Through weathering and the erosion of rocks and soil, Earth’s landscape can change drastically overtime. As a result, watersheds may disappear if the land making the watershed is worn away, and the water collected is <span>able to flow back into the river, as the area is level with the rest of the land.</span>
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The ABO blood group classification is based on antigens on red blood cells and antibodies found in blood plasma.</span>Blood type A has antigen A on the red blood cells and anti - B antibodies in the blood.Blood type B has antigen B on the red blood cells and anti - A antibodies in the blood.Blood type AB has both antigen A and B on the red blood cells but has no anti-A nor anti - B antibodies in the blood<span>Blood type O has no antigen on the red blood cells and has both anti -A and anti B antibodies in the blood.</span>
Oh this one is so cool!
It basically all boils down to Vitamin D! We need this essential vitamin to help our body build hormones and regulate calcium. Our bodies make Vitamin D when we are exposed to the UV rays found in sunlight. But as we all know, too much sunlight isn’t good because these UV rays can harm us. Melanin (the chemical that our bodies produce to darken skin tone and hair color) provides protection from UV rays by absorbing them. However, this means that the more melanin that is produced by someone’s body results in less absorption of UV rays and a decrease in Vitamin D production. But for someone living around the equator or in the tropics that doesn’t matter because there’s lots of sun all the time. So for humans living in these areas where there’s lots of sunlight year round, it’s beneficial to have darker skin to protect from the harm of UV rays. People living in these areas still get plenty of Vitamin D though because of that year round sunshine.
Now what about those who’s skin has less melanin, such as those found in the higher latitudes? Well with less sunlight year round, their bodies had to adapt to be able to get enough Vitamin D. So less melanin is produced by the body in order to absorb the lesser amounts of UV rays to make Vitamin D. Lighter skin is, therefore, more beneficial the farther away you go from the tropics.
So essentially:
Pro of Darker Skin tones
-Protection from harmful UV rays
Con of Darker Skin tones
-Less absorption of UV rays and less production of Vitamin D
Pro of Lighter Skin tones
-Greater absorption of UV rays and more Vitamin D production
Con of Lighter Skin tones
-Less protection from harmful UV rays (resulting in sunburns and, in extreme cases, skin cancer)
This is of course the biology answer. The social impacts of different skin tones is a whole different story that you can ask in the history section.
<h2>Cell Analogy</h2>
Explanation:
As we see that parents control everything in the house. Similarly,the nucleus controls everything in the cell.
A door is analogous to the cell membrane because it allows people come and go. Similarly,the cell membrane in a cell can allow certain things to enter and exit.
The cytoplasm fills the space in a cell. It is similar to air which is filled everywhere in the house.
- Nuclear membrane: Security guard
The nucleus in a cell is protected by nuclear membrane. The nuclear membrane is analogous to secuity guard. As people in a house are protected by security guard, similarly nucleus is protected by nuclear membrane.
- Endoplasmic reticulum: Hall ways
Endoplasmic reticulum transport things to other places in the cell. It is similar to hallways which help us to reach different places in the house.
The golgi bodies modify,sort and package proteins.
It send them to other parts of the cell when needed.
It is similar to a Car which transports people and can store stuffs.
The mitochondria in a house is analogous to Stove as it breaks down nutrients and turns them into energy. Similarly, the Stove in our house, cooks foods and it is converted into energy when consumed.
The ribosomes are a cell structure that make protein. It is same as a kitchen in our house where people make food or proteins.
