Orcas, or killer whales, are natural predators of sea otters. It has been observed that in regions where the sea otters are not present, sea urchins grow rapidly and destroy much of the natural kelp vegetation.

Which of these statements is correct in this context?

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.

The image shows the evolution of a species of fish. a few fish from a population developed different social behaviors and evolved into different species. two fish according to the image, the fish underwent . the new species of fish had mating seasons that were different from that of the original fish. because of the differences in mating seasons, the fish underwent reproductive isolation. this mode of isolation would be .

Drag the tiles to the correct boxes to complete the pairs. match each cell organelle with its description.