Page 129 - Biology Form Two
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Biology for Secondary Schools
3. Explain the importance of blood (d) oxygenated blood from the
circulation. lungs enters the left auricle
4. Describe what will happen to the through the pulmonary vein;
flow of blood in the left side of the (e) the left auricle pumps blood
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heart if the bicuspid valve stops to to the left ventricle; and
function effectively. (f) the left ventricle pumps
5. Briefly explain the effects of HIV blood to all parts of the body
on white blood cells. through the aorta.
6. Why is the human circulatory 4. The main blood vessels are
system referred to as a double arteries, veins, and capillaries.
circulatory system? 5. Arteries are muscular vessels
that transport blood away from
7. Explain the symptoms and control the heart. Arteries contract and
measures for three common relax, hence creating a pulse.
disorders of the human circulatory
system. 6. Veins are less muscular than
arteries. They transport blood
towards the heart.
Chapter summary
1. The mammalian heart is 7. Capillaries are very small vessels
responsible for pumping blood to whose walls are one cell thick.
all parts of the body. It has four They are in direct contact with the
chambers: two auricles (atria) and body tissues.
two ventricles. 8. Blood is a fluid tissue consisting
2. Valves in the heart and veins of plasma, red blood cells, white
prevent the back flow of blood. blood cells, and platelets.
3. The flow of blood in the heart is 9. The grouping of human blood is
as follows: done following the ABO blood
(a) deoxygenated blood from the grouping system and the Rhesus
body enters the right auricle factor.
through the vena cava;
10. Blood transfusion is the transfer of
(b) the right auricle pumps blood blood from a donor to a recipient
to the right ventricle;
of the same species.
(c) the right ventricle pumps 11. Agglutination occurs if transfused
blood to the lungs through blood is incompatible with the
the pulmonary artery;
recipient’s blood.
Student’s Book - Form Two 123
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BIOLOGY FORM 2 NEW.indd 123
