Important Questions Class 7 Science Chapter 9: Life Processes in Animals

Life processes are essential activities that living beings perform to survive.
Nutrition and respiration help animals obtain nutrients, release energy and remove waste products.

Life processes in animals explain how food and oxygen help the body grow, repair, work and release energy. Important Questions Class 7 Science Chapter 9 help students practise nutrition in animals, human digestive system, digestion in humans, saliva and starch, stomach, small intestine, large intestine, rumination, breathing in humans, respiration, alveoli, breathing in other animals and circulatory system. The CBSE 2026 chapter explains these processes through chapati chewing, iodine test, breathing model, lime water test, ruminants, birds, fish, frogs and earthworms.

Key Takeaways

• Digestion: Digestion breaks complex food components into simpler forms inside the alimentary canal.
• Small Intestine: Digested nutrients are mainly absorbed through the walls of the small intestine.
• Breathing: Breathing involves inhalation of air into lungs and exhalation of air from lungs.
• Respiration: Respiration uses oxygen to break down glucose and release energy.

Important Questions Class 7 Science Chapter 9 Structure 2026

Important Questions Class 7 Science Chapter 9 with Answers

Life Processes in Animals explains nutrition and respiration in humans and other animals.
Students should connect every answer with digestion, absorption, breathing, gas exchange or energy release.
These life processes in animals class 7 questions follow the NCERT 2026 chapter flow.

1. What does Important Questions Class 7 Science Chapter 9 mainly teach?

Important Questions Class 7 Science Chapter 9 mainly teach nutrition, digestion, absorption, breathing, respiration and animal adaptations. The chapter explains how animals obtain nutrients and release usable energy.

1. Nutrition Skill: Trace food through the alimentary canal.
2. Digestion Skill: Explain breakdown of complex food.
3. Breathing Skill: Explain inhalation and exhalation.
4. Respiration Skill: Explain energy release from glucose.
5. Final Result: Chapter 9 teaches digestion and respiration in animals.

2. What is the name of Class 7 Science Chapter 9?

The name of Class 7 Science Chapter 9 is Life Processes in Animals. It explains nutrition and respiration in detail.

1. Chapter Number: 9.
2. Chapter Name: Life Processes in Animals.
3. Textbook: Curiosity.
4. Final Result: Chapter 9 is about nutrition and respiration in animals.

3. What are life processes?

Life processes are essential activities needed for survival of living beings. Nutrition, respiration, excretion and reproduction are examples.

1. Nutrition: Provides food and nutrients.
2. Respiration: Releases usable energy.
3. Excretion: Removes waste.
4. Reproduction: Produces new individuals.
5. Final Result: Life processes keep living beings alive.

Class 7 Science Chapter 9 Important Questions

Class 7 Science Chapter 9 important questions focus on how animals use food and oxygen.
Animals eat different kinds of food and digest them in different ways.
The chapter shows that body systems work together to sustain life.

4. Why do animals need food?

Animals need food to obtain energy and materials for growth and repair. Food helps them carry out life processes.

1. Energy: Needed for movement and work.
2. Growth: Builds body parts.
3. Repair: Helps damaged tissues recover.
4. Final Result: Food supports energy, growth and repair.

5. What complex components are present in animal food?

Animal food contains complex components such as carbohydrates, proteins and fats. These must be broken into simpler forms before use.

1. Carbohydrate: Provides energy.
2. Protein: Supports growth and repair.
3. Fat: Stores and supplies energy.
4. Final Result: Food contains complex nutrients.

6. Why must complex food components be broken down?

Complex food components must be broken down because the body cannot use them directly. Simpler forms can be absorbed and transported.

1. Complex Form: Too large for direct use.
2. Digestion: Breaks food into simpler forms.
3. Absorption: Simple nutrients enter blood.
4. Final Result: Digestion makes nutrients usable.

7. What is the alimentary canal?

The alimentary canal is a long tube through which food passes during digestion. It starts at the mouth and ends at the anus.

1. Starting Point: Mouth.
2. Path: Food pipe, stomach and intestines.
3. Ending Point: Anus.
4. Final Result: Alimentary canal carries food through the body.

