How does transformation differ from transduction in horizontal gene transfer?

• A. Transformation requires bacteriophages to transfer DNA; Transduction uses uptake of free DNA.
• B. Transformation involves uptake of free DNA from the environment; Transduction uses bacteriophages to transfer DNA.
• C. Transformation uses uptake of free DNA from the environment; Transduction uses conjugation to transfer DNA.
• D. Transformation uses plasmids; Transduction uses pili.

Answer: (B)

Transformation is the process where competent bacteria take up naked DNA from their surroundings and potentially incorporate it into their genome. Transduction, on the other hand, uses bacteriophages to move genetic material from one bacterium to another, depositing DNA via a phage particle rather than by the cell taking up free DNA itself. This distinction matters: transformation relies on uptake of free DNA, while transduction relies on phage-mediated transfer. The other scenarios mix in conjugation elements (like pili) or assume plasmid-based transfer, which are features of different horizontal gene transfer pathways and not the defining difference between transformation and transduction.