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Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
PLANT TRANSPORT
WORKBOOK
Name:_________________
Tutor Group:____________
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Wellsway School Science Team
Transport and Water Relations
Curriculum 2006
Triple Science - Biology workbook
1. HOW PLANTS TAKE UP WATER & TRANSPIRE
1.
OBJECTIVES:
Do plants have a circulatory system?
How are substances carried throughout a plant?
What evidence is there for this transport?
What substances do plants need?
By the end of this topic you should:
(a) Understand the role of osmosis and transpiration in the movement of water through a
plant.
(b) Observe root hairs; investigate water loss in plants using a bell jar, nail varnish
replicas to show stomata, the use of a simple potometer to demonstrate water uptake.
(c) Know the role of xylem and phloem in transport within plants and carry out an
investigation into the movement of a dye through the xylem.
(d) Appreciate that modelling may be used to understand how processes may work as
illustrated by the representation of areas of a plant by the model proposed by Munch and
the uses and limitations of the model (details of Mass Flow hypothesis not required).
(e) Know the importance of water to plants and its use in photosynthesis, transport of
minerals and support.
(f) Know that for healthy growth plants require nitrate, potassium and phosphate.
(g) Observe the effects of minerals on plant growth.
2.
Investigating water transport in the xylem.
a. Stand a stick of celery* in a beaker containing about 1 cm depth of coloured dye.
*(ideally with some leaves still attached – the celery we eat is a leaf stalk).
b. Leave it for at least 45 minutes (while you are waiting, continue with section 3).
c. Remove from the dye and lay the stalk on a tile or paper towel.
d. Carefully cut across the stalk 20 mm from the bottom and observe the cut end.
e. Sketch this cut end in the space below and label it to show the distribution of the
coloured dye, and write the name of the tissue where most of the dye is found.
f. Repeat step c. at 20 mm intervals up the stalk until no dye can be seen (or until you
reach the leaves). Estimate the distance travelled by the dye in the time you left it soaking
and calculate the rate of uptake of dye (in mm / minute).
Drawing of cut end of celery:
Distance travelled by dye (mm):
Time celery stalk was in the dye (mins):
Rate of uptake of coloured dye (mm / minute):
How do you think this rate compares with the normal uptake of liquids by an intact celery
plant? Support your answer with reasons:
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3.
Curriculum 2006
Triple Science - Biology workbook
If appropriate, watch the video, MSS presentation or PowerPoint on plant transport.
Read your textbook or support material on plant transport.
Discuss with your teacher what a plant transports, why & how.
a. Write down a list of materials transported in a plant. Include where they are
transported from, and where they are transported to.
1. Water. Soil water roots xylem stem leaf air
2. Mineral ions (N,P,K). Soil water roots xylem stem leaf.
3. Carbon dioxide. Air stomata air spaces leaf cells.
4. Oxygen. leaf cells air spaces stomata Air.
5. Dissolved food. E.g. glucose, sucrose, amino acids. Leaves phloem stem flowers roots (also storage organs).
b. Suggest reasons why plants have a transport system like animals, but no pump
(heart) unlike animals.
Animals need much more energy (for movement) which could not
be supplied quickly enough without a pump.
4.
Make a fully labelled and annotated drawing to show the distribution of transport
tissues in a ROOT (colour in the xylem in red & the phloem in blue):
5.
Make a fully labelled and annotated drawing to show the distribution of transport
tissues in a STEM (colour in the xylem in red & the phloem in blue):
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6.
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Curriculum 2006
Triple Science - Biology workbook
Make a fully labelled and annotated drawing to show the distribution of transport
tissues in a LEAF(colour in the xylem in red & the phloem in blue) :
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7.
Curriculum 2006
Triple Science - Biology workbook
If you have finished….
