The answer is; the melanin in darkly pigmented skin protects DNA from UV radiation, and UV radiation can cause skin cancer
In Africa, due to its equatorial latitude location, receives direct sunlight at more or less 90 degrees most of the year. These highly concentrated rays increase the UV radiation exposure that can cause damage to cell DNA. Selection pressure, therefore, favored individuals with high melanin concentrations that protect against UV. Therefore population evolved towards high melanin densities in the skin.
1.) everything that can be observed or explained scientifically. - natural phenomenon
2.) a well-supported explanation of all the evidence related to a natural phenomenon. - Theory
3.) the procedure of scientific inquiry used to investigate natural phenomena. -scientific method
Cell wall - Adds structural support to the cell. Holds the cells together
Cell membrane - Serves as a barrier to the cell and allows more nutrient and molecules to move in and out of the cell without letting things that can harm the cell in.
Outer membrane - Serves the same basic functions a the cell membrane. (Depending on how complicated the class your in is, I would visit this website for more information... https://en.wikipedia.org/wiki/Bacterial_outer_membrane )
Pili - Help the cell move and attach the bacteria to surfaces are other cells.
DNA - Contains the genetic instructions on what the cell can physically do, operate, and reproduce.
Flagellum - Helps the cell move. It kind of acts like a propeller for the cell so that it can move around.
In the United States the direction the continental polar air mass move South toward the Gulf of Mexico to replace the rising maritime tropical air mass.
Answer: Option A
<u>Explanation:</u>
Air masses are large bodies of air moving horizontally in a very uniform way. Continental polar air mass is an air mass that forms near the poles. It originates in northern Canada and Alaska and move south then East.
The continental polar masses are the causes for the severe cold weather in the South during the cold months. Maritime tropical mass are warm and have high moisture content. During winter it comes in contact with the continental polar mass hence getting stabilized.
I am certain your answer is true.good luck
