1. What is food?
2. What are the 7 food substances required by the human body?
3. What is the relationship between food substances and food?
4. Which food substances can provide energy?
5. Which food substance contains the most energy (calculated per unit mass)?
6. Which of the three energy-providing food substances can provide energy more readily than the other two?
7. In what way will the human body store energy?
8. What elements do carbohydrates composed of?
9. What types of carbohydrates are categorized into?
10. Name all the examples of monosaccharides? What of food are they stored in?
11. What are the characteristics of monosaccharides?
12. What are the major functions of monosaccharides?
13. What are the examples of disaccharides? What are the monosaccharides that they are composed of?
14. What are the characteristics of disaccharides?
15. Why are monosaccharides and some disaccharides called reducing sugars?
16. Which process is being carried out when monosaccharides combines to become disaccharides?
17. What are the examples of polysaccharides? What are their main functions?
18. What are the features of polysaccharides?
19. What kinds of food are rich in starch?
20. What are the functions of carbohydrates?
21. How will the body process excess carbohydrates?
22. What are the elements that make up lipids?
23. What is the commonest type of lipid? What is it composed of?
24. What is the difference between lipid, fat and oil?
25. What is the source of fat?
26. What are the functions of lipids?
27. What are the elements that proteins are composed of?
28. What is the basic unit of protein?
29. The structure of amino acids includes
30. How can protein be formed from amino acids?
31. According to the need of the human body, what are the two kinds of amino acids?
32. What is the source of protein?
33. What are the functions of proteins?
34. What is the name of the disease that is caused by a severe lack of protein? What are the signs of the disease?
35. What is the consequence of excessive intake of protein?
36. What are the sources of calcium?
37. What are the functions of calcium?
38. What are the diseases that is caused by calcium deficiency?
39. What is the source of iron?
40. What is the function of iron?
41. What is the disease that is caused by iron deficiency? What is the symptom of this disease?
42. What are the sources of vitamin A?
43. What is the function of vitamin A?
44. What are the diseases caused by a deficiency of vitamin A? What is the symptom of this disease?
45. What are source of vitamin C?
46. What is the characteristic of vitamin C
47. What is the function of vitamin C?
48. What are the diseases caused by a deficiency of vitamin C? Signs and symptoms?
49. What are the source of vitamin D?
50. What are the functions of vitamin D?
51. What are the diseases that is caused by calcium deficiency?
52. What are the vitamins that is water soluble? What are the vitamins that are fat soluble?
53. What are the functions of dietary fibre to humans?
54. What is the source of dietary fibre?
55. What is the disease that is caused by a deficiency of dietary fibre?
56. How to test for reducing sugar?
57. How can the presence of starch be test?
58. How to test for vitamin C?
59. Which food test require heating?
60. What is balanced diet?
61. What are the food substances that are needed more by children?
62. What food substances do males need more than females?
63. What food substances do females need more than males?
64. What food substances do pregnant women need more?
65. What does breast feeding woman need more in food substances? (Fact: Breast feeding women do not have menstruation)
66. What is the disease that is caused by an excessive intake of fat?
67. What are the diseases that come along with obesity?
1. What is food?
Substances that can perform the following functions to certain organisms, including
(1) providing energy
(2) act as material for growth
(3) support activities of the body, maintain health
Note: The same substance can be food for one organism but not for another. For example, paper is a food for Fungi which is a saprophyte but not a food for human because human lack the enzyme to speed up the digestion of cellulose.
2. 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
3. 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.
4. Which food substances can provide energy?
(1) carbohydrates
(2) lipids
(3) Protein
5. Which food substance contains the most energy (calculated per unit mass)?
Lipid (about twice that of carbohydrate and protein)
6. Which of the three energy-providing food substances can provide energy more readily than the other two?
carbohydrates
7. In what way will the human body store energy?
The human body store energy
as glycogen (carbohydrate) stored in the liver cells and muscle cells
as subcutaneous fat (lipid) stored in adipose tissue consisting of fat cells.
Note: Without the carbohydrates and lipids store, the body will consume the protein in muscles to produce energy.
