Diffusion, Osmosis and Active Transport Grade Ten – BGCSE Biology Movement in and out of cells

Order of Presentation Movement in and out of cells Definition of diffusion Examples of diffusion Definition of Osmosis Examples of Osmosis Definition of Active Transport Examples of Active Transport

Particles of oxygen, carbon dioxide, glucose and water are always in motion.

An example of diffusion

Concentration gradient A difference in concentration of molecules in physical space is called a concentration gradient.

Movement of Particles

Diffusion Movement of particles from an area of high concentration to an area of low concentration.

Osmosis Dilute solution Concentrated solution Movement of water from a dilute solution to a concentrated solution across a partially permeable membrane.

Plant cells in solution How does the water move?

Turgid and flaccid How did the cells become i) flaccid and ii) turgid?

Red blood cells in solutions – animal cell In concentrated solution In dilute solution Same concentration

What kind of solution is found in Beaker A, B and C What kind of solution is found in Beaker A, B and C? How does this affect the red blood cell?

Across a semi-permeable membrane

Concentration same on both sides of semi-permeable membrane

Paramecium Contractile vacuole which balances water in aquatic environment.

Ileum of the small intestine

Active Transport Cell membrane is the movement of molecules across a cell membrane in the direction against the concentration gradient and requires energy from the cell.

Active Transport Cell membrane Happens when the cell has special receptors for materials needed by the cell, even though the cell already has a high concentration of the material. Materials are brought in by the cell.

1. Why does oxygen enter the red blood cell? Review 1. Why does oxygen enter the red blood cell?

There is more oxygen outside the cell than inside the cell So oxygen diffuses into the cell

Root Hair Cell Minerals diffuse into root hair cell, then water by osmosis and finally by active transport any other minerals that might be present.

2. How do diffusion, osmosis and active transport differ?

Summary Materials needed by cells move into the cell first by diffusion, water moves by osmosis and finally by active transport. Diffusion and osmosis do not require energy by the cell and are along the concentration gradient. Active transport involves movement against the concentration gradient and requires energy.