Unit 1: The Living World: Ecosystems

Ecosystem

A community of living organisms interacting with their physical environment, including biotic and abiotic components.

Biotic Components

Living or once-living parts of an ecosystem (e.g., plants, animals, fungi, bacteria).

Abiotic Components

Non-living physical and chemical parts of an ecosystem (e.g., sunlight, water, soil, temperature).

Mutualism

A type of organism interaction where both species benefit (e.g., bees pollinating flowers).

Commensalism

A relationship where one species benefits and the other is unaffected (e.g., barnacles on whales).

Parasitism

A relationship where one species (the parasite) benefits and the other (the host) is harmed (e.g., ticks on mammals).

Predation

An interaction where one species (the predator) hunts and kills another (the prey) for food (e.g., lion hunting zebra).

Competition

A relationship where species compete for limited resources, negatively affecting both (e.g., two bird species competing for the same food).

Resource Partitioning

When species divide a shared resource by specializing in different ways to reduce interspecific competition.

Energy Flow

The transfer of energy through trophic levels in an ecosystem, primarily originating from the sun.

Matter Cycling

The cycling of nutrients (e.g., carbon, nitrogen) within and between ecosystems.

Terrestrial Biomes

Large ecological areas on Earth's land surface, characterized by distinct climate conditions and their associated plant and animal communities.

Tundra

A cold biome characterized by treeless landscapes and low-growing vegetation, often with permafrost.

Boreal Forest (Taiga)

A cold biome comprised of coniferous forests with relatively low biodiversity.

Temperate Rainforest

A biome with moderate temperatures, high precipitation, and large trees.

Temperate Seasonal Forest

A biome with moderate temperatures, distinct seasons, and deciduous trees.

Woodland/Shrubland (Chaparral)

A biome characterized by hot, dry summers, mild, rainy winters, and fire-adapted shrubs.

Temperate Grassland

A biome with cold, harsh winters and hot, dry summers dominated by grasses.

Tropical Rainforest

A warm and humid biome with high precipitation, immense biodiversity, and rapid nutrient cycling.

Subtropical Desert

A hot and extremely dry biome with sparse vegetation that has adapted to conserve water.

Freshwater Biomes

Ecological areas characterized by low salinity, including streams, rivers, lakes, ponds, and wetlands.

Wetlands

Saturated soil areas with emergent vegetation; highly productive ecosystems crucial for filtration and habitat.

Marine Biomes

Ecological areas in water, characterized by salinity and includes oceans, coral reefs, and estuaries.

Photosynthesis

The process by which plants convert carbon dioxide from the atmosphere into glucose using sunlight.

Respiration

The process through which organisms release carbon dioxide back into the atmosphere.

Decomposition

The breakdown of dead organic matter by decomposers, releasing carbon back into the ecosystem.

Nitrogen Fixation

The conversion of atmospheric nitrogen (N2) into ammonia (NH3) by bacteria.

Nitrification

The process of converting ammonia (NH3) into nitrites (NO2-) and then nitrates (NO3-) by bacteria.

Assimilation

The process in which plants absorb nitrates or ammonia from the soil to build proteins and nucleic acids.

Ammonification

The conversion of organic nitrogen back into ammonia by decomposers.

Denitrification

The conversion of nitrates back to atmospheric nitrogen by bacteria under anaerobic conditions.

Phosphorus Cycle

The cycle of phosphorus through weathering, assimilation, and decomposition in ecosystems.

Hydrologic Cycle

The continuous cycle of water movement through evaporation, transpiration, condensation, precipitation, infiltration, runoff, and sublimation.

Gross Primary Productivity (GPP)

The total amount of solar energy captured by producers through photosynthesis over a given time.

Net Primary Productivity (NPP)

The energy available to consumers after subtracting the energy lost by producers through respiration (NPP = GPP - Rp).

Trophic Levels

The hierarchical levels in an ecosystem, representing the position an organism occupies based on its feeding habits.

Food Chain

A linear sequence showing how energy is transferred from one organism to another.

Food Web

A complex network of feeding relationships in an ecosystem, showing multiple interactions between organisms.

Ecological Succession

The gradual process of change in an ecosystem over time, involving primary and secondary succession.

Primary Succession

Succession occurring in an area previously devoid of life and soil, often following a disturbance.

Secondary Succession

Succession that occurs in an area where an existing community has been removed but soil remains.