Where does the oxygen come from that is produced as a by-product of photosynthesis?

It comes from a unicellular organism named Chloroplast that produces a green pigment substance called chlorophyll, this where oxygen is produced as a by-product of photosynthesis.

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.

not only is it colder, it also becomes darker, less salty, and more dense.