Which of the following best explains the importance of earth’s crust to living organisms? a. the continental crust allowed the evolution of life on land. b. the crust provides raw materials necessary for life. c. the crust allowed the formation of fossil fuels. d. the rock cycle recycles sedimentary rocks formed from animal shells.

The correct answer is (b). The crust provides raw materials necessary for life.

The crust is the outermost layer of the earth that is composed of several life supporting elements. Organic materials, humus, nutrients are present in this layer which is required by the plants to make food by the process of photosynthesis. This food is required by all the organisms on this earth to survive. The organisms that survive their takes the nutrients from the the organic substance to make their food and survive.

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion

a few examples of ethical concerns involving genetically engineering of humans include

-privacy of genetically tested people

- potential side effects

-long term effects