At Bodhiclasses, we strive to provide clear, concise, and concept-focused resources to help students truly understand their Science lessons. Below are solved questions from Chapter 9 – Life Processes in Animals (Class 7 Science), including analytical reasoning and application-based insights. Perfect for revision and deeper understanding!
1. Complete the journey of food through the alimentary canal by filling up the boxes with appropriate parts—
Food → Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → 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.
- Test tube A (plain chapati): Turns blue-black – indicates the presence of starch.
- Test tube B (chewed chapati): Faint or no colour change – saliva partially digests starch into sugar, so less starch is present.
- Test tube C (boiled and mashed potato): Turns blue-black – also contains starch, similar to uncooked rice or wheat.
3. What is the role of the diaphragm in breathing?
(iii) To help in inhalation and exhalation
✅ Correct Answer Explanation: The diaphragm moves down during inhalation and up during exhalation, helping expand and contract the chest cavity.
4. Match the following
| Name of the part | Functions |
|---|---|
| (i) Nostrils | (a) Fresh air from outside enters |
| (ii) Nasal passages | (d) Tiny hair and mucus help to trap dust and dirt |
| (iii) Windpipe | (e) Air reaches our lungs through this part |
| (iv) Alveoli | (b) Exchange of gases occurs |
| (v) Ribcage | (c) Protects lungs |
5. Anil claims to his friend Sanvi that respiration and breathing are the same process. What question(s) can Sanvi ask him to make him understand that he is not correct?
- “Does breathing alone release energy in the body?”
- “If breathing is just air movement, then how is energy produced inside our cells?”
✅ Explanation: Breathing is air exchange, while respiration is a chemical process in cells that releases energy by breaking down glucose with oxygen.
6. Which of the following statements is correct and why?
Tanu: We inhale air rich in oxygen.
✅ Correct Answer: Because air is a mixture of gases — about 21% oxygen. So, we inhale air rich in oxygen, not pure oxygen.
7. We often sneeze when we inhale a lot of dust-laden air. What can be possible explanations for this?
- Sneezing is a protective reflex to expel dust and allergens from the nose.
- Nasal hairs and mucus try to trap dust, but excess particles may trigger sneezing.
8. Paridhi and Anusha of Grade 7 started running for their morning workout. After they completed their running, they counted their breaths per minute. Anusha was breathing faster than Paridhi. Provide at least two possible explanations for why Anusha was breathing faster than Paridhi.
- Anusha may have run faster or longer, causing more oxygen demand.
- Her fitness level might be lower, causing quicker fatigue and faster breathing rate.
9. Yadu conducted an experiment to test his idea. He took two test tubes, A and B, and added a pinch of rice flour to the test tubes, half-filled with water and stirred them properly. To test tube B, he added a few drops of saliva. He left the two test tubes for 35–45 min. After that, he added iodine solution into both the test tubes. Experimental results are as shown in Fig. 9.15. What do you think he wants to test?
✅ Yadu wants to test the effect of saliva on starch digestion.
- Test tube A (no saliva): Turns blue-black, indicating starch is present.
- Test tube B (with saliva): No colour or faint colour – starch is broken down into sugar.
10. Rakshita designed an experiment taking two clean test tubes, A and B and filled them with lime water as shown in the figure. In test tube A, the surrounding air that we inhale was passed on by sucking air from the pipe, and in test tube B, the exhaled air was blown through the pipe (Fig. 9.16). What do you think she is trying to investigate? How can she confirm her findings?
✅ Rakshita is investigating whether exhaled air contains more carbon dioxide than inhaled air.
- Test tube A (inhaled air): No change.
- Test tube B (exhaled air): Lime water turns milky, indicating the presence of carbon dioxide.
- This confirms that carbon dioxide is a waste product of respiration and is exhaled from the body.
