WAEC Biology 2025 Theory — Question 12

Model answer

(i) Density-dependent factors vary with population size, while density-independent factors affect populations regardless of their size. (ii) Examples of density-dependent factors: disease, competition, predation and parasitism (any two). (iii) Density-dependent factors help maintain dynamic equilibrium by regulating population size based on how crowded the population becomes; as a population grows, competition for food and space intensifies, leading to higher death rates or lower birth rates. Density-independent factors can cause sudden and unpredictable changes in population size regardless of density - events like floods or wildfires may drastically reduce a population. Together, both types of factors influence population balance, resource availability and species interaction.