8. What elements do carbohydrates composed of?
Carbon (C), hydrogen (H), Oxygen (O)
Hydrogen: oxygen = 2:1
9. What types of carbohydrates are categorized into?
(1) monosaccharides
(2) disaccharides
(3) polysaccharides
10. Name all the examples of monosaccharides? What of food are they stored in?
(1) Glucose. They are stored in fruits (e.g. grapes) and honey.
(2) fructose. They are stored in fruits (e.g. grapes) and honey.
(3) galactose. They are stored in milk.
11. What are the characteristics of monosaccharides?
(1) soluble in water
(2) sweet
(3) crystallizable
(4) all are reducing sugars
12. What are the major functions of monosaccharides?
Monosaccharides are mainly used for providing energy.
13. 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)
14. What are the characteristics of disaccharides?
(1) soluble in water
(2) sweet
(3) crystallizable
(4) all are reducing sugar except sucrose
15. Why are monosaccharides and some disaccharides called reducing sugars?
Some chemical reactions involve a transfer of electrons between substances. The substances that lose electrons are said to be reducing or said to be oxidized, and the substances that gain electrons are said to be oxidizing or said to be reduced.
All monosaccharides and all dissacharides except sucrose lose electrons readily to other substances. They are called reducing sugars because they cause other substances to be reduced.
16. Which process is being carried out when monosaccharides combines to become disaccharides?
Condensation, a water molecule will be produced in the reaction.
17. 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 plant cell wall)
18. What are the features of polysaccharides?
(1) It is formed from many glucose / monosaccharide molecules through condensation.
(2) It is insoluble in water
(3) Its molecule is chain shape
19. What kinds of food are rich in starch?
Cereal (rice, wheat) and products of cereal (noodle, bread)
Potato
Certain fruits (e.g. apple, banana)
20. What are the functions of carbohydrates?
They act as
(1) the main source of energy
(2) energy reserve
(3) structural materials of the cell (e.g. cellulose are used for constructing the cell wall)
21. How will the body process excess carbohydrates?
- Stored as glycogen in the liver and muscles
- Changed into subcutaneous fat and stored under the skin inside adipose tissue that is composed of fat cells
Note: Therefore excess carbohydrates will cause an increase in weight.
22. What are the elements that make up lipids?
Carbon, hydrogen, oxygen(same as carbohydrates)
But the hydrogen to oxygen ration is higher/greater than 2:1
23. What is the commonest type of lipid? What is it composed of?
Triglyceride. It is composed of one glycerol molecule and 3 fatty acid molecules.
24. What is the difference between fat and lipid?
At room temperature, fat is in solid state, while oil is in liquid state. Both fat and oil can be regarded as lipid.
25. What is the source of fat?
Animal source: fatty meat, lard, margarine, milk.
Plant source: certain seeds, e.g. corn, peanuts, nuts, melon seeds.
26. What are the functions of lipids?
(1) As energy reserve
(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
27. What are the elements that proteins are composed of?
Proteins must have: carbon, hydrogen, oxygen and nitrogen
Some proteins have: phosphorus, sulphur
28. What is the basic unit of protein?
Amino acids. There are 20 different of amino acids each having a little difference in their side chain.
29. The structure of amino acids includes
(1) carbon atom
(2) amino group
(3) carboxyl group
(4) side chain
30. How can protein be formed from amino acids?
Through condensation, two amino acids form a dipeptide; many amino acids form a straight chain molecule called polypeptide; then the polypeptide coils into a 3D shape molecule which is called protein.
Note: The bond that is formed between the amino acid molecules is called peptide bond. The peptide bond, a strong covalent bond, can be broken down by hydrolysis in the presence of a type of digestive enzyme called proteases.
31. According to the need of the human body, what are the two kinds of amino acids?
(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 reasons why the nutritional value of different protein rich food is different. Proteins with more essential amino acids are
more nutritious.
32. What is the source of protein?
Animal source: meat, fish, beef, milk or dairy products
Plant source: peas, mushrooms
33. 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.
34. What is the name of the disease that is caused by a severe lack of protein? What are the signs of the disease?
Kwashiorkor
Signs: weak muscles, swollen abdomen
35. What is the consequence of excessive intake of protein?
Excess amino acids will be broken down to form urea in the liver.
