Define the term Mutation.
Topic: Mutation
Answer
A MUTATION is a sudden, permanent and inheritable CHANGE IN THE GENETIC MATERIAL — in the base sequence of the DNA of a gene, or in the structure or number of the chromosomes — which may be caused by radiation, chemicals or errors during cell division.
The essential words are a SUDDEN and INHERITABLE change in the GENETIC MATERIAL.
INHERITABLE is the word that matters most, because it distinguishes a mutation from an ACQUIRED character. A scar or a suntan is a change to the body that is NOT passed on; a mutation alters the DNA itself and therefore can be.
Note the qualification: only a mutation in the GERM cells (those forming gametes) is passed to the offspring. A mutation in a body cell affects only that individual — which is what most cancers are.
MUTAGENS are the agents that cause them: ultraviolet and X-rays, radioactivity, and certain chemicals such as those in tobacco smoke.
Mutations are the ultimate source of the VARIATION on which natural selection acts — which is why they matter to evolution.