Ecology is the scientific study of the interactions between organisms and their environment. It includes relationships among organisms (biotic factors) and between organisms and their physical surroundings (abiotic factors). Ecologists study populations, communities, ecosystems, and the biosphere. What does ecology study?

Ecological organization levels from smallest to largest: individual (organism), population (same species in an area), community (all populations in an area), ecosystem (community + abiotic factors), biome (large region with similar climate), and biosphere (global sum of all ecosystems). Which level includes both living and non-living components?

A food chain shows the flow of energy from one organism to another (producer → primary consumer → secondary consumer → tertiary consumer). A food web is a network of interconnected food chains. Arrows in a food chain point from the organism being eaten to the organism that eats it (direction of energy flow). Which organism is at the base (first trophic level) of most food chains?

An energy pyramid shows the amount of energy available at each trophic level. Only about 10% of the energy is transferred from one level to the next; the rest is lost as heat through metabolism. This is called the 10% rule. Why are there usually fewer top predators than producers?

A biome is a large geographical area classified by its climate, plants, and animals. Major biomes include tropical rainforest, desert, grassland (savanna and temperate), temperate forest, taiga (boreal forest), tundra, and aquatic biomes (freshwater, marine). Which biome has the highest biodiversity?

Symbiosis is a close, long-term interaction between two different species. The three main types are mutualism (both benefit), commensalism (one benefits, the other is unaffected), and parasitism (one benefits, the other is harmed). Which type of symbiosis benefits both species?

Carrying capacity (K) is the maximum population size of a species that an environment can sustain indefinitely, given the available resources (food, water, shelter, etc.). When a population exceeds carrying capacity, resources become depleted, and the population may crash (die-off). What is carrying capacity?

The carbon cycle is the movement of carbon through the biosphere, geosphere, hydrosphere, and atmosphere. Carbon is found in the atmosphere as carbon dioxide (CO₂). Plants absorb CO₂ for photosynthesis. Animals release CO₂ through respiration. Decomposers release CO₂ when breaking down dead matter. Burning fossil fuels releases ancient stored carbon. Which process removes CO₂ from the atmosphere?

Invasive species are non-native organisms that cause harm to the ecosystem, economy, or human health. They often outcompete native species because they lack natural predators or diseases in their new environment. Which of these is an example of an invasive species?

Biodiversity (biological diversity) is the variety of life on Earth at all levels: genetic diversity, species diversity, and ecosystem diversity. High biodiversity makes ecosystems more resilient to disturbances. What is the biggest threat to biodiversity?