How do some cells become brain cells and others become skin cells, when the dna in all the cells is exactly the same. in other words, if the instructions are exactly the same, how does one cell become a brain cell and another a skin cell?

According to the diagram, what sources contribute to the phosphorus found in soil? according to the diagram, phosphorus found in soil contributes phosphorus to what other sources? (site 1)

Use the drop-down menu to match the following definitions to the corresponding terms. the total variety of organisms that live in the biosphere a group of organisms that breed and produce offspring that can breed all of the biotic and abiotic factors in an area

Can someone i have no idea of how to do this.