Chapter 2 – Nutrition in animals

These NCERT Class 7 Science Chapter 2 notes explain how animals obtain energy from food and why nutrition is essential for survival. Unlike plants, animals cannot make their own food and depend on plants or other animals for nutrition.

Nutrition in Animals describes the complete process of digestion, including ingestion, digestion, absorption, assimilation, and egestion. The chapter also explains the human digestive system and different ways in which animals digest food.

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1. Introduction: why animals need nutrition

•  Animals cannot make their own food.
•  They depend on plants or other animals for food.
•  Food provides energy and helps in growth, repair, and disease protection.
•  Animals are like consumers who depend on ready-made food.

2. Meaning of nutrition in animals

•  Nutrition in animals means taking food, digesting it, absorbing nutrients, and using them for body functions.
•  Animals show heterotrophic nutrition (hetero = other).

3. Steps of nutrition in animals

•  Ingestion means taking food into the body.
•  Digestion means breaking food into simpler substances.
•  Absorption means nutrients absorbed into blood.
•  Assimilation means use of nutrients by body cells.
•  Egestion means removal of undigested food.
•  Nutrition works like cooking, eating, using energy, and throwing waste.

4. Human digestive system

•  The digestive system breaks complex food into simple form.
•  Mouth is the entry point of food.
•  Oesophagus carries food to stomach.
•  Stomach mixes food with digestive juices.
•  Small intestine completes digestion.
•  Large intestine absorbs water.
•  Anus removes waste from body.

5. Digestion in mouth

•  Teeth chew food into small pieces.
•  Saliva mixes with food.
•  Amylase enzyme digests starch.
•  Mouth starts digestion like a mixer grinder.

6. Digestion in stomach

•  Food is mixed with digestive juices.
•  Hydrochloric acid (HCl) kills germs.
•  Enzymes digest proteins.

7. Digestion in small intestine

•  Major digestion takes place here.
•  Liver releases bile juice.
•  Pancreas releases digestive enzymes.
•  Bile helps digestion of fats.
•  Enzymes digest carbohydrates, proteins, and fats.

8. Absorption and assimilation

•  Villi absorb digested food in small intestine.
•  Nutrients reach blood.
•  Body cells use nutrients for energy and growth.

9. Large intestine and egestion

•  Large intestine absorbs water.
•  Waste is stored in rectum.
•  Egestion removes waste through anus.

10. Digestion in ruminants

•  Cow, buffalo, and deer are ruminants.
•  They swallow grass quickly.
•  Stomach has four chambers.
•  Cud comes back to mouth.
•  Rumination is chewing cud again.
•  Cows chew food twice for digestion.

11. Feeding and digestion in amoeba

•  Amoeba is a single-celled organism.
•  Pseudopodia capture food.
•  Food vacuole digests food.

12. Importance of proper digestion

•  Digestion provides energy.
•  It helps in growth and repair.
•  It maintains good health.

13. Important keywords with simple definitions

•  Heterotroph – organism that depends on others for food.
•  Ingestion – taking food into the body.
•  Digestion – breaking food into simple substances.
•  Absorption – movement of nutrients into blood.
•  Assimilation – use of nutrients by body cells.
•  Egestion – removal of undigested food.
•  Ruminant – grass-eating animal with four-chambered stomach.
•  Rumination – process of chewing cud again.
•  Villi – finger-like structures that absorb nutrients.

Understanding NCERT Class 7 Science Chapter 2 – Nutrition in Animals helps students learn how food is converted into energy inside the body. The chapter clearly explains digestion in humans, ruminants, and simple organisms like amoeba.

These concepts are important for school examinations and foundation-level science preparation. Students should next read Chapter 3: Fibre to Fabric to understand how natural fibres are obtained and converted into clothes.

FAQs

Q1. What is explained in NCERT Class 7 Science Chapter 2?
The chapter explains nutrition in animals, digestion process, and the human digestive system.

Q2. What are the main steps of nutrition in animals?
The steps are ingestion, digestion, absorption, assimilation, and egestion.

Q3. How do ruminants digest food?
Ruminants chew grass quickly, store it in the stomach, and later chew cud for proper digestion.

Q4. How does digestion take place in amoeba?
Amoeba uses pseudopodia to capture food and digests it inside a food vacuole.

Q5. Why is NCERT Class 7 Science Chapter 2 important for exams?
It covers digestion and nutrition, which are basic concepts frequently asked in school and foundation-level exams.

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