| Ecosystems | A biological community of interacting organisms and their physical environment. |
| Biotic Factors | Living things in an ecosystem |
| Abiotic Factors | Non-living factors including temperature, water, sunlight, wind, rocks and soil |
| Population | A group of organisms of the same species populating a given area |
| Communities | Different populations that live together in a defined area |
| Habitats | Places where animals or plants naturally live and grow |
| Invasive Species | Species that enter new ecosystems and multiply, harming native species and their habitats |
| Symbiosis | The relation between two different species of organisms that are interdependent |
| Mutualism | A close relationship; both species benefit |
| Commensalism | A close relationship; one species benefits, the other doesn't benefit but isn't harmed |
| Parasitism | A close relationship; one species benefits, the other is harmed |
| Potential Niche | The entire range of resource opportunities an organism is potentially able to occupy within an ecosystem |
| Fundamental Niche | Niche where an organism is actually able to live |
| Producer | Organisms that can make their own food |
| Consumer | Organisms that take in food material and are above producers on the energy pyramid |
| Herbivores | Consumers that only consume plants |
| Carnivores | Consumers that only consume animals |
| Omnivores | A consumer that eats both plants and animals |
| Decomposers | Organisms that break down wastes and dead organisms and return raw materials to the environment |
| Food Chain | A series of steps in which organisms transfer energy by eating and being eaten |
| Food Web | Shows how food chains are related within an ecosystem |
| Trophic Level | Organism in a food chain that represents a feeding step in the passage of energy and materials through an ecosystem |
| Carbon Cycle | The organic circulation of carbon from the atmosphere into organisms and back again |
| Ecological Succession | The gradual and orderly process of change in an ecosystem brought about by the progressive replacement of one community by another until a stable climax is established |
| Pioneer Species | The first species to live in an area of primary succession |
| Climax Community | A stable, mature community that undergoes little or no change in species over time. |
| Growth Rate | Rate of increase or decrease of a population |
| Generation Time | Average time between one generation of offspring and the next |
| Exponential Growth | Occurs when the individuals in a population reproduce at a constant rate |
| Carrying Capacity | Largest number of individuals of a population that a environment can support |
| Tundra | Cold and largely treeless across northern North America |
| Tropical Rainforest | Hot, moist biome where it rains all year long. Known for its dense canopies of vegetation that form three different layers. |
| Shrubland | Made up of shrubs or short trees. Many shrubs thrive on steep, rocky slopes. |
| Savanna | Often described as an area of grassland with dispersed trees or clusters of trees. The lack of water makes the savanna a difficult place for tall plants such as trees to grow. Grasses and trees that grow in the savanna have adapted to life with little water and hot temperatures. |
| Temperate Deciduous Forest | Distinct seasons and moderate climate |
| Grassland | Grasslands are generally open and continuous, fairly flat areas of grass. They are often located between temperate forests at high latitudes and deserts at subtropical latitudes. |
| Taiga/Boreal Coniferous Forest | A forest biome dominated by coniferous trees |
| Grassland | Prairies, steppes, pampas, veldts; near the equator, characterized by treeless areas and tall grasses. |
| Desert | Desert biomes are the driest of all the biomes. In fact, the most important characteristic of a desert is that it receives very little rainfall. Most deserts receive less than 300 mm a year compared to rainforests, which receive over 2,000 mm. |
| Ecology | The study of interactions between organisms and their environment |
