152-Disc_Gilroy4_Assign-2024sp

docx

School

University of Wisconsin, Madison *

*We aren’t endorsed by this school

Course

152

Subject

Biology

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by DeaconDinosaur4111

Intro Bio 152 – Discussion assignment for week of February 19 th Water potential 1. You have a small, flaccid, living plant cell. You put this cell into a large open beaker of distilled water and allow it to reach equilibrium. HINTS: The beaker is much, much, much larger than the plant cell. Since it is distilled water, that means there are no solutes in it. Finally, the pressure potential of an open beaker of water is 0. a. In reaching equilibrium, would water move into the cell, move out of the cell, or can you not answer this question without more information? Explain your answer. Because the solute potential and pressure potential are at 0 pascals, and the water contains no solutes, the water will move into the cell to attempt to achieve equilibrium. b. After reaching equilibrium, what would be that cell’s water potential (Ψ)? After reaching equilibrium, since the water potential of the open beaker is 0 pascals, the cell’s water potential will remain 0. c. After reaching equilibrium, would that cell be plasmolysed, flaccid, or turgid? After reaching equilibrium, the cell will be turgid because the water enters the cell which increases the cells water pressure and volume. 2. The following question is about a different cell from the one above. You drop a root hair cell (Ψ s = -1.4 and Ψ p = 0.7) into a very large open beaker containing a solution with Ψ S = -0.4. HINT: Like in the previous question, the beaker is much, much, much larger than the root hair cell of the plant. a. When the root hair cell equilibrates, what will be its resulting overall Ψ? When the root hair cell equilibrates, the resulting Ψ will be -0.4 pascals. b. Will Ψ S of the cell become more positive or more negative ? The Ψ of the cell will become more negative because the water potential in the beaker (-0.4) is higher than the water potential in the cell (-0.7) therefore water will move out the cell into the solute. c. Will Ψ P of the cell become more positive or more negative? d. What will the effect be on the root hair cell (e.g., flaccid, plasmolyzed, etc.)? Bulk flow 3. Fill in the following table regarding bulk flow in plants Vascular tissue type Type of pressure (positive or negative) responsible for bulk flow in that tissue What this type of bulk flow is called How these forces are generated in the plant Xylem Negative pressure Transpiration stream Transpiration creates a negative pressure that carries water through the roots to the xylem vessels. Phloem Positive pressure Pressure flow Pressure flow is driven by pressure gradients Page 1 of 5

through loading sugars, uptake of water, unloading of sugar, and recycling of water. Difference in pressure potential between source and sink allows for bulk movement of sugar. 4. If xylem cells are dead when functional, why must phloem cells be alive when functional? Phloem cells need to be alive for the stems from the active, energy dependent, and nutrient transport in plant. While the passive physical process driving water and mineral transport in the xylem doesn’t require cells to be alive. For questions 5-8, model the processes the questions ask about. Draw them in a way that will help you learn them – do NOT just copy figures from the text or lecture. If your drawings require short explanations in order for someone else to understand them, provide those explanations (but please don’t write a lot – this should be a figure, not a textbook). During discussion this week, you might demonstrate one of these to the rest of the class, so be sure you’re comfortable with the answers. 5. How does water move from the soil into a plant’s vasculature system? In your model and explanation, make sure you address the following questions: What is the Casparian strip? Why is it important? How does it allow selectivity of substances entering the plant via the roots? What is the symplastic route? The apoplastic route?  The casparian strip is in the endodermis, acting as a barrier to the apoplastic route, forcing water and dissolved substances into the symplastic route for selective entry into the plant’s vascular system. Water proofing. Page 2 of 5

6. How are photosynthates (i.e., the products of photosynthesis – sugars) loaded into sieve tubes? In your model and explanation, make sure you address the following questions: Where is this occurring? Why does this process take energy? What is the mechanism that brings the sugars in? This is occurring in the leaf. The reason why this process takes energy is because active transport is needed to move the sugars against their concentration gradient into the sieve tubes which requires energy. Sugars are actively transported into sieve tubes via companion cells. 7. Model the translocation of photosynthates (i.e., the products of photosynthesis – sugars) through sieve tubes and their eventual movement into sinks. In developing your model and explanation, make sure you address the following questions: What force moves the phloem sap through a sieve tube? How is this force generated? Does phloem sap always move upward through the plant? Downward? Once at a sink, how does the sugar leave the sieve tube? The force is the pressure gradient between the source known as the pressure flow. This pressure is generated by active transport of sugars into the sieve tubes at the source, which raises the pressure that drives the flow towards sinks. Phloem can move both upward and downward. At the sink, sugars are transported out of the sieve tubes. Page 3 of 5

