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.
The answer to this is Lipids, nucleic acids, proteins, glycerol and fatty acids.
The names of the respiratory structures involved include the following: nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli.
<h3>What is respiration?</h3>
Respiration is defined as the oxygenation of blood through the intake of oxygen and the removal of carbon dioxide.
The pathway of oxygen gas molecule from the surrounding air through the respiratory system to the blood include respectively the following:
- Nasal cavities (or oral cavity): This has a direct association with the outside oxygen from the environment.
- pharynx: This so also called the throat.
- trachea: This is also called the wind pipe.
- Primary bronchi (right & left): This divides from the trachea to form two bronchi.
Learn more about respiration here:
brainly.com/question/2809259
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The answer is Complement
this is for my Gradpoint fellas
These substances are called reactants.
