Class 7 Science Chapter 9: Life Processes in Animals Solutions

Question 1.
Cows keep chewing the food even when they are not actively grazing or eating anything. Why? (Page 127)

Answer:

Cows keep chewing even when they are not actively eating because they ruminate, or chew cud, which helps in digesting their food more efficiently. This process allows them to extract essential nutrients from tough plant material.

Question 2.

Is the process of respiration the same in all animals? (Page 128)

Answer: No, respiration is not the same in all animals. It varies based on factors such as their size, habitat, and level of complexity.

Question 1.

Complete the journey of food through the alimentary canal by filling up the boxes with appropriate parts

Answer:

Question 2.
Sahil placed some pices 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.

Answer:
The observations can be explained by the given table:

Question 3.
What is the role of diaphragm in breathing?

(i) To filter the air
(ii) To produce sound
(iii) To hep in inhalation and exhalation
(iv) To absorb oxygen

Answer:
(iii) To help in inhalation and exhalation

Question 4.

Answer:

Question 5.
Anil claims to his friend Sanvi that respiration and breathing are the same process. What question(s) Sanvi ask him to make him understand that he is not correct?

Answer:

Sanvi can ask Anil the following questions to help him understand that breathing and respiration are different processes:

• Do plants breathe? How do they obtain oxygen?

• Does the carbon dioxide we breathe out come from breathing or from respiration?

• Is it possible to carry out respiration without breathing for a short period?

• Can you think of an example where breathing occurs but respiration does not?

Question 6.

Which of the following statement is correct and why?

Anu: We inhale air.

Shanu: We inhale oxygen.

Tanu: We inhale air rich in oxygen.

Answer: Tanu’s statement is correct. We inhale air that is rich in oxygen—about 21% of the air we breathe in is oxygen. The air we exhale contains a higher amount of carbon dioxide compared to the air we inhale.

Question 7.

We often sneeze when we inhale a lot of dust¬laden air. What can be possible explanations for this?

Answer: When we breathe in air containing a lot of dust, the dust particles are trapped by the tiny hairs inside the nasal cavity. These particles irritate the lining of the nose, triggering a sneeze. Sneezing helps push out the dust and other foreign particles, allowing cleaner air to enter the body.

Question 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 breating faster than Paridhi. Provide at least two possible explanations for why Anusha was breathing faster than Paridhi.

Answer: Two possible reasons are:

• Anusha may not be physically fit, which could make her lungs work less efficiently.

• She may be suffering from asthma or a cold, causing difficulty in getting enough oxygen.

Question 9.

Yadu conducted an experiment to test his idea. He took two test tubes, A and B, and added a pinch of rich 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?

Fig. Experimental results

Answer: Yadu wants to check whether starch is present in both test tubes.

Question 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?

Fig. Experimental set-up

Answer:

Rakshita is investigating the gases involved in breathing. The lime water in test tube B turned milky, while the lime water in test tube A showed no change. Since lime water becomes milky in the presence of carbon dioxide, this shows that exhaled air contains more carbon dioxide than inhaled air.

Activity 9.1: Let Us Investigate (Page 123)

Table 9.1: Action of saliva on starch

Activity 9.2: Let Us Make a Model (Page 130)

Observation and Conclusion:

• This experiment demonstrates how inhalation and exhalation take place during breathing. When the rubber sheet at the bottom of the bottle is pulled downward, the space inside the bottle increases. This causes air to enter the balloon, making it inflate, similar to how the lungs fill with air during inhalation. It shows that when the diaphragm moves downward, it creates more space in the chest cavity, allowing air to flow into the lungs.

• When the rubber sheet is pushed upward, the space inside the bottle decreases and the pressure inside increases. As a result, air is forced out of the balloon. This represents exhalation, during which the diaphragm relaxes and moves upward, reducing the chest cavity space and pushing air out of the lungs.

Activity 9.3: Let Us Explore (Page 131)

Fig. (a) Air is passed into lime water with a pichkari/syringe

(b) Air is exhaled into lime water

Observation:
The lime water in test tube B turns milky when it receives exhaled air, while the lime water in test tube A shows no change.

Conclusion:
This shows that exhaled air contains carbon dioxide. Lime water reacts with carbon dioxide to form calcium carbonate, which gives it a milky appearance. Since the change occurs only in test tube B, it confirms that the air we breathe out has more carbon dioxide than the air we breathe in.

Life Processes in Animals: Class 7 Science Chapter 9 Overview

Understanding life processes such as nutrition, circulation, respiration, excretion, and reproduction is essential for scoring high in exams. Mastering these concepts will help you grasp the vital processes that ensure the survival of humans and other animals.

Chapters like digestive system and breathing mechanism introduce important terms such as alimentary canal, small intestine, and gills. Focus on differences between physical and chemical processes like breathing and respiration for conceptual clarity.

Review chapter highlights and diagrams to boost understanding. Regular revision of NCERT topics and exercise questions will ensure you retain facts and score well in your Class 7 Science tests.