Nutrition in Animals Class 7 Questions

Nutrition in animals class 7 questions explain how animals obtain and use food.
Some animals suck nectar, some drink milk, some swallow prey and some filter food particles.
Food habits differ, but animals need nutrients for life processes.

8. What is nutrition in animals?

Nutrition in animals is the process of taking food and using it for energy, growth and body repair. It includes digestion and absorption.

1. Food Intake: Animals consume food.
2. Digestion: Food breaks into simpler forms.
3. Absorption: Nutrients enter blood.
4. Final Result: Nutrition helps animals use food.

9. How do different animals obtain food?

Different animals obtain food in different ways. Bees suck nectar, snakes swallow prey, and some aquatic animals filter tiny food particles.

1. Bees: Suck flower nectar.
2. Infants: Feed on mother’s milk.
3. Python: Swallows prey.
4. Aquatic Animals: Filter tiny particles.
5. Final Result: Animals show different feeding methods.

10. Why is digestion part of nutrition?

Digestion is part of nutrition because food must be broken down before nutrients can be absorbed. Without digestion, complex food remains unusable.

1. Food: Contains complex substances.
2. Digestion: Breaks them down.
3. Nutrients: Enter blood after absorption.
4. Final Result: Digestion makes nutrition possible.

11. What happens after food is digested?

After food is digested, nutrients are absorbed into blood and transported to body parts. These nutrients provide energy and support body functions.

1. Absorption: Nutrients enter blood.
2. Transport: Blood carries nutrients.
3. Use: Growth, repair and energy.
4. Final Result: Digested nutrients are used by the body.

Human Digestive System Class 7 Questions

Human digestive system class 7 questions cover the alimentary canal and associated organs.
The alimentary canal includes mouth, oesophagus, stomach, small intestine, large intestine and anus.
The liver and pancreas add digestive secretions to help digestion.

12. What are the main parts of the human digestive system?

The main parts are mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus. Liver and pancreas are associated organs.

1. Mouth: Starts digestion.
2. Oesophagus: Carries food to stomach.
3. Stomach: Churns and partially digests food.
4. Small Intestine: Completes digestion and absorbs nutrients.
5. Large Intestine: Absorbs water and salts.
6. Final Result: The digestive system has an alimentary canal and associated organs.

13. What is the correct journey of food through the alimentary canal?

The correct journey is mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus. Food moves through this tube in order.

1. Start: Mouth.
2. Middle: Oesophagus, stomach and intestines.
3. Storage: Rectum.
4. Exit: Anus.
5. Final Result: Food moves from mouth to anus.

14. What is mechanical digestion?

Mechanical digestion is the physical breakdown of food into smaller pieces. Teeth crush and chew food in the mouth.

1. Body Part: Teeth.
2. Action: Crushing and chewing.
3. Effect: Food becomes fine pieces.
4. Final Result: Mechanical digestion begins in the mouth.

15. What is digestion?

Digestion is the process of breaking complex food components into simpler forms. These simpler forms can be absorbed by the body.

1. Complex Food: Starch, proteins and fats.
2. Digestive Juices: Break them down.
3. Simple Forms: Enter blood after absorption.
4. Final Result: Digestion converts food into absorbable nutrients.

Digestion in Humans Class 7 Questions

Digestion in humans class 7 questions explain the role of mouth, food pipe, stomach and intestines.
Food is partially digested in the mouth and stomach.
Digestion is completed mainly in the small intestine.

16. How does digestion begin in the mouth?

Digestion begins in the mouth when teeth chew food and saliva mixes with it. Saliva starts breaking starch into sugar.

1. Teeth: Crush and chew food.
2. Tongue: Mixes food with saliva.
3. Saliva: Starts starch digestion.
4. Final Result: Mouth performs mechanical and partial chemical digestion.

17. What is the role of the tongue in digestion?

The tongue mixes chewed food with saliva and pushes softened food into the food pipe. It helps swallowing.

1. Mixing: Food and saliva mix.
2. Softening: Food becomes easier to swallow.
3. Pushing: Food enters oesophagus.
4. Final Result: Tongue helps mixing and swallowing.

