Leeches are soft, squishy animals with long, tube-like bodies that are made of many repeating segments. They contain a heart that pumps blood through their bodies and survive by attaching to other organisms and sucking their blood. What animal phylum do leeches belong in?

arthropods
echinoderms
chordates
annelids

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.

This is the process of making a prediction based on the results of prior observations of similar events.

The earths core is made up mainly of what 2 substances? 2. like an egg, earth has a core, a layer surrounding the core, and a thin, hard outer layer. which layers of the earth match the layers of an egg?