BIOL134

Directions to Pair Go Direct Gas Pressure Sensor by Bluetooth to Mobile Device

You do not need the “Pro” version for this assignment, you only need the free version

To connect Go Direct Gas Pressure Sensor by Bluetooth to mobile device (this is shown using an

iPhone. Other phones may have slightly different views):

1. Download Vernier Graphical Analysis app from your phone’s App store or Play store. It

looks like this:

2. Turn on sensor by pressing power button on front: (may need to charge sensor first)

3. Launch Graphical Analysis App

a. Click Sensor Data Collection

b. Click Connect

c. Click Done

Directions to Connect Go Direct Gas Pressure Sensor by USB to Computer

You do not need the “Pro” version for this assignment, you only need the free version

1. Download and Install Vernier Graphical Analysis on your computer or Chromebook.

a. http://www.vernier.com/downloads/graphical-analysis/

b. Follow your computer’s prompts to download and Install the Graphical Analysis

software to your computer. Click Finish once download is complete.

2. Connect one end of the provided USB cable to the Go Direct Sensor directly (shown with

yellow star, below), and connect the other end (the USB plug) into your computer’s USB

port.

3. Once connected, open Graphical Analysis (if not already open after the download)

Experimental Design Sheet

1. Background research with in text citations and references in APA format (50 pts):

2. Variables (10pts):

· Independent Variable:

· Dependent Variable:

· Constants:

· Control:

3 . Title (5pts):

4. Testable Question(5pts):

5. Hypothesis(5pts):

6. Methods(20 pts):

7. Data Table (5 pts):

{Insert name of Independent Variable} (units)	{Insert name of Dependent Variable} (units)	Average {insert Dependent Variable name}(units)
	Trial 1 *	Trial 2 *	Trial 3*
Control
{Insert Treatment1}	DO NOT	INCLUDE	DATA
{Insert name of Treatment 2}	DO NOT	INCLUDE	DATA
{Insert name of Treatment 3}	DO NOT	INCLUDE	DATA

Biology with Vernier © Vernier Software & Technology 1

Graphical Analysis 10

Transpiration

Water is transported in plants from the roots to the leaves, following a decreasing water potential

gradient. Transpiration, or loss of water from the leaves, helps to create a lower osmotic

potential in the leaf. The resulting transpirational pull is responsible for the movement of water

from the xylem to the mesophyll cells into the air spaces in the leaves. The rate of evaporation of

water from the air spaces of the leaf to the outside air depends on the water potential gradient

between the leaf and the outside air.

Various environmental factors, including those conditions which directly influence the opening

and closing of the stomata, will affect a plant’s transpiration rate. This experiment will measure

transpiration rates under different conditions of light, humidity, temperature, and air movement.

The data will be collected by measuring pressure changes as the plant takes up water into the

stem.

OBJECTIVES

• Observe how transpiration relates to the overall process of water transport in plants.

• Use a Gas Pressure Sensor to measure the rate of transpiration.

• Determine the effect of light intensity, humidity, wind, and temperature on the rate of

transpiration of a plant cutting.

Figure 1

Transpiration

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MATERIALS

Required:

Items with * are provided with your Vernier order, from the APUS Vernier Store, or

available for free download

Chromebook, computer, or mobile device

Graphical Analysis app*

Go Direct Gas Pressure*

plastic tubing with Luer-lock fitting*

2-way valve*

plastic syringe*

one plastic tubing clamp*

razor blade or scalpel

metric ruler

plant cuttings (preferably with woody stem)

goggles

Highly recommended:

If you are on base, or don’t have access to these items you may need to get creative with your

setup.

two utility clamps

ring stand

Depending on variable you choose to measure you may need 1 or more of the following:

desk lamp and100 watt (or equivalent) light bulb (if testing light)

plastic gallon size bag with twist tie (if testing humidity)

heater, small electric (if testing temperature)

fan with slow speed (if testing air flow)

spray bottle (if testing moisture)

Transpiration

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PROCEDURE

This video from Vernier can be a helpful resource.

https://youtu.be/oeah4AMH5sU

Please note, this video uses the old gas pressure sensor. You will instead be using the Go Direct

sensor.

Therefore, when he attaches the sensor to the LabQuest 2 device (at 5:08) you will either be (a)

connecting the Go Direct sensor to your computer by USB or (b) connecting the Go Direct

sensor by Bluetooth to your mobile device.

Please see the separate document “Connecting Go Direct Gas Pressure Sensor by Bluetooth to

Mobile Device” or read the instructions included with your go direct sensor if you need help

connecting.

1. Position the ring stand, utility clamps, and Gas Pressure Sensor as shown in Figure 1.

2. Prepare the plastic tubing.

a. Obtain a piece of plastic tubing with a 2-way valve on one end

and no connector on the other end.

b. Using a fine-tip permanent marker, make a mark on the plastic

tubing at a point 1 cm below the white plastic connector.

c. Draw some water into the syringe and connect it to the open end

of the plastic tubing.

d. Confirm the 2-way valve is in the open position and depress the

plunger of the syringe to fill the tube.

e. Tap the tubing, if needed, to expel any air bubbles that form inside. Close the 2-way

valve.

f. Bend the tubing into a U shape with both ends up. Remove the syringe, leaving the tubing

full of water.

g. Slip a plastic tubing clamp onto the tubing as shown in Figure 2.

3. Select a woody-stemmed plant with a stem roughly the same diameter or slightly larger than

the opening of the plastic tubing. Using a scalpel or razor blade, carefully make a fresh cut at

a 45° angle.

