Question

Bacteriophage viruses were added to a petri dish containing sterile agar growth medium. After a week, the dish was sampled and a number of viruses present were compared. What results would be expected?
(a) The virus population should be in exponential growth since there is sample food and no competition.
(b) After a week, the viruses should be reaching, carrying and the population will be stabilizing.
(c) After a week, the viruses should have already exhausted most of the resources in the closed petri dish and the population will be on the decline.
(d) No new viruses will be present without the presence of host bacteria.

Answer 1

Hint: As we know that bacteriophage viruses or any other viruses need host cells for their growth. In the absence of host cells, they cannot grow even if the nutrient medium is present.

Complete answer:
During a laboratory experiment, when bacteriophage viruses were added to a petri dish containing sterile agar growth medium without any other bacteria or host cell for a week. Then we observe after a week that no new viruses have been grown in that medium.

Additional Information:
- When bacteriophage viruses were added to a petri dish containing sterile agar growth medium and left for a week.
- After one week, the dish was sampled and it has been observed that a number of viruses were present.
- Then the present viruses were compared and the result was that no new viruses were present which means no new viruses were observed in the petri dish.
- This shows that no new viruses will be formed without the presence of host bacteria.
- As we know that to grow or to replicate a bacteriophage virus needs a host cell bacteria but in the provided medium the nutrient was present but the host cell was absent and in the absence of a host cell no new viruses will be formed or grow.
- The bacteriophage viruses are made up of proteins that encapsulate a DNA or RNA genome.
- When the bacteriophage injects its jeans into the bacterium the viral genes enter into the bacterial chromosome and start replicating.
- Then the newly replicated viruses are released by breaking the host cell which results in the death of the host cell.
So, the correct answer is '(d) No new viruses will be present without the presence of host bacteria'.

Note:
- The bacteriophage are made up of proteins and can encode as few as four genes to as many as hundreds of genes
- The bacteriophage viruses infect and replicate only in bacterial cells.
- The newly replicated bacteriophage viruses are released by breaking the host cell.