AS!Biology!• She left the ten leaves in set A untreated. She covered the upper surfaces of the ten...
Transcript of AS!Biology!• She left the ten leaves in set A untreated. She covered the upper surfaces of the ten...
This booklet belongs to:
AS Biology
Plant Exchange and Transport
Work booklet
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This workbook is designed to support and supplement your
learning. It includes key diagrams, experiment set ups and some past paper questions for you
to practise.
Keep it safe and tidy – it should be a revision asset if you do!
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The leaf Label these diagrams. Try and show where each type of cell is on the micrograph
as well as on the diagram.
Further thought – what kind of microscopy does this show?
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Structure and Function A typical AO2 type question – be clear what function each of the leaf structures
has. Add in other structures if you can think of any other relevant ones.
Structure Function Waxy cuticle
Guard cell
Spongy mesophyll
Palisade cells
Air spaces
Xylem
Phloem
Upper epidermis
Cellulose cell walls
Vacuoles
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Some questions
1. Flowering plants have stomata in the leaf epidermis and the epidermis of green stems. a) (i) What is a stoma and (ii) what type of cell is associated with each stoma?
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b) In relation to photosynthesis, what is the main function of stomata?
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c) Why is water lost from the gas exchange surfaces of terrestrial organisms?
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d) The density of stomata varies from 1000 to 100 000 per square centimetre. What would be the density of stomata per square millimetre, if there were 10 000 per square centimetre?
………………………………………………………………………………………… (1)
Think:
- How many marks available? - Do you need to show working/is it a good idea? - Can you tell what the question is from your answer?
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2. A student investigated the rate of transpiration from privet leaves.
• She obtained two sets of ten privet leaves.
• She left the ten leaves in set A untreated. She covered the upper surfaces of the ten leaves in set B with grease.
• She weighed each set of leaves and then tied all the leaves in each set to a separate length of thread. This is shown in the diagram.
• She then weighed each set of leaves every 20 minutes over a period of 2 hours and plotted a graph of her results.
(a) Give two environmental conditions that the student should have kept constant during this investigation.
1 ...................................................................................................................
2 ................................................................................................................... (2)
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(b) The student measured the water loss in milligrams. Explain the advantage of using ten leaves when taking measurements in milligrams.
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(c) Explain the change in mass of untreated leaves in set A shown in the graph.
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(d) The results that the student obtained for the leaves in set B were different from those for set A. Suggest an explanation for this difference.
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(Total 8 marks)
Think:
- What is the action word in each question? - You have been given graphs. Is there any opportunity in the questions to
quote data? - Can you tell what the question is from your answer?
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The Roots Label this diagram of a root hair cell.
How does this structure lend itself to the absorption of substances from the soil?
State Fick’s Law:
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How water travels through the root
Use this diagram, along with your own notes, to bullet point the pathway by which water and minerals move from the root hair cell to the xylem.
You should aim to use the following words in your description: osmosis, gradient, vacuole, cytoplasm, apoplastic, symplastic, plasmodesmata,
casparian strip, active transport
Bullet point your answer here…
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A synoptic question…
What does a plant
use water for?
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Movement in the stems This is a cross-‐section through a root. You should be able to label most of the
structures you see.
1. What type of microscopy is this?
2. How can you tell?
3. What are the two major vessels that flow through the plant?
4. In which direction do they flow? 5. What do they carry? 6. Wait, these questions would be much better tackled in a….
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Table of Comparison A really good way to display comparative information. I have included a few
columns for you to fill in – the rest is up to you. Some past questions/textbook might help you to put in relevant points
Xylem Phloem Major function
Direction of flow
Structure of vessels
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Phloem statement sorts A good opportunity for you to recognise and use statements that serve different
purposes.
