Monday, 10/1 Set up AP Lab #4: Diffusion & Osmosis Remember Lab Tuesday – Thursday Chp.6&7 TEST will be MONDAY!!!

Tuesday 10/2 Lab 4 – start today –Part A and Part B completed today Chp.6&7 Test will be MONDAY Lab continues tomorrow – dress appropriately

Set up a new page in your AP Bio Lab Notebook Title: Lab 4 – Diffusion & Osmosis Subtitle 1 st Section: Background Info –Read background info, summarize in at least 2 paragraphs –Include key words: diffusion, osmosis, concentration gradient, hypertonic, isotonic, hypotonic, solute concentration, plasma membrane, cell wall, turgor pressure, water potential, dynamic equilibrium, plasmolyze

2 nd Section: Objectives 1.Growth, reproduction, and homeostasis require that cells create & maintain internal environments that are different from their external environments 2.Growth & homeostasis of a biological system are influenced by changes in the system’s environment 3.Demonstrate diffusion across a semi-permeable membrane 4.Measure the effects of various concentrations of solute on the process of osmosis 5.Differentiate between hypotonic, isotonic, and hypertonic environments 6.Measure and calculate water potential 7.Examine the effects of osmosis on plant cells

3 rd section: Data Glue in Data Tables 1, 2, & 3 and the Plant Cell Plasmolysis data

4 th section: Analysis/ Conclusion Questions Glue in and create graphs You will be provided with these questions at the end of the lab, glue in and answer in this section

Safety Read all instructions before beginning lab. Wear PPE & apron. Wash hands before and after lab. –Pores in dialysis tubing can easily be clogged with oil & dirt from hands, keep contact to a minimum IKI (potassium iodide) solution is an irritant, can stain clothes, handle with care, and wash off spills & splashes with water.

Procedure Overview – Part A: Diffusion Fill dialysis tubing with glucose/starch soln. Test for glucose with glucose test strip. –Positive is dark green/brown Place in beaker of distilled water with IKI (potassium iodide) soln. Test soln. for glucose & record color. Wait 30 min, then record color and test for glucose in dialysis bag and in beaker.

Procedure Overview – Part B: Osmosis Fill 6 dialysis bags: water, 0.2M sucrose soln, 0.4M, 0.6M, 0.8M, & 1.0M Blot dry, weigh each one, record initial mass, and place in labeled cup Fill each cup with distilled water, wait 30 min. Remove, blot dry, weigh, record final mass Calculate percent change Graph data in analysis section

Procedure Overview – Part C: Water Potential Get 4 potato cylinders (pre-cut) Weigh all 4 together & record initial mass Place into cup of 100mL of your assigned solution, record temp, cover, wait overnight Measure final temp, blot potatoes dry, measure final mass Calculate % change & graph

Procedure Overview – Part D: Water Potential Calculation Use provided formulas Record in conclusion question #9

Procedure Overview – Part E: Plant Cell Plasmolysis Remove epidermal layer from onion Create wet mount & observe under microscope 100x mag, record observations Add 2-3 drops of 15% NaCl soln, wait 2-3 minutes, observe at 100x mag, record observations

Finish Lab Set-up Remember Lab Tomorrow – Thursday Chp.6&7 TEST will be MONDAY!!!