4. What is food?
Substances that can provide one or more of the following functions:
(1) provide energy
(2) provide raw materials for growth and repair tissues
(3) maintain health
5. What are the 7 food substances required by the human body?
(1) carbohydrates
(2) proteins
(3) lipids
(4) vitamins
(5) minerals
(6) dietary fibres
(7) water
6. What is the relationship between food substances and food?
Generally, food contains food substances in different amount.
Note: therefore, when talking about one food, it is difficult to judge whether it is nutritious enough, because the food substances inside the food is unknown.
7. Which food substances can provide energy?
(1) carbohydrates
(2) lipids
(3) Protein
8. Which food substance contains the most energy (calculated per unit mass)?
Lipid (about twice that of carbohydrate and protein)
9. Which food substance is the fastest in providing energy?
carbohydrates
10. In what way will the body store energy?
As glycogen (carbohydrate)
As subcutaneous fat (lipid)
Note: Without the carbohydrates and lipids store, the body will consume the protein in muscles to produce energy.
11. What elements is carbohydrates composed of?
Carbon (C), hydrogen (H), Oxygen (O)
Hydrogen: oxygen = 2:1
12. What are the three types of carbohydrates?
(1) monosaccharides
(2) disaccharides
(3) polysaccharides
13. What are the examples of monosaccharides? What of food are they stored in?
(1) glucose (fruits (grapes), honey)
(2) fructose (fruit, honey)
(3) galactose (milk)
14. What are the characteristics of monosaccharides?
(1) soluble in water
(2) sweet
(3) crystallizable
(4) all are reducing sugars
15. What are the major functions of monosaccharides?
Glucose is mainly used for producing energy.
16. What are the examples of disaccharides? What are the monosaccharides that they are composed of?
(1) maltose (2 molecules of glucose)
(2) sucrose (glucose+fructose)
(3) lactose(glucose + galactose)
17. What are the characteristics of disaccharides?
(1) can dissolve in water
(2) soluble
(3) crystallizable
(4) apart from sucrose, all are reducing sugar
18. Of all the monosaccharides and disaccharides, which one is not a reducing sugar?
sucrose
19. Which process is being carried out when monosaccharides combines to become disaccharides?
Condensation, a water will be produced in the reaction.
20. What are the examples of polysaccharides? What are their main functions?
(1) glycogen (it is the form of which animals store energy)
(2) starch (it is the form of which plants store energy)
(3) cellulose (it is the major composition of cell wall)
21. What are the features of polysaccharides?
(1) It is formed from many monosaccharides through condensation.
(2) It is insoluble in water
(3) Its molecule is chain shape
22. What kinds of food are rich in starch?
Cereal and products of cereal (rice, wheat, bread)
Potato
Certain fruits (e.g. apple, banana)
23. What is the general functions of carbohydrates?
(1) main source energy
(2) store energy
(3) as structural materials (e.g. cell wall)
24. How will the body process excess carbohydrates?
Stored as glycogen in the liver and muscles
Changed into subcutaneous fat and stored under the skin
Note: therefore excess carbohydrates will cause weight increase.
25. What are the elements that make up lipids?
Carbon, hydrogen, oxygen(same as carbohydrates)
But the hydrogen to oxygen ration is higher than 2:1
26. what is the most frequently seen lipid? What is it composed of?
Triglyceride. It is composed of one glycerol molecule and 3 fatty acid molecules.
27. What is the differences between fat and lipid?
In room temperature,
Fat is in solid state, while lipid is in liquid state.
28. What is the source of fat?
Animal source: fatty meat, lard, margarine, milk.
Plant source: certain seeds, e.g. corn, peanuts, nuts, melon seeds.
29. What are the functions of lipids?
(1) as energy store
(2) as insulator to reduce heat loss
(3) surrounds the organs to protect them from shock
(4) as the major component of cell membrane (phospholipid)
(5) involved in the transport of fat soluble vitamin (A & D)
(6) involved in forming some hormones, e.g. certain sex hormones
30. What are the elements that proteins are composed of?
Must have: carbon, hydrogen, oxygen and nitrogen
Some have: phosphorus, sulphur
31 What are the basic unit of protein?
Amino acids. About 20.
32. The structure of amino acids includes
(1) carbon atom
(2) amino group
(3) carboxyl group
(4) side chain
33. How can protein be formed from amino acids?
Through condensation, (2 or more amino acids)form a straight chain called peptide/polypeptide, then the polypeptide coils into a 3D shape protein molecule.
34. According to the need of the human body, how many types of amino acids are there?
(1) essential amino acids (cannot be synthesized by the human body, need to be obtained from the outside.)
(2) non-essential amino acids
Note: This is one of the reason why the nutritious value of different protein
rich food is different.
