CLASS 7 · SCIENCE · CHAPTER 9

Life Processes in Animals

Simple answers to all 10 end questions, with sample guidance for the chapter’s six exploratory projects.

16 worked answersComplete chapter answers

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Textbook pages 135–136

Question 1

Complete the journey of food through the alimentary canal by filling in the missing parts: Food → Mouth → [_] → Stomach → [_] → [___] → Anus.

Steps only

The three missing parts are the food pipe, small intestine, and large intestine.

Answer

Oesophagus → Small intestine → Large intestine.

Question 2

Pieces of chapati (A), chewed chapati (B), and boiled mashed potato (C) are each tested with iodine. What will be observed and why?

Steps only

Iodine detects starch: A and C turn blue-black; saliva may reduce the starch in B.

Answer

Chapati and potato contain starch; saliva changes some starch into sugar.

Question 3

What is the role of the diaphragm in breathing? (i) Filter air (ii) Produce sound (iii) Help inhalation and exhalation (iv) Absorb oxygen.

Steps only

The diaphragm changes chest space to help air enter and leave the lungs.

Answer

(iii) Help in inhalation and exhalation.

Question 4

Match: (i) nostrils (ii) nasal passages (iii) windpipe (iv) alveoli (v) ribcage with their functions: (a) fresh air enters (b) gas exchange (c) protects lungs (d) hairs and mucus trap dust (e) air reaches lungs.

Steps only

Nostrils a; nasal passages d; windpipe e; alveoli b; ribcage c.

Answer

(i) a,
(ii) d,
(iii) e,
(iv) b,
(v) c.

Question 5

Anil says breathing and respiration are the same. What questions could Sanvi ask to show that they are different?

Steps only

Breathing moves air; respiration releases energy from food inside the body.

Answer

They are connected but different processes.

Question 6

Which statement is correct and why? Anu: We inhale air. Shanu: We inhale oxygen. Tanu: We inhale air rich in oxygen.

Steps only

We breathe air, which contains a relatively high amount of oxygen.

Answer

Tanu is most precise: we inhale air rich in oxygen.

Question 7

Why might a person sneeze after inhaling a lot of dust-laden air?

Steps only

Dust irritates the nose, and a sneeze helps expel it.

Answer

Sneezing helps clear irritants from the nose.

Question 8

After running, Anusha is breathing faster than Paridhi. Give at least two possible explanations.

Steps only

Effort, fitness, recovery time, and health can affect breathing rate.

Answer

She may have exercised harder or recover at a different rate.

Question 9

Yadu compares rice flour mixed with water in test tube A with rice flour and saliva in test tube B. After 35–45 minutes, he adds iodine. What is he trying to test?

Steps only

Saliva changes some starch into sugar, so less starch should remain in B.

Answer

He is testing the action of saliva on starch.

Question 10

Rakshita passes inhaled air through limewater in tube A and exhaled air through tube B. What is she investigating, and how can she confirm her finding?

Steps only

Exhaled air has more CO₂; it makes limewater turn milky sooner.

Answer

Tube B should turn milky faster than tube A.

Exploratory Projects

Textbook pages 136

Question Project 1

What good practices can be included in a short report on oral hygiene?

Steps only

Brush gently twice daily, limit sugary snacks, and seek dental care when needed.

Answer

Good oral hygiene protects teeth and gums.

Question Project 2

Suggest everyday habits and foods that support a healthy digestive system.

Steps only

Choose varied, fibre-rich foods, safe water, good hygiene, and regular activity.

Answer

Healthy habits support digestion; seek help for ongoing problems.

Question Project 3

What parts should be shown and labelled in a simple 3-D digestive-system model?

Steps only

Model the food pathway and add the liver and pancreas as associated organs.

Answer

Label all main parts in the order food travels through them.

Question Project 4

What is air quality or AQI, and how can poor air affect people in different jobs?

Steps only

AQI reports air pollution; outdoor and industrial workers may encounter dust, smoke, or fumes.

Answer

Use current local data and explain that exposure varies by workplace.

Question Project 5

What is box breathing and what benefits may it have?

Steps only

Breathe in, pause, breathe out, pause for equal comfortable counts.

Answer

It may help some people feel calm; stop if uncomfortable.

