Why can't a damaged cell in the brain be replaced?

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.

Models are non-visual ways of coummincating how someone thinks about something in the natural world

Explain the significance of the increased cell specialization of the volvocine line