18. What is the oesophagus?

The oesophagus is a long flexible tube that carries food from mouth to stomach. It is also called food pipe.

1. Starting Point: Mouth region.
2. Ending Point: Stomach.
3. Other Name: Food pipe.
4. Final Result: Oesophagus carries swallowed food to the stomach.

19. How does food move down the oesophagus?

Food moves down the oesophagus by wave-like contraction and relaxation of its walls. This movement pushes food into the stomach.

1. Wall Action: Contracts and relaxes.
2. Movement: Wave-like.
3. Direction: Towards stomach.
4. Final Result: Food moves by wave-like muscular action.

20. What happens to food in the stomach?

Food is churned and mixed with digestive juice, acid and mucus in the stomach. Proteins are partly broken down there.

1. Churning: Stomach walls contract and relax.
2. Digestive Juice: Breaks proteins.
3. Acid: Kills many harmful bacteria.
4. Mucus: Protects stomach lining.
5. Final Result: Stomach partially digests food into a semi-liquid mass.

21. What is the role of stomach acid?

Stomach acid helps break down proteins and kills many harmful bacteria. It creates suitable conditions for stomach digestion.

1. Protein Digestion: Supported by acid.
2. Bacteria: Many harmful bacteria are killed.
3. Food Safety: Reduces infection risk.
4. Final Result: Stomach acid supports digestion and protection.

22. Why does mucus protect the stomach?

Mucus protects the stomach because it shields the stomach lining from acid. Without mucus, acid could damage the lining.

1. Acid: Present in stomach secretion.
2. Mucus Layer: Covers lining.
3. Protection: Prevents damage.
4. Final Result: Mucus protects the stomach wall from acid.

Saliva and Starch Class 7 Questions

Saliva and starch class 7 questions explain why chapati or rice tastes sweet after chewing.
Saliva contains digestive juice that breaks starch into sugar.
The iodine test helps show whether starch is still present.

23. Why does chapati taste sweet after chewing for some time?

Chapati tastes sweet after chewing because saliva breaks starch into sugar. This sugar gives a sweet taste.

1. Food: Chapati contains starch.
2. Saliva: Contains digestive juice.
3. Change: Starch breaks into sugar.
4. Final Result: Chewed chapati tastes sweet due to sugar formation.

24. What is the role of saliva in digestion?

Saliva moistens food and begins starch digestion. It makes food soft and easier to swallow.

1. Moistening: Softens food.
2. Digestion: Breaks starch into sugar.
3. Swallowing: Helps food move down.
4. Final Result: Saliva helps digestion and swallowing.

25. What happens when iodine is added to boiled rice?

Boiled rice turns blue-black when iodine is added because rice contains starch. Iodine gives blue-black colour with starch.

1. Food: Boiled rice.
2. Chemical: Iodine solution.
3. Observation: Blue-black colour.
4. Final Result: Blue-black colour shows starch is present.

26. What happens when iodine is added to chewed boiled rice?

Chewed boiled rice may not turn blue-black or may show only light blue-black colour. Saliva breaks much of the starch into sugars.

1. Chewing: Mixes rice with saliva.
2. Saliva Action: Breaks starch.
3. Observation: No or slight colour change.
4. Final Result: Chewed rice has less starch due to saliva action.

27. What does the saliva and starch activity prove?

The activity proves that saliva helps break starch into sugar. Iodine colour change becomes weaker after chewing.

1. Unchewed Rice: Shows starch clearly.
2. Chewed Rice: Shows less starch.
3. Reason: Saliva acts on starch.
4. Final Result: Saliva starts digestion of starch in the mouth.

Small Intestine Class 7 Questions

Small intestine class 7 questions explain digestion and absorption after stomach digestion.
It is the longest part of the alimentary canal.
It receives secretions from liver, pancreas and its own inner lining.

28. Why is the small intestine important?

The small intestine is important because most digestion and nutrient absorption happen there. It receives bile, pancreatic juice and intestinal juice.

1. Bile: Helps fat digestion.
2. Pancreatic Juice: Digests carbohydrates, proteins and fats.
3. Intestinal Juice: Further breaks food components.
4. Final Result: Small intestine completes digestion and absorbs nutrients.

