IB Biology 2015 Curriculum

1. Understandings, Applications and Skills (This is what you may be assessed on)
Statement Guidance
9.2 U.1 Plants transport organic compounds from sources to sinks
9.2 U.2 Incompressibility of water allows transport along hydrostatic pressure
gradients
9.2 U.3 Active transport is used to load organic compounds into phloem sieve tubes at
the source
9.2 U.4 High concentrations of solutes in the phloem at the source lead to water uptake
by osmosis.
9.2 U.5 Raised hydrostatic pressure causes the contents of the phloem to flow towards
sinks.
9.2 A.1 Structure–function relationships of phloem sieve tubes
9.2 S.1 Identification of xylem and phloem in microscope images of stem and root
9.2 S.2 Analysis of data from experiments measuring phloem transport rates using
aphid stylets and radioactively-labelled carbon dioxide
9.2 A.1 Structure–function relationships ofphloem sieve tubes
1. Label the cross section diagram of phloem (Slide 5)

2. 9.2 S.1 Identification ofxylem and phloem in microscope imagesofstem and root
2. Label the cross section diagram of dicot and monocot roots and stems (Slide 6 & 7)

3. 9.2 U.1 Plants transport organic compounds from sources to sinks
3. The movement of materials in a plant is called (Slide 9)
4. The movement of material down from the leaves occurs in (Slide 9)
5. Distinguish between source and sink in terms of molecules in plants. (Slide 10-11)
9.2 U.2 Incompressibility ofwater allows transport along hydrostatic pressure gradients
4. Describe the effect of hydrostatic pressure. (Slide 12-13)
5. Explain hydrostatic pressure gradients helps move sucrose. (Slide 12-13)
9.2 U.3 Active transport is used to load organic compounds into phloem sieve tubes at the source
6. Explain the flow sucrose occurs from the storage cell, to the companion cells and then into
the phloem. (Slides 14-15)
9.2 U.4 High concentrations ofsolutes in the phloem at the source lead to water uptake by osmosis
7. Why is it necessary for the veins (which contain xylem and phloem) to be relatively close
together in plants? (Slide 16-17)
8. Describe how transpiration and osmosis help movement of sucrose in a plant. (Slide 16-17)

4. 9.2 U.5 Raised hydrostatic pressure causesthe contents ofthe phloem to flowtowards sinks.
9. Explain the mechanism for movement of sucrose during translocation
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9.2 S.2 Analysis ofdata from experiments measuring phloem transport rates using aphid stylets
and radioactively-labelled carbon dioxide
10. Describe how aphids feed (Slide 20)
9. Explain how data from radioactively-labeled carbon dioxide can be used to measure rates of
phloem transport. (Slide 20-22)
Translocation Lab
Purpose
Transpiration is the loss of water through the leaves of the plant. As the temperature increases,the rate of
transpiration increases as the plant tries to cool itself and meet the demands of water use for
photosynthesis and metabolism. The movement of water out the stomata causes transpiration pull.
Transpiration pull is internal pressure,in this case suction, that is created as water moves through the
plant and out of the leaves during transpiration.
Translocation is the movement of the liquids within the plant system. As the plant absorbs water and
dissolved nutrients in the roots, the vascular system carries these substances to where the plant needs
them. Translocation also refers to the movement of dissolved sugars in the phloem. The relationship
between translocation and transpiration is recognized as a direct relationship. For example, as the rate of
transpiration increases the rate of translocation of fluids will also increase.
This activity will explore transpiration and translocation of water through the leaves and stem of a plant.
You will examine how different environmental conditions influence the rate of transpiration in plants.

5. Materials
Per pair of students:
 2 small beakers
 2 stalk of celery
 Red food coloring
 Knife
 Graduated cylinder
 Distilled water
 2 sheets paper towel
Procedure
You and a partner will conduct an investigation for transpiration rate. Your teacher will assign you an
environmental condition to test and later report the data to the entire class to compare results. Follow the
steps outlined below.
Part 1 – Setup Experiment
1. Cut ½” off the end of each stalk of celery (not the leaf end to expose the xylem).
2. Trim your longer celery stalk so both stalks are the same height. Record the height in Table 1.
3. Record observations about your celery stalks in the box on the below. Record color, texture,
turgidity, etc.
4. Use a graduated cylinder to fill the beakers with 200 ml of distilled water each.
5. Label the beakers with your group initials. Label one beaker “experiment” and one beaker
“control.”
6. Use red food coloring to dye the water to a deep red color.
7. Choose and circle the environmental condition you will test:
-Wind, higher light intensity, darkness, cold temp., warm temp, high humidity, other:
8. Place the cut end of the celery stalks in the red water. Record time of day in Table 1.
9. Place the control and experimental celery stalks in locations indicated by your teacher.
10. Make predictions for both the translocation and transpiration rates in the box below.
Observations- Day 1
Experiment Control
Predictions
Experiment
The translocation rate will be higher/lower that the
control because:
The transpiration rate will be higher/lower that the
control because:
Control
The translocation rate will be higher/lower that the
experiment because:
The transpiration rate will be higher/lower that the
experiment because:

6. Part 2 – Transpiration and translocation rates
1. Collect your experiment and control beakers.
2. Make observations in the box below.
Observations- Day 2
Experiment Control
3. Determine the number of hours the celery was left in the red water and record in Table 1.
4. Remove the celery from the red water.
5. Use a paper towel to dry off excess liquid.
6. Use your knife to remove 1 cm slices from the bottom to the top. Examine each slice for
appearance of red dye. When you stop seeing red dye, stop cutting.
7. Measure the length of the remaining celery stalk and subtract from the beginning length. Record
in Table 1.
8. Divide the length of celery with dye by hours celery was left in red water to get translocation rate
of cm/hr and record in Table 1.
9. Now find the transpiration rate. Use a graduated cylinder to measure the liquid left in your beaker
and record in Table 1 as ending water volume.
10. Find the difference between beginning (200 ml) and ending water volume and record in Table as
volume of water transpired.
11. Divide the volume transpired hours celery was left in red dye to get transpiration rate of ml/hr and
record in Table 1.
12. Report your data to the class and record classmate’s data in Table 2.
Table 1 Test Data
Experiment Control Difference
Beginning length (cm)
Time at beginning ofexperiment
Time at end of experiment
Hours celery left in red water (hrs)
Length ofcelery with dye (cm)
Ending water volume (ml)
Volume ofwater transpired (ml)
Trans-location rate (cm/hr)
Trans-piration rate (ml/hr)

7. Table 2 Class Data
Test
Translocation rate
difference (cm/hr)
Transpiration rate
difference (ml/hr)
Wind
High light
Darkness
Cold temp.
Warm temp.
High humidity
Other:
Conclusion
1. Which experimental conditions caused increased translocation rates? Which experimental
conditions caused increased transpiration rates?
2. Which variable resulted in the greatest difference in transpiration rates? Explain why this factor
might increase water loss when compared to the others.
3. What adaptations enable plants to increase or decrease water loss? How might each affect
transpiration?