11. Carbon Dioxide
Carbon dioxide is a colourless & odourless gas produced
by burning carbon and organic compounds. It is
naturally present in air and is absorbed by plants in
photosynthesis.
12. The blood gives off CO2 and take in O2. The O2 travels
away from the lungs in the oxygenated capillary. The
CO2 travels from the alveoli to the bronchiole, to the
trachea and is exhale out the nose.
How gas exchange occurs: