Answer: crossing over allows for genetic variation
Explanation:
crossing over is the exchange of genes between two chromosomes which ends up resulting in non-identical chromatids that comprise the genetic material of gametes (sperm and eggs).
Basically crossing over makes the chromatids that are held together by a centromere, no longer identical to eachother which creates genetic variation.
The term used to describe the number of individuals moving into a population is Immigration.
Answer: Nerve cell
Cells of the nervous system, called nerve cells or neurons, are specialized to carry "messages" through an electrochemical process.
Its internal mainly because none of the other words fit and because what happens with the rumbling and vomitting its INTERNAL
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