Components of Food

The food we eat contains substances called nutrients that our body needs. The major nutrients are carbohydrates and fats, which mainly give energy, proteins, which are needed for growth and repair of the body, and vitamins and minerals, which protect the body from diseases. In this chapter you will learn simple tests to find which nutrients a food contains: a few drops of dilute iodine solution turn starch blue-black, a mixture of copper sulphate and caustic soda solutions turns violet with protein, and fats leave an oily patch on paper. Food also contains dietary fibres, or roughage, which help remove undigested food, and water, which helps absorb nutrients and remove wastes. The chapter explains that a balanced diet provides all nutrients, roughage and water in the right amounts. You will learn about deficiency diseases caused by a lack of nutrients over a long time, such as scurvy from lack of vitamin C, rickets from lack of vitamin D, night blindness from lack of vitamin A, goitre from lack of iodine and anaemia from lack of iron.

Detailed Worksheet: Components of Food Section A - Definitions (10 marks) 1. What are nutrients? Name the major nutrients in our food. (2 marks) 2. What is a balanced diet? Why is it important for growing children? (2 marks) 3. What are deficiency diseases? Give two examples with their causes. (2 marks) 4. What is roughage? Name two sources of roughage. (2 marks) 5. Why are proteins called body-building foods and carbohydrates energy-giving foods? (2 marks) Section B - Calculations and Applications (15 marks) 6. Name the nutrient tested and the result in each case: (i) a food turns blue-black with iodine solution (ii) a food turns violet with copper sulphate and caustic soda solutions (iii) a food leaves an oily patch on paper. (3 marks) 7. Name the deficiency disease and one symptom caused by lack of: (i) vitamin A (ii) vitamin B1 (iii) vitamin C (iv) vitamin D (v) iodine (vi) iron. (3 marks) 8. A food label says one packet (100 g) of biscuits contains 70 g carbohydrates, 7 g protein, 18 g fat and the rest is water and minerals. (i) What mass is water and minerals? (ii) Which nutrient is present in the greatest amount? (iii) Is it a good idea to eat only biscuits for lunch? Explain. (3 marks) 9. Classify these foods as mainly carbohydrate-rich, protein-rich or fat-rich: rice, pulses, butter, potato, egg, groundnut oil, paneer, wheat, ghee. (3 marks) 10. A child drinks 2 glasses of milk daily, each of 200 mL. (i) How much milk does the child drink in a week? (ii) Name two nutrients present in milk. (iii) Why is milk considered good for bones? (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of the test for starch in a potato slice using iodine solution. Label the dropper, iodine solution, potato slice and the colour change. Write the observation and conclusion. (4 marks) 12. Draw a labelled diagram of the test for protein in a food sample using copper sulphate and caustic soda solutions in a test tube. (3 marks) 13. Draw a food plate (circle divided into parts) showing a balanced meal with cereals, pulses, vegetables, fruit and milk. Label the main nutrient given by each part. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Paheli eats only bread and jam for most of her meals and avoids fruits and vegetables. (i) Which nutrients is her diet rich in? (ii) Which nutrients is it lacking? (iii) Name two diseases she may develop over a long time. (iv) Suggest changes to make her diet balanced. (5 marks) 15. Boojho's grandmother says that vegetables should not be washed after cutting and should not be overcooked. (i) Which nutrients may be lost by washing after cutting? (ii) Which vitamin is destroyed by heating? (iii) Why should rice and pulses not be washed repeatedly? (iv) Suggest two healthy cooking practices. (5 marks) 16. A child has swollen gums that bleed and wounds that heal slowly, while another child has soft and bent bones. (i) Identify the deficiency disease in each child. (ii) Name the missing nutrient in each case. (iii) Suggest two food sources for each nutrient. (iv) Why is sunlight helpful for the second child? (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw all diagrams neatly in pencil and label every part. Write the observation and conclusion for each food test.