Name __________________________________________________________ Date ______________
Ventilation System Worksheet
1.	What normally prevents the membranes of the alveoli from sticking together during expiration?
A.	The thickness of the single-cell layer of alveoli membranes
B.	The secretion of fluids in the inner surface of the alveoli
C.	The pressure within the thoracic cavity
D.	The dense net of capillaries covering the alveoli
(Total 1 mark)
2.	Which of the following is part of the process of cellular respiration?
A.	Changes in the volume of the thoracic cavity
B.	Exchange of gases across the surface of the alveoli
C.	Exchange of gases across the surface of capillaries
D.	Glycolysis
(Total 1 mark)
3.	Up to two additional marks are available for the construction of your answers.
(2)
	Describe the structure of the ventilation system, including the alveoli.
(8)
(Total 10 marks)

4.	Capillaries surround the alveoli in the lungs. Which pair of statements correctly describes the concentrations of oxygen and carbon dioxide in the lungs?
	Oxygen	Carbon dioxide	
A.	Higher in the capillaries	Higher in the alveoli	
B.	Lower in the capillaries	Higher in the alveoli	
C.	Lower in the alveoli	Higher in the capillaries	
D.	Higher in the alveoli	Higher in the capillaries	
(Total 1 mark)
5.	What is the function of the structure labelled X?

[From: www.medical-look.com/human_anatomy/organs/Lungs.html]
A.	Gas exchange
B.	Ventilation
C.	Respiration
D.	Inspiration
(Total 1 mark)
6.		Describe the need for a ventilation system in humans.
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 (Total 2 marks)
7.	Which muscles contract to cause air to pass into the lungs through the trachea?
A.	Internal intercostal muscles and diaphragm
B.	Internal intercostal muscles and abdomen wall muscles
C.	External intercostal muscles and diaphragm
D.	External intercostal muscles and abdomen wall muscles
(Total 1 mark)
8.	What causes air to be breathed out by the lungs?
A.	The diaphragm relaxes and the ribs fall.
B.	The ribs rise and the external intercostal muscles relax.
C.	The internal intercostal muscles contract and the ribs rise.
D.	The diaphragm contracts and internal intercostal muscles contract.
(Total 1 mark)
9.	What feature of alveoli adapts them to efficient gas exchange?
A.	They have muscles which pump air in and out regularly.
B.	Their membranes are more permeable to gases than water.
C.	A constant blood supply flows through them.
D.	A dense network of capillaries surrounds them.
(Total 1 mark)
10.	What change occurs to the pressure and volume of the lungs when the external intercostal muscles contract?
A.	Both pressure and volume increase.
B.	Pressure increases and volume decreases.
C.	Pressure decreases and volume increases.
D.	Both pressure and volume decrease.
(Total 1 mark)
11.	Explain how and why ventilation rate varies with exercise.
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(Total 6 marks)