Name ______
CELL MEMBRANE LAB ACTIVITY
Station 1: SMELLY BALLOONS
The balloon is a SELECTIVELY PERMEABLE MEMBRANE that allows movement of certain molecules across. Molecules small enough to fit through the pores in the balloon will move by DIFFUSION through the membrane both in and out of the balloon. The food extract smell molecules are small enough to fit through and will diffuse through the balloon membrane and through the air. Eventually, the diffusing molecules reach the smell receptors in your nose.
Smell the skin of each balloon and record the smell you detect.
What do you smell?Balloon A
Balloon B
Balloon C
How do the smell molecules get out of the balloon? ______
This process by which molecules (solutes) move from a place of higher concentration (inside the balloon) to a place of lower concentration (outside the balloon) is called ______
Tell two ways the latex skin of a balloon is like a cell membrane.
1.______
2. ______
Station 2: PERMEABILITY IN CELLS
Observe the set up.
The plastic bag contains a solution of starch and water.
In Set-Up A the liquid in the beaker is water.
In Set-Up B the liquid in the beaker is water with 15 drops of iodine.
1. What cell structure does the plastic bag represent?
2. What do you observe inside the plastic bag of A?
What do you observe outside the plastic bag of A?
3. What do you observe inside the plastic bag of B?
What do you observe outside the plastic bag of B?
4. Which Set-Up is the control?
5. Iodine turns blue-black in the presence of starch. What process do you think occurred
that caused the results you observed? Explain your answer.
Station 3: CHECK THE VEGGIE DEMO:
What happened to the onion in salt water? Grew bigger Shrank smaller Stayed same size
What happened to the onion in tap water? Grew bigger Shrank smaller Stayed same size
USE THE DIAGRAMS BELOW THE ANSWER THE FOLLOWING:
(Black dots represent solute in a solution)
A B C
Which diagram represents the onion cell in salt water? A B C
Which diagram represents the onion cell in tap water? A B C
The salt water solution was ______compared to the carrot.
hypotonic hypertonic isotonic
The tap water was ______compared to the carrot.
hypotonic hypertonic isotonic
Why do grocery stores spray their vegetables? ______
Station 4: MEMBRANES ARE PERMEABLE
Dip the small end of the bottomless cup into the soap solution and place it bottom up on a paper towel.
Gentle squeeze the sides of the cup and record your observation.
From a height of about 3 inches squeeze a drop of food coloring over the membrane and record your observation.
1. What happens when you drop the food coloring over the membrane? Why?
2. Think about the fluid environment cells live in. What advantage is there to having a
bilayer with lipids on the inside of the membrane?
3. How is a soap membrane similar to a cell membrane? How is it different?
STAAR CONCLUSION QUESTIONS
1. In which situation would passive transport most likely be used to remove a substance from inside a cell?
Awhen the substance is composed of positive ions
Bwhen the substance is composed of large protein molecules
Cwhen the concentration of the substance is lower outside the cell than inside the cell
Dwhen the concentration of the substance is higher outside the cell than inside the cell
2. If an animal cell is placed in distilled water, it will swell and burst. The bursting of the cell is a result of
which biological process?
Aactive transportCrespiration
Benzyme activityDosmosis
3. The cell membrane of a red blood cell will allow water, oxygen, carbon dioxide, and glucose to pass
through. Because other substances are blocked from entering, this membrane is called
AperforatedCsemi-permeable
BpermeableDnon-conductive
4. When Streptococcus pneumonia are exposed to an antibiotic, the bacteria try to pump the antibiotic
out of their cells. Which of the following mechanisms is most likely used by the Streptococcus
pneumonia to pump the antibiotic out of their cells?
Aactive transportCdiffusion
Bfacilitated diffusionDosmosis
5. A cell has a defect that results in the loss of its ability to regulate the passage of water, food, and wastes
into and out of the cell. In which of the following cell structures is this defect most likely to be located?
AribosomesC cell membrane
BchloroplastsDendoplasmic reticulum
TEACHER NOTES:
Station 1
3 balloons
3 different flavors/smells (orange, peppermint, and vanilla work well)
Use a pipette to put some extract into the balloon before you blow it up and tie it
Station 2
Iodine, starch, plastic bags, water
You can do this as a demo for the whole class or set it up and allow them to rotate around
Station 3
You will need to buy a large carrot and slice it fairly thin—you need 3 slices about the same
Put one slice in salt water, one in tap water, and one without water
Do this the day before the lab. Ziploc bags work well
Station 4
You need bubbles, petri dish, food color, small paper cups (you will need a new cup for each period)
Cut the bottom out of the cup
Pour a small amount of soap bubble mix into petri dish
Lots of paper towels
1