29. How long is the small intestine?

The small intestine is about 6 metres long. It is the longest part of the alimentary canal.

1. Length: About 6 m.
2. Comparison: Nearly twice classroom height in the chapter.
3. Function: Digestion and absorption.
4. Final Result: Small intestine is long for efficient digestion and absorption.

30. What is the role of bile?

Bile neutralises acid in food coming from the stomach and breaks fats into tiny droplets. This makes fat digestion easier.

1. Source: Liver.
2. Nature: Mildly basic.
3. Function: Helps fat digestion.
4. Final Result: Bile helps neutralise acid and break fats into droplets.

31. What is the role of pancreatic juice?

Pancreatic juice neutralises acid and breaks down carbohydrates, proteins and fats. It is secreted by the pancreas.

1. Source: Pancreas.
2. Nature: Basic.
3. Food Components: Carbohydrates, proteins and fats.
4. Final Result: Pancreatic juice helps digest all major food components.

32. What is absorption of nutrients?

Absorption of nutrients is the passage of digested nutrients from the small intestine into blood. Blood then carries them to body parts.

1. Location: Small intestine.
2. Nutrients: Simple digested forms.
3. Transport: Blood vessels carry nutrients.
4. Final Result: Absorption transfers nutrients into blood.

33. How does the small intestine absorb nutrients efficiently?

The inner lining of the small intestine has thousands of finger-like projections. These increase surface area for nutrient absorption.

1. Finger-like Projections: Present in inner lining.
2. Surface Area: Increases greatly.
3. Blood Vessels: Carry absorbed nutrients.
4. Final Result: Finger-like projections make absorption efficient.

Large Intestine Class 7 Questions

Large intestine class 7 questions explain what happens to undigested food.
The large intestine is shorter but wider than the small intestine.
It absorbs water and some salts, forming semi-solid stool.

34. What is the role of the large intestine?

The large intestine absorbs water and some salts from undigested food. It changes waste into semi-solid stool.

1. Undigested Food: Enters large intestine.
2. Water: Absorbed.
3. Salts: Some salts are absorbed.
4. Final Result: Large intestine forms stool from undigested food.

35. Why is it called large intestine?

It is called large intestine because it is wider than the small intestine. It is shorter than the small intestine.

1. Length: About 1.5 m.
2. Width: Wider than small intestine.
3. Name Reason: Width, not length.
4. Final Result: Large intestine is named for its width.

36. What is stool?

Stool is semi-solid waste formed after water and some salts are absorbed from undigested food. It is stored in the rectum.

1. Source: Undigested food.
2. Water Removal: Makes it semi-solid.
3. Storage: Rectum.
4. Final Result: Stool is semi-solid digestive waste.

37. What is egestion?

Egestion is the process of removing stool from the body through the anus. It removes waste that the body does not need.

1. Waste: Stool.
2. Exit Part: Anus.
3. Process Name: Egestion.
4. Final Result: Egestion removes undigested waste.

38. Why are fibre-rich foods useful?

Fibre-rich foods help the large intestine function properly and make stool easier to pass. Fruits, vegetables and whole grains provide fibre.

1. Fibre: Adds bulk to stool.
2. Food Sources: Fruits and vegetables.
3. Benefit: Easier passage of stool.
4. Final Result: Fibre supports healthy digestion.

Rumination Class 7 Questions

Rumination class 7 questions explain digestion in grass-eating animals.
Cows and buffaloes partly chew food, swallow it and later bring it back for chewing.
These animals are called ruminants.

39. What is rumination?

Rumination is the process in which partially digested food is brought back to the mouth for gradual chewing. Cows and buffaloes show this process.

1. First Step: Animal partly chews grass.
2. Second Step: Food enters stomach.
3. Third Step: Food returns to mouth.
4. Final Result: Rumination is rechewing of partially digested food.

40. What are ruminants?

Ruminants are grass-eating animals that show rumination. Cows, buffaloes and goats are examples.

1. Food: Grass.
2. Process: Rumination.
3. Examples: Cow, buffalo and goat.
4. Final Result: Ruminants rechew partially digested food.

