by, Kaya Zepeda, Joselyne Soto, Greg Maginn, Sebastian Hickey, and Chase Lewis

To what extent will the extreme temperature of liquid nitrogen affect different plant organisms weight and physical aspects?

If the plants are exposed to the extreme temperature of liquid nitrogen then the water within the plant’s stems and leaves will freeze and drastically slow down the photosynthetic rate because enzymes will no longer function resulting in a physical deterioration of the plant such as petal and leaf wilting.

 Independent variable: Change in temperature (liquid nitrogen can be between Celsius and Celsius)  Dependent variables: Weight difference from before exposure, initial exposure, and two hours after exposure Change in physical characteristics  Controlled variables: Type of plant Amount of liquid nitrogen poured over each plant Amount of time exposed to liquid nitrogen Scale and type of measurement (grams and centimeters) Amount of time spent in sunlight after liquid nitrogen exposure Same liquid nitrogen (same temperature)

1. Gather three plants of three different types. 2. Measure each of the plants weight in grams and record physical characteristics. 3. Put each of the plants in a high aluminum basin. 4. Pour the liquid nitrogen on the plants for one minute (3 liters). 5. Wait until all the liquid nitrogen has fully evaporated before handling the plants (this may take various minutes). 6. Remove the plants from the basin and measure the weight of each plant in grams. 7. Leave plants in direct sunlight for two hours. 8. Return after the two hours is up and record any changes that have occurred such as weight and physical characteristics.

Premium Tropical Foliage Exposure Plant #1 weight Plant #2 weight Plant #3 weight Average weight Before Exposure +/- 323 gm +/- 269 gm +/-312 gm +/-301 gm After Initial Exposure +/-349 gm +/-298 gm +/-329 gm +/-325 gm Two Hours After Exposure +/-326 gm +/-278 gm +/-318 gm +/-307 gm

Red and Yellow Daisies Exposure Plant #1 weight Plant #2 weight Plant #3 weight Average weight Before Exposure +/-266 gm +/-272 gm +/-238 gm +/-259 gm After Initial Exposure +/-286 gm +/-306 gm +/-261 gm +/-284 gm 2 Hours After Exposure +/-278 gm +/-280 gm +/-241 gm +/-266 gm

Sheet Moss Balls Exposure Plant #1 weight Plant #2 weight Plant #3 weight Average Weight Before Exposure +/ gm After Initial Exposure +/ gm Two Hours After Exposure +/ gm

Our data supports the original hypothesis that if a plant is exposed to an extreme cold temperature of liquid nitrogen then the photosynthetic rate will drastically decrease due to various losses of function. For instance, the liquid nitrogen was able to denature enzymes, they lose their shape and therefore function, as well as freeze the water on the plant which caused the transpiration pull to come to a stop resulting in weakening of the plant. The decrease in photosynthetic rate was observed through the quick depreciation of the plant. The liquid nitrogen was successful in finalizing the photosynthesis process, killing the plant.

How do low temperatures affect electron flow in a material?

LEDs

In an LED light,  Electrons flow between an anode and a cathode with a certain energy called a band-gap.  The distance that the electrons travel dictates the color of the light

If LED lights of different colors are placed in liquid nitrogen, their colors will move down the spectrum because the low temperature will make it so that more electron flow is required to traverse the band-gap, which will require a shorter wavelength. ←

 Independent: The temperature of the LEDs  Dependent: The color of the lights  Constant: Liquid Nitrogen, copper wire, the battery voltage, sample of liquid nitrogen, safety materials.

1.Create circuit for light 2.Take note of color 3.Place LED in liquid nitrogen 4.Remove from liquid nitrogen and take note of color 5.Build new circuit and repeat with other lights

White Light:

Red Light:

Yellow Light:

Green Light:

Violet Light:

↑ ↑ ↑ ↑ V2 V1 G2 G1 Y2 Y1 R2 R1 V:Violet G: Green Y: Yellow R: Red

WeaknessesImprovements Evaporation of liquid nitrogen We could have conducted all trials simultaneously Time of exposure to liquid nitrogen We could have measured time of exposure White and Violet Lights turned off We could have measured amps with an ohmmeter

Circuits

As the temperature of the circuit decreases, the current (flow of electrons) will increase.

 Dependent: Current  Independent: Temperature  Constant: Voltage, wire, & the ammeter

1.Create a copper circuit with a current of at least 3 amps. 2.Subject circuits to room temperature, freezer temperature, -50 °C, and the temperature of liquid nitrogen and measure the resistance.

Temperature (°C) Current (amps) Trial 1Trial 2Trial 3Average 20.7 ± ± ± ± ± ± ± ± ± ± ± ± *18.12 ± ± ± ± 0.01

WeaknessImprovement 1.As the current encountered resistance in the circuit, the wire itself heated up. 1.Calculate the amount of heat generated by the current and add that to the temperature recorded by the thermometer to get the actual temperature of the wire. 1.The data recorded with the ammeter fluctuated frequently. 2.At least 20 trials should have been performed during the experiment. 2.During the experiment, the temperature of the circuit was higher than the temperature of used in the calculations as the coil of copper wire was not submerged in the liquid, but rather had the N 2 (l) poured over it. 3.Pour a large amount of liquid nitrogen into a container with a large opening (enough so that it doesn’t evaporate too quickly), and then submerge the circuit in the N 2 (l) for at least 10 minutes.

What is the effect of cold temperatures on the electrical resistance of metals?

● Dependent: Resistance ● Independent: Temperature ● Constant: Voltage, wire, and the ohmmeter.

1.Find the voltage of the ohmmeter 2.Create steel and copper circuits with resistance of at least one ohm 3.Subject circuits to room temperature, freezer temperature, -50 °C, and the temperature of liquid nitrogen and measure the resistance.

Metal WireTemperature (°C)Voltage (volts) Resistance (ohms) Trial 1Trial 2Trial 3 Average Copper 20.7 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± *8.92 ± ± ± ±.01 Steel 20.7 ± ± ± ± ± ± ± ± ± ± ± ± ± ± *8.92 ± ± ± ± ±.01

 The experiment demonstrates that plants are incapable of surviving extreme temperatures.  Electron flow increases in cold temperatures. It has to increase to traverse the greater band-gap created by the lower temperature.  Lower resistance in the cold means greater current and less energy lost.

Now wasn’t that pretty cool