“Bends” is a painful condition that is seen in cases of:
1. nitrogen narcosis
2. decompression sickness
3. hyperbaric oxygen therapy
4. carbon dioxide accumulation

Humans are not able to survive for long periods at very high altitudes primarily because:
1. The oxygen content is very low with respect of that found at sea level.
2. The carbon dioxide is much more than that found at sea level.
3. The partial pressure of oxygen is very low than that found at sea level.
4. The atmospheric pressure is much higher than that found at sea level, which makes the amount of oxygen available one-fourth that found at sea level.

The most efficient respiratory system amongst the following would be:
1. mammal lungs
2. reptile lungs
3. bird lungs
4. fish gills

The Bohr effect is a physiological phenomenon first described in 1904 by the Danish physiologist Christian Bohr. It explains why
1. hemoglobin binds carbon monoxide more readily than oxygen
2. hemoglobin unloads its oxygen when it encounters low pH
3. diffusion occurs so slowly over long distances
4. oxygen is present in the atmosphere in relatively low concentrations

Hemoglobin in blood can more readily combine with carbon dioxide when blood passes through the tissues. This is due to:
1. Bohr effect.
2. Haldane effect
3. chloride shift
4. Hering-Breuer Reflex

The chloride shift is also known as Hamburger phenomenon and it
1. occurs primarily in pulmonary capillaries.
2. occurs when Cl- replace HCO3- within red blood cells.
3. decreases the formation of bicarbonate ions.
4. decreases the number of hydrogen ions.

What is the correct chronological sequence of the following structures as air passes through them in inhalation?
a. alveolar duct
b. alveolus
c. respiratory bronchiole
d. terminal bronchiole
1. a, b, c, d
2. b, c, d, a
3. c, d, a, b
4. d, c, a, b

Why is oxygen transport affected in carbon monoxide poisoning?

1. More carbonic acid will be produced, and the hemoglobin will give up more oxygen to the tissue.

2. Hemoglobin will bind to less oxygen, and hemoglobin will not release as much oxygen to the tissue.

3. Carbon monoxide makes hemoglobin give up oxygen more readily in the tissues.

4. Carbon monoxide ties up hemoglobin's ability to bind to oxygen, but more hemoglobin will be produced, so no decline in oxygen in the tissue will be noticed.

Some pathogens can reach the alveoli, they can still be destroyed by:

1. macrophages in the pulmonary lymph nodes
2. NK cells in the elastic tissues of the lungs
3. cytotoxic T-lymphocytes
4. alveolar macrophages

A large proportion of oxygen is left unsused in the human blood even after its uptake by the body tissues. This ${\mathrm{O}}_2$
1. raises the ${\mathrm{P}}_{{\mathrm{CO}}_2}$ of blood to 75 mm of Hg
2. is enough to keep oxyhaemoglobin
3. helps in releasing more ${\mathrm{O}}_2$ to the epithelial tissues
4. acts as a reserve during muscular exercise