Because our eyes see what's reflected not absorbed. Leaves contain chlorophyll which contains a pigment of green that absorbs red and blue wavelengths, while reflecting green.
The red blood corpuscles have a pigment called hemoglobin that binds to the oxygen and carries it to the whole body in both the conditions, when the body is at rest or when the body is exercising. The oxygenated blood from the heart is carried to the various parts of the body and the de-oxygenated blood from various parts of the body is carried to the lungs where the exchange of gases takes place.
Mitochondria is a semi autonomous cell organelle, it is able to make its own protein because it has promiscuous DNA which has genes that have instructions to make proteins
