Chapter 2 with answer
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The document discusses nutrition and the human digestive system. It defines 7 classes of food - carbohydrates, proteins, fats, vitamins, minerals, fiber, and water. Each class is described in terms of its components, sources, and functions. The document also discusses balanced diets and factors like size, gender, jobs, climate, health, and age that determine an individual's balanced diet. It provides an overview of the human digestive system and the multi-step process of digestion that breaks down food with enzymes in the mouth, stomach, pancreas, small intestine, and large intestine.
Chapter 2 with answer
- 1. Chapter 2: Nutrition 2.1) Classes of Food 1. Importance of food a) Provides energy to carry out living processes and functions b) Provides energy to do work c) Growth of new tissues and repair damaged tissues d) Maintain good health and fight diseases 2. Food are divided into seven classes: a)Carbohydrate e)Fibre / Roughage b)Protein f)Minerals c)Fat g)Water d)Vitamin 3. Carbohydrate a) Consists of carbon, hydrogen and oxygen b) Includes sugar, starch, glycogen and cellulose c) Smallest unit is glucose d) Sources : wheat, bread, rice e) Function : Provide energy 4. Protein a) Consists of carbon, hydrogen, oxygen and nitrogen b) Some may have sulphur and phosphorus c) Smallest unit is amino acid d) Sources : fish, meat, egg e) Functions : (i) Growth and repair body tissues (ii) Form enzymes, hormones and antibodies (iii) Source of energy during starvation (iv) Prevent kwashiokor 1 © Gabriel Chua, 2013
- 2. 5. Fats a) Consists of carbon, hydrogen and fat b) Smallest unit are fatty acids and glycerol c) Sources : butter, margarine, vegetable oil, fatty meat d) Functions : (i) Source of energy (two times more than carbohydrate) (ii) Heat insulator (keeps body warm) (iii) Protect organs from injury (iv) Dissolve fat-soluble vitamins (Vitamin A, D, E & K) 6. Vitamins a) Organic compound needed in small amount. b) Vitamin deficient can cause diseases but excess of vitamins can become toxins to our body. c) Divided into water soluble (Vitamin B & C ) and fat soluble (Vitamin A, D, E & K ) Vitamin Sources Effect of deficiency A Carrots, tomatoes, egg, liver Night blindness (Xerophthalmia) B Eggs, liver, vegetable, wheat Beri-beri, pellagra, nervous disorder C Orange, lemon Scurvy D Eggs, milk, fish, liver, sun Rickets E Leafy vegetable, wheat Anaemia K Green leafy vegetable, liver, milk Blood clotting difficulty 7. Minerals 2 © Gabriel Chua, 2013
- 3. a) Inorganic compounds required in small amount. b) Needed for proper growth and development. c) Excess minerals are excreted through sweat and urine. Mineral Sources Functions Deficiency Calcium Milk, egg, Form strong bones Osteoporosis Phosphorus legumes, cheese and teeth Osteomalacia Blood clotting Rickets (calcium) Blood difficult to clot (calcium) Iodine Seafood, iodised Produce hormone for Goiter salt metabolism Growth and development Iron Liver, leafy Form haemoglobin Anaemia vegetable, meat (red blood cell) Transport oxygen around our body Sodium Table salt, fish, Nerve and muscle Muscle cramps cheese functions Weak muscles Maintain water Paralysis balance Potassium Grains, fruits (banana), vegetable 8. Fibre / Roughage a) From cellulose in plants b) Sources : leafy vegetable, brown rice, nuts and beans, fruits c) Importance : Stimulate peristalsis d) Lack of fibre causes constipation 9. Water a) Average 8 glasses per day. b) Lost a lot of water from sweat and urine c) Sources : Drinks, fruits 3 © Gabriel Chua, 2013
