A plasmid copy passes from a living donor directly into a recipient during cell contact. Which process is this?

• Uptake of naked DNA
• Direct-contact conjugation
• Inheritance during division

Which description identifies a plasmid?

• DNA that replicates separately from the chromosome
• DNA that changes position within a chromosome
• DNA that forms the bacterial chromosome and replicates with it

A daughter cell can receive an unchanged copy of its parent's chromosome but fail to inherit a plasmid.

An intact plasmid confers resistance to drugs C and D. Drug C kills noncarriers, and the two genes stay linked. Why can resistance to D remain common even when D is absent?

• Drug C favors carriers of the linked genes
• Drug C induces D resistance in cells without the plasmid
• Drug C favors the D gene after it separates from the plasmid

DNA testing finds four resistance genes on one plasmid. All four function in the recipient. Why can one conjugation event give resistance to all four drugs?

• Each transferred copy carries a different gene
• The four genes transfer as separate copies of that plasmid
• One plasmid copy carries the four genes together

After drug withdrawal, plasmid carriers grow more slowly than noncarriers. Some daughters lose the plasmid, it gives no other benefit, and no transfer occurs. What trend is expected over many generations?

• The fraction of plasmid carriers tends to increase
• The fraction of plasmid carriers tends to stay unchanged
• The fraction of plasmid carriers tends to decrease

Resistance genes are found only on plasmids, never on bacterial chromosomes.

A resistance-carrying transposon moves from a chromosome to a plasmid inside the same bacterium. No DNA enters or leaves the cell. What does this demonstrate?

• Conjugation between two cells
• Transposition within one cell
• Transduction between cells