Question 1: Define biotic factors and give three examples found in a forest ecosystem.

Answer: Biotic factors are living components of an ecosystem that influence other organisms. Examples include trees, insects, and fungi.

Question 2: Define abiotic factors and list four examples that affect aquatic ecosystems.

Answer: Abiotic factors are non-living physical and chemical components of an ecosystem. Examples include temperature, pH level, sunlight, and dissolved oxygen.

Question 3: Explain how sunlight (an abiotic factor) influences the distribution of plants in an ecosystem.

Answer: Sunlight provides energy for photosynthesis, enabling plants to produce food. Areas with more sunlight support more plant growth, affecting the distribution of plant species.

Question 4: Calculate the total biomass (in grams) if a population of 50 rabbits each has an average biomass of 2.5 kg. Show your work and provide the answer in grams.

Answer: Total biomass = number of rabbits × average biomass per rabbit (in grams) = 50 × 2500 g = 125,000 g

Question 5: Identify three biotic and three abiotic factors that could influence the growth of algae in a pond.

Answer: Biotic factors: algae competition, presence of herbivorous fish, bacteria. Abiotic factors: sunlight intensity, nutrient levels (like nitrogen and phosphorus), temperature.

Question 6: Describe an experiment to test how temperature affects the growth rate of bacteria in soil.

Answer: Set up multiple soil samples with identical conditions, varying only in temperature (e.g., 10°C, 20°C, 30°C). Measure bacterial growth by colony count or biomass after a fixed period. Ensure safety precautions by wearing gloves and working in sterile conditions.

Question 7: Which of the following is NOT an abiotic factor? A) Water B) Soil C) Predators D) Temperature

Answer: C) Predators

Question 8: Fill in the blank: In desert ecosystems, low ______ levels limit plant growth, while high ______ levels can cause water stress for animals.

Answer: water; salt

Question 9: Explain why changes in abiotic factors such as temperature and pH can lead to shifts in ecosystem composition.

Answer: Abiotic factors like temperature and pH influence the survival and reproductive success of organisms. Changes can create unsuitable conditions for some species while enabling others to thrive, leading to shifts in community composition and possibly affecting ecosystem stability.

Question 10: Apply your understanding of biotic and abiotic factors to explain how urbanization might alter local ecosystems.

Answer: Urbanization can introduce new abiotic factors such as pollution, noise, and altered temperature (urban heat island). It can also reduce habitats for biotic factors like plants and animals, leading to decreased biodiversity and changes in ecosystem processes.