Mechanism for counting cell divisions determines when cleavage ends

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.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

Which process of living things produces water that enters the water cycle