Respiration in Organisms Class 7 Science Notes - Chapter 10

All living organisms breathe to survive. Respiration is necessary for survival. When we inhale oxygen, it breaks down glucose into water and carbon dioxide. This occurs in the cells of organisms. Therefore Energy is released from the food in the process. The breakdown occurs in two forms viz aerobic respiration or anaerobic respiration.

  • Anaerobic respiration – Breakdown occurs in the absence of oxygen. Example, If the supply to the muscles is not sufficient during heavy exercise, the breakdown of food occurs through this type of respiration.
  • Aerobic respiration – Breakdown occurs in the presence of oxygen.

Breathing is a process where organisms inhale the oxygen-rich air and exhale the air rich in carbon dioxide. While we inhale the lungs expand and during the process of exhalation, they come to normal state. Dog, cow, cat, buffalo, have the respiratory organs similar to humans. Also, the breathing process is similar. Different organisms have different breathing process-

  • Earthworm – exchange of gases is carried out through their moist skin
  • Fish – exchange of gases is carried out through gills
  • Insects – exchange of gases occur through the tracheae
  • Plants – Roots take in air and stomata exchange gases

Few Important Questions

  1. Distinguish between anaerobic and aerobic respiration.
  2. Answer true or false –
    1. Frog breathes through its skins only.
    2. The chest cavity size decreases during inhalation.
  1. Which body part helps cockroaches to inhale air?
  2. Explain the process of exhalation.
  3. What is the breathing rate per minute in an adult?
  4. Why do we get cramps during heavy exercise?

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Practise This Question

Photosynthesis generates which of the following nutrients?