What statement is true about lipids
- they store energy and are inportant in the cell membrane
- they are made of only carbon and hydrogen
- they are part nucleic acids
- they consist of many glucose molecules hooked together

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.

Most animal cells membranes have proteins that pump ions out of the cell and potassium ions into the cell

All organisms contribute some water to the water cycle by conducting