Premature infants may develop respiratory distress and can land up in respiratory failure sometimes needing an intensive care for such infants. This may be due to:

1. the sudden change from the uterine environment to the air

2. the incomplete development of the lung surface

3. inadequate production of surfactant

4. mutations in the genes involved in lung formation

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

Which one of the following is the correct statement for respiration in humans?

1. Cigarette smoking may not lead to inflammation of bronchi

2. Neural signals from pneumotoxic centre in pons region of brain can increase the

duration of inspiration

3. Workers in grinding and stone breaking industries may suffer, from lung fibrosis

4. About 90% of carbon dioxide ($C{O}_2$) is carried by haemoglobin as carbamino haemoglobin

The haemoglobin of a human foetus

1. has a lower affinity for oxygen than that of the adult

2. its affinity for oxygen is the same as that of an adult

3. has only 2 protein subunits instead of 4

4. has a higher affinity for oxygen than that of an adult

When a man inhales air containing normal concentration of O₂ as well as CO he suffers from suffocation because

(1) CO reacts with O₂ reducing its percentage in air

(2) haemoglobin combines with CO instead of O₂ and forms carboxyhaemoglobin

(3) CO affects diaphragm and intercostal muscles

(4) CO affects the nerves of the lungs.