Group the following statements about phloem into the following categories
O Position in plant organs
F Functions of phloem and processes that occur within and between cells
P Pathway taken by substances within phloem tissue
S Structure of phloem tissue including cell structure and cell shape
No. Category
1 phloem tissue is between ‘arms’ of xylem in vascular tissue in root
2 transport of sucrose from roots to leaves
3 movement of hydrogen ions and sucrose into companion cell
4 phloem sap moves through phloem tissue in root
5 phloem sap moves through phloem tissue in stem
6 sieve pores in sieve plate
7 sieve tube elements have peripheral cytoplasm
8 carrier proteins in companion cell membranes
9 sieve tube elements have thin cell walls that are not lignified
10 companion cells contain mitochondria
11 transport of amino acids from roots to leaves
12 mitochondria provide ATP for active transport across companion cell membrane
13 on outside of vascular bundles in stems
14 on upper side of veins in leaves of dicotyledonous plants
15 phloem sap moves through phloem tissue in minor veins in leaf
16 sieve tube elements are stacked end to end
17 movement of sucrose between companion cell and sieve tube element
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18 sieve tube elements are elongated
19 phloem sap moves through phloem tissue in petiole and main vein of leaf
20 phloem sap flows easily, there is little resistance to flow
21 plasmodesmata between companion cell and sieve tube element
22 hydrogen ions are pumped out of companion cell
23 sieve plates
24 sieve tube elements have no nuclei
25 sieve tubes form continuous columns
26 transport of sucrose from source to sink
Match the structural features (S) of phloem tissue (sieve tube elements and companion cells) with the ways in which those features help the transport in phloem (F). Use the numbers from the table above. You may wish to use some of the functions more than once.
Structural feature of phloem tissue
How it helps transport in phloem
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Making the Grade These are two perfectly passable diagrams. However, you should be able to
improve the labels on them to bring them up to an A grade standard.
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The transpiration stream This diagram shows evapotranspiration at the leaf. The one thing this doesn’t
explain is the cohesion-‐tension theory.
Explain this first:
How does water move in at the roots? There is more than one theory/explanation to this…
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Factors affecting the rate of transpiration
Factor How this may affect transpiration
Number of leaves
Number, size and position of stomata
Presence of cuticle
Light
Temperature
Relative humidity
Air movement/wind
Water availability
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Measuring transpiration Label this diagram of a potometer
There are several important steps to setting up a photometer. Name 3 of them, and explain their importance:
1.
2.
3.
How would you measure the rate of water uptake (volume) from the leaves of the plant?
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Some questions (a) Root pressure moves water through the xylem. Describe what causes root
pressure.
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(b) A biologist investigated the rate of water movement during the day in different parts of a tree. The results are shown in the graph.
(i) Describe how the rate of water movement in the upper branches changed over the period shown in the graph.
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(ii) The rate of water movement in the upper branches was different from the rate of water movement in the trunk. Describe how.
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(iii) The results of this investigation support the cohesion tension theory. Explain how
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(Total 9 marks)
Think:
- This question is asking about a lot of differing processes. Be really sure of your key words and factual knowledge before you attempt them
- “Describe this graph” means a person should be able to draw it from your description
- These are questions where it’s easy to babble. Try and keep your answers concise and factual. Try and visualise the markscheme.
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Xerophytes This is a cross section of a marram grass leaf, taken with a light microscope.
Marram grass lives in sand dunes on windy coasts. It is therefore well adapted to dry conditions (xerophytic). Label the features that allow it to survive in theses
conditions.
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Some questions
Q1. (a) Figure 1 shows a section through the root of a young plant.
Figure 1
(i) Name the part of the plant labelled R.
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(ii) Give the letter which labels a tissue that transports solutes from the leaves.
Answer ...................................... (1)
(iii) Give the letter which labels a tissue that prevents the movement of water through the apoplast pathway.
Answer ...................................... (1)
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(b) Figure 2 shows a single stoma and surrounding cells from the leaf of a xerophytic plant.
Figure 2
(i) Explain how the cuticle reduces water loss.
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(ii) Explain how one of the other labelled parts reduces water loss.
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(Total 6 marks)
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Q2. (a) The table shows the transpiration rate of a group of plants exposed to different humidities at a temperature of 25°C.
Humidity / % Transpiration rate / arbitrary units
20 26.0
40 21.0
50 16.5
60 11.0
70 9.5
Describe and explain the relationship between humidity and transpiration rate.
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(b) The diagrams show a section through a typical leaf and a section through a leaf from a xerophytic plant. The xerophytic leaf has a lower transpiration rate than the typical leaf.
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Describe two features shown in the diagram of the xerophytic leaf which reduce transpiration rate. Explain how each of these features contributes to a lower transpiration rate.
Feature 1 ......................................................................................................
Explanation ...................................................................................................
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Feature 2 ......................................................................................................
Explanation ...................................................................................................
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(Total 7 marks)
Think:
- Lots of AO2 here – make sure you’re including the “why” as well as the “what”.
- When you are given a table, the most useful thing you can do is to draw a graph to check the trend.
- For the longer answers, make sure you could underline each individual point (for each mark). Again, visualise the markscheme.
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Extra notes
Use these last few pages to make any notes that you might find useful for your own
revision or understanding
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