Figure 2

Transpiration

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4. Connect the plant to the tubing.

a. Open the 2-way valve. Raise the end of the tubing with

the 2-way valve until the water level at that end is about

1 cm below the 1 cm mark and water completely fills the other end.

b. Carefully push the cut stem of the plant down into the end of the tubing that is completely

filled with water. Note: Be careful not to allow any air bubbles to form between the cut

portion of the stem and the water in the tube.

c. Push the plant about 1 cm into the tubing without damaging the plant. If the stem is too

large for the tubing, cut the stem at a higher point where it is smaller.

d. Squeeze the tubing clamp tight around the stem as shown in Figure 3.

5. When the tubing clamp is shut tight, invert your plant cutting to check for any leaks. If water

does leak out, turn the plant right-side up and try tightening the clamp further. Important:

Be sure the tubing is filled completely with water. The water column must be flush with the

stem. There should be no air visible at the base of the stem. If water moves down the tube

away from the stem after it has been inserted, check for a leak in the system.

6. Connect the plastic tubing to the sensor valve. Caution: Do not allow water to enter the

valve of the Gas Pressure Sensor.

7. Secure the plant in an upright position with the utility clamps as shown in Figure 1. It should

be positioned so that the cut stem is below the water level at the other end of the tubing.

8. Place a mark on the tube at the starting water level to allow you to refill the tube to the proper

level when you repeat data collection.

9. Place your plant setup in an area where the wind, humidity, and temperature are reasonably

constant. This will be your control setup.

10. Launch Graphical Analysis. Connect the Gas Pressure Sensor to your Chromebook,

computer, or mobile device.

11. Set up the data-collection mode.

a. Click or tap Mode to open Data Collection Settings.

b. Change End Collection to 15 min and rate to 4 samples/min. Click or tap Done.

12. Check the base of the plant stem in the water tube to make sure that no air bubbles or air

pockets have formed that will prevent the plant from taking up water. If an air pocket has

formed, refit the plant in the tubing before initiating data collection.

13. Start data collection.

14. When data collection has stopped, perform a linear regression to calculate the rate of

transpiration.

a. Select the data in the most linear region of the graph.

b. Click or tap Graph Tools, , and choose Apply Curve Fit.

Figure 3

Transpiration

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c. Select Linear as the curve fit. Click or tap Apply.

d. Enter the absolute value of the slope, m, as the rate of transpiration in Table 1.

e. Dismiss the Curve Fit Box.

15. Design an experiment of your choice to simulate one of the following environmental

conditions:

• the effect of light intensity

• the effect of the wind blowing on the plant

• the effect of humidity

• the effect of temperature (will need to purchase the optional temperature probe

separately from the Vernier website) APUS Vernier Store

• the effect of another self-identified environmental variable

Additional items may be needed based on chosen experimental variable:

• desk lamp and100 watt (or equivalent) light bulb (if testing light)

• plastic gallon size bag with twist tie (if testing humidity)

• heater, small electric (if testing temperature)

• fan with slow speed (if testing air flow)

• spray bottle (if testing moisture)

Be sure to address the following questions in your design:

• What is the essential question being addressed?

• What assumptions are made about the system being measured?

• Can those assumptions be easily verified?

• Will the measurements provide the necessary data to answer the question under study?

16. After checking your procedure with your teacher, obtain the materials needed for the

experiment and perform the tests. Record your values in Table 1.

PROCESSING THE DATA

1. Identify the environmental condition you tested in the blank provided in Table 1.

2. Determine the surface area of all the leaves on your plant cutting by the following method:

a. Cut all the leaves (not stems) off your plant and determine their mass using a balance.

b. Estimate the total leaf surface area in cm2 for your plant by cutting out a section of leaf

5 cm × 5 cm.

c. Determine the mass for this leaf section and divide by 25 cm2 to find the mass of l cm2 of

leaf.

d. Divide the total mass of the leaves by the mass of l cm2 to find the total leaf surface area.

e. Record the calculated surface area in Table 1.

Transpiration

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3. Divide the slope by the surface area for each test and record in the rate/area column of

Table 1. These rate values should be expressed as kPa•min–1•cm–2.

4. Subtract the control (rate/area) value from the experimental value. Record this adjusted rate

in the last column of Table 1.

5. Record the adjusted rate for your experimental test on the board to share with the class.

Record the class results in Table 2 for each of the environmental conditions tested. If a

condition was tested by more than one group, take the average of the values and record in

Table 2.

6. Make a bar graph that shows the effect of different environmental conditions on the

transpiration of water in plant cuttings. Using the data in Table 2 plot the adjusted rate for

each test on the y-axis and the test label on the x-axis.

DATA (FOR YOUR RECORDS)

Table 1

Experiment Slope

(kPa/min)

Surface area

(cm2)

Rate/area

(kPa•min–1•cm–2)

Adjusted rate

(kPa•min–1•cm–2)

Control

Experimental ______________

Table 2 Class Data

Variable Adjusted rate

(kPa•min–1•cm–2)

Light

Humidity

Wind

Temperature

QUESTIONS TO CONSIDER

1. How was the rate of transpiration affected in each of the experimental situations as compared

to the control?

2. Which variable resulted in the greatest rate of water loss? Explain why this factor might

increase water loss when compared to the others.

Transpiration

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3. What adaptations enable plants to increase or decrease water loss? How might each affect

transpiration?