A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissue. This O2

  • Raise the pCO2 of blood 75 mm of Hg.

  • Is enough to keep oxyhaemoglobin

  • helps in releasing more O2 to the epithelial tissues

  • acts as a reserve during muscular exercises

Lungs are made up of air-filled sacs the alveoli. They do not collapse even after forceful expiration, because of :

  • Residual Volume

  • Inspiratory Reserve Volume

  • Tidal Volume

  • Expiratory Reserve Volume

Reduction is vascular tissue, mechanical tissue and cuticle is characteristic of 

  • xerophytes

  • mesophytes

  • epiphytes

  • hydrophytes

Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort?

  • One can breathe out air totally without oxygen

  • One can breathe out air through eustachian tubes by closing both the nose and the mouth

  • One can consously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all

  • The lungs can be made fully empty by forcefully breathing out all air from them

Two friends are eating together on a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of

  • Diaphragm

  • Neck

  • Tongue

  • Epiglottis

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