r-plasmids are most likely acquired via which of the following processes?

• A. Transduction
• B. Conjugation
• C. Transformation
• D. Binary fission

Answer: (B)

Verified step by step guidance

1. Understand that r-plasmids (resistance plasmids) are extrachromosomal DNA elements that carry antibiotic resistance genes and can be transferred between bacteria.
2. Review the main mechanisms of horizontal gene transfer in bacteria: transformation (uptake of free DNA), transduction (transfer via bacteriophages), and conjugation (direct transfer through cell-to-cell contact).
3. Recall that conjugation involves the transfer of plasmids through a pilus connecting two bacterial cells, which is the primary method for spreading r-plasmids.
4. Recognize that transformation involves uptake of naked DNA from the environment, which is less common for plasmid transfer, and transduction involves viral vectors, which typically transfer chromosomal DNA segments rather than plasmids.
5. Note that binary fission is a method of asexual reproduction and does not involve gene transfer between different cells, so it is not a mechanism for acquiring r-plasmids.