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Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins

Urban areas use energy than rural areas, mostly because so many more people live there. a) solar power b) more; in total c) less; in total d) an electric furnace

Red blood cells are responsible for transporting oxygen in the blood. people with sickle cell anemia were born with a defective gene that results in sickle-shaped red blood cells. individuals with the disease often suffer pain in their extremities due to the build-up of these cells causing blockages in the blood vessels. the shape of the blood cells also reduces the amount of oxygen transported in the blood.