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New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
Chapter 8
p.1/4
Suggested answers to Exercise and Reading to
learn
(Note: The overseas examination boards bear no responsibility for the suggested answers
contained in this publication. Answers for HKCEE and HKALE questions are not available due
to copyright restrictions.)
Ch 8 Transport in humans
Exercise
Multiple-choice questions (p. 8-31)
1
5
9
C
B
C
2
6
10
D
B
B
3 B
7 A
11 B
4
8
12
A
B
B
Short questions (p. 8-33)
13
a
b
i
Haemoglobin
1m
ii
Carries oxygen / forms oxyhaemoglobin
1m
from lungs to tissues
1m
No nucleus / biconcave disc
14
HKCEE Biology 2006 I Q1
15
a
1m
Blood flows twice through heart
1m
per one full circulation
1m
OR
b
Pulmonary circulation / to lungs
1m
Systemic circulation / to the body
1m
Any one from:
1m
More oxygen reaches tissues / cells OR more efficient supply to tissues / cells
Helps sustain high blood pressure
Less resistance to flow
Easier to return blood to heart
More rapid circulation
Greater activity possible
Too high a pressure does not damage lungs
16
HKCEE Biology 2001 I Q3b
 Oxford University Press 2009
New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
Chapter 8
p.2/4
Structured questions (p. 8-34)
17
HKCEE Biology 2005 I Q8a
18
HKCEE Biology 2004 I Q3c
19
a
As the total cross-sectional area of vessels increases (due to branching of arteries into
arterioles) / large number of capillaries
1m
Resistance to blood flow increases and blood pressure falls
1m
OR
Formation of tissue fluid at the arterial end of capillary beds
1m
Decreases blood volume and therefore decreases blood pressure within the capillary
beds
1m
OR
Greater distance from heart
1m
Pressure gradually reduces with distance from heart / pressure is maintained by small
lumen of the arteries
1m
OR
b
Veins have a larger lumen
1m
Larger volume equals decreased pressure
1m
Any two from:
1m x 2
The arteries have a thick wall (particularly the tunica media) to resist pressure
The arteries contain numerous elastic fibres
Elastic fibres allow expansion under pressure
Small arterial lumen ensures high pressure
c
Any two from:
1m x 2
The veins have a large lumen to reduce the resistance of blood flowing into them
Veins rely on the movement of surrounding muscle tissue to move blood along
They possess valves to prevent backflow
Description of how valves work
d
i
Tissue fluid forms at the arterial end of capillary networks because of the high
blood pressure.
ii
1m
Reabsorption at the venule end is brought about osmotically because of the
lower solute potential provided by the retained proteins.
20
a
Pulmonary artery
b
S➝D➝C➝P➝X➝Q➝B➝A➝R
1m
1m
(2m for all correct answers or no marks)
c
R has a thicker wall than S.
1m
R has a smaller lumen than S.
1m
 Oxford University Press 2009
New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
d
Chapter 8
p.3/4
Blood in R has more oxygen / less carbon dioxide / more glucose than in S. (any 2)
1m x 2
e
The semilunar valves are closed.
1m
The cardiac muscle of A and C relaxes.
1m
The pressure inside A and C is lower than the pressure in P and R.
1m
Essay (p. 8-35)
21
Any 10 from:
1m x 10
Highest pressure is in the aorta / arteries / closest to heart, where there is rhythmic rise and
fall / pulse.
Pressure drops progressively from arteries to arterioles.
Pressure drops further through capillaries / progressive drop with increased distance from
heart.
Pressure in veins is low.
(Marks of the above points may be awarded on annotated graph)
Rise and fall in aorta or arteries corresponds to contraction of ventricles.
Friction with walls causes pressure drop.
Arterioles have large total cross sectional area. Capillaries give even greater cross
sectional area.
Few vessels subdividing into many smaller vessels, causing substantial pressure drop from
arterial values / narrow lumen increases friction so pressure drops.
Effect depends on whether arterioles are dilated or constricted / reference to elastic recoil
in artery walls / maintains pressure.
Pressure also drops in capillaries because of leakage of fluids into tissues.
Pressure in veins / away from heart is non-rhythmic because influence of ventricles has
been dissipated.
Pressure in veins can be increased by squeezing action of (skeletal) muscles.
This works because of the presence of valves in veins.
Reading to learn (p. 8-36)
1
Blood is returned to the heart from different organs through blood vessels, instead of being
used up as suggested by Galen.
1m
Blood cannot flow from one ventricle to the other through pores in the septum of the heart,
because there is no pore in the septum. Blood flows from one ventricle to the other through
blood vessels.
1m
 Oxford University Press 2009
New Senior Secondary Mastering Biology
Suggested answers to Exercise and Reading to learn
2
Chapter 8
p.4/4
Some of the deoxygenated blood in the right atrium and ventricle will bypass the lungs.
1m
Blood in the right atrium and ventricle directly goes to the left atrium and ventricle and
pumped to different parts of the body.
1m
Organs and tissues cannot get enough oxygen supply from the blood.
3
4
1m
Harvey used careful calculations and repeated experiments to show blood was not used up,
but flowed in a closed loop.
1m
He dissected the septum of the heart to show it contained no pores.
1m
Yes, scientists should be skeptical of other people’s findings.
1m
Though Galen’s idea remained unchallenged for over 1000 years, Harvey was skeptical of
the idea and did experiments to prove that it was wrong. Because of his skeptics and hard
work, he finally worked out the correct theory of blood flow
1m
 Oxford University Press 2009