Compare blood cells to plant cells, including details about color, general shape, and size. Write this as a complete sentence or paragraph.

Blood cells and plant cells differ significantly in terms of color, general shape, and size. Blood cells, specifically red blood cells, are typically red due to the presence of hemoglobin, a protein that binds to oxygen. They are generally biconcave in shape, resembling a donut without a hole, and are about 6-8 micrometers in diameter. On the other hand, plant cells are generally green due to the presence of chlorophyll, a pigment necessary for photosynthesis. They are typically rectangular or square in shape due to the rigid cell wall that surrounds them, and are larger than blood cells, with a size ranging from 10 to 100 micrometers.