9700_y16_sy

Cambridge International AS and A Level Biology 9700 syllabus Syllabus content
9 Gas exchange and smoking
The gas exchange system is responsible for the uptake of oxygen into the blood and excreting carbon
dioxide. An understanding of this system shows how cells, tissues and organs function together to
exchange these gases between the blood and the environment. The health of this system and of the
cardiovascular system is put at risk by smoking.
Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and
unfamiliar contexts.
Learning outcomes
Candidates should be able to:
9.1 The gas exchange system
The gas exchange surface
in the lungs is extensive,
very thin, well supplied with
blood and well ventilated.
The trachea and bronchi
provide little resistance to the
movement of air to and from
the alveoli.
a) describe the gross structure of the human gas exchange
system
b) observe and draw plan diagrams of the structure of the walls
of the trachea, bronchi, bronchioles and alveoli indicating
the distribution of cartilage, ciliated epithelium, goblet cells,
smooth muscle, squamous epithelium and blood vessels
c) describe the functions of cartilage, cilia, goblet cells, mucous
glands, smooth muscle and elastic fibres and recognise these
cells and tissues in prepared slides, photomicrographs and
electron micrographs of the gas exchange system
d) describe the process of gas exchange between air in the
alveoli and the blood
9.2 Smoking
Smoking is one of the major
avoidable risk factors of
chronic, life-threatening
diseases of the gas exchange
and circulatory systems.
a) describe the effects of tar and carcinogens in tobacco smoke
on the gas exchange system with reference to lung cancer and
chronic obstructive pulmonary disease (COPD)
b) describe the short-term effects of nicotine and carbon
monoxide on the cardiovascular system
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