APES Exam Review Unit 3

Unit 3: Populations

Key Concepts:

  1. Population Dynamics: How populations of organisms change over time. Factors that influence population size include birth rates, death rates, immigration, and emigration.

  2. Carrying Capacity: The maximum number of individuals an environment can support based on resources like food, water, and shelter.

  3. Reproductive Strategies: There are two main types of strategies:

    • K-strategists: Species that produce fewer offspring but invest more time and energy in raising them (like humans, elephants).

    • R-strategists: Species that produce many offspring but don’t invest much in raising them (like mosquitoes, frogs).

  4. Population Growth Models:

    • Exponential growth: When a population grows rapidly without limits (J-shaped curve).

    • Logistic growth: When a population’s growth slows as it reaches carrying capacity (S-shaped curve).

Key Terms:

  • Density-dependent factors: Factors that affect population growth based on the population’s size (like food availability, disease).

  • Density-independent factors: Factors that affect population growth regardless of size (like natural disasters).

  • Age Structure: The distribution of individuals in different age groups in a population (affects population growth).

Important Ideas:

  • Human Population Growth: Humans have experienced exponential growth over the past few centuries due to advances in medicine, agriculture, and technology.

  • Sustainability and Overpopulation: Overpopulation can lead to resource depletion and environmental degradation.

Human Impact on Populations:

  • Habitat Destruction: Urbanization, agriculture, and deforestation reduce natural habitats and affect population sizes.

  • Pollution: Can affect population health, leading to declines or changes in species.