Question

complete the table to compare the three types of passive transport. simple diffusion facilitated diffusion osmosis molecules cross the membrane through the phospholipids molecules cross the membrane through proteins molecules move down their concentration gradient molecules move without using cellular energy

Explanation:

• Simple diffusion: Small non - polar molecules (e.g., oxygen, carbon dioxide) cross the membrane through the phospholipids. They move down their concentration gradient without using cellular energy.
• Facilitated diffusion: Polar or large molecules (e.g., glucose, ions) cross the membrane through proteins (channel or carrier proteins). They also move down their concentration gradient without using cellular energy.
• Osmosis: Water molecules cross the membrane. Water moves down its concentration gradient (from an area of high water concentration to low water concentration). In animal cells, water can cross through the phospholipids (to a limited extent) and through aquaporins (proteins). In plant cells, most water crosses through aquaporins. And it occurs without using cellular energy.

Answer:

	simple diffusion	facilitated diffusion	osmosis
molecules cross the membrane through proteins	$\square$ (no)	$\square$ (yes)	$\square$ (yes for aquaporin - mediated water movement in many cases)
molecules move down their concentration gradient	$\square$ (yes)	$\square$ (yes)	$\square$ (yes)
molecules move without using cellular energy	$\square$ (yes)	$\square$ (yes)	$\square$ (yes)