F4 Biology teaching notes Ch 5: NE 21

5.3  Food tests (Book 1A, p. 5-19)

Food substances	Food Test 食物試驗	Positive result 陽性反應
(1)Glucose	Using glucose test paper	Depends on the colour chart on the packing of the test paper
Reducing sugar	(2) Benedict’s test (本立德測試)	(After heating, the blue solution changes to form) a brick-red (3) precipitate
Starch	(4) Iodine test	Iodine solution changes from brown to (4) blue-black / dark blue.
(5)Lipids	Grease spot test	A (6) translucent spot is left, which disappears after immersing it in an (7) organic solvent.
Protein	Using protein test paper	Depends on the colour chart on the packing of the test paper
(8)Vitamin C	Using DCPIP solution	(9) Decolourization of the DCPIP solution.

5.4  Balanced diet (均衡膳食) (Book 1A, p. 5-25)

A  The food pyramid (食物金字塔) (Book 1A, p. 5-25)

Ø   (1) Balanced diet (均衡膳食) consists of all the food substances

in the right (2) amounts and (3)proportions

Ø   We can make use of the (4) food pyramid (食物金字塔) as a guideline to plan a balanced diet.

Ø   In the food pyramid, foods are classified into six food groups:     

Food group				Relative amount to be eaten
I	Cereals and grains	(5) d		a	Eat less
II	Dairy products	(6) b		b	Eat moderately
III	Fat, oil, salt and sugar	(7) a		c	Eat more
IV	Fruits	(8) c		d	Eat the most
V	Meat, eggs and beans	(9) b
VI	Vegetables	(10) c

B  Factors affecting our dietary requirements (Book 1A, p. 5-26)

Factor	Effect on dietary requirement
Age	Children require the greatest amount of (11) energy per unit body mass, as: Ø  their surface area to volume ratio (表面積與體積比) is the highest among all age groups: n highest rate of (12) heat loss n have higher (13) metabolic rate to produce heat n need more energy to compensate (補充) to support the active metabolism Ø  they have the highest growth rate Children and teenagers need a large amount of (14) proteins, calcium and iron for building body tissues.
Sex	Ø   After puberty, males generally need (15) more / less energy than females. This is because they usually have a higher (16) metabolic rate to support: n their (17) larger / smaller body size (amounts of muscles) n (18) faster / slower heat loss through the body surface, as they have (19) more / less fat under the skin: Ø   Males need more (20) proteins than females for the growth and repair of muscles. Ø   Females need more (21) iron than males to replace the loss during (22) menstruation (月經).
Level of activity	People who are more physically active need more energy for muscular activities.
Body status	Ø   Pregnant women need: n more energy and proteins for the growth of the (23) foetus (胎兒) n more (24) iron for the formation of foetal red blood cells n more (25) calcium for the formation of foetal bones Ø   Breast-feeding mothers need an extra supply of various types of nutrients for (26) milk production.

C  health problems if we eat too little or too much (Book 1A, p. 5-28)

Ø  If we take in more energy than we need, we may become (27) overweight (過重).

The condition of being seriously overweight is called (28) obesity (肥胖症).

Ø  under-intake of nutrients:

n  may lead to (29) malnutrition

n  and even different (30) deficiency diseases

n  may be caused by (23) anorexia nervosa (神經性厭食):

² a disease of under-eating

² Patients refuse to eat because they are afraid of gaining weight (psychological cause)