Ribose is a small molecule that can diffuse across cell membranes through simple diffusion, facilitated by its size and structure. It moves along its concentration gradient from an area of high concentration to an area of low concentration. This process does not require energy from the cell.
Water molecules freely diffuse across a semipermeable membrane.
selectively permeable
osmotically active
Gases diffuse most efficiently across a thin membrane or barrier. This is because a thin membrane allows for quicker movement of gas molecules from an area of high concentration to an area of low concentration.
Most small non polar molecules can diffuse across the membrane. Water is polar but diffuses across the cell through aquaporins. There are also proteins that actively transport substances across the cell membrane such as ions (ex.The Na/K pump). It can get a little confusing. I tried to be as simple as possible. I don't know if this is what you were looking for.
Ions can't diffuse across membranes, they must used channels to transport across
Water molecules freely diffuse across a semipermeable membrane.
Oxygen molecules diffuse across the membrane.
selectively permeable
selectively permeable
osmotically active
No, oxygen cannot directly diffuse across a cell membrane. Instead, it crosses the cell membrane with the help of specific transport proteins, such as aquaporins and oxygen channels. These proteins facilitate the movement of oxygen from areas of high concentration to low concentration.
CO2, H2O, and O2 can all diffuse across a cell membrane. Also, small polar molecules (uncharged) and hydrocarbons easily diffuse across.
Gases diffuse most efficiently across a thin membrane or barrier. This is because a thin membrane allows for quicker movement of gas molecules from an area of high concentration to an area of low concentration.
Its too large
Carbon dioxide, oxygen and some nonpolar molecules diffuse easily.
Most small non polar molecules can diffuse across the membrane. Water is polar but diffuses across the cell through aquaporins. There are also proteins that actively transport substances across the cell membrane such as ions (ex.The Na/K pump). It can get a little confusing. I tried to be as simple as possible. I don't know if this is what you were looking for.