Question

Ganong’s respiroscope is used to demonstrate
A. Production of carbon dioxide during aerobic respiration.
B. Production of heat during aerobic respiration.
C. Evolution of oxygen during photosynthesis.
D. Evolution of carbon dioxide during fermentation.

Answer 1

Hint: A glass apparatus having a bulb-like structure along with a bent neck and vertical tube is known as a respiroscope. The experiment carried out using this device is known as Ganong's respiroscope experiment. The rate of respiration of a living organism can be measured using ganong’s respirometer by measuring its rate of exchange of oxygen and/or carbon dioxide.

Complete answer:
Option A - Production of carbon dioxide during aerobic respiration: The ganong’s respiroscope experiment uses germinating seeds to study the evolution of carbon dioxide during the process of aerobic respiration. During the process of respiration, germinating seeds absorb oxygen from the respiroscope and liberate carbon dioxide. A vacuum is created when caustic potash absorbs carbon dioxide. KOH solution rises in the tube, proving that carbon dioxide is liberated during respiration.
Hence the correct option is A.
Option B - Production of heat during aerobic respiration: Respiration is an exothermic process. Energy from food is released in the form of ATP and heat during the process of respiration. But this cannot be measured using Ganong’s respiroscope.
Hence option B is not correct.
Option C - Evolution of oxygen during photosynthesis: During the process of photosynthesis, energy of light is used to split water molecules into its protons and electrons. And as a by-product, oxygen is evolved. This can be measured using audus apparatus.
Hence option C is also not correct.
Option D - Evolution of carbon dioxide during fermentation: Fermentation is an anaerobic process and it results in frothing, which is mainly due to the evolution of carbon dioxide. There are many methods and apparatus used for measuring this but ganong’s respiroscope is not used for this.
Hence option D is also not correct.

So, Option A. Production of carbon dioxide during aerobic respiration, is the correct answer.

Note:
The apparatus used for Ganong's respiroscope experiment consists of a bulb-like part and a bent tube. In the bulb, some germinating seeds are taken and the mouth of the bent tube is kept immersed in a beaker which contains caustic potash (KOH) solution. The whole apparatus is fixed onto a stand. This makes the enclosed air inside the flask to be completely cut off from the outside atmosphere. The whole apparatus is left undisturbed for a few hours and after that it can be observed that KOH solution rises in the bent tube, which suggests that \[C{O_2}\] is liberated.