2016年3月2日 星期三

F4 Bio 2nd Term Test 1 Ch6

F4 Biology 2nd Term Test 1:
Ch 6: Human Nutrition

A.     Multiple Choice (10marks)
Q.
1
2
3
4
5
6
7
8
9
10
Answer
B
D
D
D
C
A
B
A
B
C
Wrong no.
17
17
11
15
11
16
11
19
15
15

B     Conventional questions
1      a      It stores bile temporarily.                                                                                                1
Con: It produces bile juice/salt/pigment, stores fat, stores pancreatic juice (X)
        b
Structure
Role in chemical digestion
X
Digestive enzymes on its epithelium help break down disaccharides and peptides.
Y
It produces digestive enzymes that help break down starch, proteins and lipids.
Z
It produces a digestive enzyme that helps break down proteins.
Rel: Role = 角色
        Many students write something not related to chemical digestion

2      (a)    There are numerous villi on the inner wall of the small intestine.                                   1
(b)    (1.8 / 20) cm
        = 0.09 cm                                                                                                                        1
(c)    Alternate contraction and relaxation of the muscles bring about peristalsis,                  1
which brings newly digested food molecules into close contact with the villi for absorption.                                                                                                                      1
Peristalsis also causes the villi to move. This keeps a steep concentration gradient
of food molecules across the wall of the small intestine to increase the rate of
diffusion of food molecules.                                                                                          1
Con: The muscle layers in the wall which called villi… (X)




3      (a)    X: stomach                                                                                                                      1m
Con: oesophagus / gall bladder (X)
Y: duodenum                                                                                                                   1m
Con: stomach, intestine (X)

(b)    (i)    Gastric juice produced by the gastric glands on the stomach wall                                    1m
contains hydrochloric acid, making the food acidic.                                                        1m
(ii)   Bile produced by the liver and pancreatic juice produced by the pancreas                      1m
contain sodium hydrogencarbonate, thus the pH of the food increases.                          1m

(c)    Such variation provides suitable pH for the enzymes in different parts of the
alimentary canal to act on.                                                                                                       1m

(d)    Ileum is very long. This allows sufficient time for complete absorption.
/ The inner wall of the ileum is highly folded / has many finger-like projections / villi.
This increases the surface area for absorption.
/ The epithelium of villi is very thin / only one-cell thick. This provides a short distance for diffusion of food molecules into the blood and lymph.
/ The cell membrane of the epithelial cells of the villi has a large number of  microvilli / brush borders. This increases the surface area for absorption.
/ Villi have lacteals and capillaries. They allow the absorbed food molecules to be carried away rapidly, thus keeping a steep concentration gradient to increase the rate of diffusion.
/ Peristalsis brings food molecules into close contact with the villi. This helps keep a steep concentration gradient to increase the rate of diffusion.

                   (any 2)                                                                                                                     2m x 2

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