Diffusion and osmosis

What is diffusion?

The spontaneous movement of molecules, ions and atoms from an area of high concentration to an area of low concentration of that molecule, atom or ion until dynamic equilibrium is achieved

What is the diffusion gradient?

Diffusion gradient is the difference in concentrations of that molecule, atom or ion in the two areas

How is diffusion a passive process?

It does not require energy for movement and the movement occurs down a concentration gradient

What does the rate of diffusion depend on?

1.) Concentration gradient: The steeper the gradient, the faster the rate of diffusion
2.) Distance at which diffusion occurs: If the distance is shorter then the rate of diffusion will be faster
3.) Pressure acting in the system: The more pressure acting upon it, the faster the rate of diffusion
4.) The temperature: The higher the temperature, the faster the rate of diffusion

What are some examples of diffusion?

1.) The movement of gas during gaseous exchange, cellular respiration and photosynthesis
2.) Movement of nutrients into cell
3.) Movement of metabolic waste out of the cell

What is osmosis?

The movement of water across a differentially/selectively permeable membrane from an area of high water potential to an area of low water potential down a water potential gradient until dynamic equilibrium is achieved

What is water potential?

The tendency for water molecules to move out of a solution

what substance has the most water potential and why?

Pure water has the highest water potential as there is no solvent present to decrease the kinetic energy of the water molecules

Examples of osmosis

1.) The absorbtion of water from soil and into the plant
2.) in kidneys, osmosis helps regulate the ion concentration in the body

What happens to plant and animal cells when places in a isotonic solution

The cell neither gains or looses water

What happens when an animal cell is placed in a hypotonic solution?

The water will move into the animal cell and it will become swollen and eventually burst (lysis)

What happens when an plant cell is placed in a hypotonic solution?

The water will move into the cell and the cell will become turgid; the pressure of the cell wall then prevents the inflow of water

What happens when an animal cell is placed in a hypertonic solution?

The water will move out the cell and the animal cell will shrivel and shrink(crenation)

What happens when an plant cell is placed in a hypertonic solution?

The water will move out of the cell and the vacuole loses water and the cell becomes flaccid. The cytoplasm then pulls away from the cell wall and the cell is now plasmolyzed

Explain active transport

When energy is used to move molecules against a concentration gradient

How do molecules move against the concentration gradient?

They use energy and carrier molecules

Explain how energy and carrier molecules move molecules against the gradient

The carrier molecules use the energy provided by the cell, which was released during cellular respiration, to attach themselves to the molecules on the one side of the membrane that has a low concentration and moves them across the membrane to the area of high concentration

Examples of active transport

1.) The uptake of mineral ions into root hair cells of plants
2.) The uptake of glucose in the intestines of humans
3.) The reabsorbtion of glucose into the kidney
4.) The sodium pump into the kidneys