Alternative Carbon Fixation Pathways
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Photorespiration is an alternative pathway that occurs when Rubisco captures O2 instead of CO2 during the Calvin cycle, especially during high temperatures when plants close their stomata to reduce water loss. This pathway uses up fixed carbon and wastes energy.
What is photorespiration?
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About 85% of plants on earth experience this metabolic pathway as they execute the
normal or standard process of carbon fixation wherein, CO2 with Rubisco produces 3-PGA, a
3-carbon compound. They belong to the category of C3 plants which employ the "C3 pathway"
as a precursor to Calvin cycle (Bear & Ritoul, 2018).
normal or standard process of carbon fixation wherein, CO2 with Rubisco produces 3-PGA, a
3-carbon compound. They belong to the category of C3 plants which employ the "C3 pathway"
as a precursor to Calvin cycle (Bear & Ritoul, 2018).
Metabolic pathway used by 85% of plants during carbon fixation. C3 plants use "C3 pathway" to produce 3-PGA, a 3-carbon compound, with CO2 and Rubisco.
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C4 and CAM plants are plant species that have evolved counter-mechanisms to combat photorespiration. C4 plants physically separate the locations of the light-dependent reaction and the Calvin cycle, while CAM plants open their stomata at night to reduce water loss and fix carbon dioxide into organic acids.
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What are C4 and CAM plants?
What are C4 and CAM plants?
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CAM photosynthesis is a process used by some plants to counter photorespiration by separating carbon fixation and the Calvin cycle by time instead of space.
What is CAM photosynthesis?
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Crassulacean Acid Metabolism
**What does CAM stand for?**
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PEP carboxylase fixes CO2 into oxaloacetate during the CAM pathway.
PEP carboxylase fixes CO2 into oxaloacetate during the CAM pathway.
What is the role of PEP carboxylase in the CAM pathway?
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In C4 plants, after the initial fixation of CO2 by PEP carboxylase, oxaloacetate is formed and then converted to malate or another organic acid that is temporarily stored in leaf vacuoles.
Oxaloacetate is then converted to malate or into another organic acid that is temporarily stored in leaf vacuoles.
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During daytime, photosynthesis can still occur as the organic acids stored in the vacuoles are released and broken down into CO2 for attachment to Rubisco, eventually allowing the Calvin cycle to occur.
During daytime, photosynthesis can still occur as the organic acids stored in the vacuoles are released and broken down into CO2 for attachment to Rubisco, eventually allowing the Calvin cycle to occur.
What happens during photosynthesis when plants close their stomata during the daytime?
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CAM plants are very efficient in using and storing water, allowing them to thrive well in arid habitats like deserts.
CAM plants are very efficient in using and storing water, allowing them to thrive well in arid habitats like deserts.
What is the advantage of CAM plants in arid habitats?