What may have caused the explosion of life during the Cambrian period

What do science, technology, and disease have to do with each other?

How can you tell the difference between rough er from smooth er?

Cattle with brown fur and cattle with white fur will produce a reddish roan calf . when examined closely, the calf show about an even number of brown hairs and white hairs that give a reddish appearance when viewed from far away. the fact that both the brown fur allele and the white fur allele are expressed equally in the offspring is an example of