IGCSE - Gas exchange

What is the approximate percentage of oxygen in expired air?

• 0.04%

• 4%

• 16%

• 21%

Compare with atmospheric air, air breathed out by a human contains

• less water vapour, less carbon dioxide

• less water vapour, more carbon dioxide

• more water vapour, less carbon dioxide

• more water vapour, more carbon dioxide

What is the path of carbon dioxide as it leaves the lungs?

• alveolus --> bronchiole --> bronchus --> trachea

• alveolus --> bronchus --> bronchiole --> trachea

• trachea --> bronchiole --> bronchus --> alveolus

• trachea --> bronchus --> bronchiole --> alveolus

In some amphibians, gas exchange occurs through the whole skin surface. What are the most likely characteristics of the skin surface?

• Large surface area, thick skin

• Large surface area, thin skin

• Small surface area, thick skin

• Small surface area, thin skin

What describes the action of the intercostal muscles and the diaphragm when we breathe out?

• external intercostal muscles contract, internal intercostal muscle relax, diaphragm falls

• external intercostal muscles contract, internal intercostal muscle relax, diaphragm rises

• external intercostal muscles relax, internal intercostal muscle contract, diaphragm falls

• external intercostal muscles relax, internal intercostal muscle contract, diaphragm rises

When the external intercostal muscles contract, how do the pressure and the volume inside the lungs change?

• pressure decreases, volume decreases

• pressure decreases, volume increases

• pressure increases, volume decreases

• pressure increase, volume increases

The air breathed out by a mammal contains 80% of nitrogen. Where does the nitrogen in the air breathed out come from?

• It is a product of proteins broken down in the mammal

• It is a product of respiration

• It is exchanged for oxygen which is taken into the blood

• It is in the air that was breathed in

• A

• B

• C

• D

What makes alveoli suitable as a gas exchange surface?

• Presence of both large total surface area and well-supplied with blood vessels

• Presence of large total surface area only

• Well-supplied with blood vessels only

• Absence of both large total surface area and well-supplied with blood vessels

What is the name of the tube that is also known as your wind pipe?

• esophogus

• bronchi

• trachea

• alveoli