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JAMB Biology 2005 Question 20

Question 20

Respiration

A test tube containing yeast in glucose solution was suspended in a covered conical flask containing alkaline pyrogallol. The bubbles of carbon (IV) oxide produced indicate that the yeast cells are

  1. A.respiring in the absence of oxygen
  2. B.liberating oxygen on their own
  3. C.living and consuming oxygen
  4. D.being killed by the alcohol produced
Show the answer and explanation

Answer: A (respiring in the absence of oxygen)

Explanation

Alkaline pyrogallol absorbs oxygen, so the yeast has no oxygen. Bubbles of carbon(IV) oxide show it is still respiring anaerobically (fermentation).