41. Why do cows keep chewing even when not grazing?

Cows keep chewing because partially digested food returns to the mouth from the stomach. They chew it thoroughly during rumination.

1. Earlier Food: Partly chewed grass.
2. Return: Food comes back to mouth.
3. Chewing: Gradual and thorough.
4. Final Result: Cows chew returned food during rumination.

42. How long can a cow spend chewing food in a day?

A cow can spend about 8 hours a day chewing food. This helps it digest grass more effectively.

1. Animal: Cow.
2. Activity: Chewing food.
3. Duration: About 8 hours daily.
4. Final Result: A cow may chew food for about 8 hours per day.

43. How is digestion in birds different from humans?

Birds do not have teeth, but they have a gizzard. The gizzard helps break down food with contractions and swallowed grit.

1. Teeth: Absent in birds.
2. Gizzard: Special chamber.
3. Grit: Small stones help grinding.
4. Final Result: Birds use gizzard instead of teeth for food breakdown.

Respiration in Animals Class 7 Questions

Respiration in animals class 7 questions explain how nutrients release energy.
Glucose breaks down with oxygen to form carbon dioxide, water and energy.
Different animals use different breathing organs.

44. What is respiration?

Respiration is the process by which nutrients are converted into usable energy. Oxygen helps break down glucose inside the body.

1. Nutrient: Glucose.
2. Gas Needed: Oxygen.
3. Products: Carbon dioxide, water and energy.
4. Final Result: Respiration releases energy from glucose.

45. Write the word equation for respiration.

The word equation is glucose + oxygen → carbon dioxide + water + energy. It shows how energy is released in the body.

1. Reactants: Glucose and oxygen.
2. Products: Carbon dioxide and water.
3. Useful Output: Energy.
4. Final Result: Respiration produces energy from glucose.

46. Why do animals need respiration?

Animals need respiration to release energy from food. This energy helps them walk, run, play and think.

1. Food: Provides glucose.
2. Oxygen: Helps break glucose.
3. Energy: Supports activities.
4. Final Result: Respiration provides usable energy.

47. Is respiration the same as breathing?

No, respiration is not the same as breathing. Breathing is a physical process, while respiration is a chemical process inside the body.

1. Breathing: Air enters and leaves lungs.
2. Respiration: Glucose breaks down using oxygen.
3. Output: Energy is released.
4. Final Result: Breathing and respiration are different processes.

Breathing in Humans Class 7 Questions

Breathing in humans class 7 questions explain inhalation, exhalation and respiratory organs.
Humans breathe through nostrils, nasal passages, windpipe and lungs.
The diaphragm and ribs help air move in and out.

48. What is breathing?

Breathing is the process of inhaling and exhaling air. It brings oxygen-rich air into lungs and removes carbon dioxide-rich air.

1. Inhalation: Air enters the lungs.
2. Exhalation: Air leaves the lungs.
3. Purpose: Gas exchange support.
4. Final Result: Breathing moves air in and out of lungs.

49. What are the main parts of the human respiratory system?

The main parts are nostrils, nasal passages, windpipe, lungs, alveoli, rib cage and diaphragm. These parts help breathing and gas exchange.

1. Nostrils: Air enters and leaves.
2. Windpipe: Carries air to lungs.
3. Lungs: Contain alveoli.
4. Diaphragm: Helps inhalation and exhalation.
5. Final Result: Respiratory system supports breathing and gas exchange.

50. Why should we breathe through the nose?

We should breathe through the nose because tiny hair and mucus trap dust and dirt. This helps clean the air before it enters lungs.

1. Nasal Hair: Traps dust.
2. Mucus: Traps dirt particles.
3. Protection: Cleaner air enters lungs.
4. Final Result: Nose filters inhaled air.

51. What happens during inhalation?

During inhalation, ribs move up and outwards, and the diaphragm moves downwards. Chest space increases, and air enters lungs.

1. Ribs: Move up and outward.
2. Diaphragm: Moves downward.
3. Chest Space: Increases.
4. Final Result: Inhalation fills lungs with air.

