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59 Cards in this Set
- Front
- Back
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Name the main photosynthetic tissue in the leaf. |
Palisade mesophyll |
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What is the role of stomata? |
They are essential for gas exchange in the leaf |
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Give four adaptions of leaves. |
They have a large surface area, they are thin so light penetrated photosynthetic tissues, the palisade layer is densely packed and contains a lot of chloroplasts, air spaces allow carbon dioxide to diffuse to photosynthetic cells |
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Why does the light dependent stage take place? |
In the thylakoid membrane and thylakoid cavity of chloroplasts |
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Where does the light independent stage take place? |
In the stroma of chloroplasts |
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Where are photosynthetic pigments found? |
Within the thylakoid membranes of chloroplasts |
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Name the primary pigment |
Chlorophyll a |
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Which wavelength of light does chlorophyll a absorb? (Both wavelength and colour) |
Blue and red wavelength (425nm to 675nm) |
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Which wavelength of light does chlorophyll b absorb? |
Blue and red (450nm to 640nm) |
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Which wavelength of light do carotenoids absorb? |
Violet/ blue (475nm) |
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Suggest an experiment to measure the rate of photosynthesis? |
Count the number of bubbles produced by pond weed over a set period of time |
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Explain why accessory pigments are important in photosynthesis. |
Accessory pigments are important as they absorb wavelengths of light not absorbed by the primary pigment |
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Which macronutrient is needed for the production of chlorophyll a? |
Magnesium |
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How do you calculate Rf values? |
Rf values= distance travelled by the pigment / distance travelled by solvent |
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Why do you had acetone? |
To dissolve the phospholipid membrane to extract the pigments |
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Why do you add a solvent? |
To dissolve the solute and carry the pigment up the chromatography filter paper |
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Why does one substance move farther than another? |
The more soluble the pigment is in the solvent the further travels |
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How do you identify pigment use in the RF value? |
Each pigment has a unique RF so you can compare RF values of unknown substances to RF values of known pigments |
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What do absorption spectrums show? |
The amount of light absorbed by each photosynthetic pigment at each wavelength of light |
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Why is little absorbed between 530 nm and 640nm? What is the relationship between an absorption spectra and the action spectrum? |
Plants don’t absorb green light it is reflected |
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What is the relationship between absorption spectrum and action spectrums? |
There is a correlation between the two spectra this suggests that the pigments are responsible for absorbing the light used in photosynthesis |
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What is the role of photosystems? |
To absorb photons of light |
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What happens to NADP in the light dependent reaction? |
It is reduced to form NADPH/H+ |
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What is released as a by product in the light dependent reaction? |
Oxygen gas |
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What are the two light dependent reactions? |
Cyclic and non-cyclic photophosphorylation |
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How many electrons are raised to a higher energy level in the light dependent reaction? where are they passed to? |
2, they are passed to an electron acceptor |
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Where does the electron acceptor pass the electrons? |
Along a chain of carriers thorough a proton pump to photosystem I. |
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What happens as the electrons pass from carrier to carrier? |
Their energy levels decrease |
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What happens when the electrons pass through the pump? |
Energy is released from the electrons and is used to provide energy to pump hydrogen ions from the stroma across the thylakoid membrane into the thylakoid cavity. |
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What is created as the H+ ions move into the thylakoid cavity? |
An electrochemical gradient |
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What happens to the H+ ions that allows the formation of ATP from ADP and Pi? |
They flow down the proton gradient through protein channels, providing energy for the formations of ATP by ATP synthetase |
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What happens at photosystem I? |
It absorbs photons of light, causing the two electrons to be raised to a higher energy level where they are picked up by another electron acceptor. |
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What does it mean by photosystems act as transducers? |
The transfer light energy to high energy electrons, which fuels proton pumps and synthesises ATP |
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What happens when the electrons reach the second electron acceptor? |
They are passed outside of the thylakoid membrane into the stroma where they reduce NADP |
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As the electrons are not recycle back into the chlorophyll what is this process known as? |
Non-cyclic photophosphorylation |
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Why does photolysis occur? |
To replace the electrons lost by photosystem II, and to help maintain the electrochemical gradient between the thylakoid cavity and the stroma |
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How are the accessory pigments structures in photosystems? |
They are grouped into clusters with associated proteins, forming an antenna complex |
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How does the antenna complex help the photosystems complete it’s role? |
The accessory pigments absorb photos of light and funnel this energy down the antenna complex to the reaction centre below. |
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Which molecules are found in the reaction centre? |
Chlorophyll a |
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What happens when the photons of light reach chlorophyll a? |
Electrons are excited to become high energy electrons |
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Which wavelength of light does photosystem a best absorb? |
700nm |
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Which wavelength of light does photosystem b best absorb? |
680nm |
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What is the name for ATP being synthesised from ADP and Pi in the light dependent reaction? |
Photophosphorylation |
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What is the name for the splitting of water using light? |
Photolysis |
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Which photo system is involved in cyclic phosphorylation? |
Only PS I |
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Why is ATP also required for the reduction of G3P? |
ATP is hydrolysed and the G3P is phosphorylated resulting in the formation of two molecules of triode phosphate |
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One carbon atom is then removed from the Calvin cycle and can be used to product glucose what happens to the remaining 5 carbon atoms? |
They are used to regenerate RuBP |
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What happens when the amount of CO2 falls? |
Less RuBP is used to fix CO2, but it continues to be regenerated so the concentration increases. However, as less RuBP is used to fix CO3, less of the 6C compound forms and less GP is formed. |
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What happens in the dark? |
GP increases in the dark as CO2 is fixed to RuBP, but there is less of the light dependent products such as reduced NADP and ATP, so less GP is reduced to TP. Glucose falls because it is used up in respiration and not replaced and RuBP falls as it is used by but not regenerated. |
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Other than glucose name three other products made from the carbon removed from the Calvin cycle. |
Hexose phosphates (sucrose, starch and cellulose), amino acids and lipids |
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Which species use cyclic phosphorylation? |
Bacteria, primitive plants or higher plants when CO2 is in short supply |
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Where are the electrons realised from in cyclic phosphorylation? |
The magnesium ion at the centre of the chlorophyll molecule |
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What are the products of the light dependent stage of photosynthesis used for in the Calvin cycle? |
ATP and NADPH/H+ are used in the fixation of carbon dioxide |
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Where does the light independent stage take place? |
In the stoma of the chloroplasts |
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What is carbon dioxide from the atmosphere fixed with? |
Ribulose -1,5- bisphosphate |
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Which enzyme catalyses the reaction between our RuBP and CO2? |
Rubisco |
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What does the reaction between RuBP and CO2 form? |
And unstable six carbon compound |
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What does the unstable six carbon compound split off into? |
Two molecules of glycerate 3 phosphate |
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What is glycerate 3 phosphate then reduced using? |
NADPH/H+ |
