AP Lab 4: Diffusion and Osmosis November 18-23

Order Wednesday – part A (PMPH A/B due) Thursday – part B, set up D Friday – D final masses, C (PMPH C/D due) Monday – class data, Prelab Graph due Tuesday – class data Monday - due

Part A Purpose is to see how SA:V ratios affect diffusion in a cell Basic Procedure: – Cut out 3 sized agar cubes – Calculate SA:V ratio – Make predictions of fastest diffusion – Place into beaker of NaOH for 10 minutes. – Blot and cut in half – Measure depth of diffusion H1: Which sized cell will diffuse faster? H0: Size doesn’t matter – SA:V ratio has no effect on diffusion

Part B Purpose is to see what substances go through a dialysis tube Basic Procedure In tube: 15 ml glucose/starch soln Beaker: distilled water and 4 ml of IKI Qualitative data before and after 30 minutes H1: Which materials will go through the membrane? H0: No materials will go through the membrane.

HOW TO OPEN A DIALYSIS BAG How to open a dialysis bag

Part C Purpose is to see the effects of different concentrations of sucrose solutions on dialysis tubing Basic Procedure – 5 dialysis tubes  25 ml of Om, 0.2M, 0.4M, 0.6M and 0.8M sucrose solutions – Initial mass – Place in distilled water for 30 minutes – Final mass, % change in mass, class averages, graph and standard error calculations and put on graph H1: Which tube will lose/gain most mass? H0: different sucrose solutions don’t affect osmosis in a dialysis tube.

Part D Purpose is to determine the water potential of 3 different potatoes. Procedure: 5 pieces of each potato and get initial mass Put each potato in each solution: 0M, 0.2M, 0.4M, 0.6M and 0.8 M (color coded) Final Mass Figure out which color is which solution Percent change in mass, class averages, graph, figure out molarities of each potato Calculate water potential H1: Which potato will have the highest/lowest water potential? Ho: All three potatoes have the same water potential.

Part E Purpose is to observe hypertonic, isotonic and hypotonic environments with a plant cell Basic Procedure: – Elodea normal water – high power – Elodea distilled water – high power – Elodea salt water – high power – Draw each and label in notebook

Inquiry Purpose is to predict and see what will diffuse through a dialysis bag using various substances. Materials available: – 1M NaCl solution – 1M Sucrose solution – 1M glucose solution – 5% albumin solution (egg white solution) – 0M distilled water