Question

Which of the following characteristics of a plasmid is not true?
(A). Loss of plasmids can lead to the death of bacterial cells.
(B). Plasmids can code for important characteristics such as antimicrobial resistance.
(C). Plasmids are extrachromosomal DNA.
(D). Plasmids cannot move from one bacterial cell to another.
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), and (D) only.
• C. (A) and (B) only.
• D. (C) and (D) only.

Hint:

Remember that plasmids are dispensable (non-essential) for basic cell survival and can be naturally transferred between bacteria via conjugation.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Plasmids are small, circular, double-stranded DNA molecules found in bacteria that replicate independently of the bacterial chromosome.

Step 2: Detailed Explanation:
Let us evaluate each statement regarding plasmids to identify which are NOT true:

• Statement (A): Loss of plasmids can lead to the death of bacterial cells: This is False. Plasmids are extrachromosomal elements that carry non-essential genes. Bacterial cells can lose plasmids (curing) and continue to grow and reproduce normally under standard conditions.

• Statement (B): Plasmids can code for important characteristics such as antimicrobial resistance: This is a True characteristic. Plasmids often carry genes that confer resistance to antibiotics, heavy metals, or code for virulence factors.

• Statement (C): Plasmids are extrachromosomal DNA: This is a True characteristic. They are physically separate from the genomic DNA of the bacterium.

• Statement (D): Plasmids cannot move from one bacterial cell to another: This is False. Conjugative plasmids can easily transfer between bacterial cells via conjugation (horizontal gene transfer).
Since statements (A) and (D) are NOT true, they represent the correct choices.

Step 3: Final Answer
The incorrect characteristics of plasmids are (A) and (D) only.