a population of mice exists with both brown and black varieties. the mice live among sandy beach dunes where hawks prey on the mice. a field biologist
studying the mice counted the numbers of brown and black mice and found there were more brown mice than black ones. she concluded the sand dunes
provided camouflage for the brown mice keeping them hidden from the hawks. the coloration of the mice is an example of a [an] -

Adaptation

Explanation:

In this case predation is the selection pressure for natural selection in the mice population. Because the black mice stand out against the brown sand dunes backdrop, they are easily located and predated on by the hawks. Therefore, black mice have a lower chance (compared to brown mice) to reach reproductive age and pass down their genes to the next generation. With subsequent generations, therefore, there will be more and more brown mice in the population.

The coloration of the mice is an example of a Genetic Mutation  

Explanation:

The coloration of the mice in sand dunes were thought by the scientists is the result of genetic mutation only. The change in a single nucleotide can affect the survival fitness of living things on earth. Research works show that the mice that lives in the mainland is darker in color than the mice living near sandy beach.

It shows that the change of atmosphere geared the color evolution. Though there are controversies among scientists on this belief that a single gene could be responsible for the variations of mice.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.