STD 7 Basic Science: Unit 10 Safety in Food Too - Questions and Answers | Teaching Manual


Textbooks Solution for Class 7th Basic Science (English Medium) സുരക്ഷ ഭക്ഷണത്തിലും | Text Books Solution Basic Science Unit 10 Safety in food too | Teaching Manual & Teachers Handbook
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Chapter 10: Safety in Food Too - Questions and Answers 

Safety in Food Too
1. Which are the months in which mangoes are available in plenty?
Answer: March, April, May

2. Look at the given pictures. How is each variety of food stored without getting stale? (Textbook Page: 132)
• Are cherries and gooseberries preserved in the same solution?
- gooseberries preserved in salt solution
- cherries are preserved in a sugar solution

• What are the ways in which the food substances given above are preserved?
Remember to classify them on the basis of the method of preservation and write them down in your science diary.
Mode of preservation
  In salt solution  In sugar solution By drying Kept in refrigerators
Gooseberry 
Mango
Pineapple
Carrot		Cherry
Apple
Strawberry
Gooseberry		Chilly
Grapes
Tamarind
Ginger
Apple
Grapes
Orange
Tomatoes

3. Certain food items when dried well do not get decayed. What could be the reason?
Answer: When the food substances are dried, the water content is lost. Due to this, the food substances exist without damage.

4. When will microorganisms be in an active state?
Answer: The action of microorganisms takes place under humid conditions and appropriate temperatures.

5. The taro leaf's stem is immersed in a beaker containing salt solution. What happens to the leaf after some time?
Answer: When the stem of taro leaf is kept immersed in salt solution, the water in the stem cells flows into the salt solution As a result the stem cells of the taro leaf shrink and the stem withers. 

When the stem of taro leaf is kept immersed in salt solution, the water in the stem cells flows into the salt solution. As a result, the stem cells of the taro leaf shrink and the stem withers. When food substances are kept in salt solution, the salt draws the water content not only from the food substances but also from the microorganisms present in the food. Microorganisms are destroyed when water in the cytoplasm is lost. The same process takes place when substances are kept in sugar solution. This is why food substances kept in concentrated solutions of salt and sugar do not decay.
6. Why does the tender mango kept in salt solution shrink?
Answer: Salt draws the water content from tender mango. The concentration of the salt solution is more than that of the water inside the mango. So when it is kept in a salt solution, the water from the mango flows into the salt solution. Due to this, the tender mango kept in the salt solution shrunk.

7. Food substances kept in refrigerators do not get decayed. Why?
Answer: They do not get decayed because the microorganisms in food are inactive at a very low temperature.

8. How does food get decayed? 
Answer: Food gets decayed mainly due to the decomposition activities of bacteria, fungi etc. Most microorganisms are generally destroyed at a high temperature At a very low temperature the microorganisms become inactive

9.  What are the safety measures adopted by World Health Organisation (WHO) to prevent food-borne diseases?
Answer: 
• Clean the food substances thoroughly before cooking.
• Store cooked and uncooked items separately.
• Cook food substances in the appropriate manner.
• Store food substances at safe temperatures.
• Use pure water and pure raw materials.

10. Explain the process of Pasteurisation?
Answer: It is the modern method of preserving milk. Milk is heated at 70 °C for 30 seconds and quickly cooled to 10°C. The cell membrane of the microorganisms in the milk ruptures due to the sudden change in temperature. Thus they are destroyed. This method is called pasteurization.
• It was developed by the French scientist Louis Pasteur.

11. Fish should be washed thoroughly in water as soon as it is brought. What could be the reason? 
Answer: Ammonium chloride is added for obtaining low temperatures and for fast solidification while making ice. Ammonium chloride is harmful to our intestines. Hence it should be washed thoroughly in water.

12. What is used for preserving fish and meat on an industrial basis?
Answer: Large freezers

13. What is added for obtaining low temperature and for fast solidification while making ice?
Answer: Ammonium chloride

14. How Food substances can be preserved for a long period of time?
Answer: Food substances can be preserved for a long period of time if microorganisms are prevented from entering them.

