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The basic unit of structure and function in living things


A group of similar cells that perform a particular function


A structure in the body that is composed of different kinds of tissue


A behavior or physical characteristics that allows an organism to survive or reproduce in its environment

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents


The joining of a sperm cell and an egg cell

asexual reproduction

A reproductive process that involves only one parent and produces offspring that are identical to the parent.


One of the major groups into which biologists classify members of the animal kingdom


An animal that has a backbone


An animal that does not have a backbone

bilateral symmetry

Body plan with two halves that are mirror images

radial symmetry

The quality of having many lines of symmetry that all pass through a central point.


The immature form of an animal that looks very different from the adult


An invertebrate animal that uses stinging cells to capture food and defend itself


The cnidarian body plan characterized by a vaselike shape and which is usually adapted for life attached to an underwater surface.


The cnidarian body plan characterized by a bowl shape and adapted for a free-swimming life.


A group of individual organisms living or growing together

coral reef

A diverse environment named for the coral animals that make up its stony structure


The organism that benefits by living on or in a host in a parasitism interaction


The organism that a parasite or virus lives in or on

free-living organism

An organism that does not live in or on other organisms


A carnivore that feeds on the bodies of dead organisms


A muscular opening at the end of the rectum through which waste material is eliminated from the body

closed circulatory system

A circulatory system in which blood moves only within a connected network of tubes called blood vessels

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