(a) Carbon dioxide is fixed in the two following ways:
(i) By the process of photosynthesis in plants.
(ii) Many marine animals use carbonates dissolved in sea-water to make their cells.
(b) Diseases caused due to an increased content of pollutants in the air produced due to the burning of fossil fuels are- ophthalmic problems, skin injuries, gastro-intestinal, cardio-vascular and respiratory diseases and some types of cancer.