52. What happens during exhalation?

During exhalation, ribs move down and inwards, and the diaphragm moves upwards. Chest space reduces, and air moves out.

1. Ribs: Move down and inward.
2. Diaphragm: Moves upward.
3. Chest Space: Decreases.
4. Final Result: Exhalation pushes air out of lungs.

53. What does the rubber sheet represent in the breathing model?

The rubber sheet represents the diaphragm. Pulling it downward inflates the balloons like lungs during inhalation.

1. Balloons: Represent lungs.
2. Y-shaped Tube: Represents air passage.
3. Rubber Sheet: Represents diaphragm.
4. Final Result: The rubber sheet models diaphragm movement.

54. What does the lime water test show about exhaled air?

The lime water test shows that exhaled air contains more carbon dioxide than inhaled air. Exhaled air turns lime water milky.

1. Test Tube A: Air from surroundings.
2. Test Tube B: Exhaled air.
3. Observation: Test tube B turns milky.
4. Final Result: Exhaled air has more carbon dioxide.

Alveoli Class 7 Questions

Alveoli class 7 questions explain gas exchange inside the lungs.
Alveoli are small balloon-like sacs surrounded by blood vessels.
Oxygen enters blood, and carbon dioxide leaves blood at the alveoli.

55. What are alveoli?

Alveoli are small balloon-like sacs in the lungs where gas exchange occurs. They are surrounded by fine blood vessels.

1. Location: Lungs.
2. Shape: Small sacs.
3. Function: Exchange oxygen and carbon dioxide.
4. Final Result: Alveoli are gas exchange sites in lungs.

56. How does gas exchange happen in alveoli?

Oxygen from alveoli passes into blood, and carbon dioxide from blood passes into alveoli. The exhaled air carries carbon dioxide out.

1. Oxygen: Moves from alveoli to blood.
2. Carbon Dioxide: Moves from blood to alveoli.
3. Blood: Transports gases.
4. Final Result: Alveoli exchange oxygen and carbon dioxide.

57. What percentage of oxygen is present in inhaled and exhaled air?

Inhaled air has nearly 21% oxygen, while exhaled air has nearly 16–17% oxygen. Not all oxygen is used.

1. Inhaled Oxygen: Nearly 21%.
2. Exhaled Oxygen: Nearly 16–17%.
3. Conclusion: Some oxygen remains unused.
4. Final Result: Exhaled air still contains oxygen.

58. What percentage of carbon dioxide is present in inhaled and exhaled air?

Inhaled air has nearly 0.04% carbon dioxide, while exhaled air has nearly 4–5% carbon dioxide. Respiration produces carbon dioxide.

1. Inhaled Carbon Dioxide: Nearly 0.04%.
2. Exhaled Carbon Dioxide: Nearly 4–5%.
3. Reason: Body releases carbon dioxide.
4. Final Result: Exhaled air has more carbon dioxide.

59. Why does breathing rate increase after running?

Breathing rate increases after running because the body needs more energy. More oxygen is needed to break down glucose faster.

1. Running: Muscles work harder.
2. Energy Need: Increases.
3. Oxygen Need: Increases.
4. Final Result: Exercise increases breathing rate.

Breathing in Other Animals Class 7 Questions

Breathing in other animals class 7 questions explain animal adaptations to habitat.
Some animals breathe through lungs, some through gills and some through skin.
Different body structures help animals survive in different environments.

60. How do birds, elephants, lions and snakes breathe?

Birds, elephants, lions and snakes breathe through lungs. Their lung structures differ, but lungs perform gas exchange.

1. Birds: Lungs.
2. Elephants: Lungs.
3. Lions: Lungs.
4. Snakes: Lungs.
5. Final Result: Many land animals breathe through lungs.

61. How do fish breathe?

Fish breathe through gills. Gills exchange oxygen and carbon dioxide between blood and gases dissolved in water.

1. Body Part: Gills.
2. Medium: Water.
3. Gas Exchange: Across gill surfaces.
4. Final Result: Fish use gills for breathing.

62. How do frogs breathe?

Tadpoles breathe through gills, while adult frogs use lungs on land and skin in water. This helps frogs live in both habitats.

