1. How did we use indicators in the Diffusion Lab?
#30 Warm UP
How did we use indicators in the Diffusion Lab?
SWBAT explain diffusion and osmosis by answering analysis questions in their lab packets
Standard:
1.2g Each cell is covered by a membrane that performs a number of important functions for the cell. These include: separation from its outside environment, controlling which molecules enter and leave the cell, and recognition of chemical signals. The processes of diffusion and active transport are important in the movement of materials in and out of cells. 1.2h Many organic and inorganic substances dissolved in cells allow necessary chemical reactions to take place in order to maintain life. Large organic food molecules such as proteins and starches must initially be broken down (digested to amino acids and simple sugars respectively), in order to enter cells. Once nutrients enter a cell, the cell will use them as building blocks in the synthesis of compounds necessary for life.
WARM UP discussion:
Find your Diffusion Lab

2. Review of the Cell Membrane
The Cell Membrane is Semi-Permeable or Selectively Permeable
Small molecules (like glucose) are able to pass through the membrane while large molecules (like starch) cannot pass through

3. What we used for the lab
Dialysis Tubing – used to make a “cell” that will allow small particles to pass through and not large particles
Glucose Solution – a simple sugar made of one small molecule of sugar
Starch Solution – a complex carbohydrate made of hundreds of simple sugars bonded together

4. Indicators
Starch Indicator Solution – (Iodine), a really small molecule (It’s only 2 atoms big)
Glucose Indicator Solution – Benedict’s solution

5. Initial Cell “Cell” with glucose and starch
Water and starch indicator solution

6. The Final Cell The water stayed amber The cell turned blue-black
Water from outside the cell tested positive for glucose

7. What Happened??
Glucose was small enough to pass through the membrane so it ended up in the water outside the cell
Starch was too big to pass through the membrane so it didn’t get out of the cell
Iodine (starch indicator solution) was small enough to pass through the membrane so it ended up in the cell turning the cell blue-black

8. RED ONION IN FRESH WATER

9. CELL WALL
CELL MEMBRANE
CYTOPLASM

10. RED ONION IN SALT WATER

11. CELL WALL
CELL MEMBRANE
CYTOPLASM

12. Activity – Analysis Questions
Your table will be assigned one question from the analysis section on pages 8 and 9
Work on the question with your table for 5 minutes and put your answer on your easel.
Be ready to share and explain to your classmates
** If you finish early, check that ALL other sections of the lab are complete

13. REGENTS PRACTICE Reflection Answer on looseleaf and attach to lab
How did we observe diffusion and osmosis in this lab activity? Did this help with your understanding of these concepts? Explain.
Why was lab safety important during this activity?
What was your favorite part of this lab? What was most challenging?