Aim: What is Diffusion?• Do Now: Predict what will happen with the diffusion

demonstration.

• Tuesday 10/21 background information for Science Project due

• Wednesday 10/22; Read pages 184-189 answer questions 189 #’s 1-5

• Thursday 10/23 Exam

• Project #1 due on 11/12.

Diffusion Physical Demonstration

• In diffusion all substances move from a higher concentration to a lower concentration

• Once the concentrations are equal on both ends we have reached “Dynamic Equilibrium”

• Dynamic=Running all the time• Equilibrium=Balance

Sketch the beaker & contents….Before After

•Beaker contains water and iodine.•Dialysis bag contains a starch solution.

Conclusions

• Why did the iodine move freely across the membrane while the starch did not?

• What process was demonstrated in this experiment?

Aim: What are some factors that affect the rate of diffusion?

• Do Now: What is facilitated diffusion?

• Background Information due tomorrow via turnitin.com. Worth 3 HW’s. NO LATE PAPERS WILL BE ACCEPTED! Include bibliography!

• Wednesday 10/22; Read pages 184-189 answer questions 189 #’s 1-5

• Thursday 10/23 Exam

• Project #1 due on 11/12.

How does Glucose enter a cell membrane?

• Glucose is a big molecule

• It emits a charge• Cannot readily

permeate lipid bilayer• Uses Facilitated

Diffusion to enter membrane

• DOES NOT USE ENERGY

Group Activity• In pairs please read “Analyzing Data” page 188.

• Answer questions 1-4 on a sheet of loose leaf paper to be collected at the end of the period.

• Do Not copy questions

• Hand in one paper for each pair of students

Aim: What is Active Transport and Osmosis?• Do Now: What are some factors that affect the rate of

diffusion?

• Background Information due today via turnitin.com by 11:59pm! Worth 3 HW’s. NO LATE PAPERS WILL BE ACCEPTED! Include bibliography!

• Tomorrow 10/22; Read pages 184-189 answer questions 189 #’s 1-5

• Thursday 10/23 Exam

• Project #1 due on 11/12.

How do substances move across a cell membrane?

• Diffusion and facilitated diffusion

• Osmosis (water)

• Active Transport: Requires ENERGY

Permeability of Lipid Bilayer

• Hydrophobic molecules cross with ease– Why? – They are all nonpolar– Examples: Hydrocarbons

Carbon DioxideOxygen

• Hydrophillic Molecules and Ions cannot pass with ease

• Why?• They are have charges• Examples: Glucose

Water

Na+ K+

Main Question: How will Ions and hydrophillic molecules permeate the membrane if the phospholipids won’t allow them to?

Active Transport: Up Close and Personal

• Na+ -- K+ Pump

• Moving Against the “concentration gradient”

• Movement from low to high concentrations

• Requires ENERGY!

Osmosis is…

The diffusion of water

Water moves from an area of high water concentration (low solute concentration) to an area of low water concentration (high solute concentration).

Remember: Water always wants to move to a place where it can dissolve something

Osmosis Demonstration• Goal: To predict what will happen when eggs are placed in

the following solutions:SyrupTap Water

Procedure: Egg placed in white vinegar overnight to remove

shell. Membrane exposed Tonight they will each be placed in the above

solutions. What measurement of the eggs will we need to

take in order determine if osmosis occurred?

Aim: How can we demonstrate Osmosis?

• Do Now: What is Osmosis and how does it differ from diffusion?

• Have out HW questions pg 189 #’s 1-5

• Test tomorrow 10/23!!!

• Project #1 due on 11/12.

Predictions

• In pairs discuss the answers to the following questions…

• Place the answers in your notebook

• What do you predict will happen to the egg in the syrup? Why? How will you know?

• What do you predict will happen to the egg in the tap water? Why? How will you know?

Data Table: Period 3Substance egg Substance egg submerged insubmerged in

Egg’s mass (g) Egg’s mass (g) before placed in before placed in

substancesubstance

Egg’s mass (g) Egg’s mass (g) after removed after removed

from substancefrom substance

SyrupSyrup 56.45g56.45g

Tap WaterTap Water 62.00g62.00g

Definitions

• Solute• Solvent • Hypertonic• Hypotonic• Isotonic

Qualitative Data: How do the eggs look?

Egg immersed in Syrup (Hypertonic Solution)

Egg immersed in Distilled Water (Hypotonic Solution)

Egg immersed in Tap Water (Isotonic Solution?)

Egg immersed in Syrup (Hypertonic Solution)

Egg immersed in Tap Water (Hypotonic Solution)

Isotonic Solution ?

Compare the following solutions to each other, using the terminology

we just discussed:

• 10% salt solution vs. distilled water• 20% salt solution vs. 10% salt solution• 20% salt solution vs. 20% salt solution• Distilled water vs. 20% salt solution

Selectively Permeable Membrane

In which direction will the water move? Why?

Describe the solutions in terms of concentration.

Onion Cell Plasmolysis

Onion Cell Wet MountOnion Cell in 10% salt solution

Summary

What is osmosis? Where does water always want to travel? Why doesn’t osmosis require energy? What happens to a cell when it is placed in a

hypertonic solution? Hypotonic solution? Isotonic solution?

REVIEW QUESTIONS

• What are two ways in which substances can move across a membrane? Which requires energy?

• How do these two ways differ from each other?

• What types of substances rely on active transport for admission into the cell? Why?