Question 1: Define a bacterial cell and describe its main structural components.

Answer: A bacterial cell is a prokaryotic microorganism that lacks a true nucleus, with components including a cell wall, cell membrane, cytoplasm, ribosomes, a single circular DNA molecule, and sometimes flagella. Its main structures are the cell wall, cell membrane, nucleoid region, and pili.

Question 2: Explain how bacterial reproduction occurs and name the process involved.

Answer: Bacterial reproduction occurs mainly through binary fission, where a single bacterial cell divides into two identical daughter cells after replicating its DNA.

Question 3: What is the function of the bacterial flagella?

Answer: Bacterial flagella enable movement, allowing bacteria to navigate their environment.

Question 1: Calculate the surface area of a spherical bacterial cell with a diameter of 2 micrometres (μm). Use the formula for the surface area of a sphere: 4πr². (Recall: 1 μm = 1 × 10⁻⁶ m).

Answer: Surface area = 4 * π * (radius)² = 4 * π * (1 × 10⁻⁶ m)² ≈ 12.57 × 10⁻¹² m².

Question 2: If a bacterial cell divides every 20 minutes, how many cells will be present after 2 hours starting from a single cell? Assume binary fission and no cell death.

Answer: Number of divisions = 2 hours / 20 minutes = 6. Number of cells = 2⁶ = 64.

Question 1: Describe a safe method to culture bacterial cells in a laboratory setting, including safety precautions.

Answer: Bacterial cultures should be grown in sterile conditions using sterilised equipment and growth media. Safety precautions include working in a sterile environment, wearing protective clothing, and properly sterilising or disposing of cultures after use to prevent contamination and infection.

Question 2: Identify variables that could affect the growth rate of bacteria in an experiment and suggest controls to manage these variables.

Answer: Variables include temperature, pH, nutrient availability, and oxygen levels. Controls should include maintaining constant temperature and pH, using the same nutrient medium, and ensuring consistent oxygen supply across all samples.

Question 1: A bacterial population was measured at 1 × 10⁶ cells at the start of an experiment. After 3 hours, the population increased to 8 × 10⁶ cells. Assuming exponential growth, calculate the growth rate per hour.

Answer: Using the formula N = N₀ * 2^(t/T), where N=8×10⁶, N₀=1×10⁶, t=3 hours, solve for T (doubling time): 8×10⁶ / 1×10⁶ = 8 = 2^(3/T). Taking log base 2: log₂8 = 3/T → 3 = 3/T → T=1 hour. The growth rate is therefore such that the population doubles every hour.

Question 1: Explain how bacteria are used in biotechnology and give one example of a product produced through bacterial fermentation.

Answer: Bacteria are used in biotechnology to produce antibiotics, enzymes, and other chemicals through fermentation. An example is the production of insulin using genetically modified bacteria.

Question 2: Describe one way bacterial resistance to antibiotics impacts healthcare and suggest a scientific approach to address this issue.

Answer: Bacterial resistance to antibiotics can lead to infections that are difficult to treat, increasing morbidity and mortality. Scientific approaches include developing new antibiotics, using combination therapies, and implementing strict antibiotic stewardship programmes to prevent resistance development.