Both carbon dioxide and oxygen move across the respiratory membrane due to:

1. gravity	2. blood pressure
3. diffusion	4. active transport

With respect to the atmospheric air, the deoxygenated blood flowing into lung capillaries has a higher concentration of:

Hemoglobin carrying carbon dioxide is called as:

A measure of the amount of air a person inhales during a normal breath is:

The amount of air that remains in a person's lungs after fully exhaling is known as:

Gas exchange in the human lungs takes place across the respiratory membrane which is made up of:

1. alveolar macrophages and the alveolar cell membrane

2. alveolar cell membrane and its basement membrane

3. alveolar cell membrane and capillary membrane

4. alveolar cell membrane, capillary membrane, and fused basement membranes

The external intercostal muscles and the diaphragm contract:
1. during inhalation
2. during exhalation
3. during both inhalation and exhalation
4. during neither inhalation nor exhalation.

Carbon dioxide is transported in blood by all the following mechanisms except:
1. bound to the protein portion of hemoglobin
2. bound to the iron atoms of hemoglobin
3. dissolved in plasma
4. as bicarbonate

The conversion of carbon dioxide into carbonic acid in the red blood cells is catalyzed by the enzyme:

The efficiency of a respiratory system is enhanced by all the following except: