Speciation occurs when: A. two populations become geographically isolated
B. enough differences accumulate between two populations that they can no longer interbreed
C. gene mutations accumulate
D. all of the above

Average annual precipitation and are the two major features that define the biomes on earth.

Dna, in the nucleus carries the genetic code for making proteins in ribosomes. in the diagram, b, represents the proteins produced. dna cannot leave the nucleus to carry the genetic information to the ribosome where proteins are produced. how does the genetic code get from the nucleus to the ribosome? what does a represent? now

The two main stages of cell division are called