They move waste and nutrients through the intestines.
Answer:
If humans were still hunting and gathering food instead of farming - taken into account that the entire population hunts and gathers food in the context of this question - the majority of people would have dark-skin complexions.
Explanation:
This is easily explained by a hunter-gatherer's way of living. Before humans learned to raise animals and grow crops, the majority of us were hunters and gatherers. Hunters and gatherers lived, and still continues to live, their lives very differently from how we are living at present. They'd spend hours hunting - as their name suggests - and catching food out in the wild, which exposes them to a higher amount of sunlight than our everyday way of living. To cope with this, evolution also played an important part in determining the survival of these people in the scorching sun - they evolved to producing high amounts of melanin. Melanin is a dark pigment that helps protect our skin cells against the harmful UV rays from the sun. Lighter skinned people have less melanin than darker skinned people, and when that extra melanin is produced, you'd see it as a tan. Hunter-gatherers produced high amounts of melanin, primarily because they had adapted to spending a large fraction of their time out in the open. The melanin acts like a built-in sunscreen for them, protecting them from getting skin cancers like melanoma.
Answer:
Due to its high magnification power.
Explanation:
A scientist used a light microscope to view an algal cells because light microscope is able to magnify objects up to about a thousand times. Various cellular organelles, such as nuclei, chloroplasts, and mitochondria etc can also be seen clearly with the help of light microscope so that's why scientist used light microscope to study algal cells.
