Osmosis and Diffusion Web Lesson

a. Hypotonic Hypotonic refers to the solution in a concentration gradient having the lesser concentration (of solute ). Hypotonic refers to the solution in a concentration gradient having the lesser concentration (of solute ). –A hypotonic solution would have a greater concentration of solvent but a lesser concentration of solute than a hypertonic one.

b. Hypertonic Hypertonic refers to the solution in a concentration gradient having the greater concentration (of solute ). Hypertonic refers to the solution in a concentration gradient having the greater concentration (of solute ). –A hypertonic solution would have a lesser concentration of solvent but a greater concentration of solute than a hypotonic one.

c. Isotonic Isotonic means having equal concentration. Isotonic means having equal concentration.

d. Diffusion Diffusion is the movement of particles (ions or molecules) from an area of higher concentration to an area of lower concentration. Diffusion is the movement of particles (ions or molecules) from an area of higher concentration to an area of lower concentration.

e. Osmosis Osmosis is the diffusion of water from a hypotonic solution into a hypertonic solution across an selectively permeable membrane. Osmosis is the diffusion of water from a hypotonic solution into a hypertonic solution across an selectively permeable membrane.

f. Passive Transport Passive Transport is the movement of ions or molecules across a membrane without the expenditure of energy. Diffusion and osmosis are examples of passive transport. Passive Transport is the movement of ions or molecules across a membrane without the expenditure of energy. Diffusion and osmosis are examples of passive transport.

g. Thermal Motion Thermal Motion is the constant random movement of particles in a liquid or gas resulting from the absorption of heat from the particles' surroundings. The more heat absorbed the faster the speed of the particle. Thermal Motion is the constant random movement of particles in a liquid or gas resulting from the absorption of heat from the particles' surroundings. The more heat absorbed the faster the speed of the particle.

h. Concentration Gradient Concentration Gradients - A concentration gradient exists when two or more solutions of differing concentrations are separated by a membrane. Concentration Gradients - A concentration gradient exists when two or more solutions of differing concentrations are separated by a membrane.

i. Solution Solution(s) is a homogeneous mixture of two (or more) forms of matter. Solution(s) is a homogeneous mixture of two (or more) forms of matter. The components of solutions are called solute and solvent. The components of solutions are called solute and solvent. In living systems the most common types of solutions are a solid dissolved in water (such as salt water) or a gas dissolved in water (for example oxygen dissolved in water). In living systems the most common types of solutions are a solid dissolved in water (such as salt water) or a gas dissolved in water (for example oxygen dissolved in water).

2.What happens to particles as temperature increases? Why? How does this influence diffusion? What happens to particles as temperature increases? What happens to particles as temperature increases? They move faster. They move faster. Why? Why? They absorb energy from their surroundings. They absorb energy from their surroundings. How does this influence diffusion? How does this influence diffusion? It increases the rate of diffusion It increases the rate of diffusion

3.Thermal motion is random. True or false? What causes a particle to change direction? Thermal motion is random. True or false? Thermal motion is random. True or false? True True What causes a particle to change direction? What causes a particle to change direction? Bumping into other particles or objects. Bumping into other particles or objects.

3. What are the two consequences of continuous random molecule movement? 1. molecules tend to move away (disperse) from centers of concentration 2. molecules of different types tend to intermix.

4. What is the end result of dispersion of molecules (like perfume) from a point of high concentration? They eventually become evenly distributed They eventually become evenly distributed

5. What is a homogeneous mixture? A mixture that has an even distribution of all molecules. A mixture that has an even distribution of all molecules.

6 Name two properties of diffusion for like and unlike particles. 1. Unlike molecules will intermix to form a homogeneous solution 2. Like particles will spread from an area of high concentration to an area of low concentration

7. In the example of NaCl in water, why do water and NaCl behave separately? They each follow concentration gradients high to low but they move in opposite directions

8. Why are the terms diffusion and osmosis used to describe the behaviour? Diffusion describes the movement of NaCl particles from areas of high concentration to areas of lower concentration Diffusion describes the movement of NaCl particles from areas of high concentration to areas of lower concentrationand Osmosis describes the movement of water from areas of high concentration to areas of lower concentration Osmosis describes the movement of water from areas of high concentration to areas of lower concentration

9 Define the term permeable membrane. Is cellophane permeable or impermeable? A permeable membrane – a membrane that allows molecules to pass through it A permeable membrane – a membrane that allows molecules to pass through it Yes cellophane is permeable – to ions and small molecules Yes cellophane is permeable – to ions and small molecules

10. For the example #3 given, describe the concentration gradients for the NaCl and water. Which way will molecules move? Water will move down its concentration gradient form high to low and will move from side A to side B NaCl will also move down its concentration gradient from high to low and will move from side B to side A

11. When does diffusion stop? Does all movement of particles stop at this point? Why or why not? Diffusion stops when the concentration on each side of the permeable membrane is equal. Diffusion stops when the concentration on each side of the permeable membrane is equal. Movement still occurs but there is no net movement of particles across the permeable membrane Movement still occurs but there is no net movement of particles across the permeable membrane

12 In example #4, what causes the concentration gradient to occur? Identify the hypertonic solution and the hypotonic solution.

13. What direction of particle diffusion occurs when a concentration gradient exists across a permeable membrane? As long as the membrane is permeable to the solute, it will move from high to low, and water (the solvent) from high to low – in opposite direction As long as the membrane is permeable to the solute, it will move from high to low, and water (the solvent) from high to low – in opposite direction

14. What does the term isotonic mean? Why does it indicate the end of diffusion Isotonic means both solutions on either side of the membrane have equal concentrations of solute Isotonic means both solutions on either side of the membrane have equal concentrations of solute

15. What is a selectively permeable membrane? A membrane that allows some particles to pass through it but not others A membrane that allows some particles to pass through it but not others

16. In example#5, why is osmosis the only type of diffusion? The membrane is permeable to water but not the other molecule, therefore water is the only part of the solution to move from an area of high to an area of low concentration The membrane is permeable to water but not the other molecule, therefore water is the only part of the solution to move from an area of high to an area of low concentration

17. Explain why the final result of example#5 may not result in isotonic solutions on either side of the membrane. Isotonic solutions will not occur because gravity will prevent the water level on side A from rising, thus preventing enough osmosis to create equal concentrations of solute on either side of the membrane