The haemoglobin of a human foetus
1. has a lower affinity for oxygen than that of the adult
2. has the same affinity for oxygen 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

People living at sea level have around 5 million RBC per cubic millimeter of their blood whereas those living at an altitude of 5400 metres have around 8 million. This is because at high altitude:
1. people get pollution-free air to breathe and more oxygen is available
2. atmospheric O₂ level is less and hence more RBCs are needed to absorb the required amount of O₂ to survive
3. there is more UV radiation which enhances RBC production
4. people eat more nutritive food, therefore more RBCs are formed

The majority of carbon dioxide produced by our body cells is transported to the lungs:

Consider the following statements:

Which of the above statements are true?

Name the pulmonary disease in which alveolar surface area involved in gas exchange is drastically reduced due to damage in the alveolar walls.

The figure shows a diagrammatic view of human respiratory system with labels A, B, C and D. Select the option, which gives correct identification and main function and/or characteristic.
  
1. A-trachea-long tube supported by complete cartilaginous rings for conducting inspired air
2. B-pleural membrane-surrounds ribs on both sides to provide cushion against rubbing
3. C-alveoli-thin walled vascular bag-like structures for exchange of gases
4. D-lower end of lungs-diaphragm pulls it down during inspiration

Which one of the following statements is incorrect?
1. The residual air in lungs slightly decreases the efficiency of respiration in mammals
2. The presence of non-respiratory air sacs increases the efficiency of respiration in birds
3. In insects, circulating body fluids serve to distribute oxygen to tissues
4. The principle of counter current flow facilitates efficient respiration in gills of fishes

Which of the following match is correct?
1. Emphysema : reduction of surface area of alveoli and bronchi
2. Pneumonia : occupational disease with asbestos
3. Silicosis : inflammation of alveoli
4. Asthma : excessive secretion of bronchial mucus

When a man inhales air containing normal concentration of O₂ as well as CO he suffers from suffocation because
1. CO reacts with ${\mathrm{O}}_2$, reducing its percentage in air
2. haemoglobin combines with CO instead of ${\mathrm{O}}_2$ and forms carboxyhaemoglobin
3. CO affects diaphragm and intercostal muscles
4. CO affects the nerves of the lungs

Respiration is controlled by
1. medulla oblongata
2. cerebellum
3. hypothalamus
4. cerebrum