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
