Question

In a microbiology laboratory, the technician uses heat to sterilise the nutrient solution that is used to grow 4. a fungus. When the heating system broke down, he sterilised the solution by passing It on a sterile environment) through a sterile filter with a pore size of 0.2 micrometers. When the fungus was grown on the filtered nutrient solution, it stopped growing and looked unhealthy within a few days. Which statements is the most likely explanation for the observed effects on the fungus ?

• A. The nutrient solution contained a virus
• B. Heating makes the glucose in the nutrient solution more digestible
• C. Filtering removed one of the larger nutrients
• D. The nutrient solution contained a bacterium that was pathogenic to the fungus.

Answer 1

The correct option is A The nutrient solution contained a virus

A) Viruses inhibit the growth of other organisms by entering the host organism and using its genetic material and nutrition to reproduce. Hence, the fungus stops growing.

B) The fungus absorbs glucose. Heating glucose will destroy it and the fungus will not be able to digest it.
C) Glucose is a micro-molecule which passes through the filter. The fungus mainly requires glucose to survive. Filtering did not affect the fungus.
D) Bacteria are too large to penetrate the filter and hence cannot affect the fungus.
So the correct answer is 'The nutrient solution contained a virus'.