Chapter Summary with NCERT Solution Class 7 Chapter 9 Life Processes in Animals 2025

Life Processes in Animals – Chapter Summary with NCERT Solution

Life Processes in Animals (AI Generated)

Life processes are the basic activities that all living beings perform to stay alive. Animals, including humans, carry out processes such as nutrition, digestion, respiration, circulation, excretion, and reproduction. In this chapter, we mainly learn about nutrition and digestion in animals, and how different animals respire. Understanding these processes helps us know how our body gets energy, how food is used, and how we breathe and stay active.

Nutrition in Animals

Animals cannot make their own food like plants. They depend on plants or other animals for nutrition. To use the energy present in food, the body must break down complex food components like carbohydrates, proteins, and fats into simpler forms. This breakdown process is called digestion, and it happens in a long tube known as the alimentary canal.

1. Digestion in Humans

The journey of food begins in the mouth, where teeth crush food into small pieces. Saliva mixes with food and starts digesting starch, which is why chewing chapati for long makes it taste sweet. This is the first step of mechanical and chemical digestion.

Food then travels through the food pipe (oesophagus) to the stomach. Here, food is churned and mixed with digestive juices, acid, and mucus.

• The acid kills harmful germs.
• The digestive juice breaks down proteins.
• Mucus protects the stomach walls from acid.

From the stomach, food enters the small intestine, which is nearly 6 meters long. Here, three juices act on food:

• Bile from the liver breaks fat into small droplets.
• Pancreatic juice breaks carbohydrates, proteins, and fats.
• Intestinal juice completes digestion.

The inner surface of the small intestine has tiny finger-like structures called villi. These help absorb nutrients into the blood. Blood carries these nutrients to all parts of the body for energy, growth, and repair.

The leftover undigested food goes to the large intestine, where water and salts are absorbed. The remaining waste becomes stool, stored in the rectum and released through the anus. Eating fibre-rich food keeps our digestive system healthy.

2. Digestion in Other Animals

Different animals have different digestive systems based on their food habits.

• Ruminants (cows, buffaloes): They swallow grass quickly and later bring it back to the mouth for chewing. This process is rumination, and such animals are called ruminants.
• Birds: They do not have teeth. They have a special organ called the gizzard, which breaks down food using muscular movements and swallowed stones.

Thus, digestion varies from animal to animal depending on their diet.

Respiration in Animals

Like digestion, the process of respiration also differs among animals. Respiration means breaking down food using oxygen to release energy. Breathing and respiration are not the same:

• Breathing = inhaling oxygen-rich air and exhaling carbon dioxide
• Respiration = using oxygen to release energy from food

1. Respiration in Humans

Humans breathe through the respiratory system, which includes nostrils, nasal passages, windpipe, lungs, and alveoli.

Air enters through the nostrils, where tiny hairs and mucus trap dust. The air moves through the windpipe into the lungs. Inside the lungs, tiny balloon-like sacs called alveoli help in the exchange of gases:

• Oxygen goes from alveoli → blood
• Carbon dioxide goes from blood → alveoli

During inhalation:

• Ribs move upward and outward
• Diaphragm moves downward
• Chest space increases

During exhalation:

• Ribs move inward
• Diaphragm moves upward
• Air is pushed out

Human exhaled air contains more carbon dioxide than inhaled air.

2. Respiration in Other Animals

Animals breathe differently depending on their environment:

• Fish breathe through gills, which absorb oxygen dissolved in water.
• Frogs breathe through: - gills as tadpoles, lungs and moist skin as adults
• Earthworms breathe through skin.
• Birds, mammals, reptiles breathe using lungs, but their lung structures vary.

Each species adapts its respiratory system to its habitat.

Conclusion

Life processes like digestion and respiration are essential for animals to survive. Food is broken down into simple nutrients, absorbed, and transported throughout the body. Oxygen helps release energy from food through respiration. Different animals have different digestive organs and breathing mechanisms based on their lifestyle and habitat.

This chapter helps us understand how wonderfully the animal body works to maintain life and ensure that every cell gets the nutrients and energy it needs.

~~~The End~~~

Chapter 9 Life Processes in Animals

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