1. Tadpole: Gills.
2. Adult Frog on Land: Lungs.
3. Adult Frog in Water: Skin.
4. Final Result: Frogs use different breathing methods at different stages.

63. How do earthworms breathe?

Earthworms breathe through moist skin. Oxygen and carbon dioxide exchange across their skin.

1. Body Part: Moist skin.
2. Need: Skin must stay moist.
3. Gas Exchange: Through skin surface.
4. Final Result: Earthworms use moist skin for breathing.

64. Why do animals have different breathing mechanisms?

Animals have different breathing mechanisms because they live in different habitats. Their bodies are adapted to land, water or both.

1. Water Habitat: Gills help fish.
2. Land Habitat: Lungs help mammals and birds.
3. Wet Soil Habitat: Moist skin helps earthworms.
4. Final Result: Breathing organs match animal habitats.

Circulatory System Class 7 Questions

Circulatory system class 7 questions explain how nutrients and gases move inside the body.
Blood transports absorbed nutrients and oxygen to body parts.
The heart pumps blood through blood vessels.

65. What is the circulatory system?

The circulatory system transports nutrients, oxygen and other substances throughout the body. It includes heart, blood and blood vessels.

1. Heart: Pumps blood.
2. Blood: Carries substances.
3. Blood Vessels: Form transport pathways.
4. Final Result: Circulatory system transports materials inside the body.

66. What is the role of blood in the body?

Blood carries nutrients and oxygen to different body parts and carries waste products away. It connects digestion, respiration and excretion.

1. Nutrients: From small intestine.
2. Oxygen: From lungs.
3. Waste: Carried away from cells.
4. Final Result: Blood transports useful substances and wastes.

67. What is the role of the heart?

The heart pumps blood through blood vessels. This helps deliver oxygen and nutrients to all parts of the body.

1. Organ: Heart.
2. Action: Pumps blood.
3. Result: Continuous transport.
4. Final Result: Heart is the pumping organ of the circulatory system.

68. How are digestion, respiration and circulation connected?

Digestion provides nutrients, respiration uses oxygen to release energy, and circulation transports nutrients and oxygen. These systems work together.

1. Digestion: Produces simple nutrients.
2. Respiration: Releases energy from glucose.
3. Circulation: Carries nutrients and gases.
4. Final Result: Body systems coordinate to sustain life.

NCERT Class 7 Science Chapter 9 Questions

NCERT Class 7 Science Chapter 9 questions test the alimentary canal, saliva, breathing, respiration and gas exchange.
Students should answer using process names and activity observations.
These NCERT Class 7 Science Chapter 9 questions follow the 2026 exercise pattern.

69. Complete the journey of food through the alimentary canal.

The journey is mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus. Food follows this pathway during digestion.

1. First Part: Mouth.
2. Next Part: Oesophagus.
3. Main Digestion: Stomach and small intestine.
4. Waste Exit: Rectum and anus.
5. Final Result: Food travels from mouth to anus.

70. What happens when iodine is added to chapati pieces?

Chapati pieces turn blue-black because they contain starch. Iodine gives blue-black colour with starch.

1. Food: Chapati.
2. Test: Iodine solution.
3. Observation: Blue-black colour.
4. Final Result: Chapati contains starch.

71. What happens when iodine is added to chewed chapati?

Chewed chapati may show no colour change or a light blue-black colour. Saliva breaks much of the starch into sugar.

1. Chewing: Mixes chapati with saliva.
2. Saliva: Breaks starch.
3. Observation: Less blue-black colour.
4. Final Result: Chewed chapati has reduced starch.

72. What happens when iodine is added to boiled and mashed potato?

Boiled and mashed potato turns blue-black because it contains starch. Iodine detects starch in the food.

1. Food: Potato.
2. Component: Starch.
3. Iodine Result: Blue-black colour.
4. Final Result: Potato contains starch.

73. What is the role of diaphragm in breathing?

The diaphragm helps in inhalation and exhalation. It moves down during inhalation and moves up during exhalation.

1. Inhalation: Diaphragm moves downward.
2. Exhalation: Diaphragm moves upward.
3. Effect: Chest space changes.
4. Final Result: Diaphragm helps air move in and out.

