What is Respiration in Organisms Class 7: Complete NCERT Guide

Definition of Respiration in Organisms for Class 7

Respiration is a biological process in which organisms break down glucose (a type of sugar) to release energy. This energy is essential for all life activities such as movement, growth, and repair.

In simple terms, respiration is how living beings breathe and get energy from food. The general equation for aerobic respiration is:

$$\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon dioxide} + \text{Water} + \text{Energy}$$

This process happens in every cell of an organism, making it a fundamental topic in Class 7 NCERT Science.

Types of Respiration: Aerobic and Anaerobic

Respiration in organisms is mainly of two types:

• Aerobic Respiration: Requires oxygen to break down glucose completely. It produces carbon dioxide, water, and a large amount of energy.
• Anaerobic Respiration: Occurs without oxygen. It produces less energy and results in by-products like lactic acid or alcohol.

Examples:

• Humans use aerobic respiration normally.
• Yeast performs anaerobic respiration during fermentation.

How Do Humans and Animals Breathe?

Humans and most animals breathe through specialized organs called lungs or gills (in aquatic animals). The process involves:

1. Inhalation: Taking in oxygen-rich air. 2. Gas Exchange: Oxygen passes into the blood; carbon dioxide passes out. 3. Exhalation: Releasing carbon dioxide-rich air.

The oxygen is then used in cells to break down glucose and release energy. This continuous cycle is essential for survival.

Worked Example: If a person inhales 500 ml of air containing about 21% oxygen, approximately 105 ml of oxygen enters the lungs. The body uses most of this oxygen for respiration.

Respiration in Plants: How It Happens

Many students think plants only perform photosynthesis, but plants also respire. Plant cells take in oxygen and break down glucose to release energy, especially at night when photosynthesis stops.

Key points:

• Plants respire through tiny openings called stomata.
• The process is similar to animals but slower.
• Energy from respiration helps plants grow and repair cells.

Unlike photosynthesis, respiration happens all the time, day and night.

Importance of Respiration in Organisms

Respiration is critical because it:

• Provides energy for all life processes.
• Helps maintain body temperature in warm-blooded animals.
• Supports growth, repair, and movement.
• Removes waste gases like carbon dioxide.

Without respiration, organisms cannot survive. It connects the food we eat with the energy our bodies need.

Summary: What is Respiration in Organisms Class 7 NCERT

To recap:

• Respiration is the process of releasing energy from food.
• It can be aerobic (with oxygen) or anaerobic (without oxygen).
• All living organisms, including humans, animals, and plants, respire.
• The energy released powers vital functions.

Understanding respiration helps Class 7 students grasp how life functions at the cellular level, a key part of the NCERT Science curriculum.