Plant cells have cell walls and chloroplasts. A cell wall provides rigid support, while chloroplasts convert solar energy to chemical energy.
Cell membranes are composed of two phospholipid layers and have two main functions - forming a boundary between the inside and outside of the cell, and controlling the passage of materials.
Materials move across membranes through passive transport mechanisms like diffusion and osmosis, moving down concentration gradients without cell energy input. Some molecules require transport proteins to cross membranes.