Describe how the structure of xylem and phloem tissue makes them suitable for carrying
out their functions of transporting materials around a plant (use labelled & annotated
drawings to help you if you wish):
Xylem
1. D_______, hollow cells with no e_____ walls. Forms an
unbroken cyl__________ from root to stem to leaf;
2. Small lumen (cav_______). Enables an unbroken column of
water to form;
3. Supported by lignin (W_______!). Stops it from collapsing.
Phloem
1. Living cells which can control movement of food by ACTIVE
TRANSPORT;
2. End walls perforated with pores, again to control the movement
of food;
3. Small COMPANION CELLS beside the phloem elements
provide ENERGY for active transport.
8.
Uptake of water in the root.
If possible, observe the roots of a plant, and the tiny root hairs which grow out from the
walls of the roots.
Discuss with your teacher how water (and mineral ions) are absorbed from the soil,
across the root tissues and into the xylem.
In the space below, make a clear, labelled drawing to show the pathway of water (and
mineral ions) across a root to the xylem:
B4U, PAGE 226, MIDDLE DIAGRAM
Using your knowledge of osmosis, EXPLAIN clearly how water is able to pass across the
root in this way (useful terminology: soil water; cell sap; high / low; water potential;
selectively permeable membranes):
Soil water normally has a H_________ water potential (i.e. there’s more
water there!) than the C_______ S______ inside the root cells.
So water passes across the selectively permeable membranes of the root
hair cells by O__________ (from higher to lower water potential), so the cells
g________ water.
Water passes right across the root in the same way, until it enters the
X___________ vessels.
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9.
Curriculum 2006
Triple Science - Biology workbook
Transpiration and the transport of water through the stem and leaf.
a. Observe the 2 potted plants which were set up 24 hours ago. Note that both pots are
covered with polythene bags, but only plant A is covered with a polythene bag (or bell
jar). Complete the table below, which compares the loss in mass in each plant over 24
hours:
Plant:
Sketch of plant:
A
B
Mass at start (g)
Mass after 24 hours
(g)
Loss in mass (g)
Effect of clear liquid
in bag/jar on cobalt
N/A
chloride*:
*(Cobalt chloride paper turns from blue to pale pink/white when water is added to it.)
Write a conclusion, explaining the different results in the 2 plants:
Conclusion:
b. Write down a clear definition of transpiration:
(B4U,
PAGE 227)
Transpiration is the LOSS of WATER from a plant, mainly
through the microscopic pores on the underside of the
leaves, called STOMATA.
The loss takes place by E_____________ & D_________.
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Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
10. If possible, observe the leaf of a plant, and the tiny stomata (pores) which are found in
the lower epidermis of the leaf.
Discuss with your teacher how water (and mineral ions) are absorbed from the root
xylem, up the stem, into the leaf xylem, and into the leaf cells.
In the space below, make a clear, labelled drawing to show the pathway of water (and
mineral ions) from the leaf xylem to the leaf cells. Show also the pathway of water vapour
across the intercellular air spaces and out through the stomata:
Using your knowledge of osmosis, EXPLAIN clearly how water is able to pass across the
leaf in this way (useful terminology: water in xylem; cell sap; high / low; water potential;
selectively permeable membranes; evaporation; water vapour; diffusion.):
4 bullet points at the bottom of p227, B4U.
Also
• Water is drawn across the leaf from the leaf xylem by
O____________ (as water evaporates from spongy
mesophyll cells, it decreases their W__________
P_____________, so water flows across the leaf).
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Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
11. If you have finished…
Observing stomata:
Make a nail varnish replica of the lower epidermis of a Tradescantia leaf, and observe it
carefully under a microscope. Draw, label and annotate clearly what you see:
Nice green stoma on p228, B4U!
12. Investigating the factors affecting transpiration.
Watch the teacher demonstration of the potometer.
a. Label and annotate the drawing below of a potometer:
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Curriculum 2006
Triple Science - Biology workbook
b. What is the purpose of the tap and reservoir?
To return the air bubble to the “start”.
c. What exactly does the potometer measure?
The uptake of water by a cut shoot.
d. Why can’t the potometer be used to measure, precisely, the rate of transpiration?
