The given figure shows the diagrammatic view of human respiratory system (sectional view of the left lung is also shown). Regarding the parts labelled as P, Q, R and S, which of the following statements are true?
 

I:	P is an incomplete cartilaginous ring seen only in trachea and principal bronchus.
II:	Q is the point where the trachea divides into a right and left primary bronchus and corresponds to the level of 5th thoracic vertebra.
III:	R shows the double-layered pleura where the outer pleural membrane is in close contact with the thoracic lining.
IV:	S is pleural cavity with minimal amount of pleural fluid which reduces friction on the lung surface.

 
1. Only I, II and III
2. Only I, III and IV
3. Only II, III and IV
4. I, II, III and IV

It is necessary that lungs must be present in anatomically air-tight chamber because: 

The conducting part of the human respiratory system is not involved in:

The major mode of transport of carbon dioxide in human body is:

The formation of oxy-hemoglobin at the alveoli is favored by all the following except:

Which of the following equations regarding the calculation of pulmonary capacities would be correct?

The partial pressure of oxygen in oxygenated blood is about:

The volume of thoracic chamber in the antero-posterior axis can be increased by:
1. Contraction of diaphragm
2. Relaxation of diaphragm
3. Contraction of external intercostals
4. Contraction of internal intercostals

The alveoli are lined with:
1. Simple cuboidal epithelium
2. Pseudo-stratified columnar ciliated epithelium
3. Transitional epithelium
4. Simple squamous epithelium

The binding of carbon dioxide to hemoglobin:
I: is related to the partial pressure of carbon dioxide
II: is affected by the partial pressure of oxygen
1. Only I is correct
2. Only II is correct
3. Both I and II are correct
4. Both I and II are incorrect