Respiration in Organisms

7th Class Science | Understanding How Life Breathes

Introduction

Respiration is a biochemical process that takes place in all living organisms. It is essential for life because it provides energy to perform various biological activities. Through respiration, organisms break down food (mainly glucose) in the presence or absence of oxygen to release energy. This energy is then used for growth, repair, movement, and maintaining bodily functions.

Key Point: Respiration is not the same as breathing, although they are closely related. Breathing is the physical process of taking in oxygen and releasing carbon dioxide, while respiration occurs at the cellular level to release energy.

Types of Respiration

• Aerobic Respiration: This type of respiration occurs in the presence of oxygen. It is the most common form and takes place in most plants and animals. During aerobic respiration, glucose reacts with oxygen to form carbon dioxide, water, and energy.
• Equation: Glucose (C₆H₁₂O₆) + Oxygen (O₂) → Carbon dioxide (CO₂) + Water (H₂O) + Energy (ATP)
• Anaerobic Respiration: This occurs without oxygen. It takes place in some microorganisms and human muscle cells during vigorous exercise. It produces less energy and forms by-products like lactic acid or alcohol.
• Example: Yeast undergoes anaerobic respiration to produce alcohol in brewing industries.

Respiration in Humans

The human respiratory system consists of organs that help us breathe and allow the exchange of gases. Oxygen from the air is taken into the body, and carbon dioxide is expelled. The main parts involved are:

• Nostrils: Air enters through the nose and is filtered.
• Nasal Cavity: Warms and moistens the air.
• Trachea: The windpipe that transports air to the lungs.
• Bronchi: The trachea divides into two bronchi, each leading to a lung.
• Lungs: Spongy organs where gas exchange occurs in alveoli.
• Diaphragm: A muscle that helps in breathing by expanding and contracting the lungs.

Breathing includes two actions:

• Inhalation: Taking in oxygen-rich air.
• Exhalation: Releasing carbon dioxide-rich air.

Respiration in Plants and Animals

Respiration is essential not only in humans but also in all other organisms. Here’s how it varies:

• Plants: Respire through small pores called stomata in leaves and lenticels in stems. They use oxygen and release carbon dioxide continuously, both day and night.
• Fish: Use gills to extract oxygen from water. Water flows over the gills, and oxygen diffuses into the blood.
• Insects: Have a network of air tubes called tracheae that carry oxygen directly to cells.
• Frogs: Can respire through their moist skin as well as lungs, especially when in water.

Importance of Respiration

Respiration plays a critical role in the survival of living organisms:

• Provides Energy: Respiration supplies the energy needed for all biological activities.
• Maintains Body Functions: Enables movement, circulation, digestion, and cellular repair.
• Eliminates Waste: Helps in removing carbon dioxide, a waste product of respiration.
• Supports Growth and Reproduction: Energy released is used in growth and formation of new cells.