How does the movement of substances takes place into the cell?

Diffusion is the spontaneous movement of a substance down its concentration gradient from higher to lower concentration.  If you have a bottle of perfume and take the cap off.  The perfume molecules will waft out and diffuse into the air where there is a lower concentration of them. 

Factors that affect the RATE of diffusion

1. Difference in concentration between the inside and outside of the cell.  The bigger the difference between concentrations, the diffusion will be faster.

2. The size of the chemical substance.  O2 is two atoms. Glucose is 24 atoms big.  Protein is massive.  Oxygen can easily diffuse across a cell membrane.  Sugar can kind of, that’s why it’s assisted by a transporter protein to facilitate it.  The proteins don’t move at all.

3. Temperature. Higher temps = molecules move faster. ‘Nuff said.

4. Whether the chemical substance is water-soluble or lipid soluble.  The lipid soluble goes through faster because the cell membrane is phospholipids and can easily diffuse through a fatty membrane.

1. Diffusion- The process in which substances like CO₂ & oxygen move from  region of high concentration to a region of low concentration.
2. Osmosis- It is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration .