Food Notes PDF - Biology CH 2

SUNRISE ENGLISH PRIVATE SCHOOL, ABU DHABI -BIOLOGY - CH 2 Components of food-NOTES Nutrients Food substances that provide nourishment to the body. Carbohydrates These are energy-giving compounds. They may be simple carbohydrates or complex carbo...

SUNRISE ENGLISH PRIVATE SCHOOL, ABU DHABI -BIOLOGY - CH 2 Components of food-NOTES Nutrients Food substances that provide nourishment to the body. Carbohydrates These are energy-giving compounds. They may be simple carbohydrates or complex carbohydrates. Simple carbohydrates provide instant energy and are soluble in water like sugar. Complex carbohydrates are insoluble compounds like starch. Fats These are very high energy-giving compounds. They produce greater amount of energy than carbohydrates. Fats are available in oil-rich foods. Proteins These are body-building foods. They help in the growth of the body. Requirement of proteins per day depends on the age and body weight of the person. Vitamins These are organic substances that protect the body from diseases. There are water-soluble vitamins (Vit B and C) and fat-soluble vitamins. (vit A, D, E and K) Minerals These are elements required by the body in small amounts. Essential for growth and development of bones, teeth and red blood cells. Also help in proper functioning of the nervous system and circulatory system. Roughage It is dietary fibre present in the food. It facilitates regular movement of the bowels and prevents constipation. LAB ACTIVITY Test for Starch Aim: To test the presence of starch in our food. Method: Take a raw potato and cut it into two equal halves. Add two drops of iodine solution on the cut end of the potato, and observe. Observation: On adding iodine, potato will turn into blue-black. Conclusion: Potato contains starch and starch gives a blue-black colour with iodine. Test for Protein Aim: Take pieces of boiled egg(white portion) in a test tube. Method: Add two drops of Copper Sulphate solution and 10 drops of caustic soda(NaOH) solution in a test tube with the help of dropper. Shake the test tube well and allow it to stand for a few minutes Observation: The content of the test tube turns violet. Conclusion: The violet colour indicates the presence of proteins in the boiled egg. I. ANSWER THE FOLLOWING 1. Raghav puts a food sample on a piece of paper and crushes it. The paper becomes translucent. In which nutrient is the food rich in? A. The food is rich in fat. 2. Two drops of iodine solution are put on a slice of bread and some grape juice. Why does bread turn blue-black in colour but grape juice does not, when they both are carbohydrates? A. Iodine reacts with starch to give a blue-black colour. Bread contains starch but grapes contain sucrose. 3. Sita avoids eating vegetables but likes to eat biscuits, noodles and white bread. She frequently complains of stomachache and constipation. What are the food items that she should include in her diet to get rid of the problem? Give reason. A. Sita must include whole grains, pulses, fresh fruits and vegetables in her diet as she seems to lack roughage. 4. Rahul was having difficulty in seeing things in dim light. The doctor tested his eyesight and prescribed a particular vitamin supplement. He also advised him to include a few food items in his diet. A) Which deficiency disease is he suffering from? Night blindness B) Which food component may be lacking in his diet? Vitamin A c) Suggest some food items that he should include in his diet. Carrot, papaya, mango, milk and fish oil 5. While using iodine in the laboratory, some drops of iodine fell on Ria’s socks and some fell on her teacher’s saree. The drops of iodine on the saree turned blue-black while their colour did not change on the socks. What can be the possible reason? A. The saree of Ria’s teacher might have been starched, and starch turns blue- black with iodine solution. Ria’s socks did not have starch on it thereby showing no change. 6. Mention the importance of roughage in our diet. a) Roughage adds bulk to the food. This helps our body to get rid of undigested food and thereby prevents constipation. b) Roughage can absorb a great quantity of water and helps to retain water in the body. 7. Explain the major functions of water in our body. a) It transports substances and nutrients inside our body. b) It regulates the temperature of our body by sweating. c) It helps our body absorb nutrients from the food we eat. d) Water acts as an important medium for various chemical reactions. 8. Why are vitamins important for us? Vitamins are required in small quantities for normal functioning of our body. They protect us from various diseases, so they are important for us. 9. How does a person become obese? Overeating of fat rich-foods and lack of physical activities make a person obese. 10. How do we get most of the water needed by our body? Most of the water needed by our body comes from plain drinking water and beverages like tea and coffee. We also get some water from the food items we eat like fruits, vegetables, meat and fish. 11. Give few cooking practices that lead to the loss of nutrients in food materials. A) If cooking is done in excess of water and the water is thrown away after cooking, many water-soluble vitamins and minerals are lost. b) If cooking is done at high temperature, many proteins and vitamins are destroyed. c) Washing of some peeled and cut vegetables and fruits d) Repeated washing of pulses and rice. 12. Differentiate between the two types of carbohydrates found in our food. The two types of carbohydrates in our food are starch and sugars. Sugars are simple carbohydrates and found in the form of glucose and fructose. They have a sweet taste. They provide instant energy. E.g. glucose and cane sugar. Starch is a complex carbohydrate. It is the reserve food material of plants. Pure starch is tasteless and odourless white powder. It provides energy comparatively slowly than sugars. E.g. Rice, wheat and potato. 13. Define balanced diet. Is it the same for every person? Why/Why not? A balanced diet is a diet that contains adequate amount of all the essential nutrients, roughage and water for the proper growth and development of the body. It is not same for every person. It depends on sex and age of the person, occupation and special needs. 14 How are roughages important to us? Give the sources of roughages Roughages add bulk to the food and help us to get rid of undigested food sources-Whole grains ,pulses ,green leafy vegetables potato etc Roughages are also called as dietary fibres