What human body part mostly represents chloroplast and why?

Chloroplasts convert light energy into sugars. This is also like the human digestive system. The food that we consume is digested and converted into energy. Our intake of calories and carbohydrates provides us with energy so that we can do everyday things like ride a bike or go for a run. Hope this helps.

Iwould say overuse ( but not 100% sure ) in the u.s. we tend to overuse water by leaving it running, throwing it away, taking long showers, etc.