Life Processes in Animals 7th Class
Class 7 Science – Questions & Answers
1. Complete the journey of food through the alimentary canal by filling up the boxes with appropriate parts—
Food → Mouth → ______ → ______ → Anus
Food → Mouth → Oesophagus (food pipe) → Stomach → Intestines (small then large) → Anus. Food is chewed, pushed, churned, absorbed, then waste exits.
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: chapati turns deep blue-black; raw starch present.
• Test tube B: little or no blue; saliva broke much starch.
• Test tube C: darkest blue-black; boiled potato still rich in untouched starch. Iodine colours only unbroken starch.
3. What is the role of the diaphragm in breathing?
Correct option (iii). The diaphragm flattens downward, pulling air in; then domes upward, pushing air out, so lungs work smoothly.
4. Match the following:
| Name of the part | Functions |
|---|---|
| (i) Nostrils | (a) fresh air from outside enters |
| (ii) Nasal passages | (d) trap hair and mucus help to trap dust and dirt from the air we breathe |
| (iii) Windpipe | (e) air reaches our lungs through this part |
| (iv) Alveoli | (b) exchange of gases occurs |
| (v) Ribcage | (c) protects lungs |
(i)–a, (ii)–d, (iii)–e, (iv)–b, (v)–c. This pairing shows how every structure has its special breathing task.
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?
Sanvi might ask, “Does breathing produce energy like respiration? Where inside the cell is glucose changed into energy? Can air alone release ATP?”
6. Which of the following statements is correct and why?
Anu: We inhale air.
Shanu: We inhale oxygen.
Tanu: We inhale air rich in oxygen.
Tanu is correct. Inhaled air is mostly nitrogen with about 21 percent oxygen. Our lungs grab this oxygen; the rest passes out.
7. We often sneeze when we inhale a lot of dust-laden air. What can be possible explanations for this?
Dust irritates delicate nasal lining. Sneezing is a quick reflex that forcefully expels dusty air, protecting lungs from harmful particles.
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 farther, using more energy. Her muscles then demanded extra oxygen and released more carbon dioxide, raising breath 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 is checking whether saliva’s enzyme amylase breaks starch into sugar. Less blue colour in tube B shows starch was digested.
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?
She is investigating carbon dioxide levels. Exhaled air should turn lime water milky faster, proving we breathe out more CO₂. Measuring time to turn milky confirms it.
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