Wednesday, February 27, 2013

EarthQuake Triangulation Questions

Triangulating Earthquakes: Analysis Questions

1)   Where is the epicenter for this earthquake located

2)  Refering to fig. 17- 13 on pg. 455 in Glencoe Earth Science book, which plates are most likely involved/ associated with this EQ?

3)  What type of plate boundary is this?

4)  Briefly describe the plate motions associated with this boundary.

Friday, February 15, 2013

biology membranes minilab

Modeling Origins of Life: the phospholipid membrane
When we see a cell membrane in a biology textbook it looks like each of the molecules had to be one by one purposely placed there then somehow bonded into place. But that is not the case. In this experiment a small amount of egg yolk provides the cell membrane forming molecules so that with a shake we amazingly "self-assemble" real phospholipid membranes around oil and water droplets to demonstrate how easily polar forces construct such an important part of a living organism.
Materials: 125 ml flask with stopper, 50 ml graduated cylinder, Cooking oil, egg yolk , Eyedropper pipette, Water

Test tube brush & soapy water

1.   Add ~100 ml of water to flask. To that add 25 ml of oil.

  1. Cover then shake for a second or two. Mixture should at first appear milky but quickly start separating.
  2. While waiting for the oil to return to a clear layer on top.  Use the eyedropper to extract ~2 drops of egg yolk.
  3. By now the oil should have formed a clear layer on top. We first shook it to prove that it will do this. Notice that it is pure oil that can be seen through to the other side.
  4. Then add one drop of the egg yolk into the flask.  Adding too much can cause the oil to form such small droplets it becomes a colloid, like milk.
  5. The drop of yolk will fall through the oil but float on the water so you can see it stuck in the middle.
  6. Shake for a second or two like before.
  7. Now watch what happens to the oil layer this time. It should soon look like a giant piece of tissue, like you're looking at cells under a microscope; but in this case, you see them with your own eyes!

·       The less dense ones which contain only oil and have a phospholipid monolayer around them go to the top.

·       The smaller phospholipid bilayer vesicles contain water inside and will be at the bottom of the layer, with some moving in the thermal convection currents of the water.


Phospholipid and cholesterol form membranes due to their having one end called a "head" which is attracted to the polar water, and on the other end are "tails" made of oil chains which are attracted to the nonpolar oil. Phospholipids and similar compounds will form a single "monolayer" membrane around grease, oil, and dirt, by their nonpolar "hydrophobic" tails sticking to the dirt while the water loving "hydrophilic" heads point outward to contact the water.

A phospholipid membrane which forms around a small droplet of water (instead of oil) is called a "Vesicle" which has a phospholipid "bilayer" where instead of a single membrane where all the tails stuck into an oil droplet there is a second inner membrane that has the phospholipid molecules pointing the other way so their heads contact the water droplet on the inside, with the tails of the inner membrane strongly attracted to the tails of the outer membrane which squeezes out anything that tries to come between them.

Vesicles are also very good at trapping such things as RNA and DNA which might end up included in your experiment, especially if you poked through the egg yolk's nucleus when you took the sample.

Analysis Questions:

  • What are the bilayer membranes most like in cell biology?  Monolayer membranes?
  • Describe how this activity is representative of evidence for a possible theory in the origin of life. 
  • Did you notice any of the droplets growing or dividing?  Explain how this might be relevant to the origin of life.
  • What aspects of complete living single cell are missing in this demo?
  • What happened when you added Fe particles?  How might this relate to endosymbiont theory?

Monday, February 11, 2013

Demonstration: Model of Convection Currents

Objectives: in this demonstration you will see how convection currents may explain the driving forces behind plate tectonics.  Each student should record the prelab, data table and the analysis observations in their notebook.

