BIO Ch. 3 - The Biosphere
The biosphere is composed of an ever-changing mix of living and nonliving components. These components are constantly interacting to form the environments in which organisms struggle to survive and reproduce.
3.1 What is Ecology?
Ecology is the scientific study of interactions among organisms and between organisms and their physical environment. The biological influences on organisms are called biotic factors. Physical components of an ecosystem are called abiotic factors. Modern ecologists use three methods in their work: observation, experimentation, and modeling. Each of these approaches relies on scientific methodology to guide inquiry.
3.2 Energy, Producers, and Consumers
Primary producers are the first producers of energy-rich compounds that are later used by other organisms. Organisms that rely on other organisms for energy and nutrients are called consumers.
3.3 Energy Flow in Ecosystems
Energy flows through an ecosystem in a one-way stream, from primary producers to various consumers. Pyramids of energy show the relative amount of energy available at each trophic level of a food chain or food web. A pyramid of biomass illustrates the relative amount of living organic matter available at each trophic level of an ecosystem. A pyramid of numbers shows the relative number of individual organisms at each trophic level in an ecosystem.
3.4 Cycles of Matter
Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Water continuously moves between the oceans, the atmosphere, and land—sometimes outside living organisms and sometimes inside them. Every organism needs nutrients to build tissues and carry out life functions. Like water, nutrients pass through organisms and the environment through biogeochemical cycles. The carbon, nitrogen, and phosphorus cycles are especially critical for life. If ample sunlight and water are available, the primary productivity of an ecosystem.
ONLINE RESOURCES
BrainPOP - Water Cycle
BrainPOP - Carbon Cycle
Interactive - Carbon Cycle
PBS Interactive - Carbon Dioxide and the Carbon Cycle
BrainPOP - Nitrogen Cycle
PBS Interactive - Nitrogen Cycle