To obtain oxygen.............
Answer/Explanation:
a. When pesticides is sprayed on the leaf, the population of non-resistant insects reduce drastically as many would not be able to survive or reproduce.
b. Resistant insects that are few initially would be able to survive the spray of pesticides. Overtime, these few resistant insects reproduce more offsprings that carry the resistant genes to these pesticides. As a result, the population of resistant insects become increased more than the non resistant insects.
Answer:
the cup like opening becomes the mouth in placental mammals, including humans.
