Firstly they are not membranes and they are villi's which increase the surface area during digestion
This will help http://www.answers.com/Q/What_is_the_result_of_the_diversity_of_organisms_present_on_earth
The correct answer is indicator species.
Learning about the different body parts will help us better understand human life and health because it can make us care about others instead of just are selves and encourage us to do something about the health difficulties in life.