35. What is the source of protein?
Animal: meat, fish, eff, milk or dairy products
Plants: peas, mushrooms
36. What are the functions of proteins?
(1) form body tissue, for growth and repair
(2) form enzymes, used for catalyzing chemical reactions
(3) form antibodies, used for defense against diseases
(4) form certain hormones, used for regulating metabolism
(5) After carbohydrates and lipids are used up, they are used for
producing energy.
37. What are the diseases that is caused by a severe lack of protein? What are the signs of the disease?
Signs: weak muscles, swollen abdomen
38. What is the consequence of excessive intake of protein?
Excess amino acids will be broken down to form urea.
During the process, carbohydrates and lipids will be formed.
39. What are the sources of calcium?
Animal: bones, canned sardines, milk
Plants: green vegetables (kale, broccoli and spinach), tofu.
40. What are the functions of calcium?
(1) composition of bones and teeth
(2) involved in muscle contraction
(3) involved in blood clotting
(4) involved in transmission of nerve impulses
41. What is the diseases that is caused by calcium deficiency?
Children: rickets: causing the legs to bend
Old people: osteoporosis
42. What is the source of iron?
Animal: blood, beef, liver
Plant: pea, spinach
43. What is the function of iron?
It is one of the composition of haemoglobin, and haemoglobin is responsible for transporting oxygen.
44. What is the disease that is caused by iron deficiency? Symptoms?
Anaemia
dizziness
45. What are the source of vitamin A?
Liver oil, Liver (because vitamin A is soluble in lipid), egg, milk, carotene containing food
46. What is the function of vitamin A?
(1) form a pigment (visual purple) on the retina, required in vision in dim light
(2) maintaining healthy epidermis (including cornea, skin, the lining of the alimentary canal and the inner wall of breathing system)
47. What are the diseases caused by a deficiency of vitamin A? Signs and symptoms?
(1) night blindness.
(2) drying up of cornea and skin
(3) easy infection of the lining of the lungs and trachea
48. What are source of vitamin C?
Fresh vegetable (especially green pepper, broccoli, guavas, kiwi fruits, oranges, lemons)
49. What is the characteristics of vitamin C
Water soluble
Easily damaged by high temperature and oxygen.
50. What is the function of vitamin C?
(1) maintain healthy connective tissues
(2) promotes the absorption of iron
51. What are the diseases caused by a deficiency of vitamin C? Signs and symptoms?
Scurvy
Signs include:
(1) bleeding gums
(2) poor healing of wounds
(3) small red spots on the skin
Symptoms include:
(1) joint pain
52. What are the source of vitamin D?
High fat fish (salmon D, tuna fish)
Liver oil
Egg yolk
Exposure of skin to ultraviolet light of sunlight
53. What are the functions of vitamin D?
Promote the absorption of calcium and phosphorus
54. What are the diseases that is caused by a lack of vitamin D? signs?
rickets
55. what are the vitamins that is water soluble? What are the vitamins that are fat soluble?
Water soluble: Vitamin C, therefore it cannot be stored.
Fat soluble: vitamin A and D
56. What is the function of dietary fibre to human?
(1) add bulk to food, promote peristalsis
(2) Store large amount of water, keep the faeces soft.
57. What is the source of dietary fibre?
Fruits and cereals
58. What is the disease that is caused by a deficiency of dietary fibre?
constipation
59. How to test for reducing sugar?
(1) Add benedict’s solution to an unknown solution
(2) heat in water bath
(3) if the colour turns from blue to brick red, reducing sugar is present
60. How can the presence of starch be test?
(1) add iodine solution
(2) if colour turns from brown to blue black, starch is present.
61. How to test for vitamin C?
(1) Add the sample to DCPIP solution (note: not DCPIP to the sample!)
(2) If the colour turns from blue to colourless, vitamin C is present.
62. Which food test require heating?
Benedict’s test
63. What is balanced diet?
A diet which has all the food substances in the right amount and proportions.
Note: different people differs in the amount and proportions required.
64. What are the food substances that are need more by children?
(1) protein
(2) Calcium
(3) Iron
65. What food substances do males need more than females?
Protein
Food that contains more energy
66. What food substances do females need more than males?
Iron, they need it to replenish the blood lost through menstruation.
67. What food substances do pregnant women need more?
Energy rich food substances
Protein
Iron
68. What does breast feeding woman need more in food substances?
Apart from, iron, all others are in greater need.
68. What food substances do breast feeding women need more?
Except for iron, all other food substances are required in greater amount.
69. What is the disease that is caused by a deficiency of food?
Anorexia
70. What is the disease that is caused by an excessive intake of fat?
obesity
71. What are the problems that come along with obesity?
(1) diabetes
(2) heart diseases
(3) stroke
(4) arthritis