Water & Nutrient Transport in Plants TLN

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College of Charleston *

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Apr 3, 2024

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Water & Nutrient Transport in Plants Team Lab Notebook (TLN) During lab this semester you will be working in small teams to complete each lab. To facilitate this, each team member will take on different role(s) during the lab. These roles are: 1) Computer operator – operates the LoggerPro software, and is the TLN recorder. 2) Experimenter – sets up experiment, operates experimental equipment, constructs experimental cells (on teams of four, 2 people should be assigned to this role). 3) Data & Research Specialist – this person keeps a separate data notebook; records data in MS Excel; constructs graphs; performs the statistical analyses; records ideas/research related to experiment conclusions. These roles should rotate throughout the semester! All members of the team should be consulting the lab manual throughout the entire lab for more specific guidance on today’s lab exploration. Team Name: Mitochondrihoes Team Members Present: Katherine Hale, Cameryn Freeman, Jackson Griffith Date: Activity 1. Revisiting the homework questions 1) How do very tall plants (like trees) transport water all the way to the leaves despite the high pressures needed to do this? (2) Very tall plants are able to utilize capillary action to transport water up the xylem against gravity. 2) Do plants create a positive pressure, which pushes water up the xylem from below, or do they generate a negative pressure (tension), which sucks water up the xylem from above? Briefly describe how plants generate this pressure or tension. (2) Plants create a negative pressure, tension, to pull water up the xylem. The tension is generated by the process of transpiration, where water evaporates from leaves and created a negative pressure gradient within the xylem that pulls the water through the plant’s vascular system. 3) Does the plant expend any energy (ATP) to do this once water has entered the roots? Explain. (2) The generation of pressure or tension in the xylem involves passive processes that do not directly require energy (ATP) once water has entered the roots. The main driving forces behind the movement of water in the xylem are physical and biochemical processes that occur naturally, such as osmosis, root uptake, root pressure, and transpiration-driven tension. 4) Why is it necessary for a plant to transport water from the roots to the leaves? (1)

Plants need to transport water from the roots to the leaves because the leaves are the primary site for photosynthesis. One of the reactants necessary to start the photosynthetic reaction is water, along with carbon dioxide. If the plant did not transport water from the roots to the leaves, then the leaves would be unable to perform photosynthesis and the plant would have no energy since there is no glucose to start cellular respiration. 5) What plant tissues are involved in this transport process? (1) The vascular tissues of the plant are involved in the transport process (xylem and phloem). Activity 2. Measuring the Pressure Generated through Leaf Transpiration (3) 1. In what way do you expect the pressure recorded by the sensor to change and why? Consider the following as you generate your team’s predictions: a. Will the pressure increase, decrease or stay constant over time? b. Will the rate of change in pressure stay fairly constant, or do you expect it to change over the course of the experiment? c. Briefly explain why the pressure would change in the way you predict? a) The pressure will increase. b) The rate of change in pressure will slow down over the course of the experiment. c) The pressure will increase because without a root system, the plant will not be able to use the xylem for water transport, and will have to rely on capillary action against gravity. The rate of change in pressure will slow down because as the leaf transpires, there will be less water to bring up, therefore slowing the process. Control Trial Data (4) – While the control trial data is being collected, complete Activity 3 below. Then come back and record the control data below and in the class data spreadsheet on the teaching computer. Team Data Table Plant Species Regression line equation Rate of pressure change (kPa/sec) 1 Leaf Surface Area (cm 2 ) Rate per unit surface area (kPa/sec/cm 2 ) Ferns y=-0.01147x+102.4 -0.01147 690.83 cm 2 -1.66*10 -5 1 Refer to the Activity 2 – Recording Data section in the lab manual, which provides a method for determining the surface area of your leaves.

