Write short note on 'Biological clocks'

It is an aging clock & acts an age predictor that can be used to measure the age of most plant tissues, cell types or organs. Salient features of this clock include its high accuracy and applicability to a broad spectrum of tissues & cell types. It can be used to identify tissues that show evidence of accelerated age due to disease. It also helps to study the circadian rhythms of living organisms. It is an inherent periodicity in the physiological processes of living organism that is not dependent on the periodicity of external factor. An internal system organisms that control the various functions of plants like photosynthesis, photoperiodism, vernalization etc in plants.