NCERT Solutions for Class 6 Science Chapter 3

Q3. A teacher says that good food may act as medicine. Ravi is curious about this statement and has some questions for his teacher. List at least two questions that he can ask.

Ans:

• How can food help in curing diseases?
• Which nutrients in food act like medicine and protect our body?
• Can a balanced diet prevent diseases?
• Why do doctors recommend certain foods during illness?

Q4. Not all delicious foods are necessarily healthy, while not all nutritious foods are always enjoyable. Share your thoughts along with a few examples.

Ans: Not all delicious foods are necessarily healthy. For example, foods like burgers, pizzas, chaat and chips are very tasty but contain excess oil, spices and refined flour(maida), which can be harmful to our health.

On the other hand, not all nutritious foods are always enjoyable. Foods like boiled vegetables, pulses and leafy vegetables may not be very tasty, but they are rich in important nutrients like proteins, vitamins and minerals that keep our body healthy.

Q5. Medu does not eat vegetables but enjoys biscuits, noodles and white bread. He often has stomach ache and constipation. What changes should he make in his diet to get rid of these problems? Explain your answer.

Ans: Medu’s problem is mainly due to eating junk and low-fibre food like biscuits, noodles and white bread, and avoiding vegetables. These foods lack roughage (dietary fibre), which is essential for proper digestion.

To get relief from stomach ache and constipation, Medu should:

• Include green vegetables, fruits and salads in his diet
• Eat whole grains instead of refined foods (like white bread)
• Drink plenty of water
• Reduce intake of junk and processed foods

Adding more dietary fibre (roughage) to his meals will help prevent constipation and improve digestion overall.

Q6. Reshma had trouble seeing things in dim light. The doctor tested her eyesight and prescribed a particular vitamin supplement. He also advised her to include a few food items in her diet.

(i) Which deficiency disease is she suffering from?

(ii) Which food component may be lacking in her diet?

(iii) Suggest some food items that she should include in her diet to overcome this problem (any four).

Ans:  (i) Reshma is suffering from night blindness.

(ii) This is caused due to a deficiency of Vitamin A in her diet.

(iii) To overcome this problem, she should include foods like carrot, mango, papaya and milk in her diet.

Q7. You are provided the following:

(i) Canned fruit juice

(ii) Fresh fruit juice

(iii) Fresh fruit

Which one would you prefer and why?

Ans: Fresh fruit is the best option because it provides natural fibers and nutrients in their unprocessed form. Canned fruit juice may contain added sugar and preservatives, and fresh fruit juice might lose some fiber during processing.

Q8. Gourav got a fracture in his leg. His doctor aligned the bones and put on a plaster. The doctor also gave him calcium tablets. On the second visit, the doctor gave him Vitamin D syrup along with calcium tablets. Refer to Fig. 3.5 and answer the following questions:

(i) Why did the doctor give calcium tablets to Gourav?

(ii) On the second visit, why did the doctor give Vitamin D syrup along with calcium tablets?

(iii) What question arises in your mind about the choices made by the doctor in giving the medicines?

Ans: (i) The doctor gave calcium tablets to help in healing and strengthening the broken bones.

(ii) Vitamin D was given because it helps the body absorb calcium properly, which supports faster bone healing.

(iii) A question that arises is: Why is Vitamin D necessary along with calcium for proper bone healing?

Q9. Sugar is an example of carbohydrates. Sugar is tested with iodine solution but it does not change to blue-black colour. What can be a possible reason?

Ans: Sugar is a carbohydrate, but it is not starch. Iodine solution gives a blue-black colour only with starch, not with other carbohydrates like sugar. Therefore, no colour change is observed.

Q10. What do you think of Raman’s statement, “All starches are carbohydrates but not all carbohydrates are starches.’’ Describe the design of an activity to test your answer.

Ans: Raman’s statement is correct. All starches are carbohydrates, but some carbohydrates like sugar are not starch.

Activity to test:

• Take two samples: starch solution (e.g., potato paste) and sugar solution.
• Add a few drops of iodine solution to both.
• Observe the changes.

Observation:

• Starch solution turns blue-black.
• Sugar solution shows no change.

Conclusion:
This proves that all carbohydrates are not starches.

Q11. While using iodine in the laboratory, a few drops of iodine fell on Mishti’s socks and a few fell on her teacher’s saree. The drops of iodine on the saree turned blue-black while the colour on the socks did not change. What can be a possible reason?

Ans: The saree might have been starched, so it contained starch, which turned blue-black with iodine.
The socks did not contain starch, so no colour change was observed.

Q12. Why are millets considered a healthy choice of food? Can eating just millets suffice for the nutritional requirements of the body? Discuss.

Ans: Millets are considered a healthy food because they are rich in vitamins, minerals (like iron and calcium), and dietary fibre. They are also easy to digest and provide energy.

However, eating only millets is not sufficient for the body’s nutritional needs. Our body requires a balanced diet that includes all nutrients such as proteins, fats, vitamins and minerals.

Therefore, millets should be included as a part of a balanced diet, not consumed alone.

Q13. You are given a sample of a solution. How would you check the possibility of it being an iodine solution?

Ans:  To check if a solution is iodine, perform a starch test:

• Take a food item containing starch (like potato or rice).
• Add a few drops of the given solution to it.
• If the colour changes to blue-black, the solution is iodine.

This is because iodine reacts with starch to give a blue-black colour.