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
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
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 countercurrent flow facilitates efficient respiration in gills of fishes
In the tissues, high concentrations of carbon doxide
1. increases the affinity of haemoglobin to both oxygen and hydrogen
2. increases the affinity of haemoglobin to oxygen but decreases its affinity to hydrogen
3. decreases the affinity of haemoglobin to oxygen but increases its affinity to hydrogen
4. decreases the affinity of haemoglobin to both oxygen and hydrogen.
During winter a person died during sleep, the room was closed and a container with burnt
charcoal was found in the room. What may be the possible reason of his death?
1. non-availability of oxygen
2. Hb has more affinity to combine with carbon monoxide
3. Hb has more affinity to combine with nitrogen
4. combined effect of 1. and 3.
The respiratory centre in the brain is stimulated by
1. CO2 concentration in venous blood
2. O2 concentration in artery blood
3. CO2 concentration in artery blood
4. O2 concentration in venous blood.
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 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.
Respiration is controlled by
1. medulla oblongata
Chemosensitive area of respiratory centre medulla is affected by
1. less CO2 and H+ ions
2. less O2 and H+ ions
3. excess CO2 and H+ ions
4. excess O2 and H+ ions.