g3 Flashcards
(25 cards)
What is an ecosystem?
All the living things plus the non-living things interacting in a place.
What is a biogeochemical cycle?
How chemicals move between living things and the environment.
Name four major biogeochemical cycles.
Carbon, Water (Hydrologic), Nitrogen, Phosphorus.
What is the carbon cycle?
Plants take in CO₂, animals breathe it out; carbon moves through life and the Earth.
How does the water (hydrologic) cycle work?
Water evaporates, rains down, moves through plants and soil.
What is nitrogen fixation?
Special bacteria turn nitrogen gas into forms plants can use.
What cycle does not have a gas form?
Phosphorus cycle.
What happens when nutrients are added too much to water?
Eutrophication — water loses oxygen, life dies off.
What does the 1st Law of Thermodynamics say?
Energy can’t be created or destroyed, only changed.
What does the 2nd Law of Thermodynamics say?
Energy transfer loses some energy as heat.
What are trophic levels?
Steps in the food chain: producers, consumers, decomposers.
How much energy moves to the next trophic level?
About 10%.
What limits the number of top predators?
Loss of energy at each trophic level.
What is a trophic cascade?
Changes at the top of the food chain ripple down to lower levels.
What is top-down control?
Predators control the levels of animals below them.
What is bottom-up control?
Producers control the levels of animals above them.
What is ecological succession?
Natural rebuilding of ecosystems over time.
What are the three steps of succession?
Facilitation, inhibition, tolerance.
What is facilitation?
Early species make it easier for new ones to grow.
What is inhibition?
Early species stop new ones from growing.
What is tolerance?
Species survive without being helped or hurt.
What is island biogeography?
Big and close islands have more species; small and far islands have fewer.
What does high biodiversity usually mean for an ecosystem?
More stable and healthy.
What is species richness?
The number of species.
