Answer:
its a and b for this anwser
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.
Answer and Explanation:
The cell was placed in a hypertonic solution. Glucose is a monosaccharide while starch is a polysaccharide. The concentration on the outside is higher compared to that on the inside. The cells have cell membrane that is semi-permeable.
Movement of molecules is dependent on the concentation gradient. However, the size of molecules determine the diffusion rate. Small and light molecules diffuse faster than large and heavy molecules thus glucose diffused faster than starch.
The cell membrane being permeable suggested that it allows molecules of small sizes to pass but not large ones.
