NCERT Solutions for Class 7 Science Chapter 9 Life Processes in Animals

Question 1. Complete the journey of food through the alimentary canal by filling up the boxes with appropriate parts—

Food → Mouth → _______ → Stomach → _______ → _______ → Anus

Answer:

The complete journey of food through the alimentary canal to the anus is given below:

Food → Mouth → Esophagus → Stomach → Small Intestine → Large Intestine → Anus

Question 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.
Answer:

Question 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

Answer: (iii) To help in inhalation and exhalation

Explanation:
The diaphragm is a dome-shaped muscle that is present below the lungs. It moves down when a person inhales and moves up when they exhale. In this way, air enters and leaves the lungs, which is an important part of the breathing process.

Question 4: Match the following

Answer:

Question 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?

Answer:

To make Anil understand that he is not correct, Sanvi can ask the following questions:

1. Does the process of breathing release energy like respiration does?

2. Can you explain how breathing and respiration happen in different organs?

3. Why do we need oxygen when we breathe in? What does it do inside our bodies?

Question 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.

Answer: From the above statements made by Anu, Shanu, and Tanu, only Anu is correct.

Question 7: We often sneeze when we inhale a lot of dust-laden air. What are possible explanations for this?

Answer:

Sneezing is a natural reaction that protects our respiratory system. When we inhale a lot of dust-laden air, the dust particles irritate the linings of our nose. This irritation then sends a signal to the brain, which causes sneezing. This sneezing forcefully then removes the dust and harmful particles from our nose. Thus, this reaction helps to clean the nose and respiratory pathway.

Question 8: Paridhi and Anusha of Grade 7 started running for their morning workout. After they completed their run, 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.

Answer:

Two possible explanations for why Anusha was breathing faster than Paridhi are:

1. Anusha might be less fit or less used to running, so her body needs more oxygen and removes more carbon dioxide, which makes her breathing faster.

2. Anusha could have run faster or for a longer time than Paridhi, so her body needs to work harder to get 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 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 minutes. After that, he added iodine solution to both the test tubes. Experimental results are as shown below. What do you think he wants to test?

Answer:
By conducting this experiment, Yadu wants to test how saliva helps in the digestion of starch.

Explanation:

• Rice flour contains starch, and Iodine changes its colour and turns black when starch is present.

• In test tube A, starch does not get digested as no saliva is present in that test tube, so iodine turns black in colour.

• In test tube B, saliva, which is added by Yadu, has broken down the starch, and that's why iodine does not change its colour.

This shows that saliva helps in breaking down starch into simpler sugars.

Question 10: Rakshita designed an experiment taking two clean test tubes, A and B, and filled them with lime water. 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. What do you think she is trying to investigate? How can she confirm her findings?

Answer:

1. What is she trying to investigate?
   With the help of this experiment, Rakshita is trying to find out whether exhaled air contains carbon dioxide or not.

2. How can she confirm her findings?

• Once the experiment is done, Rakshita will observe what happens to the lime water present in both the test tubes.

• If the lime water present in test tube B, in which the exhaled air was passed, turns milky, it means that carbon dioxide is present in the exhaled air.

• If the lime water present in test tube A, having surrounding air, remains clear, then it shows that the surrounding air has very little carbon dioxide compared to exhaled air.