Rate of Respiration and Factors Affecting It

The rate of respiration can be measured by the amount of CO₂ released per unit time. It varies in different organs and with age.

In general the factors which affect respiration include internal factors such as minerals, structure of respiratory tissue or organ, the activity of the respiratory enzymes and the type of substrate; and external factors such as oxygen, water, and temperature.

Type of substrate

Respiratory substrate may be carbohydrate, protein or fats. The kind of substrate being oxidized can be determined by measuring the Respiratory Quotient of the respiratory tissue or oxygen. 

R.Q. = Volume of CO₂ evolved / Volume of O₂ consumed

Temperature

The temperature between 30-35°C is most suitable for respiration. This is because the enzymes can work best in this range. Respiration is reduced beyond 50°C and also at very low temperatures (0-10°C).

Oxygen

The rate of respiration increases with rise in oxygen concentration. As O₂ concentration increases from zero, the rate of respiration increases. However, beyond a limit the rate of increase falls.

Carbon dioxide

Rate of respiration decreases if CO₂ is allowed to accumulate surrounding the respiratory tissue.

Water

Respiration is very slow if the water content of the protoplasm is low as in dry, matured seeds. Dormant seeds show very low rate of respiration. If water is supplied to dry seeds, respiration starts immediately.