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What is the difference between aerobic and anaerobic respiration?

Class 10 ScienceNCERT chapter: Life Processesइसे हिंदी में पढ़ें

Exam-ready answer

Aerobic respiration occurs in the presence of oxygen, breaks down glucose completely into carbon dioxide and water, and releases more energy. Anaerobic respiration occurs without oxygen, breaks down glucose partially into ethanol and carbon dioxide (or lactic acid), and releases less energy.

Explanation

Respiration is the process of breaking down food to release energy. In aerobic respiration, glucose is broken down in the presence of oxygen inside the mitochondria. The overall equation is: Glucose (C6H12O6) + Oxygen (6O2) → Carbon dioxide (6CO2) + Water (6H2O) + Energy. This releases a large amount of energy.

In anaerobic respiration, glucose is broken down without oxygen. In yeast, it produces ethanol and carbon dioxide: Glucose → Ethanol + Carbon dioxide + Energy. In our muscle cells during vigorous exercise, when oxygen is insufficient, glucose is converted into lactic acid, which causes cramps. This releases less energy.

Aerobic respiration takes place in the cytoplasm and mitochondria, while anaerobic respiration occurs only in the cytoplasm. Aerobic respiration is common in most plants and animals, whereas anaerobic respiration occurs in yeast, some bacteria, and in human muscle cells during heavy exercise.

Points to remember

  1. Aerobic respiration: requires oxygen, occurs in mitochondria, produces CO2 + H2O, releases more energy (about 38 ATP per glucose).
  2. Anaerobic respiration: occurs without oxygen, in cytoplasm, produces ethanol + CO2 (in yeast) or lactic acid (in muscles), releases less energy (about 2 ATP per glucose).
  3. Equation for aerobic respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy.
  4. Equation for anaerobic respiration in yeast: C6H12O6 → 2C2H5OH + 2CO2 + Energy.
  5. In human muscle cells, anaerobic respiration produces lactic acid, causing cramps.

Exam tip

Always write the balanced chemical equation for both types of respiration and mention the site of occurrence (mitochondria for aerobic, cytoplasm for anaerobic) to score full marks.

Questions students also ask

Why do we get muscle cramps after heavy exercise?
During heavy exercise, oxygen supply to muscles is insufficient, so muscles respire anaerobically. This produces lactic acid, which accumulates and causes cramps.
Which respiration releases more energy?
Aerobic respiration releases more energy (about 38 ATP per glucose molecule) because glucose is completely broken down into carbon dioxide and water. Anaerobic respiration releases less energy (about 2 ATP).
Where does aerobic respiration take place in the cell?
Aerobic respiration takes place in the cytoplasm and mitochondria. The mitochondria are the main site for the complete breakdown of glucose.

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