Question

Explain the experiment of Ganong's respiroscope.

Answer 1

Let us know what respiroscope means. As the name indicates it measures the rate of respiration of a living organism. Respiration involves inhaling oxygen and then releasing carbon dioxide. So it measures the rate at which oxygen and carbon dioxide are exchanged. In other ways, it measures the respiratory quotient which is the ratio of carbon dioxide liberated to the oxygen used.

Complet answer:
We have got an idea of the use of a respiroscope, now let's get into the details of the experiment. It was conducted by Ganong. The apparatus required are any respiring material such as leaves, flowers, seeds etc; respiroscope and $10\%$ KOH solution. The respiroscope consists of a glass bulb with bent neck which further continues as a straight vertical tube. Some respiring material is taken into the glass bulb and the tube is immersed into a beaker containing KOH solution. The glass bulb has a stopper which regulates the movement of air into it. Cut down the oxygen supply and leave the set up for a few hours.
Observation: You will observe that the level of KOH rises. This is because the seeds absorb the oxygen from the respiroscope and liberates carbon dioxide which is in turn absorbed by KOH and creates a vacuum by which the solution in the tube rises.

Note:
When you perform this experiment using different tissues like leaves,seeds and flowers, it is said that the germinating seeds show higher respiration rate than any other as the thumb rule states that higher the metabolic activity, highest is the respiration rate. The metabolic activity of germinating seeds is more and hence they do respire more.