The partial pressure of oxygen in the alveoli of the lungs is
1. equal to that in the blood
2. more than that in the blood
3. less than that in the blood
4. less than that of carbon dioxide

Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because
1. there is a negative pressure in the lungs
2. there is a negative intrapleural pressure pulling at the lung walls
3. there is a positive intrapleural pressure
4. pressure in the lungs is higher than the atmospheric pressure

Reduction in pH of the blood will
1. reduce the blood supply to the brain
2. decrease the affinity of hemoglobin with oxygen
3. release bicarbonate ions by the liver
4. reduce the heart rate

Name the chronic respiratory disorder caused mainly by cigarette smoking
1. asthma
2. respiratory acidosis
3. respiratory alkalosis
4. emphysema

Approximately seventy percent of carbon dioxide absorbed by the blood will be transported to the lungs
1. as bicarbonate ions
2. in the form of dissolved gas molecules
3. by binding to RBC
4. as carbamino-haemoglobin

People who have migrated from the planes to an area adjoining Rohtang Pass about six months back
1. have more RBCs and their haemoglobin has a lower binding affinity to ${\mathrm{O}}_2$ 
2. are not physically fit to play games like football
3. suffer from altitude sickness with symptoms like nausea, fatigue, etc.
4. have the usual RBC count but their haemoglobin has very high binding affinity to ${\mathrm{O}}_2$

Two friends are eating together on a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of
1. diaphragm
2. neck
3. tongue
4. epiglottis

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

What is true about RBCs in humans?

Which two of the following changes (1-4) usually tend to occur in the plain dwellers when they move to high altitudes (3,500 m or more)?

(a) Increase in red blood cell size
(b) Increase in red blood cell production
(c) Increased breathing rate
(d) Increase in thrombocyte count 

1. (b) and (c)
2. (c) and (d)
3. (a) and (d)
4. (a) and (b)