Question 1: Define fungi and explain their key characteristics relevant to their role as pathogens.

Answer: Fungi are a kingdom of eukaryotic organisms characterised by a cell wall made of chitin, with organisms such as moulds, yeasts, and mushrooms. As pathogens, fungi can infect plants and animals by penetrating tissues and producing spores that spread the infection.

Question 2: Describe the mechanism by which fungi infect plant tissues.

Answer: Fungi infect plant tissues mainly through the production of hyphae that penetrate plant cell walls, often entering through wounds or natural openings, and then grow within the tissues, causing disease.

Question 3: Explain why fungi are considered both decomposers and pathogens in ecosystems.

Answer: Fungi decompose dead organic matter, recycling nutrients, and also act as pathogens by infecting living organisms, causing diseases that can influence ecological balances.

Question 1: A fungal culture doubles in size every 24 hours. If the initial size is 1 cm³, what will be its size after 5 days? Show your calculation using the formula: Final size = Initial size × 2^n, where n = number of doubling periods.

Answer: Final size = 1 cm³ × 2^5 = 1 cm³ × 32 = 32 cm³

Question 1: Design a simple experiment to test the effect of temperature on fungal growth. Include the variables you would control and measure, as well as safety precautions.

Answer: The experiment involves growing fungi at different temperatures (e.g., 10°C, 20°C, 30°C). Controlled variables include nutrient medium, humidity, and incubation time. The independent variable is temperature; the dependent variable is fungal growth, measured by colony size or mass. Safety precautions include wearing gloves, sterilising equipment, and working in a sterile environment to prevent contamination and infection.

Question 1: A study shows that a fungal pathogen infects 75% of a crop field within two weeks. The infection rate increases by 5% each subsequent week. How many percent of the field will be infected after 4 weeks? Show your calculations.

Answer: Initial infection after 2 weeks: 75%. Each week adds 5% of the remaining uninfected area: Week 3: 75% + 5% of (100% - 75%) = 75% + 1.25% = 76.25% Week 4: 76.25% + 5% of (100% - 76.25%) = 76.25% + 1.87% ≈ 78.12%. Therefore, approximately 78.12% of the field will be infected after 4 weeks.

Question 1: Identify one industrial application of fungi and explain its significance.

Answer: Fungi such as Saccharomyces cerevisiae are used in baking and brewing to produce bread and alcohol, providing a renewable source of food and beverages, and playing a key role in biotechnology.

Question 2: Discuss a modern technology that utilises fungi for environmental benefit.

Answer: Mycoremediation uses fungi to degrade environmental pollutants such as hydrocarbons and heavy metals, helping to clean contaminated soils and water sources sustainably.

Question 1: Evaluate the potential risks and benefits of using genetically modified fungi in agriculture.

Answer: Benefits include enhanced resistance to pests and diseases, increased crop yields, and reduced need for chemical pesticides. Risks involve unintended environmental consequences, gene transfer to wild fungi, and ecological imbalance. Careful regulation and testing are necessary to balance benefits and risks.