In the past, Earth has experienced only one mass extinction.

Which of the following happened during the precambrian era? the first prokaryotic cells the first eukaryotic cells development of photosynthesis all of the above

Which of the following molecules can be broken down into simple sugars? a. nucleic acid b. protein c. lipid d. carbohydrate

Which kind of mutation has occurred when the codon for an amino acid is changed to a stop codon? a. a silent mutation b. a missense mutation c. a frameshift mutation d. a nonsense mutation