AP BIOLOGY

Detailed explanation-1: -Although most mutations are believed to be caused by replication errors, they can also be caused by various environmentally induced and spontaneous changes to DNA that occur prior to replication but are perpetuated in the same way as unfixed replication errors.

Detailed explanation-2: -Mutations result either from errors in DNA replication or from the damaging effects of mutagens, such as chemicals and radiation, which react with DNA and change the structures of individual nucleotides. All cells possess DNA-repair enzymes that attempt to minimize the number of mutations that occur (Section 14.2).

Detailed explanation-3: -Any change in the DNA sequence of a cell. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect.

Detailed explanation-4: -B. Silent mutations are a result of the redundancy (degeneracy) of the genetic code: This is false, as silent mutations are the result of a base substitution that has no discernible effect on the amino acid sequence of a protein.

Detailed explanation-5: -Transcription errors can mimic mutations. DNA replication errors are a powerful source of human disease. The mutations that are generated by these errors give rise to mutant proteins that drive the pathology of countless genetic diseases.