The molecule that can MOST easily pass through the plasma membrane without assistance is carbon dioxide (CO2). Diffusion is a type of passive transport that occurs when molecules move in favor of a concentration gradient.
During diffusion, molecules move high concentration to a region of low concentration.
Oxygen (O2) and carbon dioxide (CO2) are non-polar gasses that move across cell membranes by a process called simple diffusion.
Simple diffusion is a type of passive transport that does not require energy to move substances across cell membranes.
Glucose is produced by plants through photosynthesis. In this process, the plant uses light energy from the Sun to convert carbon dioxide and water into glucose and oxygen. Algae and certain bacteria and other unicellular organisms also produce glucose through photosynthesis.