Question Project 6

How might birds’ respiratory systems help them fly at high altitudes where oxygen is low?

Steps only

Lungs and air sacs move air efficiently to support flight’s high energy needs.

Answer

Birds’ respiratory system supports efficient oxygen intake at high altitudes.

Choose your location

Life Processes in Animals

Let Us Enhance Our Learning

Complete the journey of food through the alimentary canal by filling in the missing parts: Food → Mouth → [_] → Stomach → [_] → [___] → Anus.

Answer

Pieces of chapati (A), chewed chapati (B), and boiled mashed potato (C) are each tested with iodine. What will be observed and why?

Answer

What is the role of the diaphragm in breathing? (i) Filter air (ii) Produce sound (iii) Help inhalation and exhalation (iv) Absorb oxygen.

Answer

Match: (i) nostrils (ii) nasal passages (iii) windpipe (iv) alveoli (v) ribcage with their functions: (a) fresh air enters (b) gas exchange (c) protects lungs (d) hairs and mucus trap dust (e) air reaches lungs.

Answer

Anil says breathing and respiration are the same. What questions could Sanvi ask to show that they are different?

Answer

Which statement is correct and why? Anu: We inhale air. Shanu: We inhale oxygen. Tanu: We inhale air rich in oxygen.

Answer

Why might a person sneeze after inhaling a lot of dust-laden air?

Answer

After running, Anusha is breathing faster than Paridhi. Give at least two possible explanations.

Answer

Yadu compares rice flour mixed with water in test tube A with rice flour and saliva in test tube B. After 35–45 minutes, he adds iodine. What is he trying to test?

Answer

Rakshita passes inhaled air through limewater in tube A and exhaled air through tube B. What is she investigating, and how can she confirm her finding?

Answer

Exploratory Projects

What good practices can be included in a short report on oral hygiene?

Answer

Suggest everyday habits and foods that support a healthy digestive system.

Answer

What parts should be shown and labelled in a simple 3-D digestive-system model?

Answer

What is air quality or AQI, and how can poor air affect people in different jobs?

Answer

What is box breathing and what benefits may it have?

Answer

How might birds’ respiratory systems help them fly at high altitudes where oxygen is low?

Answer

How can we help?

Let Us Enhance Our Learning

Complete the journey of food through the alimentary canal by filling in the missing parts: Food → Mouth → [___] → Stomach → [___] → [___] → Anus.

Answer

Pieces of chapati (A), chewed chapati (B), and boiled mashed potato (C) are each tested with iodine. What will be observed and why?

Answer

What is the role of the diaphragm in breathing? (i) Filter air (ii) Produce sound (iii) Help inhalation and exhalation (iv) Absorb oxygen.

Answer

Match: (i) nostrils (ii) nasal passages (iii) windpipe (iv) alveoli (v) ribcage with their functions: (a) fresh air enters (b) gas exchange (c) protects lungs (d) hairs and mucus trap dust (e) air reaches lungs.

Answer

Anil says breathing and respiration are the same. What questions could Sanvi ask to show that they are different?

Answer

Which statement is correct and why? Anu: We inhale air. Shanu: We inhale oxygen. Tanu: We inhale air rich in oxygen.

Answer

Why might a person sneeze after inhaling a lot of dust-laden air?

Answer

After running, Anusha is breathing faster than Paridhi. Give at least two possible explanations.

Answer

Yadu compares rice flour mixed with water in test tube A with rice flour and saliva in test tube B. After 35–45 minutes, he adds iodine. What is he trying to test?

Answer

Rakshita passes inhaled air through limewater in tube A and exhaled air through tube B. What is she investigating, and how can she confirm her finding?

Answer

Exploratory Projects

What good practices can be included in a short report on oral hygiene?

Answer

Suggest everyday habits and foods that support a healthy digestive system.

Answer

What parts should be shown and labelled in a simple 3-D digestive-system model?

Answer

What is air quality or AQI, and how can poor air affect people in different jobs?

Answer

What is box breathing and what benefits may it have?

Answer

How might birds’ respiratory systems help them fly at high altitudes where oxygen is low?

Answer

Complete the journey of food through the alimentary canal by filling in the missing parts: Food → Mouth → [_] → Stomach → [_] → [___] → Anus.