The organs that break down food so that it can be used by the body

A group of similar cells that perform a common function.

A molecule that is made up of amino acids and that is needed to build and repair body structures and to regulate processes in the body.

One set of instructions for an inherited trait.

In a eukaryotic cell, one of the structures in the nucleus that are made up of DNA and protein; in a prokaryotic cell, the main ring of DNA

The system that collects and excretes nitrogenous wastes and excess water from the body in the form of urine.

The ability to store and recall past experience.

One of the smallest bodies that are found in the cytoplasm of a cell and that are specialized to perform a specific function

In a eukaryotic cell, a membrane-bound organelle that contains the cell's DNA and that has a role in processes such as growth, metabolism, and reproduction.

An organism that consists of more than one cell

A genetically determined characteristic

One of the alternative forms of a gene that governs a characteristic, such as hair color

A specialized structure that contains the ends of sensory neurons and that responds to the specific types of stimuli.