Im not writing your essay but some plants are used as medication and other remedies. plants are important because they provide food, medicine, oxygen, etc.
The best answer to the question 'What are the nonliving components of the environment that shape an ecosystem?' would be letter d. Abiotic factors are those components of the environment that are non-living or does not have life. All the other choices have life.
The main difference between the organisms are the uses of the appendage and the size and number of certain bones. The human arm is used for a variety of functions while the lizard's and the cat's are used for walking an climbing, the whale's for swimming, the frog's for support and the bird's and the bat's for flying.