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image - a reproduction of the appearance of a person or thing laser - an instrument that makes a thin, powerful light magnet - a piece of iron or other material that has a pulling force; this pulling force is called magnetism molecule - the smallest amount of a chemical substance that can exist nerve - a thin piece of tissue that sends information through the body to and from the brain nucleus - the center part of an atom or cell nucleic acid - a molecule that holds the genetic information necessary for life; there are two kinds of nucleic acid: DNA and RNA nutrient - a food or substance that makes plants, humans or animals grow organ - a part of the body that has a special purpose, such as the heart or brain organism - a living thing, often so small it can be seen only through a microscope particle - a very small piece of matter proteins - substances responsible for the growth of tissue and for fixing damaged tissue robot - a machine that moves and performs tasks tissue - living material; a group of cells that are similar in appearance and do the same thing virus - a kind of organism that causes disease x-rays - a kind of radiation that can pass through most solid materials, often used in medicine | 
