All energy on Earth except nuclear energy comes originally from
1) fossil fuels 2) The sun
3) electricity 4) the oceans

Acell in the human nervous system whose primary function is to form myelin and the blood-brain barrier, respond to injury, remove debris, and enhance learning and memory is called a(n) cell.

Crossing over and independent assortment are important activities that occur during meiosis. what is the significance of these activities

This is a situation in which genes are attached to an organism's sex chromosomes; the sex of an organism influences the expression of a gene.