| Date | May 2017 | Marks available | 3 | Reference code | 17M.2.HL.TZ1.4 |
| Level | Higher level | Paper | Paper 2 | Time zone | Time zone 1 |
| Command term | Explain | Question number | 4 | Adapted from | N/A |
Question
Most of the surface of the Earth is covered with a wide diversity of ecosystems. Outline two general characteristics of all ecosystems.
Vascular plants can be found in a wide variety of ecosystems.
Outline active transport in phloem tissue.
Vascular plants can be found in a wide variety of ecosystems.
Explain how a plant replaces the water it loses in transpiration.
Markscheme
a. organisms/community plus the environment / biotic and abiotic «components»
b. interactions
c. ecosystems show sustainability
d. nutrients are recycled in ecosystems
e. energy flows through ecosystems
f. producers «are part of all ecosystems»
g. decomposers/saprotrophs «are part of all ecosystems»
a. active transport/pumps used to load sugars/sucrose into phloem/companion cells/sieve tubes
b. loading in sources/unloading in sinks
OR
sucrose/sugars moved from source to sink
c. active transport moves H+ out of phloem/sieve tubes «to make H+ gradient in the leaf/source»
d. H+ gradient used for co-transport of sucrose into phloem/sieve tubes/companion cells
Accept protons or hydrogen ions instead of H+ ions.
Accept the equivalent of mpc and mpd for unloading in the sink.
a. transpiration/evaporation of water causes suction/tension
b. water sucked/drawn out of xylem «in leaf»
c. water moves up in xylem
d. due to suction/tension/pulling forces
e. cohesion of water/hydrogen bonds between water molecules
f. movement from roots to leaves
g. water enters root by osmosis/due to higher solute concentration inside root
Examiners report
Syllabus sections
- 18N.1.HL.TZ0.32: A fungicide dissolved in water was applied to the soil in which a rose plant was growing. It...
- 22M.1.HL.TZ1.32: Which graph represents the effect of humidity on the transpiration rate in plants?
- 22M.1.HL.TZ1.33: The diagrams represent cross sections of the stem and root of a plant. Which tissues...
- 17M.3.HL.TZ2.3b: Predict, with a reason, what will happen to the pressure in this tube as transpiration occurs.
- 18M.1.HL.TZ1.32: How do water molecules enter root cells? A. Transpiration B. Tension C. Capillary...
- 20N.1.HL.TZ0.32: The graph shows the percentage of stomata that are open in two different species of plants...
- 17M.1.HL.TZ1.32: Which process and cause are responsible for water uptake by the roots?
- 18M.3.HL.TZ1.3a: Suggest a possible research question that could be investigated using a potometer.
- 17N.1.HL.TZ0.34: Cobalt chloride paper is blue when dry but turns pink with water. Blue cobalt chloride paper...
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19M.3.HL.TZ1.2d.i:
Label with an R the tissue where the red dye would appear.
- 19M.2.HL.TZ1.4b: Explain how the properties of water allow it to move through xylem vessels.
- 18N.3.HL.TZ0.2c: Describe the distribution of vascular tissues in the stem of dicotyledonous plants.
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19M.1.HL.TZ2.38:
The image is a cross section through an Ammophila leaf, which grows on coastal sand dunes.
[Source: Charles Good: The Ohio State University at Lima]
What feature suggests that Ammophila is a xerophyte?
A. The leaf surface area is increased.
B. The rolled leaf reduces the upper epidermis area.
C. The rolled leaf protects the lower epidermis from the wind.
D. The lower epidermis can transpire more easily.
- 19N.3.HL.TZ0.2b: State the independent variable in this investigation.
-
20N.3.HL.TZ0.1b:
The mean stomatal density for the lower epidermis of P. decandrum was around 600 per mm2. Predict how the stomatal density for the upper epidermis would compare.
- 17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
- 18M.3.HL.TZ2.3a: Outline how the rate of water uptake is recorded in this potometer.
- 19N.3.HL.TZ0.2a.ii: Transpiration continued after the fifth leaf had been removed. Suggest what can be concluded.
- 19N.1.HL.TZ0.32: Which process is most responsible for movement of water from roots to leaves of a plant on a...
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19N.1.HL.TZ0.33:
In the micrograph of a plant stem, which letter indicates the xylem?
[Source: adapted from Kelvinsong/https://creativecommons.org/licenses/by/3.0/deed.en]
- 18M.3.HL.TZ2.3b: State a variable that needs to be controlled in this experiment.
-
21M.1.HL.TZ2.32:
The apparatus in the diagram was used to assess the effects of factors on transpiration rates.
[Source: Republished with permission of Springer-Verlag from Experimentelle Pflanzenphysiologie: Band 2, Peter Schopfer, 1st edition, 1st Jan 1989; permission conveyed through Copyright Clearance Center, Inc.]
Which factor would be a controlled variable in an experiment designed to assess the effects of temperature on transpiration rate?
A. The opening and closing of stomata
B. The intensity of light striking the plant
C. The height of the water in the reservoir
D. The evaporation of water from the leaves
- 19N.3.HL.TZ0.2a.i: Describe the trend in the data.
- 17M.3.HL.TZ2.3a: State the specific type of plant tissue that the plastic tube is meant to model.
- 19N.3.HL.TZ0.2c: Explain how the results in the graph could have been obtained.
-
18M.3.HL.TZ1.3b:
Evaluate the limitations of using a potometer in the investigation you suggested in (a).
-
21N.2.HL.TZ0.7b:
Distinguish between the xylem and phloem of plants.
- 19M.3.HL.TZ1.2a: State the function of the tap and reservoir.
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19M.3.HL.TZ1.2d.ii:
Label with a C the tissue where organic compounds are transported.
-
20N.2.HL.TZ0.7b:
Describe the processes that cause water to move from the roots of plants to their leaves.
- 17M.3.HL.TZ2.3c: Outline how this control set-up could be modified to test the effect of either humidity or...
- 16N.1.HL.TZ0.32: Excessive irrigation can cause increased salinity in the soil. What effect does this have on...
- 19M.3.HL.TZ1.2c: One criticism of the experiment is that it only measured the rate of transpiration...
- 18M.3.HL.TZ2.3c: Explain the effect of relative humidity on the rate of water uptake.
- 19M.2.HL.TZ1.4a: Xylem and phloem contain structures that are adapted for transport. Outline the differences...
- 19M.3.HL.TZ1.2b: Describe how the apparatus could be used to demonstrate that the transpiration rate is...
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22M.2.HL.TZ1.6b:
Describe how changes in weather conditions affect the transport and loss of water in plants.
