AGHS - CP Bio - Osmosis Lab - Casey Rurode | Library

Osmosis Lab
The goal of this assignment is to help you feel more comfortable with the ideas and vocabulary related to osmosis. 

Part 1- Osmosis Simulation 
This simulation models osmosis through the cell membrane of ablood cell, an elodea/aquatic plant cell, and a paramecium. 

Open this link in a new tab: 
http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS03/LS03.html

IF YOU NEED TO ENABLE FLASH, WATCH THIS SCREENCAST SHOWING YOU HOW TO ENABLE FLASH!

Once on this website you should read the explanation on the left side of your screen. Then follow this procedure to complete the data table below:

1. Select one of the 3 cells pictured and drag it into one of the beakers. 
2. Observe the process of osmosis. Determine whether water, represented with animated blue arrows, moves into, stays in equilibirum, or moves out of the cell. 
3. Record your observations in the table. 
4. Move the cell to a different beaker until all the cell has been observed in all solutions types (hypotonic, isotonic, and hypertonic).
5. Repeat the activity until all 3 cells have been observed in all 3 solution types.  
6. Answer the obserration and analysis questions below.

3

Based on what you see in the Glencoe animation, sort the cell type in each solution to the situation you observed water moving into the cell, out of it, or showing now net change

elodea in the isotonic solution
paramecium in the isotonic solution
blood cell in the isotonic solution
paramecium in the hypotonic solution
paramecium in the hypertonic solution
blood cell in the hypertonic solution
blood cell in the hypotonic solution
elodea in the hypertonic solution
elodea in the hypotonic solution

Net movement of water into the cell
Net movement of water out of the cell
No net movement of water into or out of the cell

1

What ALWAYS happens when a cell is placed in a solution that is hypotonic to the cell?

1

What ALWAYS happens when a cell is placed in a solution that is hypertonic to the cell?

1

What ALWAYS happens when a cell is placed in a solution to which is it isotonic?

1

What must be true about the cell membranes of human blood cells, elodea cells, and paramecium is water can easily move across all three cell membranes?

1

Since water transport occurs from high to low, the diffusion of water across a cell membrane is considered...

Part 2- Red Onion Osmosis Lab

To see how this lab is performed, watch the embedded video. Answer the analysis questions as or after you watch!

1

Why is it important to use the onion tissue with the red/purple pigment when preapring the slide, not the other side that is completly clear?

1

What water property allows, or which properties allow, the salt water to move continuously across the onion tissue from one side of the slide where the salt water was added, to the other, where the paper towel was held?

Here is what the red onion cells looked like after the salt solution was drawn across them. 

1

After the cells were bathed in salt water there was a visble change to the cells. Which best describes the events that altered the cells' appearance?

1

Explain the science behind your answer to the previous question? Water was pulled out of the cytoplasm and into the salt solution because...

1

Knowing what occurred in this lab, which term best describes the salt solution in relationship to the onion cells when the salt solution was first added to the cells' surrounding environment? The salt solution was ______ compared to the onion cells.

1

What term descibes the appearance of the plant cells when water has been removed from the cytoplasm and there is a visible gap between the cell membrane and the cell walls?

The second part of this experiment (starts at 2:16) was to submerge the red onion cells in fresh water using the same technique. This time the cells "swelled back up to their original size" and look like this:

1

Knowing what occurred in this lab, which term best describes the fresh water in relationship to the onion cells when the fresh water was first added to the cells' surrounding environment? The fresh water was ______ compared to the onion cells.

1

Since osmosis is a form of passive transport, what should eventually happen to the concentration of water inside of the onion cells compared to the concentration of water in the surrounding solution?

Here is the second part of the onion lab being run on human red blood cells. Watch all 22 seconds of this video to answer the next two questions!

1

How are the results of this test, of adding fresh/distilled water to the surrounding environment of human cells, similar to the results using plant cells?

1

In the video of the human red blood cells being bathed in pure water, we observed cytolysis which literally means the blood cell (cyto) was cut or broken (lysis). Why was this NOT observed in the plant cells found in the onion tissue?

Part 3- Applying Osmosis to Real Life Examples
Make sure you participate in the discussion on Schoology to apply your understanding of osmosis, and the accompanying vocabulary, correctly! All instructions are in the "Osmosis Applications" Discussion in todays "Lesson 6- Osmosis Lab" on Schoology.  