A. Choose the Correct Answer

1. Where does digestion of food begin?

a) Stomach    b) Mouth    c) Small intestine    d) Large intestine

2. Which substance in saliva helps break down starch?

a) Acid    b) Digestive juice    c) Bile    d) Mucus

3. Which organ mainly absorbs digested nutrients?

a) Stomach    b) Large intestine    c) Small intestine    d) Oesophagus

4. Which organ produces bile?

a) Pancreas    b) Liver    c) Stomach    d) Small intestine

5. Which process removes undigested food from the body?

a) Absorption    b) Digestion    c) Egestion    d) Respiration

6. Which animals are called ruminants?

a) Lions and tigers    b) Cows and buffaloes    c) Fish and frogs    d) Birds and snakes

7. Where does gas exchange occur in human lungs?

a) Windpipe    b) Nostrils    c) Alveoli    d) Rib cage

8. Which organ helps pump blood throughout the body?

a) Lung    b) Heart    c) Stomach    d) Liver

B. Fill in the Blanks

1. The breaking down of complex food into simpler forms is called ______.

2. The long tube through which food passes is called the ______ canal.

3. The food pipe is also called the ______.

4. The ______ helps break down starch in the mouth.

5. The small intestine is the main site of nutrient ______.

6. The large intestine mainly absorbs ______ and some salts.

7. Animals such as cows and buffaloes are called ______.

8. The process of bringing partially digested food back to the mouth for chewing is called ______.

9. The process of inhaling and exhaling air is called ______.

10. The tiny air sacs in the lungs are called ______.

C. True or False

1. Digestion begins in the mouth.

2. The oesophagus produces bile.

3. The stomach contains acid and mucus.

4. The small intestine absorbs digested nutrients.

5. The large intestine absorbs water and some salts.

6. Cows are ruminants.

7. Birds use teeth to chew their food.

8. Breathing and respiration are exactly the same process.

9. Oxygen passes from the alveoli into the blood.

10. Fish breathe mainly through lungs.

D. Match the Following

E. Answer in One or Two Sentences

1. What is digestion?

2. What is the role of saliva?

3. What is the function of the oesophagus?

4. Why does the stomach contain mucus?

5. What is absorption?

6. What is egestion?

7. What are ruminants?

8. What is rumination?

9. What is breathing?

10. What is respiration?

F. Differentiate Between

1. Digestion and absorption

2. Breathing and respiration

3. Inhalation and exhalation

4. Small intestine and large intestine

5. Ruminants and non-ruminants

G. Think and Answer

1. Why does chapati taste slightly sweet when it is chewed for a long time?

2. Why is the small intestine suitable for absorbing nutrients?

3. Why do we breathe through our nose rather than through our mouth?

4. Why does exhaled air turn lime water milky?

5. Why does our breathing rate increase after running?

6. Why can fish live in water even though they do not have lungs like humans?

7. Why do cows chew food even after they have stopped grazing?

8. Why is respiration necessary for our body?

H. Application-Based Questions

1. Riya chewed a piece of chapati for a long time and noticed that it tasted sweet. Explain why.

2. A student eats a meal containing carbohydrates, proteins and fats. Explain briefly how these nutrients are processed in the digestive system.

3. A person has difficulty absorbing nutrients from food because the inner lining of the small intestine is damaged. Which process is affected?

4. A runner breathes rapidly after completing a race. Why does this happen?

5. A fish is taken out of water and placed on land. Why does it have difficulty breathing?

6. A cow swallows grass quickly and later brings it back to its mouth. What is this process called and why does it happen?

I. Diagram-Based Practice

1. Draw and label the human digestive system.

2. Draw and label the human respiratory system.

3. Draw a simple diagram showing inhalation and exhalation.

4. Draw an alveolus and show the movement of oxygen and carbon dioxide.

5. Draw a simple flow chart showing the journey of food through the alimentary canal.

J. Challenge Questions

1. Why is breathing called a physical process whereas respiration is called a chemical process?

2. If a person’s breathing becomes faster during exercise, does it mean that respiration has also increased? Explain.

3. How are the digestive system, respiratory system and circulatory system connected in helping the body obtain energy?

4. Why do different animals have different breathing organs?

5. Explain how oxygen reaches different parts of the body after we inhale air.

Quick Revision

Digestion → Complex food becomes simpler.

Absorption → Nutrients enter the blood.

Egestion → Undigested waste leaves the body.

Breathing → Inhalation and exhalation.

Respiration → Glucose breaks down and releases energy.

Alveoli → Exchange of oxygen and carbon dioxide.