Photosynthesis Flashcards
Define wavelength
Is the distance from peak to peak or trough to trough and is measured in nm
Define primary pigment
Chlorophyll a, found in reaction center, absorbs light energy and exited 2 electrons
Accessory pigments
Absorbs different wavelength of light, passes energy down to primary pigment
Explain what the absorption spectrum graph represents
How much light energy is absorbed by each pigemts across the different wavelength of lights
Explain what the action spectrum graph represents
Rate of photosynthesis across the different wavelength of light
Define oxidation
Loss of electrons or hydrogens
Define reduction
Gain of electrons or hydrogens
Define electron carrier
Proton molecule that transfer electrons in the electrons carrier chain
Define photolysis
Splitting water into protons, electrons and oxygen using light energy
Define photophosphorylation
Addition of phosphate of molecules using light energy
Define photoionisation
Molecules absorb light energy, exiting electrons to leave the molecule
Describe the process- light dependent
- Chlorophyll absorbs light energy
- Exited electrons out of chlorophyll
- Electrons move along electron transport chain releasing energy
- Energy used to join ADP and Pi to form ATP by chemiosmosis
- Photolysis of water produces protons, electrons and oxygen
- NADP reduced by electrons
- Oxygen is released as waste gas, ATP and red NADP go to light independent reaction
Define chemiosmosis
- Energy is releases by electrons pass along the electron transport chain in the thylokoid membrane
- Energy used to pump protons from the photolysis of water from the stroma into the intermembranal space
- Proton gradient established
- Protons flood from intermembranal space to stroma down concentration gradient
- Causing ATP synthesis to smash ADP + Pi forming ADP
Describe the pathway taken by which carbon dioxide from the atmosphere into the chloroplast
- Diffuses through stomata
- Diffuses through spongy mesophyll
- Dissolves in water around palisade cells
- Diffuses through palisade membrane
- Diffuses through palisade Cytoplasm
- Diffuses through chloroplasts envelope into the stroma
Describe the Calvin cycle/ independent reaction
- Carbon dioxide combines with ribulose bisphosphate using rubisco enzyme
- Produces an unstable 6 carbon which breaks into 2 glycerate phosphate molecules
- Glycerate phosphate reduced to triose phosphate
- Using reduced NADP and energy from ATP produced in light dependent stage
- Triose phosphate converted into glucose
- Or regenerated into ribulose bisphosphate
Define limiting factors
The factor present in the lowest amount and therefore the one that limits the rate of the overall reaction
Explain why as the temperature increases so does the rate of photosynthesis, the gradient is directly proportional
. Increase in kinetic energy
. Increase collisions
. Between the active site of RuBISCo and carbon dioxide
. More enzyme-substrate complexs
. More enzyme-product complexes
. More glycerate phosphate formed
Explain why as the temperature increaee the rate of photosynthesis decreases
. Increase in kinetic energy
. Breaks hydrogen bonds in tertiary structure
. Changes shape of active site of RuBISCo
. Active site no longer complementary to carbon dioxide
. Less enzyme-substrate complexes
. Less enzyme-product complexes
. Less glycerate phosphate formed
Describe photorespirarion
. RuBISCo optimum temperature is 25c. Above 25c RuBISCo works less efficiently
. Oxygen competes more successfully for the active site of RuBISCo and prevents the enzyme from binding to CO2
. ATP and reduced NADP from light dependent stage is wasted
. Photorespiration exceeds photosynthesis so rate of photosynthesis goes down
. Very high temperature can damage proteins involved in photosynthesis
Explain why as the light intensity increases so does the rate of photosynthesis, the gradient is directly proportional
. More light energy
. Increase excitation of electrons
. More photolysis/ photophosphorylation
. More ATP and reduced NADP made
Explain why as the light intensity increases the rate of photosynthesis stays constant
Another factor is limiting the rate. E.g temperature, carbon dioxide concentration
Explain how carbon dioxide concentration effects the rate of photosynthesis
. Increasing the concentration means more substrate available
. More collisions
. More enzyme-substrate complexes, so more enzyme-product complexes
. More glycerate phosphate produced
When there are multiple lines on the graph. How do you identify which factor is the limiting factor
. Does increasing or decreasing a factor change the rate?
. Yes= limiting factor
. No= not a limiting factor
What are greenhouses used for
. Achieve maximum yield
. Grow crops all year round
. Grow crops not native to the country