Because they are not exactly the same: some water is used in PHS
& some is used to keep cells turgid (swollen).
e. Nevertheless, since water uptake is directly proportional to transpiration, the effect of
varying different factors on the rate of transpiration can be investigated quite accurately
with the potometer.
Describe and explain the effect of each of the following 4 factors on the rate of
transpiration. Draw sketch graphs to show exactly these affect transpiration rate:
i.
Wind speed / air movements:
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ii.
Humidity (water content of the air):
iii.
Temperature:
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iv.
Curriculum 2006
Triple Science - Biology workbook
Light intensity:
If you have finished…
Carry out a computer simulation which investigates the effects of the above factors on the
rate of transpiration. If possible, record (or print out and attach) the results of the
simulation. How do the results of the simulation compare with your explanations above?
13. Write a paragraph explaining the importance of water to plants. Make sure you refer to
its use in photosynthesis, transport of minerals and support.
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Wellsway School Science Team
Curriculum 2006
14. The importance of mineral ions to plant growth.
a. Observing the effects of minerals on plant growth.
Look at the 5 tubes shown below.
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Triple Science - Biology workbook
Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
Distilled
water
No
Potassium
No
No
Phosphates
Nitrates
Construct a table highlighting the key differences in the growth of each seedling:
TUBE NO
1
2
NO OF
LEAVES
lots, green
few, yellow
SIZE OF
LEAVES
large
small
small
small
middle-sized
NO OF
ROOTS
lots
few
quite a lot
few
quite a lot
medium
small
medium
SIZE OF
ROOTS
large, long
small
3
4
few, yellow few, yellow
& purple
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few, greenyellow
b. Using your textbook, or support material, or the Internet, research and record the
importance of the following 3 mineral ions to healthy plant growth:
i.
Nitrates.
Growth of leaves & stems. Nitrogen needed for protein synthesis.
Lack – stunted growth & yellow older leaves.
ii.
Potassium.
Healthy leaves & flowers.
Help reactions in Photosynthesis & respiration to work.
Lack – yellow leaves with dead spots
iii.
Phosphates.
Healthy roots.
Help reactions in Photosynthesis & respiration to work.
Lack – poor root growth & purple younger leaves.
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Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
15. Translocation.
As well as transporting water and mineral ions from roots to stem to leaves, the plant also
carries out translocation.
a. Write a clear definition of translocation:
The transport of dissolved foods from where they are made in the
leaves to all other parts of the plant.
Foods are carried in the PHLOEM, by ACTIVE TRANSPORT.
b. Write down 3 key differences between translocation and the transport of water &
mineral ions:
TRANSLOCATION
TRANSPORT of WATER, MINS.
1.
In phloem, living tissue.
In xylem, dead tissue.
2.
Transported FROM leaves…
Transported TO leaves…
3.
…TO rest of plant.
…from roots.
4.
Transported by ACTIVE
Carried in TRANSPIRATION
TRANSPORT (needs energy). STREAM (no extra energy
needed.
c. Describe what happens to the food materials transported in the phloem. Refer to
sugars, amino acids and fatty acids in your answer:
Sugars: 1. Used for ENERGY,
2. Built up into STARCH, which is stored in SEEDS &
STORAGE ORGANS,
3. Built up into CELLULOSE, which forms the CELL WALL
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Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
Amino Acids: Built up into PROTEINS, for GROWTH
Fatty Acids: built up into FATS (LIPIDS), & stored in SEEDS.
If you have finished….
The Pressure (mass) flow hypothesis was a model proposed by Ernst Munch in
1930 that explained the mechanism of phloem translocation. Carry out Internet
research to find out how the model helps to explain how food is transported around a
plant. Summarise your findings in the space below (or print out a summary):
http://answers.yahoo.com/question/index?qid=20080509110537AAGMKEV
Best Answer - Chosen by Voters
The mass flow hypothesis in terms of plants, is the following:
The accepted mechanism needed for the translocation of sugars from source to sink is
called the pressure flow hypothesis.