2. Compare what occurred in the control trial to what you predicted in Activity 2: Question #1 above. If the findings from the control trial differed from your initial predictions/explanations, describe how they are different. Revisit the homework textbook reading, and try to explain why the pressure changed as it did in the experiment. Check your understanding with your instructor before proceeding. Contradictory to our prediction, the pressure decreased, and the rate of change was relatively constant. The pressure decreased because the loss of water in the plant through evaporation reduces the pressure of the liquid water in the leaf. Activity 3. What Environmental factors can influence the water transport in plants? (10) Environmental Factor Effect on leaf transpiration & water transport & stem pressure Justification for hypothesis & prediction using your understanding of water transport mechanisms in plants. Amount of Sunlight Hypothesized effect on transpiration/ water transport: Higher light intensity levels will result in greater transpiration rates An increase in sunlight will result in an increase in transpiration because plants open their stomata in response to light, allowing water vapor to escape from the leaves. Predicted effect on stem pressure relative to the control trial: Greater transpiration rates will result in lower stem pressure Climate (Dry vs Humid) Hypothesized effect on transpiration/ water transport: As the temperature rises, the water evaporates faster, so plants sweat faster at higher temperatures . Higher temperatures cause the plant cells which control the stoma where water is released to the atmosphere to open, whereas colder temperatures cause the openings to close . Predicted effect on stem pressure relative to the control trial: Greater transpiration rates will result in lower stem pressure Amount of Wind in Area Hypothesized effect on transpiration/ water transport: Increased movement of the air around a plant will result in a higher transpiration rate. An increase in wind speed increases the rate of transpiration as water molecules are moved away from the leaf faster. Predicted effect on stem pressure relative to the control trial: Greater transpiration rates will result in lower stem pressure

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What factor did your group choose to test? Indicate also which team you are pairing with on this experiment. We chose to test the amount of sunlight. Discuss some plants (or groups of plants) that are affected by that factor in nature. (2) Plants in rainforests are usually subject to less sunlight as a result of the tree canopies. Hypothesis: Reach consensus with the team you paired with on how the factor you chose would influence transpiration and water transport, and why. (5) If you increase the amount of sunlight, then the rate of water transport will be faster. Experimental Prediction: Reach consensus on the predicted effect of the factor you are manipulating on stem pressure. Explain your prediction (5): We predict that with an increased amount of sunlight, the rate of water transport will be faster, and our graph will show a steeper negative slope because of the more drastic difference in pressure throughout the experimental period. Experimental design (see list of considerations in the lab manual) (10): Our experiment will replicate the control in all factors except distance to lamp; in the experimental procedure, the plant will be closer to the lamp to simulate increased exposure to sunlight. Activity 4: Run the experiment, and summarize/analyze the data (15) Upload a copy of your actual MS Excel spreadsheet data to the TLN OAKS dropbox for this lab. It should include your descriptive statistics calculations, and graph/table summarizing your data for both your experimental and the class control data. If you choose to summarize your data graphically, copy and paste an image (jpeg file) of it below. (Some hints : You can copy and paste your graph into the table below. When you do this it is best to paste it an image file (i.e. .jpeg), then drag the corners to resize the image. This will prevent you from losing any formatting you did in MS Excel.) TeamData Summary Graph or Table Plant Species Regression line equation Rate of pressure change (kPa/sec) 1 Leaf Surface Area (cm 2 ) Rate per unit surface area (kPa/sec/cm 2 )

Ferns y=-0.007705x+105 -0.007705 690.83 cm 2 -1.12*10 -5 Inferential Statistics - Record your null (H o ) and alternative (H a ) hypotheses, the type of statistical analysis you performed, and the results of that analysis. Also indicate your conclusions regarding the null hypothesis (fail to reject or reject) and what this means in the context of your experimental hypothesis and prediction. (10) H o : The amount of sunlight will have no effect on the rate of pressure change. H a : The amount of sunlight will cause the rate of pressure change to more rapidly decrease in comparison to the control. Statistical Analysis: Two Sample Assuming Equal Variances to compare our control data with our experimental. Results: p-value: 0.09, t-stat: 2.23 Conclusion: We fail to reject the null hypothesis because the p-value is greater than 0.05. Activity 6. Team Conclusions: Consult the lab manual for guidance on your conclusions. Consult with your instructor if time is short and you require additional time to complete your conclusions. Copy and paste your final conclusions in the space below. ( Note: It is recommended that you use a Google Doc to write the conclusions, allowing all team members to offer editorial suggestions after one team member writes the conclusions from an agreed upon outline. Please share the link to the Google Doc with your instructor at the end of the conclusions .) (20)

