The type of molecules that pass most readily through a cell membrane are nonpolar molecules, such as water, oxygen, carbon dioxide and fatty substrates. The process by which these molecules are transported across cell me... More »

The plasma membrane, also known as the cell membrane, protects the inside of the cell and is able to select which substances are allowed into the cell. Plasma membranes are mainly made from phospholipids and cholesterol,... More » Science Biology Molecular Biology & DNA

The rate at which molecules diffuse across the cell membrane is directly proportional to the concentration gradient. This applies to simple diffusion, which is governed by Fick's law. More »

If the cell membrane becomes totally impermeable, water and dissolved gases, most notably oxygen, would no longer be able to enter or leave the cell. The cell membrane is usually permeable to a number of substances, most... More »

During photosynthesis, plants take in carbon dioxide and water, disassemble the molecules and convert them into sugar and oxygen. The water molecules are split into hydrogen and oxygen, and the hydrogen joins carbon diox... More »

Plants make oxygen by using light energy to convert water and carbon dioxide into sugar and oxygen molecules. This occurs during the process of photosynthesis. More »

During the stage of photosynthesis referred to as the light-dependent reaction, 12 molecules of water begin the process of reacting with six molecules of carbon dioxide to produce one molecule of glucose, six molecules o... More »