Steps in Respiration – Class 11 | Chapter – 17 | Biology Short Notes Series PDF

Steps in Respiration: Respiration is the process by which energy is released from food in our body. The function of respiratory system is to breathe in oxygen for respiration producing energy from food, and to breathe out carbon dioxide produced by respiration. With the help of lungs gases are exchanged between the blood and the air. Gases exchanged are oxygen and carbon dioxide.

Different Steps in Respiration









  • Breathing or pulmonary ventilation by which outside air is inhaled and carbon dioxide-rich air is exhaled.
  • Diffusion of gases occurs across the alveolar membrane.
  • Gaseous transport occurs through the blood.
  • Carbon dioxide and oxygen are diffused between the tissues and blood.
  • Oxygen is used by cells for catabolic reactions and carbon dioxide is released.
  • Glycolysis, pyruvate oxidation, the citric acid or Krebs cycle, and oxidative phosphorylation are the phases of cellular respiration.
  • In the process of glycolysis, the six-carbon sugar molecule glucose is split into two molecules with three carbons (pyruvic acid).
  • Two molecules of ATP are produced when the energy from the broken bonds is caught.
  • The three-carbon molecules produced by glycolysis are converted into carbon dioxide molecules by the Krebs cycle.
  • ATP and NADH are produced as electron donors via the Krebs cycle as well as glycolysis.
  • Water is created through the electron transport chain when oxygen and the hydrogen atoms of NADH are joined.
  • Energy is constantly being taken in during electron transit to create ATP.
  • The procedure is occasionally referred to as oxidative phosphorylation since it needs oxygen.

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