How does the genetic variation allow humans to survive long term?

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.

Is there any solid scientific evidence that humans have been cloned?

What mistake did john needham make that caused him to conclude that spontaneous generation for microorganisms occurred? a. he re-contaminated his boiled broth solutions. b. he destroyed the vital force in the solutions. c. he did not boil his broth solutions, only warmed them. d. he failed to seal his flasks of boiled broth. e. he allowed his assistant to conduct the experiment which he did not monitor closely.