Investigating Diffusion Investigating Diffusion: Student Lab Design Cell Membrane: Structure &...
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Transcript of Investigating Diffusion Investigating Diffusion: Student Lab Design Cell Membrane: Structure &...
Investigating Investigating DiffusionDiffusion: Student Lab Design
Cell Membrane: Structure & Function
Word Wall
Monomer & Polymer Glucose & Starch Diffusion (Passive Transport) Non-permeable Semi-Permeable Permeable Lipid Bi-layer
Lab Report Handout
Please have your Diffusion Lab Word document ready to begin the Experimental Design process for this lab.
Background Information: Animal and plant cells
enclose the inside contents of the cell.
Membranes are made of two sheets of fat molecules called a phospholipid bilayer.
This bilayer is flexible and lets some, but not all, molecules pass through.
Background Information: Carbohydrate Diffusion
Glucose and starch are common carbohydrates found in and outside of the average cell. These molecules pass to
and from the bloodstream.
They diffuse across the membrane based on the rules of passive transport.
Glucose
Starch
Background Information: Dialysis Tubing The dialysis tubing can be filled up (inflated)
by various fluids. The ends will be closed with string in order to
prevent leakage of fluid.
“Dialysis Tubing” will be used as the model of the cell membrane. This membrane is similar to a plastic (cellophane) material.
This tubing has properties that are similar to real membranes; it’s semi-permeable.
Question
What effect does the type of carbohydrate (starch or glucose) have on its diffusion through the membrane?
In other words, will glucose and/or starch diffuse through the dialysis tube (bag)?
Hypothesis
Create a hypothesis that predicts whether glucose glucose and/or starch starch can diffuse (pass through) the dialysis tubing and why (prediction reason).
Experimental Design
Experimental Group MV: 10 mL glucose or
starch solution Dialysis tube Cup String tap water
Benedict’s Solution Benedict’s Solution Hot plateHot plateOrOr IodineIodine
Control Group ECC: 10 mL water Dialysis tube Cup String tap water
Benedict’s Solution Benedict’s Solution Hot plateHot plateOrOr IodineIodine
Miscellaneous
Identify the following items in your lab handout: MV ECC RV CVs (minimum of 3)
Supplies Glucose Solution (for Benedict’s Test) Benedict’s Solution Starch Solution Iodine Solution 10 cm Dialysis Tubing (2) lengths of string (2) Cups Hot Plate (for Benedict’s Test) Water
Group Task
Complete the design for this experiment that can show whether glucose or starch can pass through dialysis tubing (a semi-permeable membrane).
Complete the following Steps: Follow Procedures and set up experiment Return to your seats when done Data Table (in Data & Observations)
IMPLEMENTING DESIGN
RESULTS DAY
Background Information: Chemical Indicators: Glucose TestGlucose + Benedict’s Solution with heated added (~3 min) = blue.It will gradually turn green and finally become a (burnt) orange color.
Background Information: Iodine Test
Starch can be detected by the use of iodine (IKI).
Starch + iodine = blue-purple-black color
Carbohydrate Tests: Summary
Condition Color with Iodine Test
Color with Benedict’s Test + heat
Water Yellow Blue
Starch (polymer) Purple/Black Blue
Glucose (monomer) Yellow Orange
Final Day’s Details
Throw away the dialysis bags into the trash Please leave the IKI and Benedict’s Solution
on the front counter. Discard any liquid waste from the
glucose/starch tests into the waste beaker on the front counter.
Data TableCondition Carbohydrate
Test: Color Observed
Interpretation:Diffusion did
occur (Yes or No)
MV: Glucose (monomer)
Orange Yes
ECC: Starch (polymer)
Yellow No