Prelab:  Draw both of the diagrams side by side on the same page

  1. Draw a diagram of a mid-oceanic ridge that includes how convection currents might move lithospheric plates.
  2. Diagram the convection current demo and label the parts used.
Data Table:

Thermometer A temp.
Thermometer B temp.
Thermometer C temp.
Minute zero
Minute five

Analysis Observations:

  1. What was the motion of the food color at minute zero?

  1. Describe any differences in the food colors movement just after the candles have been lit.

  1. Describe the motion of the food coloring after the candles have been lit for five minutes

  1. What is the relationship between the motion of the sticks and the motion of the water?

  1. Describe how the temperature of the water relates to the movement of the sticks/current.

  1. In relation to the Earth’s interior what do the candles, water and sticks each represent?

  1. Explain how the demonstration exemplifies the Earth’s interior convection currents.


  1. Set up the experiment as shown.  Note:  The candles should be positioned about 2 cm away from the bottom of the metal pan.
  2. Carefully fill the pan with cold water to a depth of at least 4 cm.
  3. Imagine a line that divides the pan into half and carefully drop a single drop of food coloring over the location of the un-burning candles.  Use thermometer to Record data and observations #1
  4. have the teacher lit your candles and leave the demo undisturbed for five minutes, then add a single drop of food coloring over each candle.  Use thermometer to Record data and observations #2
  5. When tiny bubbles appear at the location over the candles (or after the candle has been burning for about 10 minutes total) carefully add a single drop of food coloring to the locations over the candles.  Use thermometer to Record data and observations #3
  6. After a minute place the sticks about 3 cm to the side of the imaginary center line. 
  7. As soon as the sticks begin to move add a single drop of food coloring to locations over the candles.  Use thermometer to Record data and observations.  #4
  8. Clean up as instructed.


~2-3 cm from flame to the pan bottom

Water should be at 4-5 cm deep

ring clamp




Locations for thermometers

Side View


















Monday, February 4, 2013

Earth science - % oxygen minilab

Finding the Percentage of Oxygen in the Atmosphere
Background Information
The atmosphere of the earth is composed of a mixture of gases. The two most abundant gases are nitrogen and oxygen. Oxygen also appears in the earth's crust combined with other elements to form minerals.
In this investigation, you will study how much of the air is consumed during combustion. By measuring volume, you will be able to determine the percentage of oxygen in the air.


      What is the percentage of oxygen in the air?
Hypothesis- see board
Test- see board
Materials (per group)

Tealite  candle
400-mL plastic beaker
Flame source- from instructor
Glass-marking pencil
Large Petri dish
Paper towels
Safety goggles + aprons

      Wire or wood dowel                                                       Glass jar

Procedure- See diagram on board and  set up from Demo

1.    Using the formula for a cylinder (eR2H) measure the volume of cylinder using a ruler and metric units and record it in the Data Table. The volume is also the volume of air in the jar at the start of the experiment.

2.      Pour the water into the Petri dish. Carefully place the candle in the center of the dish. Fill dish until the candle floats but leave space so as NOT to overflow the dish when you place the jar over the candle.

3.      Carefully light the candle, and invert the jar over the lighted candle. Make sure that jar rests on the piece of wire or wood so as not to form an airtight seal with the bottom of the Petri dish. See Demo

4.      As the candle uses the oxygen in the test tube, the candle will go out and water will be drawn into the Jar to replace the oxygen.

5.      When the candle goes out, carefully mark the level of the water on the jar with the glass-marking pencil. Remove the jar and find the height of the water, using cm.  Calculate the volume of Water( this is also the volume of used up Oxygen) using (eR2H) with the new value of H and record in your data table.

6.      Dry out your jar and dry off the candle and repeat the process for two more trials.

7.      Determine the percentage of oxygen in air by using the formula below. Record this percentage in the Data Table.


% oxygen in air =
Volume of oxygen in the test tube
 X 100
Total volume of air in test tube at start


Observations DATA TABLE                                                      trial 1                trial 2                trial 3

Volume of Air in the jar at Start
Volume of water in jar Tube After Candle Goes Out
Volume of Oxygen (should be same as above)
Percentage of Oxygen in Air



1.      Would the same result for the percentage of oxygen in air be obtained if a larger test tube was used? A larger candle?

2.      Why does the water rise in the test tube as the candle goes out?

3.      Nitrogen is the other major component of air (78.1%). What property of nitrogen have you discovered as a result of this experiment?

4.      How much oxygen is present in 5 L of air?


Critical Thinking and Application

1.      Why is oxygen such an important part of the earth's atmosphere?

2.      Based on your observations, what is an effective method of putting out a small fire?

3.      "As the altitude of an area increases, the density of the atmosphere decreases." How can this statement be used to explain why it is more difficult to breathe in Denver, which has an altitude of more than 1500 meters, than in Houston, which is at sea level?