Chapter-Chapter 9. Life Processes in Animals Science Curiosity class 7 in english Medium CBSE Notes

Chapter 9: Life Processes in Animals

Introduction: All living organisms need energy to survive and perform various activities such as movement, growth, and reproduction. This energy is obtained through different biological processes known as life processes.

Animals carry out several life processes to maintain their body functions. These processes include nutrition, respiration, transportation, and excretion.

This chapter covers the following topics:

• Life processes in animals
• Nutrition and digestion
• Respiration
• Transportation of substances
• Excretion
• Coordination and control (basic idea)

What are Life Processes? Life processes are the basic activities that are essential for maintaining life in organisms.

Without these processes, living organisms cannot survive.

Example: Eating food, breathing, and removing waste are all life processes.

Nutrition in Animals: Nutrition is the process by which animals take in food and use it for energy, growth, and repair of the body.

Animals cannot prepare their own food, so they depend on plants or other animals.

Steps of Nutrition:

• Ingestion: Taking in food
• Digestion: Breaking down food into simpler substances
• Absorption: Taking nutrients into the blood
• Assimilation: Using nutrients for energy and growth
• Egestion: Removal of undigested waste

Example: Humans eat food, digest it in the stomach, absorb nutrients, and remove waste from the body.

Key Point: Life processes are essential for survival and proper functioning of living organisms.

Digestive System in Humans: The digestive system is responsible for breaking down food into simpler substances that can be absorbed by the body. It consists of several organs that work together in a proper sequence.

Main Organs of Digestive System:

• Mouth: Food is chewed and mixed with saliva, which begins digestion.
• Esophagus: A tube that carries food from mouth to stomach.
• Stomach: Food is churned and mixed with digestive juices.
• Small Intestine: Digestion is completed and nutrients are absorbed.
• Large Intestine: Water is absorbed and waste is formed.

Example: When we eat food, it is first chewed in the mouth and then passes through different organs where digestion takes place step by step.

Respiration: Respiration is the process of taking in oxygen and releasing carbon dioxide. It helps in releasing energy from food.

Types of Respiration:

• Aerobic Respiration: Occurs in presence of oxygen and releases more energy.
• Anaerobic Respiration: Occurs in absence of oxygen and releases less energy.

Example: Humans perform aerobic respiration during normal breathing.

Respiratory System in Humans: This system helps in breathing and exchange of gases.

• Nose: Air enters the body
• Trachea: Carries air to lungs
• Lungs: Exchange oxygen and carbon dioxide

Key Point: Digestion provides nutrients, while respiration releases energy from food.

Transportation of Substances: In animals, different substances like oxygen, nutrients, and waste need to be transported from one part of the body to another. This process is called transportation.

This work is carried out by the circulatory system.

Main Parts of Circulatory System:

• Heart: A muscular organ that pumps blood throughout the body.
• Blood: A fluid that carries oxygen, nutrients, and waste.
• Blood Vessels: Tubes that carry blood to different parts of the body.

Example: Oxygen from lungs is carried by blood to all body parts.

Excretion: Excretion is the process of removing waste materials from the body. These waste products are formed during different life processes.

Excretory Organs:

• Kidneys: Filter waste from blood
• Ureters: Carry urine from kidneys to bladder
• Urinary Bladder: Stores urine
• Urethra: Removes urine from body

Example: Urine formation helps remove harmful waste from the body.

Coordination and Control (Basic Idea): The body needs to control and coordinate different activities to function properly.

This is done by the nervous system, which sends signals to different parts of the body.

Main Parts:

• Brain: Controls activities of the body
• Nerves: Carry messages between brain and body parts

Overall Understanding: Life processes like nutrition, respiration, transportation, and excretion are interconnected. Each system works together to keep the body alive and functioning properly.

Key Point: All life processes are interdependent and essential for survival.

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