What is a reservoir and what is its
main purpose?

A reservoir is type of lake that is used to store water. Its main purpose is to collect water during very rainy times or when snow on a mountain is melting,reservoirs also control flooding.

this is math not biology xd

image result for how many calories of energy will 20 grams of carbohydrates provide in one gram provides 4 calories

consuming the right balance of protein, carbohydrates and fat can you maintain a healthy weight and optimize your energy levels. protein and carbohydrates both contain 4 calories per gram, while fat provides 9 calories per gram.