Answer:
The correct answer is: geography and UV radiation.
Explanation:
Skin variation occurred thanks to evolution, and was driven as a consequence of the geographical location of different populations of humans.
The humans that lived in hot and sunny places, closer to the equator, where much more exposed to the sun's ultraviolet radiation. In order to survive the amount of UV lights that they were exposed to, new humans in those regions were being born with a darker skin tone, which was rich in melanin (a brown pigment that protects us from the sun radiation).
Contrary to these humans that lived in the tropical areas, the humans that populated the areas that were closer to the poles, developed much lighter skin as a result of lower amounts of melanin in their skin. Since sun exposure in the poles is very limited, humans needed to receive as much as they could for the production of Vitamin D, and thus, their skins got lighter and less protected.
You could do regular daisies, or pet grass... It could be almost anything.
I hope this helps!<span />
No 2 people in the world are "exactly alike", so the odds would be 0% chance. Twins, might be closer in alike-ness, but they still aren't "exactly alike". Hope this answered your question.
Primary succession occurs in areas without life, while secondary succession occurs in places that were previously inhabitated.
Hope this helps!
:D®
Energy is usually liberated from the ATP molecule to do work in the cell by a reaction that removes one of the phosphate-oxygen groups, leaving adenosine diphosphate (ADT). When the ATP converts to ADP, the ATP is said to be spent.
