Unit D: Changes in Living Systems

A living organism in the environment.

A physical, non-living part of the environment.

All the organisms in an area as well as the abiotic factors with which they interact.

All the biotic and biotic factors present in an area that encourage the reproduction and survival of a particular organism.

Any element or compound that an organism needs for metabolism, growth or other functioning.

Microscopic, photosynthetic organisms that play a vital role in marine and freshwater ecosystems.

A rapid growth of algae that can deplete the oxygen dissolved in the water and lock the sunlight required by other organisms in the aquatic ecosystem.

The dry mass of all the living organisms occupying a habitat.

The study of the interactions of living organisms with one another and with their physical environment.

A group of organisms, all of the same species which interbreed and live in the same area at the same time.

Interacting populations living in a certain area at a certain time.

A long-lasting ecological relationship that benefits at least one organisms of two different species that live in close contact.

A symbiotic relationship in which the organism of both species benefit.

A form of symbiosis in which one organism benefits and the other organism is neither helped nor harmed.

A symbiotic relationship in which one organism called the parasite derives benefit at the expense of another organism called the host.

An interaction in which two or more organism compete for the same limited resource.

An organism that uses light energy to synthesize sugars and other organic compounds through the process of photosynthesis.

An organisms that uses other organisms as a source of energy.

An organism that eats green plants algae or phytoplanktons.

An organism that eats herbivores.

An organism that eats secondary consumers.

An organism that kills and eats other animals.

An organism that eats both plants and animals

A bird or animal that feeds on dead and decaying animals that it did not kill itself.