Why would bacteria retain a gene that gives them resistance to antibiotics?

Why would bacteria retain a gene that gives them resistance to antibiotics?

• A. They provide a growth advantage in presence of antibiotics
• B. They suppress growth in presence of antibiotics
• C. They occasionally die
• D. They confer no advantage

Answer: (D)

Antibiotic resistance genes are kept because they provide a survival and growth advantage when antibiotics are present. In those conditions, susceptible bacteria are killed or slowed, while those with the resistance gene survive and continue to multiply. This selective pressure shifts the population toward resistant cells. If antibiotics aren’t around, carrying resistance can sometimes have a cost, so the gene might be lost unless it’s linked to other benefits or easily transferred between bacteria. So the key idea is that resistance helps bacteria survive and grow in the presence of antibiotics, which is why such genes are retained.

Antibiotic resistance genes are kept because they provide a survival and growth advantage when antibiotics are present. In those conditions, susceptible bacteria are killed or slowed, while those with the resistance gene survive and continue to multiply. This selective pressure shifts the population toward resistant cells. If antibiotics aren’t around, carrying resistance can sometimes have a cost, so the gene might be lost unless it’s linked to other benefits or easily transferred between bacteria. So the key idea is that resistance helps bacteria survive and grow in the presence of antibiotics, which is why such genes are retained.