Question 1: Define antibiotics and explain their primary mechanism of action against bacteria.

Answer: Antibiotics are substances derived from microorganisms that kill or inhibit the growth of bacteria by targeting specific bacterial structures or functions, such as cell wall synthesis or protein production.

Question 2: List two differences between bacteria and viruses that affect how antibiotics work.

Answer: Bacteria are living cells that can be targeted by antibiotics, while viruses are non-living and require antiviral drugs; antibiotics target bacterial cell wall synthesis or protein production, which viruses do not have.

Question 1: Describe how penicillin kills bacteria.

Answer: Penicillin inhibits the formation of bacterial cell walls by blocking the enzymes involved in cell wall synthesis, leading to bacterial lysis.

Question 2: Which bacterial process is targeted by tetracycline?

Answer: Tetracycline targets bacterial protein synthesis by binding to the 30S subunit of the ribosome.

Question 1: A study tested the effectiveness of three antibiotics (A, B, and C) against bacteria. The zone of inhibition (in mm) was measured as follows: Antibiotic A: 12 mm, B: 20 mm, C: 8 mm. Which antibiotic is most effective? Justify your answer.

Answer: Antibiotic B is the most effective because it produced the largest zone of inhibition (20 mm), indicating it best prevents bacterial growth.

Question 2: In an experiment, bacteria were exposed to an antibiotic at a concentration of 10 µg/mL. After 24 hours, bacterial growth was completely inhibited at 15 µg/mL but not at 10 µg/mL. What does this data suggest about the minimum inhibitory concentration (MIC)?

Answer: The MIC is between 10 µg/mL and 15 µg/mL, as bacterial growth is inhibited at 15 µg/mL but not at 10 µg/mL.

Question 1: Calculate the concentration of an antibiotic solution if 0.5 grams are dissolved in 250 mL of water. (Use the formula: Concentration (mg/mL) = (mass in grams × 1000) / volume in mL).

Answer: Concentration = (0.5 g × 1000) / 250 mL = 500 mg / 250 mL = 2 mg/mL

Question 2: Propose a basic experimental setup to test the effectiveness of an antibiotic on bacterial growth, describing the variables involved.

Answer: To test antibiotic effectiveness, set up several petri dishes with bacterial cultures. Expose each dish to different concentrations of the antibiotic while keeping other conditions constant. Independent variable: antibiotic concentration; dependent variable: bacterial growth (zone of inhibition or colony count); control variables: temperature, incubation time, bacterial strain. Ensure safety by sterilizing equipment and disposing of cultures properly.

Question 1: Explain why overuse of antibiotics can lead to antibiotic resistance in bacteria.

Answer: Overuse of antibiotics applies selective pressure on bacteria, allowing resistant strains to survive and multiply, which can lead to antibiotic-resistant infections that are harder to treat.

Question 2: Describe one way in which biotechnology companies develop new antibiotics to combat resistant bacteria.

Answer: Biotechnology companies develop new antibiotics by researching and synthesizing novel compounds, modifying existing antibiotics, or using genetic engineering to produce antibiotics that can target resistant bacterial strains.