Term
| Describe the composition of a chloroplast |
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Definition
| Contains thylakoids, which stack into grana, all surrounded by stroma |
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Term
| Give the photosynthesis formula and name what is oxidised and what is reduced. |
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Definition
6 CO2 + 6 H2O ? C6H12O6 + 6 O2
Water is oxidised
Carbon dioxide is reduced
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Term
| Photosynthesis is a combination of what two processes? |
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Definition
| Light reactions and the calvin cycle (dark reactions) |
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Term
| Light reactions convert solar energy into ____ |
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Definition
| Chemical enery, ATP and NADPH |
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Term
| What are the different types of chlorophyll and what are their functions? |
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Definition
Chlorophyll a is the main photosynthetic pigment
Chlorophyll b is an accessory pigment, it absorbs different wavelengths of light because of its porphyrin ring and passes the energy to chlorophyll a |
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Term
| What is the role of chlorophyll? |
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Definition
| To absorb light and go from a ground state to an unstable excited state and release electrons |
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Term
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Definition
| A reaction center surrounded by a number of light-harvesting complexes |
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Term
| Describe light harvesting complexes |
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Definition
Consist of pigment molecules bound to proteins
Funnel the energy of photons of light to the reaction center |
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Term
| What happens when a reaction center chlorophyll molecule absorbs energy? |
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Definition
| One of its electrons gets bumped up to a primary acceptor |
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Term
| Where are photosystems I and II found? |
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Definition
| In the thylakoid membrane |
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Term
| What happens when the primary acceptor receives electrons from the reaction center chloroplasts? |
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Definition
| Depends on the photosystem, in photosystem I it triggers the production of NADPH from NADP+ reductase after the electron transport chain , in Photosystem II it triggers the production of ATP from the cytochrome complex during an electron transport chain, but also initiates Photosystem I through the reaction center (linked) |
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Term
| What is the main purpose of the dark cycle (the calvin cycle) and where does it occur? |
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Definition
Uses ATP and NADPH to convert CO2 to sugar
Occurs in the stroma, outside the thylakoids |
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Term
| Why is the Calvin cycle called the dark cycle? |
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Definition
| Because it doesn't require the input of light |
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Term
| What does the calvin cycle return to the light cycle? |
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Definition
| ADP, inorganic phosphate and NADP+ |
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Term
| In photosynthesis, water is split and oxygen released into the atmosphere. Does this occur in the light or dark reactions? |
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Definition
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Term
Name the three phases of the Calvin cycle in C3 plants and name the key molecules involved in each
1. Carbon fixation - Rubisco then ATP
2. Reduction - NADPH (sugar output)
3. Regeneration of Rubisco - ATP |
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Definition
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Term
| In photosynthesis, water and carbon dioxide enters; oxygen leaves. True or false? |
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Definition
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Term
| What happens in the calvin cycle during hot weather in c3 plants? |
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Definition
| Stomata close up, causes oxygen build up, rubisco starts incorporating oxygen instead of carbon dioxide, photosynthetic rate is reduced |
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Term
| How do C4 plants minimize the cost of photorespiration? |
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Definition
| By spatially confining the calvin cycle to very internal cells: carbon dioxide incorporated into four carbon organic acids (c4) in mesophyll cells by PEP carboxylase (NOT Rubisco). PEP carboxylase is not too sensitive to 02/CO2 ratios and can incorporate CO2 at very low concentrations. C4 is then exported to bundle sheath cells, where they release C)2 used in the calvin cycle |
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Term
| Are C4 plants better than C3 plants? Describe another type of plant that could be more efficient |
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Definition
Only at optimal (high) temperatures, at low temperatures C3 is more efficient
CAM plants: Temporal separation vs spatial separation - open stomata at night, incorporating CO2 into organic acids, close stomata during the day and CO2 is released from organic acids and used in calvin cycle |
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Term
| What is the connection between thylakoid stacks called? |
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Definition
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Term
| What is the inner space of a thylakoid called? |
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Definition
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Term
| Which are faster, light reactions of dark reactions? |
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Definition
| Light reactions are very fast, comparitively dark reactions are very slow (3.5 events per second) |
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Term
| What generates ATP and NADPH during photosystems I and II? |
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Definition
| The electron transport chain, proton gradient drivest ATPase and NADP+ reductase |
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Term
| Where is starch and sucrose synthesised and stored? |
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Definition
| Starch is synthesised and stored in chloroplasts, sucrose is synthesized in the cytosol and transported throughout plants |
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Term
| What 'fixes' CO2 into a 5C sugar during the Calvin cycle? |
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Definition
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Term
| Name the inputs and outputs of 1 turn of the Calvin cycle |
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Definition
Input: 3 ATP, 2 NADPH
Output: 1 molecule of CO2 fixed
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Term
3 CO2 + 6 NADPH + 5 H2O + 9 ATP > glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NAP+ + 9 ADP + 8 Pi (Pi = inorganic phosphate)
What is this formula? |
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Definition
| CO2 fixation in a C3 plant |
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Term
| How does rubisco end up with two 3C sugars (PGA)? And how can PGA be used to generate 6C sugars like glucose and fructose? |
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Definition
Fixes CO2 into 5C sugar, resulting 6C sugar is untable and breaks down into 2 3C sugars.
PGA is converted into G3P by NADPH and ATP which can be used to generate 6C sugars |
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