How do some cells become brain cells and others become skin cells, when the dna in all the cells is exactly the same?

Which would be the outcome in a fertilized egg if the process of meiosis did not occur? twice as many chromosomes as the parents half as many chromosomes as the parents same number of chromosomes as the parents triple the number of chromosomes as the parents?

What do scientists need to look at before developing an argument

Describe how a student should adjust the microscope to see the cells on a slide more clearly?