Explain how pesticides affect soil fertility and list three factors that could cause a decline in a herbivore population.

Here are the solutions to the questions:

1. Excessive use of pesticides may affect soil fertility in several ways:

   • They can kill beneficial soil microorganisms such as bacteria and fungi that are essential for nutrient cycling, decomposition, and nitrogen fixation.
   • They can reduce the population of soil invertebrates like earthworms, which are crucial for improving soil structure, aeration, and water infiltration.
   • The accumulation of pesticides can lead to soil contamination, making the soil toxic to plants and inhibiting their growth.
   • They can alter the chemical composition and pH of the soil, making it unsuitable for certain plant species.

2. The population change between C and D shows a decline in the herbivore population. Three factors that could have caused this decline are:

   • Increased predation: An increase in the number of predators hunting the herbivore.
   • Disease outbreak: A widespread disease could have significantly reduced the population.
   • Food scarcity: Overgrazing by the large herbivore population at point C could have led to a depletion of food resources, causing starvation.
   • Increased competition: Competition for resources with other herbivore species could have intensified.
   • Adverse environmental conditions: A sudden change in environmental conditions such as a severe drought or extreme temperatures could have led to increased mortality.

3. The data table for this question is missing from the provided image. Please provide the data to proceed with the analysis.