Question

Suppose bacteria are grown on a petri dish that contains nutrient agar and the antibiotic ampicillin. After observing the bacteria growth on the plate for two days, you notice that only some of the bacteria have survived. What is a plausible explanation for your observations?
The bacteria that survived were transformed with a plasmid that contains the resistance gene for ampicillin.
The pili of the bacterial could not attach to the ampicillin.
Some of the bacterial DNA was not able to replicate because it lacked some of its own genetic material.
F plasmids were not present to transfer bacterial DNA.

Answer 1

The correct answer is: The bacteria that survived were transformed with a plasmid that contains the resistance gene for ampicillin.  

During the process of transformation, bacteria take up foreign DNA from their environment. This property of bacteria is used for DNA cloning technique where plasmids are transferred inside bacteria. Plasmids usually contain gene for the antibiotic resistance, and that is used for the selection of transformed bacteria (bacteria with a plasmid are antibiotic-resistant).