During the process, carbohydrates and lipids will be formed.
36. What are the sources of calcium?
Animal source: bones, canned sardines, milk
Plants source: vegetables (kale, broccoli and spinach), tofu.
37. What are the functions of calcium?
(1) Component of bones and teeth
(2) Involved in muscle contraction
(3) Involved in blood clotting
(4) Involved in transmission of nerve impulses
38. What are the diseases that is caused by calcium deficiency?
Children: rickets It causes the legs to bend
Adults: osteoporosis
39. What is the source of iron?
Animal source: blood, meat that is more red (i.e. contains more red blood cells), for example: beef, liver. As such, pork contains a comparative less amount of iron.
Plant source: pea, spinach
40. What is the function of iron?
It is one of the components of haemoglobin, and haemoglobin is responsible for transporting oxygen.
41. What is the disease that is caused by iron deficiency? What is the symptom of this disease?
Name of disease: Anaemia
Symptom: Dizziness
42. What are the sources of vitamin A?
Liver oil, Liver (because vitamin A is soluble in lipid), egg, milk, carotene containing food such are carrots because carotene can be converted to become Vitamin A in the liver.
43. What is the function of vitamin A?
(1) It is needed in the formation of a pigment (visual purple) on the retina. The pigment is 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)
44. What are the diseases caused by a deficiency of vitamin A? What is the symptom of this disease?
Name of disease: night blindness
Symptom: (1) drying up of cornea and skin
(2) easy infection of the lining of the lungs and trachea by bacteria
45. What are source of vitamin C?
Fresh vegetable (especially green pepper, broccoli, guavas, kiwi fruits, oranges, lemons)
46. What is the characteristic of vitamin C
Water soluble
Easily damaged by high temperature and oxygen.
47. What is the function of vitamin C?
Vitamin C
(1) maintains healthy connective tissues.
(2) promotes the absorption of iron.
48. 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
49. What are the source of vitamin D?
High fat fish (e.g. salmon, tuna)
Liver oil
Egg yolk
Exposure of skin to ultraviolet light of sunlight
50. What are the functions of vitamin D?
Promote the absorption of calcium and phosphorus
51. What are the diseases that is caused by calcium deficiency?
Children: rickets It causes the legs to bend
Adults: osteoporosis
52. 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 and will be excreted in urine.
Fat soluble: vitamin A and D
53. What are the functions of dietary fibre to humans?
(1) add bulk to food, consequently promoting peristalsis because the bigger volume of food stimulate the nerve on the wall of the alimentary canal.
(2) Store large amount of water, therefore keeping the faeces soft.
54. What is the source of dietary fibre?
Fruits / vegetable and cereals
55. What is the disease that is caused by a deficiency of dietary fibre?
constipation
56. How to test for reducing sugar?
(1) Add Benedict’s solution to an unknown solution.
(2) Boil the mixture in a boiling water bath.
(3) If the colour of the mixture turns from blue to brick red because brick red precipitate is formed, reducing sugar is present.
57. How can the presence of starch be test?
(1) add iodine solution
(2) if colour turns from brown to blue black, starch is present.
58. How to test for vitamin C?
(1) Add the sample solution to DCPIP solution (note: not DCPIP to the sample!)
(2) If the colour turns from blue to colourless, vitamin C is present.
59. Which food test require heating?
Benedict’s test
60. 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.
61. What are the food substances that are needed more by children?
(1) Protein
(2) Calcium
(3) Iron
62. What food substances do males need more than females?
Protein and food that contains more energy
63. What food substances do females need more than males?
Iron, they need it to replenish the blood lost through menstruation.
64. What food substances do pregnant women need more?
Energy rich food substances, Protein, Iron
65. What does breast feeding woman need more in food substances?
(Fact: Breast feeding women do not have menstruation)
Apart from iron, all others food substances are in greater need.
66. What is the disease that is caused by an excessive intake of fat?
Obesity
67. What are the problems that come along with obesity?
(1) diabetes
(2) heart diseases
(3) stroke
(4) arthritis
(5) high blood pressure