What is the fundamental unit of the nervous system?

Creation of an unnaturally uniform sample to represent a diverse populationcan be avoided by: a. including only willing b. asking another scientist for .c. choosing only identical participants. d. selecting individuals at random.

Which kind of worm has a closed circulatory system? a planarian b fluke c pinworm d an earthworm

Which short-term environmental changes would a very small asteroid or comet impact on earth most likely cause? check all that apply. flooding extinction craters on surface changes in weather patterns death of organisms and populations