Aging.

Aging. 

Aging is defined as the process of progressive deterioration in the structure and junction of the cells, tissues and organs of the organism as it grows older. 

 The area of develop­mental biology which is concerned with the study of the process of aging and death is called gerontology.

Death, Significance of death, Other advantages of death.

Death

This is a well known fact that life is lost due to death and the organism reprodi compensate for this loss of life. Death is an inherent part of the life cycle of an organism. Ho' the biology of death is not completely understood as yet. Some organisms live only for short ods, while the other may have a life of several decades or even centuries. Even if an indi' meets no fatal accident, is not eaten up by a predator, or does not suffer a killing disease, comes as the natural final result of old age. As an organism grows older, its power of gradually declines and its capacity to replace the worn out cells and to repair the damaged decreases. Ultimately some vital organ, such as the heart, kidney, the brain or the liver si function altogether and death of the body occurs.

Significance of death. In biology, death has a great significance. All living plants and mals and the non-living stones, rocks, etc., are constituted of matter. They are cycled bioloj

When organisms die, microorganisms invade the dead materials. As a result the elei which the living bodies are constituted, such as C, H, N, O, Ca, K, P and S, are freed from I covalent bonds and return to the ecosystem. Thus, recycling of elements between living and living matter takes place. This type of recycling maintains the balance of matter in nature.

Other advantages of death. Reproduction and death contribute to regulate the number individuals in the population.

Dead tissues, such as heartwood and cork in plants and nails, horns, hooves and down fe ers in animals help in support and protection. The outer layer of our skin consists of dead cells protects our body from loss of body fluids and from various infections.

Mature sclerenchyma cells provide mechanical support to the plant body. Heartwood vides a strong internal mechanical support to the trunk of tree, so that, it is not uprooted. On j other hand, the dead vessels of xylem serve as channels for conducting water and minerals to heights of trees.

For instance, cells of the tail and external gills of a tadpole die according to schedule help the tadpole in becoming a frog.

During maturation of xylem vessels in angiosperms, cross walls dissolve in scheduled and long vessels are formed