Question 1: Define a bacterial cell and explain how it differs from a eukaryotic cell.

Answer: A bacterial cell is a prokaryotic cell lacking a nucleus, with a cell wall, cell membrane, cytoplasm, and genetic material in a single circular DNA molecule. Unlike eukaryotic cells, bacterial cells do not have membrane-bound organelles and are generally smaller and simpler.

Question 2: Describe the role of the flagella in bacterial cells.

Answer: Flagella are whip-like structures that enable bacterial cells to move by rotating, allowing them to navigate towards nutrients or away from harmful substances.

Question 3: Explain the function of the bacterial cell wall.

Answer: The bacterial cell wall provides structural support and protection, maintaining the cell's shape and preventing bursting in hypotonic environments.

Question 1: Calculate the surface area-to-volume ratio of a spherical bacterial cell with a diameter of 2 micrometres. Use the formulas: Surface Area = 4πr², Volume = (4/3)πr³. Provide your answer in μm²/μm³.

Answer: Surface area = 4π(1)² = 12.57 μm²; Volume = (4/3)π(1)³ = 4.19 μm³; Ratio = 12.57 / 4.19 ≈ 3.00 μm²/μm³

Question 2: If a bacterial cell divides every 20 minutes under optimal conditions, how many bacteria will be present after 2 hours starting from a single cell? Show your calculation.

Answer: Number of divisions = 2 hours / 20 minutes = 6; Bacteria count = 2^6 = 64

Question 1: Describe a basic experiment to observe bacterial cells using a microscope, including variables you would control.

Answer: A basic experiment involves preparing a bacterial culture on a microscope slide, staining it with a suitable dye (e.g., methylene blue), and observing under a light microscope. Variables to control include the temperature, stain concentration, and exposure time to ensure clear visibility of bacterial cells.

Question 2: List two safety precautions to follow when handling bacterial cultures in a laboratory setting.

Answer: Wearing gloves and lab coats to prevent contamination and always sterilising equipment before and after use.

Question 1: A bacterial population increased from 500 to 4000 in 3 hours. Calculate the average growth rate per hour and explain what this indicates about the bacteria's growth phase.

Answer: Growth factor = 4000 / 500 = 8; Growth rate per hour = 8^(1/3) ≈ 2; This indicates the bacteria are in the exponential growth phase.

Question 2: Based on the data indicating that bacteria possess a nucleoid region instead of a nucleus, explain how this affects gene expression regulation in bacterial cells.

Answer: The nucleoid region allows for rapid gene expression and regulation since it is not compartmentalized like a nucleus, enabling bacteria to quickly respond to environmental changes.

Question 1: Describe the main structural features of a bacterial cell and their functions. (6 marks)

Answer: Bacterial cells have a cell wall providing shape and protection, a cell membrane controlling entry and exit of substances, cytoplasm containing enzymes and genetic material, a nucleoid region with circular DNA, flagella for movement, and sometimes pili for attachment. These structures enable bacteria to survive, reproduce, and adapt to environments.

Question 2: Explain how antibiotics target bacterial cells and why they are effective without harming human cells.

Answer: Antibiotics target specific bacterial structures or processes, such as cell wall synthesis (e.g., penicillin), which are absent or different in human cells. This selective targeting allows antibiotics to kill bacteria without harming human cells.

Question 1: Describe how bacterial cells are utilised in the production of insulin for medical treatments.

Answer: Genetically modified bacteria are engineered to produce human insulin, which is then extracted and purified for use in diabetic treatments, providing a scalable and cost-effective insulin source.

Question 2: Explain the importance of bacterial cell research in developing bioremediation techniques to clean environmental pollutants.

Answer: Research into bacterial cells allows scientists to harness bacteria that can break down pollutants like oil spills or heavy metals, making bioremediation a sustainable method for environmental cleanup.