What are two challenges that plants had to overcome in order to survive on land

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Hedgerows have created a new ecosystem within britain’s a. farms b. cities c. forests d. industrial areas

_tissues respond quickly to outside stimuli a) epithelia b)nervous c)muscular d)muscular and nervous