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Weekly plan 10
Photosynthesis
Student book links
Specification links
Link to GCSE/AS specification
Suggested time allowed (includes contact and non-contact time):
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6 hours
1.3.1
1.3.2
1.3.3
1.3.4
4.3.1 (a)–(n)
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GCSE Photosynthesis
Food chains
Cell structure
Adaptation
AS 1.1.1 Cell structure
1.1.2 Cell membranes
2.1.1 Biological molecules
2.1.2 Nucleic acids
2.1.3 Enzymes
Suggested teaching order
1.
2.
3.
4.
5.
Function of photosynthesis as an energy conversion process
Structure and function of chloroplasts
Photosynthetic pigments
Light-dependent stage
Light-independent stage
Weekly learning outcomes
Students should be able to:
 Define the terms: autotroph and heterotroph.
 State that light energy is used during photosynthesis to produce complex organic molecules.
 Explain how respiration in plants and animals depends upon the products of photosynthesis.
 State that in plants photosynthesis is a two-stage process that takes place in chloroplasts.
 Explain with the aid of diagrams and electron micrographs how the structure of chloroplasts
enables them to carry out their functions.
 Define the term: photosynthetic pigment.
 Explain the importance of photosynthetic pigments in photosynthesis.
 State that the light-dependent stage takes place in thylakoid membranes and that the lightindependent stage takes place in the stroma.
 Outline how light energy is converted to chemical energy (ATP and reduced NADP) in the lightdependent stage.
 Explain the role of water in the light-dependent stage.
 Outline how the products of the light-dependent stage are used in the light-independent stage
(Calvin cycle) to produce triose phosphate (TP) – referring also to ribulose bisphosphate
(RuBP), ribulose bisphosphate carboxylase (rubisco) and glycerate 3-phosphate (GP).
 Explain the role of carbon dioxide in the light-independent stage.
 State that TP (and GP) can be used to make carbohydrates, lipids and amino acids.
 State that most TP is recycled to RuBP.
The web links referred to here are some that the author has found personally helpful but are not intended to be a comprehensive list, many other
good resources exist.
© Pearson Education Ltd 2009
This document may have been altered from the original
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Weekly plan 10
Key words
How Science Works
Autotroph
Heterotroph
Oxidising
Prokaryote
Decomposer Stomata
Consumer
Exergonic
Chloroplast
Digest
Organelle
Lamellae
Aerobe
Thylakoid
Photosystem
Stroma
Photolysis
Chlorophyll
Rubisco
Reduced NADP
Electron carrier
Ribulose bisphosphate (RuBP)
Glycerate 3-phosphate (GP)
Triose phosphate (TP)
Protoctist
Photosynthetic pigment
NADP
Chloroplast envelope
Endocytosis Light-independent stage
Eukaryote
Light-dependent stage
Granum
Cyclic photophosphorylation
Coenzyme
Non-cyclic photophosphorylation
Chemiosmosis
Chemoautotroph
Electron acceptor
Primary pigment reaction centre
Photoautotroph
Learning styles (S = Starter activities, M = Main activities, P = Plenary activities)
Kinaesthetic
Activities S1&3
Activities M1–3
Activities P1–3
Interpersonal
Activities S1–3
Activities M1–3
Activities P1–3
Auditory
Activities S1–3
Activities M1–3
Activities P1–3
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HSW 1 Outline how radioactively labelled oxygen and carbon
in CO2 helped scientists to understand the reactions involved
in photosynthesis.
ICT activities
Visual
Activities S1–2
Activities M1–3
Activities P1–3
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See Activities M1 and M2 below – using a word processor and
spreadsheet to process data.
See Activity M3 below – using PowerPoint or an animation
programme to produce a storyboard.
See Activity P2 below – using the Internet to create a study
stack.
Suggested starter activities
Equipment
Teacher notes
1. Play Taboo.
Cards as described
Prepare cards using key words that the students have
previously met – underneath each one include a list of
banned words. In pairs, one student describes the key word
without using the banned words.
2. In groups, brainstorm five structural features required by
chloroplasts in order to carry out photosynthesis – identify
each feature’s function.