- 4. d) Importance : (i) Helps in digestion and excretion process (ii) Controls body temperature (iii) As medium for chemical reaction in body. 10. Food test Food Test Procedure Observation 3 Starch Iodine Test 2cm starch solution + few Brown colour of iodine drops iodine turns blue-black colour Glucose Benedict 2cm3 glucose solution + Light blue colour of Solution Test 2cm3 Benedict solution Benedict solution turns Heat in water bath into red-brick precipitate Protein Millon’s 2cm3 albumen + 2 drops White precipitate is Reagent Test Million’s reagent formed when Millon’s Heat in water bath reagent is added. White precipitate turns red-brick precipitate on heating Fat Emulsion Test Ethanol + 5 drops of Milky solution cooking oil (emulsion) is formed Shake and let it settle for 2 minutes Spot Test 1 drop of cooking oil on Translucent spot is filter paper formed Allow to dry 2.2) Balanced Diet 1. Balanced diet is eating all classes of food in correct proportion. 2. Food pyramid Fats, oils and sweets Protein, dairy products Fruits and vegetable Carbohydrate 4 © Gabriel Chua, 2013
- 5. 3. Factors determining balanced diet Factor Example People with larger size needs more food and nutrients than those Size with smaller size Male usually needs more food and nutrients than female Gender Those doing heavy jobs (construction, maid) needs more food and Jobs nutrients than those doing light jobs (in the office) Those in cold climate (North Pole) needs more fatty food Climate compared to those in warm climate People with health problem needs to take care of their diet Health Old people needs more calcium to strengthen their bones but Age young people needs more carbohydrate and protein for growth and development 4. Calorific value a) Calorific value is of food is the amount of energy released from 1 gram of a particular food b) The energy stored in food is measured in calorie (cal) and Joule (J). c) 1 cal = 4.2 Joule d) Kamal has his lunch which consists of nasi lemak (421 cal), curry (530 cal), roti canai (275 cal) and a cup of Milo (316 cal). Calculate the calorific value of the lunch Kamal had in kiloJoule. 421 + 530 + 275 + 316 = 1542 cal 1542 cal X 4.2 J = 6476.4 J 5 © Gabriel Chua, 2013
- 6. 2.3) Human Digestive System 1. The process of breaking down food into soluble and diffusible molecules. 2. Carried out by enzyme, a special protein produced by body to speed up chemical reactions in body. 3. 3 main types of digestive enzymes: a) Amylase (helps in carbohydrate digestion) b) Protease (helps in protein digestion) c) Lipase (helps in fat digestion) 4. Non-digestive enzymes that help in digestion: a) Hydrochloric acid (produced in stomach ) b) Bile (produced in liver ) and stored in gall bladder 5. Human digestive system Mouth Oesophagus Liver Stomach Pancreas Duodenum Large intestine Small intestine Rectum Anus 6 © Gabriel Chua, 2013
- 7. 6. Digestion in human Mouth (enzyme salivary amylase / ptyalin) Starch Maltose Esophagus Food is churned into bolus via process peristalsis Stomach (gastric juice) Protease : Protein Polypeptides Hydrochloric acid (not enzyme): Stops action of enzyme from saliva and kills bacteria Partially digested food in stomach is known as chyme Duodenum (pancreatic juice + bile) Protease : Polypeptides Peptides Amylase : Starch Maltose Lipase : Fat Fatty acids + glycerol Bile (not enzyme): Emulsify fat, neutralize acid from stomach Small intestine Maltose Glucose Peptides Amino acids Fat Fatty acids + glycerol 2.4) Absorption of Digested Food 1. Digested food (glucose, amino acids, fatty acids and glycerol) and vitamins are absorbed by villi of small intestine via diffusion into bloodstream. 2. Adaptations of small intestine a) Has a lot of villi on its surface to increase the surface area b) Each villus has thin epithelial wall to enable diffusion of digested food. c) There is a rich network of blood capillaries in each villus. d) Long (6m) for greater absorption. e) Moist lining of epithelial wall allows digested food molecules to dissolve easily. f) Peristalsis in small intestine enhances absorption 7 © Gabriel Chua, 2013
- 8. 2.5) Reabsorption of Water and Defecation 1. Undigested food, minerals and water enters large intestine. 2. Most water and minerals are reabsorbed in the large intestine. 3. As water is absorbed, the mixture becomes solid waste, known as faeces. 4. Feaces is stored in rectum before being expelled via anus. This process is known as defecation. 5. Lack of fibre will cause constipation. 8 © Gabriel Chua, 2013