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

8. How does a plant control transpiration? In your model and explanation, make sure you address the following questions: Which part of the leaf can the plant regulate to control transpiration? How does it do this? In a leaf, the stomata, tiny openings on the leaf surface controlled by guard cells, are important. Plants open and close their stomata to regulate transpiration. When guard cells are turgid, they open the stomata. When they are flaccid, they close the stomata, thus controlling water loss and gas exchange with the environment. 9. Which concept or process this week do you feel the most comfortable with? Which do you feel the least comfortable with? Why? I feel most comfortable with plant transpiration since that was the easiest to learn during lecture. I’m least comfortable with number 7 since the process is confusing. 10. What is your plan and/or schedule for studying for the upcoming exam? Making a quizlet and use the concepts and terminology from the LLO’s. Additional practice questions – answer these if you want to challenge yourself 11. We asked ChatGPT* to describe 3 differences between transpiration and translocation. Here is what it generated. Unfortunately, two of the answers are only partially correct . For each of the points in its answer (a-c), is ChatGPT correct or only partially correct? Write Correct or Partially correct next to each of these. If a statement is Partially correct , underline the part of the answer that is incorrect or incomplete, and write a short sentence explaining what makes it so. Page 4 of 5

ChatGPT’s answer: Transpiration and translocation are two different processes that occur in plants and involve the movement of water, nutrients, and other substances within the plant. Here are three key differences between the two: a. Purpose: Transpiration is the loss of water from the leaves of a plant. It plays a role in pulling water and dissolved minerals from the roots to the rest of the plant. Translocation, on the other hand, is the movement of soluble nutrients and sugars from the leaves to the roots. Partially correct because the movement of soluble nutrients and sugars is in the entire plant which includes flowers, stem, fruits and seeds. b. Substance Moved: Transpiration involves the movement of water, whereas translocation involves the movement of sugar, but not water. Partially correct because translocation involves the movement of sugar but also some amino acids. c. Transpiration is a passive process that is driven by the difference in water potential between the soil and the atmosphere, and it requires no energy input from the plant. On the other hand, during translocation, when sugars move across the cell membrane into the sieve tube, it requires cellular energy input from the plant. Correct. 12. Consider a transpiring plant and remember how water moves from the soil to the leaves. For each pair below, circle the structure that would have the lower (i.e., more negative) water potential (Ψ). If both structures in a pair would have an equal water potential, or you do not have enough information to answer, circle both. All questions refer to a transpiring plant. Location 1 Location 2 Pair 1 In the root hair In the soil outside the root Pair 2 In the root hair Inside the xylem of the shoot Pair 3 In a leaf In the xylem of the shoot Pair 4 In the surrounding air In a leaf Page 5 of 5

Related Documents

152-Tropisms1_PrelabWkst-sp24.docx

Water & Nutrient Transport in Plants TLN.pdf

152-Lab_IP2_PrelabWksht-sp24.docx

152-WQ1_PrelabWksht-sp24.docx

Copy of Exam 1 Spring 2013.docx

152-Disc_Gilroy3_Assign-2024sp.docx

152-Disc_Baum5_Assign-2024sp.docx

BioExam 1 Spring 2016 Key and Average.docx(3).docx

Assignment Print View.pdf

Pre-Lab 2 (Part 1) Homework - 2023 Fall Introduction to Cell and Molecular Biology Laboratory (BIOL-

BIO1802_Ex 2 DLN_Spring2024.pdf

ethics final exam.docx

Recommended textbooks for you

Biology 2e

Biology

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:OpenStax

Biology: The Dynamic Science (MindTap Course List)

Biology

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Cengage Learning

Principles Of Pharmacology Med Assist

Biology

ISBN:9781337512442

Author:RICE

Publisher:Cengage

Biology (MindTap Course List)

Biology

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Cengage Learning

Biology: The Unity and Diversity of Life (MindTap...

Biology

ISBN:9781337408332

Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Publisher:Cengage Learning

Aquaculture Science

Biology

ISBN:9781133558347

Author:Parker

Publisher:Cengage

SEE MORE TEXTBOOKS

Recommended textbooks for you

Biology 2e
Biology
ISBN:9781947172517
Author:Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:OpenStax
Biology: The Dynamic Science (MindTap Course List)
Biology
ISBN:9781305389892
Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher:Cengage Learning
Principles Of Pharmacology Med Assist
Biology
ISBN:9781337512442
Author:RICE
Publisher:Cengage
Biology (MindTap Course List)
Biology
ISBN:9781337392938
Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg
Publisher:Cengage Learning
Biology: The Unity and Diversity of Life (MindTap...
Biology
ISBN:9781337408332
Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr
Publisher:Cengage Learning
Aquaculture Science
Biology
ISBN:9781133558347
Author:Parker
Publisher:Cengage