As glucose is made at the source (by photosynthesis for example) it is converted to
sucrose (a dissacharide). The sugar is then moved into companion cells and into the
living phloem sieve tubes by active transport. This process of loading at the source
produces a hypertonic condition in the phloem.
Water in the adjacent xylem moves into the phloem by osmosis. As osmotic pressure
builds the phloem sap will move to areas of lower pressure.
At the sink osmotic pressure must be reduced. Again active transport is necessary to
move the sucrose out of the pholem sap and into the cells which will use the sugar -converting it into energy, starch, or cellulose. As sugars are removed osmotic pressure
decreases and water moves out of the phloem.
So, the following is true and perhaps a more concise version, if you are learning it for an
exam:
The movement of sugars in the phloem begins in the leaves, where
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Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
(a) Sugars are loaded (actively transported) into a sieve tube.
Loading of the phloem sets up a water potential gradient that facilitates the
movement of water into the dense phloem sap from the neighboring xylem
(b). As hydrostatic pressure in the phloem sieve tube increases, pressure flow
begins
(c), and the sap moves through the phloem.
Meanwhile, where food is being used up, e.g. roots, respiring cells:
(d), incoming sugars are actively transported out of the phloem and removed as
complex carbohydrates. The loss of solute produces a high water potential in the
phloem, and water passes out
(e), returning eventually to the xylem.
16. Well done! You have now completed the Plant Transport topic.
Now you need to revise your work in preparation for the Plant transport test.
17 Useful web links:
http://www.s-cool.co.uk/topic_index.asp?subject_id=17&d=0
http://www.bbc.co.uk/schools/gcsebitesize/biology/greenplantsasorganisms/
http://swgfl.skoool.co.uk/keystage4.aspx?id=315 (good on-line tutorial)
http://www.chadevans.co.uk/asite/gcse/b02/t10.html
http://www.revisionworld.co.uk/gcse-us-grades-8-10/biology/questions/longer-questions/question9-transpiration
http://www.thestudentroom.co.uk/wiki/Revision:GCSE_Biology_-_Plant_Biology
18. Glossary. (Muddled – sort them out!)
1
Cell sap
2
Cobalt chloride paper
3
4
5
Culture solution
Diffusion
Evaporation
6
Mineral Ions
7
8
Nitrates
Osmosis
9
10
11
Phloem
Phosphates
Photosynthesis
12
13
Potassium
Potometer
14
15
16
17
Pressure flow hypothesis
Root hair
Selectively permeable
Stomata
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Translocation
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Random movement of particles from high to low
concentration.
Change of state from liquid to gas, e.g. water to water
vapour.
Liquid found in all plant cells.
Solution containing mineral ions needed for plant growth.
Indicates the presence of water, by turning from blue to pale
pink.
Diffusion of water from high to low water potential, via a
membrane
Mineral ion needed for protein synthesis & plant growth.
Tiny tubes used for carrying dissolved foods around the
plant.
Mineral ion needed for growth of roots & young leaves
Any dissolved inorganic ion needed for healthy plant growth.
Microscopic outgrowth of roots, important for absorbing
water & mineral ions. Increase surface area of root.
Munch’s model of how food is transported in the phloem.
The process by which a plant makes it s own food from
water & carbon dioxide, using sunlight energy.
Mineral ion (metal) needed for healthy growth of leaves.
Glass device which measures water uptake by a plant.
Transport of dissolved foods around a plant.
Tiny tubes which carry water & mineral ions from roots to
leaves.
A measure of the concentration of water in a solution.
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Transpiration
20
Water potential
21
Xylem
19.
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Curriculum 2006
Triple Science - Biology workbook
Membrane which only allows smaller molecules to pass
through it.
Tiny leaf pores through which water vapour is lost by
transpiration.
Loss of water vapour from a plant, mainly through stomata.
Wellsway School Science Team
20.
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Curriculum 2006
Triple Science - Biology workbook
Wellsway School Science Team
21.
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Additional notes
Curriculum 2006
Triple Science - Biology workbook
Wellsway School Science Team
Curriculum 2006
Triple Science - Biology workbook
GCSE - WJEC
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