Respiration in Organisms Class 7

 📝 Respiration in Organisms

Introduction 

Respiration is the name of the general process in which organisms convert sugar into biochemical energy using oxygen. 

`C_6H_12O_6 (aq) + 6O_2 (aq) rightarrow 6CO_2 (g) + 6H_2O (l)` + energy 

The process occurs in all organisms including animals, plants, fungi and bacteria. During respiration, energy is released. The energy is then used in different processes,necessary to support life. 

Respiration in Plants 

In plants, the processes of respiration, as well as photosynthesis occur simultaneously during the day. However,  photosynthesis does not occur in the absence of light. At night, only respiration takes place in the plant. This means that during the night `O_2` is taken in and  `CO_2` is released by plants. 

Cellular Respiration

Cellular respiration is the process n which cells produces the energy they need to stay alive. During cellular respiration, cells use oxygen to break down the sugar (glucose) to produce energy. 

Types of Respiration

• Aerobic Respiration 
• Anaerobic Respiration 

Aerobic Respiration

Aerobic respiration is the release of energy, from glucose, in the presence of oxygen. Strictly speaking, aerobic means 'in air'. However, it is the oxygen in the air, which is necessary for aerobic respiration. 

Anaerobic Respiration

Anaerobic respiration takes place in the absence of air. Here, oxygen is not used for the release of energy from food molecules, such as glucose. An organism is described as an anaerobic organism when it does not require oxygen to produce energy. 

Anaerobic respiration takes place in yeast, is put to commercial use for the production of alcoholic beverages, it is also useful for making bread and for fermenting the idli and dosa batter. 

This process is used in the brewing and baking industries. This process is also known as fermentation.

Our muscle cells can also respire anaerobically, but only for a short time, when there is a temporary deficiency of oxygen. During heavy exercise, fast running (Fig.), cycling, walking for many hours or heavy weight lifting, the demand for energy is high. But the supply of oxygen to produce the energy is limited. Then anaerobic respiration takes place in the muscle cells to fulfil the demand of energy:

  

Why do you get muscle cramps after heavy exercise?

The cramps occur when muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps. We get relief from cramps after a hot water bath or a massage. Can you guess why it is so? A hot water bath or massage improves the circulation of blood. As a result, the supply of oxygen to the muscle cells increases. The increase in the supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water.