10 BIOLOGY RESPIRATION – REVISION NOTES

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 RESPIRATION – REVISION NOTES

1. What is Respiration?

  • Respiration is the process of breaking down food to release energy.

  • Energy released is used for:

    • Growth

    • Repair

    • Movement

    • Maintenance of body functions

  • Respiration occurs day and night.

2. Difference Between Breathing and Respiration

BreathingRespiration
Physical process                    Chemical process
Exchange of gasesBreakdown of food
Occurs in lungsOccurs in cells
No energy releasedEnergy released

3. Types of Respiration

There are two types of respiration:

  1. Aerobic respiration

  2. Anaerobic respiration

4. Aerobic Respiration

  • Occurs in the presence of oxygen

  • Complete breakdown of glucose

  • Occurs mainly in mitochondria

  • Releases large amount of energy

Equation

Glucose + Oxygen → Carbon dioxide + Water + Energy

Examples

  • Humans

  • Plants

  • Most animals

5. Anaerobic Respiration

  • Occurs in the absence of oxygen

  • Incomplete breakdown of glucose

  • Releases less energy

In Yeast

Glucose → Alcohol + Carbon dioxide + Energy

In Human Muscles

Glucose → Lactic acid + Energy

  • Lactic acid accumulation causes muscle cramps.

6. ATP – Energy Currency

  • Energy released during respiration is stored as ATP.

  • ATP provides energy for:

    • Muscle contraction

    • Active transport

    • Synthesis of proteins

7. Respiration in Plants

  • Plants respire all the time.

  • Gas exchange occurs by diffusion.

  • Occurs through:

    • Stomata (leaves)

    • Lenticels (stem)

    • Root hairs (roots)

Day Time

  • CO₂ used in photosynthesis

  • O₂ released

Night Time

  • O₂ used in respiration

  • CO₂ released

8. Respiration in Animals

  • Animals require more oxygen due to higher energy needs.

  • Specialised respiratory organs are present.

Aquatic Animals

  • Use dissolved oxygen

  • Faster breathing rate

  • Example: Fish

Terrestrial Animals

  • Use atmospheric oxygen

  • Example: Humans

9. Human Respiratory System

  • Includes:

    • Nostrils

    • Nasal cavity

    • Trachea

    • Bronchi

    • Lungs

  • Trachea is supported by cartilage rings to prevent collapse.

10. Alveoli

  • Tiny air sacs in lungs

  • Site of gas exchange

  • Features:

    • Thin walls

    • Large surface area

    • Rich blood supply

11. Mechanism of Breathing

Inhalation

  • Diaphragm contracts and moves down

  • Chest cavity volume increases

  • Air enters lungs

Exhalation

  • Diaphragm relaxes and moves up

  • Chest cavity volume decreases

  • Air moves out

12. Transport of Gases

  • Oxygen transported by haemoglobin.

  • Carbon dioxide transported mainly as bicarbonates.

13. Why Diffusion is Not Enough in Humans

  • Multicellular body

  • Cells far from external environment

  • High oxygen requirement

  • Need specialised transport and respiratory systems

14. Key Exam Points

  • Respiration releases energy.

  • Aerobic respiration releases more energy than anaerobic.

  • Anaerobic respiration in muscles produces lactic acid.

  • ATP is energy currency of the cell.

  • Alveoli increase efficiency of gas exchange.

  • Respiration occurs continuously.