Overview

This topic covers the relationships between organisms and their environments. It explores ecological levels of organization, population dynamics, energy flow, and environmental interactions essential to understanding biological systems and sustainability.

Key Concepts and Structures

• Levels of Organization: Includes individual, population, community, ecosystem, biome, and biosphere.
• Population Dynamics: Focuses on size, density, dispersion, and changes over time due to births, deaths, immigration, and emigration.
• Carrying Capacity: The maximum population size that an environment can sustainably support.
• Limiting Factors: Environmental conditions such as food, water, shelter, and space that restrict population growth.
• Exponential vs. Logistic Growth: Exponential growth occurs under ideal conditions; logistic growth accounts for limiting factors and reaches a plateau.
• Energy Flow: Describes how energy moves through ecosystems via food chains and webs. Begins with producers and flows to herbivores, carnivores, and decomposers.
• Trophic Levels: Each step in a food chain/web. Only ~10% of energy is transferred from one level to the next (energy pyramid).
• Biogeochemical Cycles: Include carbon, nitrogen, phosphorus, and water cycles—essential for nutrient recycling and ecosystem balance.
• Ecological Succession: Gradual process by which ecosystems change and develop over time. Includes primary and secondary succession.
• Human Impact: Covers pollution, habitat destruction, climate change, invasive species, and conservation efforts to protect biodiversity.

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