Life Processes | Class 7 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 4 min read
Life Processes – this guide gives you a concise, exam-ready overview of Life Processes from Class 7 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
Nutrition in Animals
Nutrition is a vital life process through which animals obtain energy and nutrients necessary for growth, repair, and maintenance of their bodies. Animals consume a variety of foods depending on their habitat and physiology. For example, bees and sunbirds feed on nectar, infants feed on mother's milk, snakes swallow prey whole, and some aquatic animals filter tiny food particles from water. The food animals eat contains complex molecules like carbohydrates, proteins, and fats, which need to be broken down into simpler forms for absorption and use by the body. This breakdown occurs in a specialized long tube called the alimentary canal, which starts at the mouth and ends at the anus. Digestive juices secreted at various points in the canal chemically digest food, while mechanical processes like chewing physically break it down. The simpler nutrients are then absorbed through the walls of the alimentary canal and transported via blood to different body parts to perform various functions. This section introduces the concept of nutrition in animals, focusing on the human digestive system as a model to understand the digestion process.
📊 Diagram: Figure 9.1 shows the human digestive system with labelled parts including mouth, oesophagus, stomach, small intestine, large intestine, liver, and pancreas, illustrating the path food takes and where digestion and absorption occur.
🔗 Connection: This section sets the foundation for detailed study of digestion in humans, leading to the next section on digestion in human beings.
Frequently asked questions
1. Complete the journey of food through the alimentary canal by filling up the boxes with appropriate parts— Food → Mouth → → Stomach → → Anus
The complete journey of food through the alimentary canal is: Food → Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → Anus. Explanation: After food enters the mouth, it passes through the oesophagus to the stomach, then to the small intestine where most digestion and absorption occur, followed by the large intestine where water is absorbed, and finally the waste is expelled through the anus.
2. Sahil placed some pieces of chapati in test tube A. Neha placed chewed chapati in test tube B, and Santushti took boiled and mashed potato in test tube C. All of them added a few drops of iodine solution to their test tubes—A, B, and C, respectively. What would be their observations? Give reasons.
Observations:
- Test tube A (pieces of chapati): The iodine solution will turn blue-black indicating the presence of starch.
- Test tube B (chewed chapati): The iodine solution will not turn blue-black or will show a very faint color because chewing mixes saliva containing amylase which starts breaking down starch into sugar.
- Test tube C (boiled and mashed potato): The iodine solution will turn blue-black indicating the presence of starch.
Reason: Iodine solution reacts with starch to give a
3. What is the role of the diaphragm in breathing? (i) To filter the air (ii) To produce sound (iii) To help in inhalation and exhalation (iv) To absorb oxygen
Correct option: (iii) To help in inhalation and exhalation.
Explanation: The diaphragm is a dome-shaped muscle below the lungs that contracts and flattens during inhalation, increasing the chest cavity volume and allowing air to enter the lungs. During exhalation, it relaxes and moves upward, pushing air out. It does not filter air, produce sound, or absorb oxygen.
4. Match the following | Name of the part | Functions | | --- | --- | | (i) Nostrils | (a) fresh air from outside enters | | (ii) Nasal passages | (b) exchange of gases occurs | | (iii) Windpipe | (c) protects lungs | | (iv) Alveoli | (d) tiny hair and mucus help to trap dust and dirt from the air we breathe | | (v) Ribcage | (e) air reaches our lungs through this part |
Correct matching: (i) Nostrils — (d) tiny hair and mucus help to trap dust and dirt from the air we breathe (ii) Nasal passages — (a) fresh air from outside enters (iii) Windpipe — (e) air reaches our lungs through this part (iv) Alveoli — (b) exchange of gases occurs (v) Ribcage — (c) protects lungs
Explanation:
- Nostrils have tiny hairs and mucus to filter dust.
- Nasal passages allow fresh air to enter.
- Windpipe (trachea) carries air to lungs.
- Alveoli are sites of gas exchange.
- Ribcag
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