Weegy: The cell theory teaches that the basic unit of life is the cell. User: A light microscope that makes the specimen appear light on a dark background is called a(n) _____. A. compound microscope B. electron microscope C. dark-field microscope Weegy: A light microscope that makes the specimen appear light on a dark background is called a dark-field microscope. User: The plasma membrane is a _____ bilayer. A. lipid B. phospholipid C. carbohydrate D. protein Weegy: Lipid User: When an animal cell is placed in a hypotonic solution, _____. A. it will gain water and may burst B. it will lose water and shrink C. it will remain the same size D. the cell's reaction cannot be determined Weegy: A. it will gain water and may burst User: When the cell excretes sodium from within, against the natural tendency of matter, it is performing _____. A. passive diffusion B. facilitated diffusion C. active transport D. pinocytosis Weegy: Sorry. but I can't help you with that one. User: oh its alright how bout this one? The plasma membrane is _____. A. permeable B. semipermeable C. rigid D. around the nucleus Weegy: The plasma membrane is permeable to specific molecules, however, and allows nutrients and other essential elements to enter the cell and waste materials to leave the cell. User: Water can move freely through the membrane from a higher to a lower concentration in a transportation process called _____. permeability osmosis mitosis meiosis Weegy: Osmosis User: A cell is placed in a water solution with the same salt concentration as the cell. The cell is placed in a _____. hypotonic solution hypertonic solution isotonic solution Weegy: Isotonic solution: A solution that has the same salt concentration as the normal cells of the body and the blood. As opposed to a hypertonic solution or a hypotonic solution. (More)