Life Processes Class 10 Notes | Respiration in Humans, Plants & Animals (PART 3)

Introduction

Respiration is one of the most essential life processes that helps organisms release energy from food. Without respiration, cells cannot perform vital functions required for survival.

In this part of Life Processes, we will understand breathing, cellular respiration, aerobic and anaerobic respiration, and how respiration occurs in plants and animals. These concepts are very important for Class 10 exams and help build a strong foundation in Biology.

📘 In this part, you will learn:

• Difference between breathing and respiration

• Steps of cellular respiration

• Aerobic and anaerobic respiration

• Respiration in plants and animals

• Important exam questions

📺 Watch the video below and read the notes for better understanding

🎥 VIDEO SECTION

https://www.youtube.com/watch?v=Qzttxhf3JjY

📌 Respiration

Respiration is the process by which organisms take in oxygen from the environment and use it to break down food to release energy. This energy is essential for all cellular activities.

Respiration includes both breathing (external process) and cellular respiration (internal process).

Breathing vs Respiration

• Breathing is the physical process of inhaling oxygen and exhaling carbon dioxide

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

Cellular Respiration

Cellular respiration occurs inside cells and involves the breakdown of glucose to release energy.

Steps involved:

• Glucose molecules are broken down into pyruvic acid

• Glucose molecule is composed of six carbon atom while pyruvic acid is composed of three carbon atoms

• Pyruvic  acid::In mitochondria further breaking down of pyruvic acid takes place and the molecules formed depend on the type of respiration in a particular organism

Types of Respiration

Respiration is of two types:

1. Aerobic Respiration

• Occurs in the presence of oxygen

• Complete breakdown of food

• Produces:

  • Carbon dioxide

  • Water

• Releases more energy

👉 Occurs in:

• Humans

• Higher animals

2. Anaerobic Respiration

3. Occurs in the absence of oxygen

4. Partial breakdown of food

5. Produces:

   • Ethyl alcohol / Lactic acid

   • Carbon dioxide

6. Releases less energy

👉 Occurs in:

• Yeast

• Bacteria

• Muscle cells (during heavy exercise)

Muscle Cramps (Important Concept) : Sometimes lactic acid formed during anaerobic respiration in muscle cells get accumulated causing muscular cramps

During intense exercise:

• Oxygen supply becomes insufficient

• Glucose breaks down anaerobically

• Lactic acid accumulates

👉 This causes muscle cramps

Respiration in Plants

Plants also respire continuously, both during day and night.

Key Points:

• All parts of plants perform respiration

• Gas exchange occurs through:

  • Stomata (leaves)

  • Lenticels (stems)

• Roots absorb oxygen from soil

Additional Points:

• Oxygen diffuses into cells

• Carbon dioxide is released

• During the day:

  • Oxygen from photosynthesis is used

  • Excess oxygen is released

Respiration in Animals

Different animals have different respiratory mechanisms.

Example: Fish

• Take in water through mouth

• Pass it over gills

• Dissolved oxygen is absorbed into blood

👉 Aquatic organisms breathe faster because:

• Water has less oxygen compared to air

Human Respiratory System (Important)

Air passes through the following path:

👉 Nostrils → Pharynx → Larynx → Trachea → Alveoli

Role of Alveoli

Alveoli are tiny balloon-like structures in lungs.

Functions:

• Increase surface area for gas exchange

• Rich in blood vessels

• Oxygen diffuses into blood

• Carbon dioxide diffuses out

IMPORTANT QUESTIONS (EXAM FOCUS)

1. Sequence of air passage:

👉 Nostrils → Pharynx → Larynx → Trachea → Alveoli

2. Why do aquatic organisms breathe faster?

👉 Due to low oxygen availability in water

3. Difference between aerobic and anaerobic respiration?

Aerobic	Anaerobic
Oxygen present	No oxygen
Complete breakdown	Partial breakdown
More energy	Less energy

4. Why do runners get muscle cramps?

👉 This is a due to the absence of oxygen in the muscles and the liberation of lactic acid in muscle leads to muscle cramps

5. How are lungs designed for gas exchange?

• Presence of alveoli

• Large surface area

• Rich blood supply

5. How are lungs design in human being to maximize the area of exchange of gases

👉 Within the lungs the passage devide into smaller and smaller tubes which finally terminate into balloon like structure which are called alveolie.The alveolie provide a surface where the exchange of gases can takes place. The walls of the alveoli contain an extensive network of blood vessels. The blood bring carbon dioxide from the rest of the body for release into the alveoli and oxygen in the alveolar air is taken up by the blood in the alveolar  blood vessel to be transported to all the cells in the body

6. How does aerobic respiration differ from anaerobic respiration

7.. Explain the three Pathways of Breaking Down in Living Organism

8. Rate of breathing in aquatic organism much faster than interested organism

This is because the amount of dissolved oxygen is low compared to the amount of oxygen in the air

9.Differences between aquatic and Terrestrial organism in relation to respiration

Terrestrial organism	Aquatic organism
Organism live on land	Organism live inside water
Presence of oxygen is more	Take oxygen from dissolved in water and presence of oxygen is less
No need to respire fast	Need to respire fast
No adaptation for respiration	More adaptation for respiration
Ex: Human	Ex: Fish