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Respiration in Organisms

Types of Respiration (Group A)

During which physical activity do you think is the breathing rate highest?

This question can be answered by performing a few activities. However, let us first understand what breathing rate is.

The number of times a person inhales and exhales, or breathes in one minute is known as the breathing rate.

Breathing rate changes from time to time as the requirement for oxygen changes in the body. Therefore, let us start by performing some activities to have a better understanding of the respiratory system.

Try counting your breaths.

Breathing rate can be calculated by counting the number of breaths you take. So, calculate your breathing rate

  • while at rest

  • during normal walk

  • after a brisk walk of 10 minutes

  • after running very fast for 10 minutes

Now, make a table and note down your breathing rate during each activity.

You will notice that your breathing rate is the minimum when you are at rest and maximum when you run very fast. What is the reason for this difference?

After heavy exercising, the body requires extra energy. The breathing rate tremendously increases to provide more oxygen to the body. Thus, the oxygen taken in will aid in cellular respiration. This will lead to the release of energy from food, which will be then available to the body.

You know that all activities performed by the body require energy. Where does the body get energy from? The food we eat contains stored energy.

How is the energy stored in food released to be used by the body?

You know that during the process of breathing, we take in air. Oxygen is taken in, while carbon dioxide is released out of the body during breathing. Oxygen is then circulated to all cells of the body. Food (glucose) is broken down in the cells with the help of oxygen.

The process in which food is broken down in the cells to release energy is known as cellular respiration.

Have you ever wondered what will happen if no or very little oxygen is available to cells? Will the process of cellular respiration stop?

Two types of respiration take place in the cells. One occurs in the presence of oxygen, while the other occurs in the absence of it. The process of breakdown of food (glucose) in the presence of oxygen is known as aerobic respiration. It takes place in all organisms and leads to the production of carbon dioxide, water, and energy.

Food is also broken down in the absence of oxygen. This process is known as anaerobic respiration. It occurs in organisms such as yeast. This process leads to the production of alcohol and carbon dioxide.

GlucoseWithout oxygen  Alcohol + Carbon dioxide

Difference between Aerobic and Anaerobic respiration

Aerobic respiration Anaerobic respiration

It occurs in the presence of O2.

It occurs in the absence of O2.

It involves the exchange of gases between an organism and outside environment.

Exchange of gases is absent.

It occurs in the cytoplasm and mitochondria.

It occurs only in the cytoplasm.

It always releases CO2 and H2O.

End products may vary.

It yields 38 ATP.

It yields 2 ATP.

Example: Cells in our body

Example: Yeast and muscle cells


Have you experienced pain in your arms or legs after exercising for a long time?

When you exercise, your body experiences a temporary deficiency of oxygen and the muscle cells begin to undergo anaerobic respiration to provide energy to the body. This leads to the production and accumulation of lactic acid, which leads to muscle cramps and pain in the body.

Do you know why yeast is used for preparing wine and beer?

Yeast performs the process of anaerobic respiration, which leads to the production of alcohol by incomplete breakdown of sugar. It is for this reason that yeast is used in the production of wine and beer.

How do we confirm that carbon dioxide is produced during respiratio…

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