🔹 What is Respiration?

Respiration is a biochemical process in which living cells break down food (glucose) to release energy.

This energy is used for:

  • Growth

  • Movement

  • Repair of cells

  • Maintaining body temperature

  • All life processes

👉 In simple words:

Respiration = Breaking down food to release energy.

🔬 Cellular Respiration

Respiration takes place inside the cells, mainly in a cell organelle called the mitochondria (also called the “powerhouse of the cell”).

📌 Basic Equation of Respiration:

Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP)

Chemical equation:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

The energy released is stored in the form of ATP (Adenosine Triphosphate).

🔹 Types of Respiration

1️⃣ Aerobic Respiration

  • Occurs in presence of oxygen

  • Produces large amount of energy

  • End products: Carbon dioxide and Water

  • Occurs in mitochondria

Example: Humans, animals, plants

2️⃣ Anaerobic Respiration

  • Occurs in absence of oxygen

  • Produces less energy

  • End products:

    • In yeast → Alcohol + CO₂

    • In muscles → Lactic acid

Example:

  • Fermentation in yeast

  • Muscle cramps during heavy exercise

🔄 Difference Between Breathing and Respiration

Breathing

Respiration

    Physical process 

        Chemical process

   Occurs in lungs

        Occurs in cells

   Inhalation & exhalation

       Breakdown of glucose

   No energy released

       Energy released


Steps of Respiration 

Respiration occurs in three main steps:

1️⃣ Glycolysis

  • Occurs in cytoplasm

  • Glucose breaks into pyruvate

  • Small amount of energy released

2️⃣ Krebs Cycle

  • Occurs in mitochondria

  • Produces CO₂ and energy

3️⃣ Electron Transport Chain

  • Produces maximum ATP

🌱 Respiration in Plants

Plants also respire like animals.

  • They take in oxygen through stomata

  • Release carbon dioxide

  • Respiration occurs day and night

👉 Important: Photosynthesis and respiration are opposite processes.

💪 Why Respiration is Important?

Respiration helps in:

✔ Energy production

✔ Muscle movement

✔ Brain functioning

✔ Growth and repair

✔ Maintaining life

Without respiration, cells cannot survive.

⚠ Common Exam Questions (CBSE Pattern)

  1. Define respiration.

  2. Write the chemical equation of aerobic respiration.

  3. Differentiate between aerobic and anaerobic respiration.

  4. What is ATP? Why is it called energy currency?

  5. Why do we get muscle cramps during heavy exercise?

📌 Conclusion

Respiration is a vital life process that releases energy from food. It occurs in all living organisms and ensures survival by providing energy for all biological activities.