15. What are the precautions to be adopted to prevent the staling of packed food?
Answer: 
• Airtight packing
eg: biscuit, bread etc.
• Packing after evacuating air (Vacuum packing)
eg: Almonds (Badam), Cashewnuts etc.
• Sterilised after packing
eg: Tinned food articles

16. What are Preservatives?
Answer: Preservatives are substances added to food items to preserve
them for a long time. Salt solution, sugar solution, oil, vinegar etc. are commonly used traditional preservatives. Apart from these, synthetic chemicals are also used. 
Eg: sodium benzoate, potassium sulphate.

17. Which device is used to measure The quality of milk?
Answer: lactometer

18. What is Adulteration?
Answer: Adulteration is adding food items of cheap and low-quality materials that resemble food substances.
Eg: 
• Adding water or rice soup to milk 
• Mixing brick powder with chilly powder
• Mixing powdered tamarind seed coat with coffee powder

19. Adulterating food in this way can lead to several health problems.
Look at a few examples.
 Food
substance  		 Adulterant Possible disorder/ disease 
  Pepper Dry papaya seed, mineral oil coating Stomach getting upset, Liver disease
  Dal Kesari dal Paralysis
  Milk Water, Starch Quality reduction
  Chilli powder  Brick powder Stomach -Liver-related diseases
  Sugar Chalk powder, semolina, fine sand Stomach -Liver-related diseases
  Tea Artificial colour Stomach diseases

20. What is the use of a Lactometer?
Answer: lactometer is used to find out the quantity of water added to the milk.

21. How can you find out whether milk is adulterated with water?
Answer:
Procedure: Take three boiling tubes. Fill three fourth of one of them with milk, the second one with a small amount of pure water and the third one with equal amount of milk and water. Immerse the lactometer first in pure water than in milk and finally in the mixture of milk and water.
Observation: The lactometer remains at the highest level in the boiling tube in which milk is filled. In the test tube filled with water, it remains the lowest.

22. How can starch be detected if it is added to milk?
Answer:
Procedure: Take 5 ml milk in a test tube and add 2-3 drops of iodine solution to it.
Observation: If the solution turns dark blue,it can be inferred that a lot of starch is mixed.

23. Which agency tested The quality of food substances?
Answer: Food Safety and Standards Authority of India (FSSAI)

24. What is AGMARK? 
Answer: This emblem shows that the quality of food substances like grains and fruits and partially processed the foodstuffs like vermicelli is ensured.

Let us Assess

1. Why are the wounds on the body washed with salt solution?
a. To remove the water content in the wound
b. For blood clotting
c. To destroy germs
d. To relieve pain
Answer: a. To remove the water content in the wound

2. Coconuts are broken and dried for copra. Why?
a. To remove water content
b. For colour
c. For coconut oil
d. To provide fragrance to coconut oil
Answer: a. To remove water content

3. A small amount of chilly powder is put into water to find whether it is adulterated with brick powder. Why?
a. Both brick powder and chilly powder are red in colour
b. Chilly powder dissolves in water
c. Brick powder is heavier than chilly powder
d. Brick powder dissolves in water
Answer: c. Brick powder is heavier than chilly powder

4. "Gargling your throat with warm salt solution for some time will help relieve throat pain". This is Amal's opinion. Can you give an explanation for this suggestion?
Answer: Salt absorbs the water content from the cells of microorganisms. Microorganisms are destroyed when water in the cytoplasm is lost. This will help relieve throat pain.

5. Write down the various factors to be considered for selecting food items of good quality.
Answer:
• Signs indicating the quality
• Packing date and expiry date 
• The proportions of ingredients
• Names of manufacturers and Maximum Retail Price (MRP)
•  Signs indicating the use of vegetarian - non-vegetarian substances

6. The signs found on the packaging of food items are given below. What do these indicate?
Answer: These symbols are marked to distinguish between vegetarian and non-vegetarian food items.





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