Use the results from the Practical activities in Activities M1
and M2 below to help start a discussion on how a
chloroplast’s structure is related to its function.
3. Play Chinese whispers.
One student from each group whispers one thing they know
about photosynthesis, etc.
4. Make a 3D model of a chloroplast.
Provide a range of discarded dry
packaging, as well as teat pipettes,
balloons and clear plastic bags.
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Weekly plan 10
5. Examine plant cells (e.g. leaf) under microscope and
observe (and measure) length of chloroplasts
Microscopes, lamps, prepared slides of
T.S. leaf, eyepiece graticule, stage
micrometer
Suggested main activities
Equipment
Teacher notes
1. Practical activity 5: Extracting chloroplasts using
ultracentrifugation
See technician worksheet.
See teacher worksheet.
2. Practical activity 6: Using extracted chloroplasts in the Hill
reaction
See technician worksheet.
See teacher worksheet.
3. Produce a cartoon storyboard to show the reaction
pathways involved in photosynthesis.
Card, paper, colours
Suggested plenary activities
Equipment
1. Play Snap.
Cards with (i) key words from this Weekly
Plan written on one half and (ii) their
definitions written on the other half
Teacher notes
2. In groups, students design a role-play to show what
happens in either the light-dependent or light-independent
stages.
3. Play True or false.
Read out some facts about photosynthesis – students move
to different corners of the room depending if they think these
facts are true, false or not sure.
Homework suggestions
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Write the script for a radio advertisement for herbicides, that act by inhibiting photosynthesis – research the action of one of these herbicides and include in the
broadcast. (Record the advertisement to be played in a subsequent lesson.)
Compare and contrast photosynthesis and respiration.
Write the transcript of a chat room discussion between the major scientists involved in discovering the mechanism of photosynthesis – go back as far as Jan van
Helmont and as far forward as Rudolph Marcus, including a summary of their work.
Cross-curriculum links
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Chemistry – redox, ionisation
Physics – energy, radioactivity, light and absorption spectra
© Pearson Education Ltd 2009
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Weekly plan 10
Stretch and Challenge
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The links to the AS specification stated on page 1 are a good opportunity to develop Stretch and Challenge skills.
Two species of marine molluscs, Elysia viridis and Elysia chlorotica, incorporate chloroplasts from algae into their cells. Suggest what benefits the molluscs gain by
such an arrangement.
Research the action of rubisco in the light-independent stage and explain why illumination of chloroplasts will lead to optimum conditions for the enzyme. Suggest why
there has been no selection of plants with rubisco enzymes having reduced oxygenase activity. Suggest how genetically modified plants with an altered tertiary
structure of rubisco could improve the efficiency of photosynthesis. Explain why plant tissues contain the enzyme catalase and why rubisco is described as the most
important enzyme on Earth.
Potential misconceptions
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Present photosynthesis after respiration – in contrast to the order given in the specification – as the progression of ideas works better.
Some students may still think that plants photosynthesise, while animals respire.
Some students may still think that plants only respire at night.
It is easy for students to confuse the mechanisms of respiration and photosynthesis.
Students can find the concept of energy difficult to understand.
Help students understand the 3D nature of chloroplasts.
It is important to clarify the nature of reduction and oxidation reactions early on, as these can be confusing at GCSE.
When you present an overview to the students, it is worth doing so against a diagram of the chloroplast – they can link the stages to the different locations early on.
Students often miss the s out of bisphosphate.
Students often confuse NADP with NAD and these can also appear in diagrams with H added, e.g. NADH! – refer to NADP or reduced NADP as appropriate.
Only present the level of detail given in the textbook – although many other textbooks will give much more detail, it is more important for students to pick up the main
ideas rather than the detail of every compound produced.
Some students will find it difficult to simply accept that energy is released when electrons pass along a chain of electron carriers.
Spend some time on terminology such as carboxylation, photphosphorylation, cyclic and non-cyclic photophosphorylation.
It is worth reinforcing the relationship between proton concentration and pH.
Notes
© Pearson Education Ltd 2009
This document may have been altered from the original
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