In short, air pollution is foul air injurious to health. Air Pollution is anything that goes into the air that is harmful.Most air pollution is man-made. The largest contributor to airpollution is the burning of fossil fuels such as gas and coal. Someof the most common forms of air pollution are: Particulate matterNitrogen oxide (and other oxides of nitrogen) Sulfur oxide AcidRain VOC's (volatile organic compounds) Air pollution can also besaid as the accumulation in the atmosphere of substances that insufficient concentrations, endanger human health or produce othermeasured effects on living matter and other materials. Among themajor sources of pollution are power and heat generation, theburning of solid wastes, industrial processes, and, especially,transportation.
Answer: unfavourable ph condition for the pepsin
Explanation: during digestion, enzymes are needed to aid the process.digestive enzymes are biological catalyst that breakdown large food particles into digestible form .
As biological catalyst, enzymes require an optimum temperature and pH condition.outside this temperature or pH,the enzyme is denatured.
In the stomach, hydrochloric acid is required to convert pepsinogen into it's active form,pepsin.the acid also creates an optimum low pH that pepsin needs to function.
As the food moves to the small intestine,the pH is alkaline and is unfavourable for pepsin to function.
I believe that it's Bilateral symmetry. Hope it's right. :)