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.
Answer:
There is no diagram in this question but the question can still be answered without it.
B. hold the cell membrane together, and proteins move chemicals across the cell membrane
Explanation:
The fluid mosaic model, which describes the structure of the cell membrane, reveals that it contains both lipids and protein constituents. These components, however, performs different functions in the cell membrane of organisms.
The lipid component of the cell membrane, which comprises of glycolipids and cholesterol, hold the cell membrane together while proteins called transport proteins help move chemicals across the cell membrane.
True.
All living things have cells.
Answer: A contractile vacuole (CV) is an organelle, or sub-cellular structure, that is involved in osmoregulation and waste removal. ... In freshwater environments, the concentration of solutes inside the cell is higher than outside the cell. Under these conditions, water flows from the environment into the cell by osmosis. The contractile vacuole (CV) complex is an osmoregulatory organelle of free-living amoebae and protozoa, which controls the intracellular water balance by accumulating and expelling excess water out of the cell, allowing cells to survive under hypotonic stress as in pond water.
Explanation:
