants are the sites of photoperiodic perception.

This can be shown by experiment on leaf Xanthium pennsylvanicum, which is a short day plant. If the plant is defoliated and then allowed to flower under short day condition, it will not flower.