1. Describe what happens during: (a) mechanical digestion ( 2mrks)
(b) chemical digestion. ( 2mrks)​

Are substances released into the environment that in excess amounts cause damage

14. which of the following codons code for threonine? a. ucg b. ugu c. cga d. aca

Which of the following types of pollution is most responsible for large numbers of deaths worldwide because of unsafe drinking water? (a) nutrient pollution (b) thermal pollution (c) pathogen pollution (d) sediment pollution