33.

Explain the following :

(i) Grafting
(ii) Vital capacity
(iii) Ureotelism
(iv) Epigeal germination.

(i) Grafting is an artificial form of vegetative propagation in which parts of two young plants are joined together, first by artificial means and then by tissue regeneration. Typically, a twig or bud is cut from one plant and joined to a rooted plant of a related species or variety. The twig or bud is called the scion, and the plant onto which is it grafted (and that provides the roots) is called the stock. The scion eventually develops into an entire shoot system.

(ii) Vital Capacity : It represents the total volume of air that can be breathed out with maximum effort after a maximum inspiration. It represents the maximum capacity of an individual to renew air in his respiratory system. It amounts to 4.5 litres.

(iii) Ureotelism: Elimination of nitrogenous wastes mainly as urea is called ureotelism. Animals excreting urea are ureotelic organisms, e.g.. amphibians like frog, toads etc.

(iv) Epigeal germination : The kind of germination in which the hypocotyl grows first and the cotyledons come above the surface of soil and act as the first leaves of the seedling is called epigeal germination, e.g.. bean, cotton, gourd, castor germination in the seeds of the plants is epigeal nature.