Question

4. Suppose a scientist’s swan-necked flasks containing boiled broth became cloudy twenty-four hours after boiling. Which of these options is the most likely explanation for the turbidity?

a. Spontaneous generation.

b. Contaminating acidophiles survived this extreme condition.

c. Extremophilic organisms like Listeria monocytogenes were present prior to boiling.

d. Organisms of the Bacillus genus were present prior to boiling.

e. Solid material in the broth dissolved during boiling.

Answer 1

Answer: d) Organisms of the Bacillus genus were present prior to boiling.

Explanation:

Bacillus genus are sporing organisms. They from endospores when exposed to unfavorable conditions. These spores are resistant to heat, so they survived the boiling procedure. And after 24 hours, they again started forming the bacteria, thus producing turbidity

Moreover, other options stand incorrect as-

Spontaneous generation theory has long been disapproved.

Acidophiles can survive in low pH and not in high temperature.

Extremophilic organisms like Listeria monocytogenes can survive at 0° C but they are susceptible to high temperature and die at around 75°C

Solid material in the broth dissolved during boiling is an incorrect statement as in Swan neck flask experiment, broth is free of any such solid impurities.