Team Conclusion Water Transpiration in Plants Today in lab, we explored water and nutrient transport in plants and how the physical and chemical properties of water and transport tissues would affect the rate of transpiration. The control experiment we ran consisted of a fern clipping at the bottom of the stand, far from the lamp. We ran this trial for 5 minutes, collecting data every second. We measured the rate of pressure change using a pressure sensor to be -0.01147kPa/sec. Using this value, along with the leaves’ surface area, we were able to calculate the rate per unit surface area to be -1.66E-5kPa/sec/cm 2 . My group and our partner’s group (7 and 8) investigated how the amount of sunlight would affect the rate of pressure change in the plant’s stem. We hypothesized that an increased amount of sunlight would cause the rate of pressure change to be more negative in comparison to the control. Our reasoning for this hypothesis was that with more sunlight, there would be more transpiration since plants would open their stomata and allow the water vapor to escape from the leaves into the atmosphere. Our results and t-test analysis confirmed that our data was insignificant in proving the amount of sunlight would affect the rate of pressure change in the plant’s stem since our p-value was greater than 0.05 at 0.09. A source of error in this experiment could have been the amount of trials conducted, as well as discrepancies due to using artificial light instead of actual sunlight. If we were to run this trial again, we would perform more trials to ensure the accuracy of our hypothesis. In an article from StudySmarterUK, increased light intensity will generally result in greater transpiration rates. This contradicts the data we found for our experiment. Our data shows that there is no statistical significance

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between the amount of sunlight and the rate of transpiration in plants. Our data may not be consistent with the StudySmarterUK article since there were so few trials. References Factors Affecting Transpiration: Internal | StudySmarter. (n.d.). StudySmarter UK. Retrieved February 14, 2024, from https://www.studysmarter.co.uk/explanations/combined-science/synergy/factors-affe cting -transpiration/#:~:text=External%20Factors%20Affecting%20Transpiration,-There %20ar e%20several&text=Light%20intensity%20%2D%20higher%20light%20intensity,to % The following rubric will be used by your instructor to grade your conclusions. Criteria Exceeds Standard Meets Standard Partially Meets Standard Does not meet standard 5 points 4 points 3 points 0-2 points Explanation s of Results Insightful use of biological knowledge/concepts to explain the results. Adequate use of biological knowledge/concepts to explain the experiment's results. Biological knowledge/concepts were used to explain the results but some misconceptions are clearly present. Little to no attempt to explain the results. Experiment al Limitations Presents limitations or flaws in the experimental design Insightful suggestions for improving or extending the experiment are clearly presented. Presents the limitations or flaws in the experimental design. Adequate suggestions for improving or extending the experiment are presented. Limitations or flaws in the experimental design presented are not significant. Suggestions for improving or extending the experiment are therefore not likely to be adequate. The author is unaware or does not address the limitations or flaws in the experimental design.

Background Biological Research Insightful and comprehensive outside research (textbook, articles) are used to better understand the results. Adequate outside research (textbook, articles) is used to better understand the results. Insufficient research is used or discussed. No or insufficient research was done or discussed. Writing Well-organized, clear, and concise. No grammar or spelling errors, sources properly cited in APA or CSE style formatting. Organization, clarity or concision could be better. No grammar or spelling errors, sources properly cited in APA or CSE style formatting. Organization, clarity or concision could be better. May be some minor grammar or spelling errors, or citations may not be complete or in an improper format. Poor organization of ideas. Writing is unclear, cumbersome. May be several or significant grammar or spelling errors or citations are incomplete or not provided. Homework Activity – Be sure to complete the homework activities described in your lab manual. After completing the checklist below, one member of the team should upload this TLN, along with your MS Excel data file to the Lab #4 TLN – Plant Water Transport OAKS Dropbox for grading. Make sure the names of all team members present in today’s lab are included on this TLN. Complete the cleanup checklist BEFORE you leave lab · All members of the team have a copy of this TLN. · Our work area is clean, and dry. · Our pressure sensors are neatly stored on the table, cords are untangled, and coiled neatly, but NOT wrapped around the probe. · Our lab table and stools are wiped down. · Trash is discarded. · Class common work area is clean and materials/instruments/specimens are returned to their proper place. · All members of the team completed and submitted a peer evaluation form. · Log off your computer, but leave it on. Your lab instructor must initial here, indicating that your work area is clean before you may leave the lab. Failure to clean up, or leave lab without your instructor’s initials, will result in 10 points deducted from this week’s TLN grade.

Water & Nutrient Transport in Plants TLN

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