Autotrophs
An organism that makes their own food (complex organic compounds) from inorganic molecules using energy (chemical/ light) Producers in an ecosystem
Key Terms
Autotrophs
An organism that makes their own food (complex organic compounds) from inorganic molecules using energy (chemical/ light) Producers in an ecosystem...
Chemosynthesis
Making food using chemical energy
Photoautotrophs
Organisms that photosynthesise using sunlight
Relationship between respiration and photosynthesis
All organisms respire but not all photosynthesise Reverse processes
When do plants photosynthesise
In the day but always respire The intensity of light has to be sufficient to allow photosynthesis to replenish carbs used in respiration
Compensation point
The rate of photosynthesis is equal to the rate of respiration No net loss or gain of mass (carbs) CO2 uptake in Ps = CO2 production is R
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| Term | Definition |
|---|---|
Autotrophs | An organism that makes their own food (complex organic compounds) from inorganic molecules using energy (chemical/ light) Producers in an ecosystem |
Chemosynthesis | Making food using chemical energy |
Photoautotrophs | Organisms that photosynthesise using sunlight |
Relationship between respiration and photosynthesis | All organisms respire but not all photosynthesise Reverse processes |
When do plants photosynthesise | In the day but always respire The intensity of light has to be sufficient to allow photosynthesis to replenish carbs used in respiration |
Compensation point | The rate of photosynthesis is equal to the rate of respiration No net loss or gain of mass (carbs) CO2 uptake in Ps = CO2 production is R |
Compensation period | Time it takes to reach the compensation point |
Photosystems | Particles attached to thylakoid membranes Contain photosynthetic pigments which carry out the absorption of light in two distinct chlorophyll complexes |
Photosystem I (PSI) | Funnel-shaped Absorption wavelength is 700 nm Found in intergranal lamellae |
Photosystem II (PSII) | Funnel-shaped Absorption wavelength is 680 nm Found on the grana |
Chlorophyll a | Reflects blue-green |
Chlorophyll b | Reflects yellow - green An accessory pigment Absorbs light wavelengths 400-500nm (blue) and 640 (red) |
Accessory pigments | Carotenoids Xanthophyll Chlorophyll b Pass emitted electrons to the primary pigments which are then emitted (light harvesting pigments) This drives photosynthesis |
Carotenoids | Reflect yellow Absorb blue (400-500nm) |
Xanthophyll | Reflects yellow Absorbs blue/green (375-550) |
Absorption spectrum | Results of the calorimeter test plotted on a graph |
Action spectrum | Combined absorption spectra of pigments |
Structure of chlorophyll molecule | Porphyrin head - hydrophilic, flat head lies parallel to thylakoid membrane for maximum absorption Lipid soluble tail - hydrophobic, lies in thylakoid membrane Side chains - determines which wavelengths are absorbed |
Excitation of pigments by light | Chlorophyll pigments absorb light, electrons enter an ‘excited state’ This is unstable and electrons return to ‘ground state’ Lost excitation energy gets trapped during photosynthesis |
Chlorophyll excitement equation | chlorophyll –> chlorophyll^+ + e^- Reduced —-> oxidised + excited elctron |