Trachea is invested with incomplete cartilaginous rings. They:

1.	serve as a point of attachment for some muscles of expiration.
2.	support muscular attachments to the thyroid cartilage and epiglottis.
3.	prevent the trachea from collapsing.
4.	attach the trachea to the esophagus posteriorly.

Alveoli in the lungs are lined by:
1. a simple squamous epithelium.
2. a pseudostratified ciliated columnar epithelium.
3. a simple cuboidal epithelium.
4. a transitional epithelium.

Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration, because of
1. Residual Volume (RV)
2. Inspiratory Reserve Volume (IRV)
3. Tidal Volume (TV)
4. Expiratory Reserve Volume (ERV)

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