Question

For a population of bacteria exposed to an antibiotic, most of them get killed but few survive and again increase their number.

Choose the correct statement for the explanation of the experiment.

• A. Some of the bacteria tried and successfully adapted to the new conditions in the petri dish.
• B. Some members of the bacteria population developed a resistance to the antibiotic immediately.
• C. Some members of the bacteria population already had a resistance to the antibiotic so they were not killed.
• D. Some of the bacteria quickly evolved into a new species that resists the antibiotic.
• E. Some of the bacteria protected themselves from the antibiotic long enough to develop a resistance.

Answer 1

The correct option is C Some members of the bacteria population already had a resistance to the antibiotic so they were not killed.

Even after exposure to the antibiotic, a few bacteria are surviving, this is because, some members already had a resistance to the antibiotic and so these bacteria were not killed and survived which again reproduced, thereby increasing their numbers.

Thus, the correct answer is option C.