Question: 141: Pathogenic bacteria gain resistance to antibiotics due to changes in their :
(1) Cosmids
(2) Plasmids
(3) Nucleus
(4) Nucleoid
Answer: Option (2)
Explanation:
Bacteria often possess extra-chromosomal circular DNA molecules called plasmids.
Plasmids can carry genes that provide resistance against antibiotics, known as antibiotic resistance genes.
These plasmids are commonly referred to as R-plasmids.
Changes in plasmids, such as acquisition of resistance genes through mutation or horizontal gene transfer, enable pathogenic bacteria to survive in the presence of antibiotics.
Cosmids are artificial vectors used in genetic engineering and are not naturally responsible for antibiotic resistance.
Bacteria do not have a true nucleus, so option (3) is incorrect.
The nucleoid contains the main bacterial chromosome, but antibiotic resistance is primarily associated with plasmid-borne genes.
Therefore, pathogenic bacteria gain resistance to antibiotics due to changes in their plasmids.