They appear to be green because of the chloroplast in the cells.
They Are probably more nocturnal <span />
Assuming maintains internal conditions means homeostasis, your body defecates and urinates any toxins from food or drink. this is because some food is harmful to your blood, heart, stomach, etc and can cause even more harm if they are not eliminated.
hope this helps!!! :)
Rain water gets polluted because of the water cycle bringing water into the atmosphere