Breathing and Exchange of Gases

Which one of the following statements is incorrect?

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

People living at sea level have around 5 million RBC per cubic millimetre of their blood whereas those living at an altitude of 5400 metres have around 8 million. This is because at high altitude

1. people eat more nutritive food, therefore more RBCs are formed
2. people get pollution-free air to breathe and more oxygen is available
3. atmospheric O2 level is less and hence more RBCs are needed to absorb the required amount of O2 to survive
4. there is more UV radiation which enhances RBC production.

Blood analysis of a patient reveals an unusually high quantity of carboxyhaemoglobin content. Which of the following conclusions is most likely to be correct? The patient has been inhaling polluted air containing unusually high content of

1. carbon disulphide
2. chloroform
3. carbon dioxide
4. carbon monoxide.

When CO2 concentration in blood increases breathing becomes

1. shallower and slow
2. there is no effect on breathing
3. slow and deep
4. faster and deeper

Given below are four matchings of an animal and its kind of respiratory organ: The correct matchings are

1. (A) and (B)
2. (A), (B) and (C)
3. (B) and (D)
4. (C) and (D).