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Diffusion:
Diffusion:
The net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration.
Diffusion down the concentration gradient (from higher to lower concentration) does NOT require energy. It is considered PASSIVE Transport.
In the gif above, the two glasses of water are at different temperatures.
Based on the rate of diffusion of the food coloring, which glass has a higher temperature? The glass on the left
Brownian Motion:
Brownian Motion:
Brownian motion, also called Brownian movement, any of various physical phenomena in which some quantity is constantly undergoing small, random fluctuations. It was named for the Scottish botanist Robert Brown, the first to study such fluctuations (1827).
The rate of motion is directly related to the temperature of particles in motion.
Random Walk
Random Walk
Using a Random Walk code you can model Brownian Motion. This is often used as NPC motion in video games.
CO2 enters the lungs through the pulmonary arteries. These arteries then divided into smaller and smaller vessels called capillaries. CO2 which has been dissolved in the blood plasma diffuses out of the capillaries into the alveoli.
Oxygen gas diffusing through the thin layers of the alveolus. Binding with the hemoglobin within the red blood cells, changing the color of the RBCs from 'purple' to bright red.
Following the concentration gradient (higher to lower), O2 breaks free of the hemoglobin and exits the blood stream when the concentration gradient is sufficient to draw the O2 out of the blood. Glucose is also transported into the cells by the same process, insulin aides in this transfer of glucose due to the size of the glucose molecule.
As CO2 builds up (higher concentration) in the cells it moves into the blood stream, where it is then transported to the lungs.
The image above is from the exhibition Body Worlds. The model was created by injecting the body with a plastic that hardened within the blood vessels, a process called PLASTINATION.
Blood Speed in Various Blood Vessels
Blood Speed in Various Blood Vessels
Blood travels a different speeds in different blood vessels. The speed of blood is inversely related to the area of the vessels. This can be seen in the graph to the left. As the area of vessels increases (within capillaries) the speed of the blood decreases.
This slower speed helps to facilitate the transfer gases, nutrients and waste.
You would not expect to make a delivery while traveling at high speeds in a car towards Al Ain.
Sucrose Diffusion Lab
Sucrose Diffusion Lab
Objective: To determine the relationship between solution concentration and the diffusion of water in/out of cells.
Background:
Diffusion is the movement of substances from an area of high to low concentration
Osmosis is the movement of water from low to high solute concentration across a semipermeable membrane
Visking tubing is semi-permeable: it allows some particles to pass through, and does not allow others to pass through (based on size of particle).
The solutions you are working with today have various concentrations of sucrose (0%, 5%, 10%, and 20%)
Water has the molecular formula of H2O and molecular weight of 18.01528 g/mol
Sucrose has the molecular formula of C12H22O11 and molecular weight of 180.156 g/mol
Sucrose is the scientific name of table sugar. A plant makes glucose and this is converted into sucrose and fructose.
Water and other substances can move into and out of these cells through the plasma membrane.
Each group obtain four 18 cm lengths of Visking tubing.
Tie one end of the tubing.
Using a graduated cylinder and pipette, put 10 mL of the “tubing solution” in the Visking tubing.
Tie the other end, being careful not to lose any of the solution inside.
Your group should have 4 Visking tubes, each with the “tubing solution”. .
Take and record the mass of each tube.
Place your 4 filled tubes into 4 beakers at the same time with 100 mL of
Solution A(0%), Solution B(5%), Solution C(10%), and Solution D(20%), making sure the tubes are completely covered.
After 15 minutes, remove each of the tubes. For each tube, gently dry the outside of the tube, then measure and record the mass.
Calculate the change in mass, then the percent change in mass for each of the tubes
Using the data in your table, create a graph in Google Sheets and paste it on this document.
Questions to consider:
Questions to consider:
Concept: Why did some of the visking tubes gain mass and others lose mass?
Lab Eval: Why was it important to use the percent difference of the mass as opposed to simply the change in mass?
Lab Eval: Evaluate the experiment to determine how we (as a class could have collected better data).
Data Analysis: What is the significance of the x-intercept from the graph?
Data Extrapolation: On a graph, sketch a prediction of the trend line if you were to allow the experiment to continue for an additional 10 minutes. What about 24 hours?
Potato Diffusion / Osmosis Lab
Potato Diffusion / Osmosis Lab
Objective: To determine the relationship between solution concentration and the diffusion of water in/out of cells.
Background: Potatoes are the storage facility for potato plants. The plant makes glucose and this is converted into sucrose and fructose. Some of the potato glucose is converted to starch and stored in the millions of cells that make up the potato. These cells are normal plant cells with a cell wall and a plasma membrane.
Water and other substances can move into and out of these cells through the plasma membrane. Diffusion is the movement of a substance from an area of higher concentration to an area of lower concentration.
Label 5 test tubes with sucrose solutions - (0%, 5%, 10%, 15%, 20%)
Using the core borer, cut out plugs of potato,
Using the scalpel, cut 5 potato cores into 5cm pieces
Using the balance, weigh the potato cores and record the initial mass for each potato core (Put this in the Initial Mass column of Table 1)
Place one of the cores that you measured into each test tube
Add 10 ml of the sucrose solutions to each test tube
Cover the test tube with parafilm to prevent evaporation.
Leave the potato cores in solution until next class period.
Take out the potato cores of the solutions, blot them dry with a paper towel.
Using the balance, weigh the potato cores and record the final mass for each potato core (Put this in the Final Mass column of Table 1)
Record the final mass of the potato cores that were placed in each solution (Put this in the Final Mass column of Table 1)
Compute the percent change for each solution. Enter this value on the class data sheet: Potato Diffusion Data (Link in GC)
Observations to Make:
Before and After of Each:
Mass of each potato core entered in table below.
Photo of cores on graph paper (w/labeled cores)
Written description (any observations that you made about the cores before and after)
Questions to consider:
Questions to consider:
Concept: Why did some of the potato cores gain mass and others lose mass?
Lab Eval: Why was it important to use the percent difference of the mass as opposed to simply the change in mass?
Lab Eval: Evaluate the experiment to determine how we (as a class could have collected better data).
Data Analysis: What is the significance of the x-intercept from the graph?
Data Extrapolation: On a graph, sketch a prediction of the trend line if you were to experiment using sweet potatoes in place of the Russet potatoes we used in class.
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