AP BIOLOGY

Detailed explanation-1: -Environmental exposures such as tobacco smoke, UV light, and aristolochic acid can result in increased mutation rates in cancer genomes. Mutation rates across individuals are also impacted by variability in the activity of certain cellular processes.

Detailed explanation-2: -Mutations can result from errors in DNA replication during cell division, exposure to mutagens or a viral infection.

Detailed explanation-3: -Cigarettes and tobacco products contain chemicals referred to as carcinogens, which are mutagens that are also known to cause cancer. All cancer cells have DNA mutations, and it is the carcinogens that cause the mutations. Carcinogens cause mutations by damaging the way the cell repairs DNA or makes proteins.

Detailed explanation-4: -A priori, nucleotide mutation rates are expected to depend upon three factors [2]: (i) the intrinsic stability of nucleotides and their sensitivity to mutagenic agents; (ii) the fidelity of DNA replication; and (iii) the efficiency of the DNA repair machinery.