Natural selection only occurs with which type of variation? environmental variation genetic variation artificial variation neutral variation

Pepsin is an enzyme in the stomach that breaks polypeptides into amino acids. pepsin functions best at a ph of around 1.5. what would be the most likely result if the ph of the stomach were increased to 5

For a comparative or experimental investigation, scientists often make a testable about a scientific question, and then they test it in the investigation. a. control b. hypothesis c. procedure d. system

I’m stuck on this question cuz i’m stupid sksksksk