. Explain Factors Influencing Respiration
1. Temperature: It is noticed that rate of respiration follows Vant Hoff’s law. It states that the respiratory rate is doubled for every rise in temperature by 10°C. Hence, it is also known as law of Q10. The optimum temperature for respiration is 30 to 40°C in different species of plants.
2. Oxygen: Oxygen is a must for aerobic respiration, though it is not necessary for anaerobic respiration. The minimum oxygen concentration at which aerobic respiration occurs is called extinction point. It is around 3 – 10% of oxygen. However in facultative anaerobes like yeast and bacteria increase in concentration decreases the rate of glucose breakdown. Oxygen has its role in terminal oxidation of aerobic respiration.
3. Carbon dioxide: The atmosphere has a carbon dioxide concentration of 0.03% and it is almost constant. However, any increase in the carbon dioxide concentration has a retarding influence on respiration.
4. Water: Hydration of the medium is a basic requirement for all metabolic activities. Respiratory enzymes become active only in a hydrated medium. Increased rate of respiration is seen if there is slight dessication of tissues. But if hydration is either high or low, respiration is decreased.
5. Light: Light indirectly affects the rate of respiration, as it operates by supplying respiratory material in the form of carbohydrates in plants containing chlorophyll. The fact that respiration proceeds at night as well as in daytime also indicates that light has no major role in respiration. A part of the effect on the rate is caused by the rise in temperature resulting from absorption of the sun’s energy by the cell.
6. Inorganic salts: The rate of respiration usually increases when a plant tissue is transferred from water to salt solution. Such an increase over normal rate is called salt respiration or anion respiration. This is due increase in anion transport.