Consider the following statements: 1. Biofilms can form on medical implants within human tissues. 2. Biofilms can form on food and food processing surfaces. 3. Biofilms can exhibit antibiotic resistance. Which of the statements given above are correct?

Answer: D. All three statements about biofilms are correct. A biofilm is a community of microorganisms (bacteria, fungi, algae) embedded in a self-produced extracellular polymeric substance (EPS) matrix, attached to a surface. (1) Biofilms on medical implants: CORRECT. Biofilms are a major problem on catheters, prosthetic joints, heart valves, contact lenses, dental implants. They are responsible for chronic implant infections requiring device removal. Estimated 60-80% of human bacterial infections involve biofilms. (2) Biofilms on food and food-processing surfaces: CORRECT. Biofilms form on cutting boards, conveyor belts, drains, pipes in food processing plants. Salmonella, Listeria, E. coli biofilms are major sources of foodborne contamination. Hard to clean even with sanitisers. (3) Antibiotic resistance: CORRECT. Bacteria in biofilms can be 100 to 1000 times MORE RESISTANT to antibiotics than free-floating planktonic bacteria. The EPS matrix limits antibiotic penetration; slow-growing dormant cells inside biofilms evade antibiotic action. All three statements accurate. Source: NIH biofilm research / NCERT Class 11 Biology Ch 2 (Biological Classification).