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

Chemosensitive area of respiratory centre medulla is affected by
1. less ${\mathrm{CO}}_2$ and ${\mathrm{H}}^{+}$ ions
2. less ${\mathrm{O}}_2$ and ${\mathrm{H}}^{+}$ ions
3. excess ${\mathrm{CO}}_2$ and H+ ions
4. excess ${\mathrm{O}}_2$ and H+ ions.

Oxygen binding to haemoglobin in blood is

In the given diagram, the functional residual capacity will be depicted by:

  
1.  B + F
2.  B + D + F
3.  A - [B + C]
4.  A - E

In the given diagram of the oxygen dissociation curve, under normal physiological conditions, the partial pressure of oxygen at the tissue level is represented by:
   
1. A
2. B
3. C
4. D

Assertion: Gas exchange with water as the respiratory medium is much more demanding than breathing air.
Reason: Air contains much more O2 than water at the same ${\mathrm{PO}}_2$.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false