74. Match nostrils with their function.

Nostrils allow fresh air from outside to enter the respiratory system. Air also leaves through them during exhalation.

1. Part: Nostrils.
2. Function: Air entry and exit.
3. Process: Breathing.
4. Final Result: Nostrils allow air movement.

75. Match nasal passages with their function.

Nasal passages contain tiny hair and mucus that trap dust and dirt. They help clean inhaled air.

1. Part: Nasal passages.
2. Structures: Hair and mucus.
3. Function: Trap dust and dirt.
4. Final Result: Nasal passages filter inhaled air.

76. Match windpipe with its function.

The windpipe carries air from nasal passages towards the lungs. It branches before entering the lungs.

1. Part: Windpipe.
2. Function: Air passage.
3. Destination: Lungs.
4. Final Result: Windpipe carries air to lungs.

77. Match alveoli with their function.

Alveoli are the sites where gas exchange occurs. Oxygen enters blood, and carbon dioxide leaves blood.

1. Part: Alveoli.
2. Function: Gas exchange.
3. Location: Lungs.
4. Final Result: Alveoli exchange gases.

78. Match rib cage with its function.

The rib cage protects the lungs. It also moves during breathing.

1. Part: Rib cage.
2. Function: Protection.
3. Organ Protected: Lungs.
4. Final Result: Rib cage protects lungs.

79. Which statement is correct: We inhale air, oxygen, or air rich in oxygen?

The correct statement is we inhale air rich in oxygen. Inhaled air contains nearly 21% oxygen and other gases.

1. Air: Mixture of gases.
2. Oxygen: Nearly 21%.
3. Correct Statement: Air rich in oxygen.
4. Final Result: We inhale air rich in oxygen.

80. Why do we sneeze after inhaling dust-laden air?

We sneeze because dust irritates the nasal passages. Sneezing helps remove dust and dirt from the air passage.

1. Dust: Enters nose.
2. Irritation: Occurs in nasal passages.
3. Sneezing: Expels unwanted particles.
4. Final Result: Sneezing helps clear dust from the nose.

Class 7 Science Chapter 9 Questions and Answers

Class 7 Science Chapter 9 questions and answers should use simple process-based explanations.
Students should avoid mixing breathing with respiration.
These answers support quick revision for school tests.

81. What question can Sanvi ask Anil if he says breathing and respiration are same?

Sanvi can ask, Does breathing release energy from glucose inside the body? This helps show that respiration and breathing differ.

1. Breathing: Moves air in and out.
2. Respiration: Releases energy from glucose.
3. Key Difference: Physical process and chemical process.
4. Final Result: Breathing and respiration are not the same.

82. Why may Anusha breathe faster than Paridhi after running?

Anusha may breathe faster because she ran harder or needs more oxygen after exercise. Her body may require more energy.

1. Reason 1: Higher running effort.
2. Reason 2: Lower fitness level.
3. Reason 3: Higher oxygen demand.
4. Final Result: Faster breathing can show greater oxygen need.

83. What did Yadu test using rice flour, saliva and iodine?

Yadu tested whether saliva breaks down starch. The test tube with saliva shows less blue-black colour after iodine.

1. Rice Flour: Contains starch.
2. Saliva: Acts on starch.
3. Iodine: Tests starch.
4. Final Result: The experiment tests action of saliva on starch.

84. What did Rakshita test using lime water?

Rakshita tested whether exhaled air contains more carbon dioxide than inhaled air. Lime water turns milky with carbon dioxide.

1. Test Tube A: Inhaled surrounding air.
2. Test Tube B: Exhaled air.
3. Observation: Exhaled air makes lime water milky.
4. Final Result: The experiment tests carbon dioxide in exhaled air.

85. Why is smoking harmful to the respiratory system?

Smoking damages lungs and increases the risk of respiratory diseases. It can cause persistent coughing, infections and lung cancer.

1. Lungs: Get damaged.
2. Diseases: Risk increases.
3. Passive Smoking: Harms others too.
4. Final Result: Smoking harms smokers and people nearby.

Class 7 Science Important Links