How are scientists able to use fossils of extinct organisms as evidence?

What would be the most likely result if the ph of the stomach were increased to 5

Complete the possible outcomes for each generation in the pedigree chartaa aa aa

How does the molecular clock work? a. it analyzes the brain functionality of two different species. b. it examines and compares the physical characteristics of two different species. c. it illustrates relationships between two different species. d. it compares the number of mutations that exist in the dna of two different species.