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

Assertion: In nasal cavity, mucus which lies superficial to the microscopic cilia filters inspired air.
Reason: The cilia of the respiratory epithelium move the secreted mucus and particulate matter towards the external nostrils.

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

Assertion: The terminal bronchiole is the most distal segment of the conducting zone.
Reason: They are the narrowest airways of the lungs.

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

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R): 
 

In the light of the above statements choose the correct answer from the options given below: