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

COLD(ER) THAN ICE?by, Kaya Zepeda, Joselyne Soto, Greg Maginn, Sebastian Hickey, and Chase

Lewis

BIOLOGY

Question:To what extent will the extreme

temperature of liquid nitrogen affect different plant organisms weight and

physical aspects?

Hypothesis: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.

Variables: Independent variable: Change in temperature (liquid nitrogen can be

between - 210 Celsius and -195.8 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)

Procedure: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.

Data Collection and Processing 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

Data Collection and Processing

Red and Yellow Daisies

Exposure Plant #1 weight

Plant #2weight

Plant #3weight

Averageweight

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

Data Collection and Processing

Sheet Moss Balls

Exposure Plant #1 weight

Plant #2weight

Plant #3weight

AverageWeight

Before Exposure +/- 56.7 gm

+/- 56.7 gm

+/- 56.7 gm

+/- 56.7 gm

After Initial Exposure

+/- 56.7 gm

+/- 56.7 gm

+/- 56.7 gm

+/- 56.7 gm

Two Hours After Exposure

+/- 56.7 gm

+/- 56.7 gm

+/- 56.7 gm

+/- 56.7 gm

Before Exposure

During Exposure

After Initial Exposure

Two Hours after Exposure

Conclusion:

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.

CHEMISTRY

Question How do low temperatures affect electron

flow in a material?

PART 1LEDs

BackgroundIn 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

HypothesisIf 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.

←

Variables 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.

Procedure1.Create circuit for light2.Take note of color3.Place LED in liquid nitrogen4.Remove from liquid nitrogen and take note of color5.Build new circuit and repeat with other lights

Data:White Light:

Red Light:

Yellow Light:

Green Light:

Violet Light:

Conclusion

↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑V2 V1 G2 G1 Y2 Y1 R2 R1

V:VioletG: GreenY: YellowR: Red

Error

Weaknesses Improvements

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

PART 2Circuits

Hypothesis

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

Variables Dependent: Current

Independent: Temperature

Constant: Voltage, wire, & the ammeter

Procedure

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.

Data

Temperature (°C)

Current (amps)

Trial 1 Trial 2 Trial 3 Average

20.7 ± 0.1 3.01 ± 0.01 3.00 ± 0.01 3.00 ± 0.01 3.00 ± 0.01

-11.5 ± 0.1 3.39 ± 0.01 3.40 ± 0.01 3.39 ± 0.01 3.39 ± 0.01

-49.5 ± 0.1 4.07 ± 0.01 4.05 ± 0.01 4.04 ± 0.01 4.05 ± 0.01

-195.8* 18.12 ± 0.01 18.18 ± 0.01 18.04 ± 0.01 18.11 ± 0.01

Data

-200 -150 -100 -50 0 500

2

4

6

8

10

12

14

16

18

20

Current vs Temperature

Temperature (°C)

Curr

ent

(Am

ps)

Conclusion As the temperature decreased, the

current of the wire increased exponentially.

Less frequent vibration of the atoms results in fewer collisions with the electrons running through the wire.

ErrorsWeakness Improvement

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 N2 (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 N2 (l) for

at least 10 minutes.

PHYSICS

QuestionWhat is the effect of cold temperatures on

the electrical resistance of metals?

HypothesisWhat is the effect of cold temperatures on

the electrical resistance of metals?

Variables● Dependent: Resistance

● Independent: Temperature

● Constant: Voltage, wire, and the ohmmeter.

Procedure1. Find the voltage of the ohmmeter2. Create steel and copper circuits with

resistance of at least one ohm3. Subject circuits to room temperature,

freezer temperature, -50 °C, and the temperature of liquid nitrogen and measure the resistance.

Data

Metal Wire Temperature (°C) Voltage (volts)Resistance (ohms)

Trial 1 Trial 2 Trial 3 Average

Copper

20.7 ± 0.1 8.92 ± 0.01 1.03 ± .01 1.03 ± .01 1.04 ± .011.03 ± .01

-11.5 ± 0.1 8.92 ± 0.01 0.87 ± .01 0.86 ± .01 0.87 ± .010.86 ± .01

-49.5 ± 0.1 8.92 ± 0.01 0.72 ± .01 0.70 ± .01 0.73 ± .010.72 ± .01

-195.8* 8.92 ± 0.01 0.16 ± .01 0.16 ± .01 0.13 ± .010.15 ± .01

Steel

20.7 ± 0.1 8.92 ± 0.01 1.01 ± .01 1.00 ± .01 1.01 ± .011.01 ± .01

-11.5 ± 0.1 8.92 ± 0.01 0.90 ± .01 0.90 ± .01 0.90 ± .010.90 ± .01

-49.5 ± 0.1 8.92 ± 0.01 0.78 ± .01 0.79 ± .01 0.77 ± .010.78 ± .01

-195.8* 8.92 ± 0.01 0.35 ± .01 0.33 ± .01 0.36 ± .010.35 ± .01

Data

-200 -150 -100 -50 0 500

0.2

0.4

0.6

0.8

1

1.2

Temperature vs Resistance

CopperSteel

Temperature (°C)

Resis

tance (

ohm

s)

Conclusion As the temperature decreased, the

resistance of the wires diminished linearly.

Environmental Connection 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.

THE ENDNow wasn’t that pretty cool