2.67 - Excretion

a) In plants:

1) Photosynthesis =absorbing light energy
CO2 + H2O --------> C6H12O6 + O2
O2 is the waste molecule, the release of metabolic waste is an example of excretion

2) Respiration
C6H12O6 + O2 ---------> ATP + CO2 +H2O
The CO2 is also metabolic waste so plants excrete:
-Oxygen
-Carbon Dioxide

b) In Humans (Human organs of Excretion)

1) Lungs - excretion of metabolic waste = Carbon dioxide
2) 2 kidneys - excretion of excess water, urea(nitrogen wastes from amino acids) and salt
3) Skin - mostly water and salts and a bit of urea