1. Diffusion Through a Membrane State Required Lab
Part A: Model Cell

2. Making The Cell What is located inside the cell in the beginning?
Glucose and
starch were added to the inside of the model cell.

3. This is what the experiment looks like in the beginning
Inside
Starch and Glucose are added inside the cells.
Outside
Water and Starch Indicator Solution are added to the outside of the cell.

4. What’s happening after the 1st 10 minutes?
The cell is starting to turn black. Why?
Because Starch Indicator solution is moving across the membrane into the cell.
Remember
Starch + starch indicator= black color

5. Is This The Final or Initial State?
Answer
Final State

6. Label The Contents Of Your Cells
Initial State
Final State
H20, Glucose, & Starch Indicator Solution G
H20 and Starch Indicator Solution
S G G
G S S
S S G G
Starch and Glucose
Glucose, Starch, and Starch Indicator Solution G

7. Watch the video clip “Reviewing the Diffusion Through a Membrane” lab to help you complete the Analysis Questions. The video clip is located on my website underneath this ppt.

8. Part B: Osmosis Red Onion Cells

9. What happened to the onion cells in salt water?
Onion Cells under Normal Condition
Onion cells in Salt Water
What happened to the onion cells in salt water?
Water leaves the cell making the cytoplasm smaller.
Added
Salt water

10. Onion Cells under salt water Onion Cells after adding Distilled Water
What happened to onion cells after you added distilled water?
The onion cells expanded back to normal size because the water diffused back into the cell, due to higher conc. of water outside than inside.
Added
distilled water

11. Question #1
Answer
The outside of the cell would turn blue black instead of the inside of the cell.
During the lab, one group of students messed up. They poured the starch indicator solution into the cell and filled the beaker with starch and glucose solution. State what their results would look like.

12. Question #2 Normal plant cell Plant cell in salt environment.
The salt would damage or kill the plants. The salt environment would cause water to move out of the plant cell leading to dehydration and eventually death.
Normal plant cell

13. Question # 3
When a person is given an I.V., the fluid has a little salt in it just like our blood. Explain how the use of distilled water in place of saline solution would up set homeostasis.

14. Question # 3: Answer
100 % water
Homeostasis would be upset because since I.V. has distilled water, there would be a higher concentration of water outside of the cell, the water then would move into the cell causing it to burst.
98 % water

15. Question # 4
Many fresh-water one –celled organisms have structures called contractile vacuoles. These structures collect and pump out excess water that accumulates inside the cell. Name the process that causes water to flow into these organisms. Osmosis. Explain why the contractile vacuoles would be of little value to one-celled organisms living in salt water?
Contractile vacuoles are of no value to salt water organisms because since there is a higher conc. of water inside the cell, the water would diffuse out automatically; therefore, the contractile vacuoles are no longer needed to pump out excess water.
Salt Water = Low concentration of water
High conc. Of water

16. Question #5 Why does eating popcorn make you thirsty?
Popcorn is very salty and may cause water to leave the cells of your mouth due to diffusion. This makes a person even more thirsty.
Water leaving the cell

17. 6) Why is the digestion of starch to glucose necessary?
Starch is big and must be broken down into glucose so it can diffuse across a cell membrane. Glucose is small enough to diffuse across a cell membrane.
Starch (carbohydrate): too big to diffuse into the cell membrane.
Glucose: small enough to diffuse into the cell membran.

18. Your homework Is to finish your lab
Your homework Is to finish your lab! If it is not done it will be a Zero. No excuses!
The Mad Scientist