Question

Moist germinated seeds were placed in a thermos flask A, and germinating seeds, which were boiled and then soaked in 5 percent formalin, were placed in thermos flask B. Thermometers were inserted in the flask and the mouth of each flask plugged with moist cotton wool. The two flasks were fixed upside down as shown in the fig. 10.9. The temperature on both thermometers was noted. After about 48 hours, the temperature in flask A was found to be much higher than that in flask B.

(a) State the object of using the apparatus.

(b) Explain, why a rise in temperature occurs in flask A.

(c) If 5 percent formalin was not used after boiling the seeds, the temperature of flask B would have risen considerably. Explain.

Answer 1

(a) To show that heat is evolved during respiration
(b) In flask A, moist seeds respire and produce heat that increases the temperature.
(c) If formalin was not used, bacteria will grow on the dry seeds and respire anaerobically to produce a little heat.