TRANSPIRATION: Investigation 11
Learning Objectives:

To investigate the relationship among leaf surface area, number of stomata, and the rate of transpiration

To design and conduct an experiment to explore other factors, including different environmental variables, on the rate of transpiration

To investigate the relationship between the structure of vascular tissues (xylem and phloem) and their functions in transporting water and nutrients in plants
Before doing this laboratory you should understand: a)
How water moves from roots to leaves in terms of physical/chemical properties of water and the forces b) provided by differences in water potential
The role of transpiration in the transport of water within a plant c) The structures used by plants to transport water and regulate water movement
Before attempting to answer these questions READ the
PowerPoint
on my website, and then do the key concepts on the virtual lab:
Lab Bench Activity # 9
PreLab Total Points: 94 POINTS
1.
What is a ‘potometer?’ (1 point)
2.
Diagram and label a potometer (4 points)
3.
Why and how will you measure the area of leaves used? (2 points)
4.
Name three functions of transpiration. (3 points)
5.
How is the molecular structure of water significant to the transport of water in plants? (4 points)
6.
Explain the purpose of each of the following with regard to transpiration. (6 pts) a.
Cuticle: b.
Guard cells: c.
Leaf hairs:
7. When you receive a bouquet of flowers, it is recommended that you cut a couple of inches off of the stems before placing them in a vase. Why do you think this is? (4 points)
8. One of the following statements is not true. Decide with one is false and explain your answer. (4 points)
“The guard cells of non-desert plants often close during the daytime and open at night to conserve water.”
1

“The guard cells of desert plants often close during the daytime and open at night to conserve water.”
9. Which conditions will transpiration occur quicker than the control and why? (2 points)
10. Do all plants have stomata? Is there any relationship between the number of stomata and the environment in which the plant species evolved? (4 points)
11. Are leaf surface area and the number of stomata related to the rate of transpiration? (2 points)
12. What might happen to the rate of transpiration if the number of leaves or the size of leaves is reduced? (4 points)
13. Do all parts of a plant transpire? (2 points)
14.
Do all plants transpire at the same rate? (2 points)
15. Is there a relationship between the habitat in which plants evolved and their rate of transpiration?
(2 points)
16. What other factors, including environmental variables, might contribute to the rate of transpiration? (2 points)
17.
What structural features and/or physiological processes help plants regulate the amount of water lost through transpiration? (4 points)
18. How do plants maintain the balance between the transport of CO
2
and O
2
and the amount of water lost through transpiration? (4 points)
19. Use the chart at the bottom to label the parts/function of the leaf (22 points) :
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# Name
1
2
3
4
5
Use 5 – 7 words to define function
6
7
8
9
10
Cuticle
Collenchyma Supporting and strengthening tissue; may photosynthesize
20. With the data below, construct a graph using Excel, and calculate the rates of transpiration for each condition. (3 points for each line (12 points))
Condition 0 min
3 min
6 min
9 min
12 min
15 min
18 min
21 min
24 min
27 min
30 min
Wind
Room
Heat
Humid
0 3.70 7.77 9.87 12.34 14.19 16.29 17.90 19.87 21.60 23.45
0 0.67 1.34 1.94 2.61 3.13 3.63 4.33 4.78 5.30 5.75
0 2.15 4.27 5.89 8.15 9.41 10.96 11.53 12.74 13.90 16.42
0
Measurements are in mL.
1.59 1.70 1.85 1.97 2.21 2.46 2.70 2.83 3.13 3.39
Time is measured in minutes (min)
Leaf surface area has been taken into consideration with this data.
21.
Calculate the RATES OF TRANSPIRATION (4 points)
Condition
Wind
Rate of Transpiration (mL/M 2 /min)
Room
Heat
Humid
Calculations:

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THE INVESTIGATIONS
Getting Started
These questions are designed to help you understand concepts related to transpiration in plants before you design and conduct your investigation(s).
1. If a plant cell has a lower water potential than its surrounding environment, make a prediction about the movement of water across the cell membrane. In other words, will the cell gain water or lose water? Explain your answer in the form of a diagram with annotations.
2. In the winter, salt is sometimes spread over icy roads. In the spring, after the ice has melted, grass often dies near these roads. What causes this to happen? Explain your answer in the form of a diagram with annotations.
3.
a thin section of stem from your plant and examine it to identify the vascular tissues (xylem and phloem) and the structural differences in their cells. Describe how the observed differences in cellular structure reflect differences in function of the two types of vascular tissue.
4. If you wanted to transplant a tree, would you choose to move the tree in the winter, when it doesn’t possess any leaves but it is cold outside, or during the summer, when the tree has leaves and it’s warm and sunny? Explain your answer.
BioFlix
COHESION OF WATER
TRANSPORT OF SUGARS
MR. ANDERSON: PLANT TRANSPORT AND NUTRITION flashcards
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