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

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

Question 2: Explain how abiotic factors such as temperature and soil pH can affect plant growth in an ecosystem.

Answer: Temperature influences metabolic rates and growth; extreme temperatures can hinder development. Soil pH affects nutrient availability; if the pH is too acidic or alkaline, plants may struggle to absorb essential nutrients.

Question 3: Calculate the total biomass if a forest contains 1500 kg of trees and 300 kg of insects. Express your answer in kilograms.

Answer: 1800 kg

Question 4: Identify three abiotic factors that are essential for maintaining a healthy freshwater ecosystem.

Answer: Water temperature, oxygen levels, and pH balance.

Question 5: Which of the following is NOT an abiotic factor? A) Sunlight B) Bacteria C) Soil minerals D) Water pH

Answer: Bacteria

Question 6: Fill in the blank: In a desert ecosystem, the primary abiotic factor responsible for limiting plant growth is __________.

Answer: water scarcity

Question 7: Describe a practical experiment to investigate the effect of soil moisture on plant growth. Include the variables involved and safety precautions.

Answer: An experiment can involve growing identical plants in soils with varying moisture levels (independent variable). The dependent variable is plant growth (height/biomass). Controlled variables include plant species, sunlight, and pot size. Use gloves when handling soil and ensure proper drainage to prevent waterlogging. Record growth over time to analyse the impact of soil moisture.

Question 8: Interpret the following scenario: In a pond, an increase in nutrient levels leads to algal blooms, which decrease oxygen levels in the water. Explain the impact on aquatic organisms.

Answer: The decrease in oxygen levels can cause stress or death in aquatic organisms such as fish and invertebrates, leading to a decline in biodiversity and disruption of the ecosystem.

Question 9: A scientist measures the pH of soil in two different habitats: Habitat A has a pH of 5.5, and Habitat B has a pH of 7.0. Which habitat is more likely to support a diverse range of plant species? Justify your answer.

Answer: Habitat B with pH 7.0 is more likely to support diverse plant species because it is closer to neutral pH, which is optimal for most plants' nutrient absorption and growth.

Question 10: Explain how human activities such as deforestation and pollution can alter biotic and abiotic factors in an ecosystem.

Answer: Deforestation reduces the number of trees and other plants (biotic factors), disrupting food webs and habitat. Pollution introduces harmful substances into soil, water, and air, altering abiotic factors such as pH, oxygen levels, and nutrient content, which can negatively affect organisms and ecosystem stability.