Lab #3: Plant Transpiration Worksheet

Lab #3:  Plant Transpiration Worksheet
(Worth 126 possible points)

Table I:  Total Amount of Water (mL) Transpired in One Hour
(Worth 36 possible points)
Plant Type   Normal Conditions (@21oC)   With Heater
(@27oC)   With Fan (@21oC)   With Lamp (@21oC)
Arrowhead   3.6   6.6   7.5   4.0
Coleus   0.9   3.9   6.0   3.0
Devil’s Ivy   2.9   4.1   4.6   3.0
Dieffenbachia   4.1   6.0   7.7   3.9
English Ivy   1.8   3.2   5.1   2.1
Geranium   1.2   5.8   4.7   2.4
Rubber Plant   4.9   6.8   8.4   4.3
Weeping Plant   3.3   4.9   6.1   2.5
Zebra Plant   4.2   6.1   7.6   3.2

Lab Questions:

1.    Transpiration in plants is driven by which of the following?
a.   Gravity
b.   Capillary action
c.   Static electricity
d.   All of the above
(Worth 5 possible points)

2.   Which of the following statements about stomata is true?
a.   They are found on plant roots.
b.   They permit the intake of carbon dioxide.
c.    They permit the intake of oxygen.
d.    All of the above.
(Worth 5 possible points)

3.   Water can be lost by a plant through which process(es)?
a.   Evaporation
b.   Transpiration
c.   Condensation
d.   A and B
(Worth 5 possible points)

4.    Which environmental condition in your experiments served as the control?
a.   Heat
b.   Wind
c.   Light
d.   None of the above
(Worth 5 possible points)

5.   In your experiments, transpiration was observed by which of the following?
a.   Directly measuring the amount of water leaving the leaves through transpiration.
b.   Directly measuring the amount of water leaving the leaves through evaporation.
c.   Directly measuring the amount of water absorbed through the plant sprig’s stem.
d.   All of the above.
(Worth 5 possible points)

6.    Which environmental condition(s) always led to an increase in transpiration rate in each plant tested?
a.   Heat
b.   Wind
c.   Light
d.   A and B
e.   All of the above
(Worth 5 possible points)

7.    Wind did not have the greatest effect on transpiration rate in which plant type?
a.   Arrowhead
b.   Geranium
c.   Rubber Plant
d.   Weeping Plant
e.   None of the above
(Worth 5 possible points)

8.    Colder temperatures cause stomata to remain closed. Based on this information, if a plant were grown below 21oC, what would you expect transpiration rates to do?
a.    Increase
b.   Decrease
c.   Remain the same
(Worth 5 possible points)

9.    Wind appeared to increase the rate of transpiration in most plants tested.  This is most likely due to which fact?
a.   Humidity was increased
b.   Evaporation was increased
c.   Stomata were forced to close
d.   All of the above
(Worth 5 possible points)

10.    Cacti grow in arid regions such as deserts. Compared to other plants, b  transpiration in cacti would most likely be which of the following?
a.    Lower
b.   Higher
c.   The same
(Worth 5 possible points)

11.   Describe the process of transpiration in vascular plants.
(Worth 5 possible points)
Water is transpired from the plant’s leaves via stomata, carried there via leaf veins and vascular bundles within the plant’s cambium layer. The movement of water out of the leaf stomata creates, when the leaves are considered collectively, a transpiration pull. The pull is created through water surface tension within the plant cells. The draw of water upwards is assisted by the movement of water into the roots via osmosis. This process also assists the plant in absorbing nutrients from the soil as soluble salts, a process known as absorption. Surprisingly, the movement of water upwards requires very little or no energy from the plant. Hydrogen bonds exist between water molecules, which cause them to line up, as the molecules at the top of the plant evaporate, they pull the next one up to replace it, which in turn pulls on the next one in line.
12.   Describe any control groups used in the investigation.
(Worth 5 possible points)

The control groups include plants examined outside the presence of the three stimuli (heater, fan, lamp).

13.   What environmental factors that you tested increased the rate of transpiration?
(Worth 5 possible points)

      The heater, fan, and lamp increased the rate of transpiration.


14.   Was the rate of transpiration increased for all plants tested?
(Worth 5 possible points)

      Yes

15.   Did any of the environmental factors (heat, light, or wind) increase the transpiration rate more than the others? Why?
(Worth 5 possible points)

The fan increased transpiration the most – 6.4.  The fan increased plan respiration by transporting water away from the plant.

16.   Which species of plants that you tested had the highest transpiration rates? Why do you think different species of plants transpire at different rates?
(Worth 5 possible points)

The rubber plant was observed with the highest rate of transpiration. Each species of plant has a transpiration rate ideal for its domestic environment. Higher transpiration rates may be indicative of a wetter climate, while lower transpiration rates may be used to conserve water in places like a desert where rainfall is minimal.

17.   Suppose you coated the leaves of a plant with petroleum jelly. How would the plant's rate of transpiration be affected?
(Worth 5 possible points)

      The jelly would prevent transpiration from occurring.

18.   Of what value to a plant is the ability to lose water through transpiration?
(Worth 5 possible points)

Transpiration is the "engine" that pulls water up from the roots to:    
•   supply photosynthesis (1%-2% of the total)
•   bring minerals from the roots for biosynthesis within the leaf
•   cool the leaf



If you cannot read this please refer to the attached document.