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Questions and Answers
What role does RuBisCO play in C₃ plants?
What role does RuBisCO play in C₃ plants?
- It increases the concentration of O₂ for photorespiration.
- It serves as a transportation molecule for glucose.
- It catalyzes the reaction of CO₂ fixation in mesophyll cells. (correct)
- It fixes CO₂ in bundle sheath cells.
Which enzyme do C₄ plants utilize to fix CO₂ initially?
Which enzyme do C₄ plants utilize to fix CO₂ initially?
- Carbonic anhydrase
- NADP+ reductase
- PEP carboxylase (correct)
- RuBisCO
What is a significant advantage of the C₄ photosynthetic pathway?
What is a significant advantage of the C₄ photosynthetic pathway?
- Enhanced growth rate in low light conditions.
- Higher RuBisCO concentrations.
- Reduced photorespiration. (correct)
- Increased oxygen production.
How do C₄ plants minimize competition between CO₂ and O₂ in the photosynthetic process?
How do C₄ plants minimize competition between CO₂ and O₂ in the photosynthetic process?
What is the main consequence of photorespiration in plants?
What is the main consequence of photorespiration in plants?
Flashcards
Photorespiration
Photorespiration
A process where oxygen competes with carbon dioxide for the enzyme RuBisCO, reducing photosynthesis efficiency by wasting carbon.
C₃ plants
C₃ plants
Plants that fix CO₂ directly in the mesophyll cells, using RuBisCO, making them susceptible to photorespiration, especially in high light intensity or warm and dry conditions.
C₄ plants
C₄ plants
Plants that initially fix CO₂ in mesophyll cells using PEP carboxylase, concentrating CO₂ near RuBisCO in bundle sheath cells. This minimizes O₂ competition and photorespiration.
RuBisCO
RuBisCO
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PEP carboxylase
PEP carboxylase
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Study Notes
Photorespiration in C3 and C4 Plants
- Photorespiration is a process where O₂ competes with CO₂ for the active site of the enzyme RuBisCO.
- RuBisCO is the key enzyme in the Calvin cycle, which is part of photosynthesis.
- In C₃ plants, photorespiration can occur when O₂ concentration is high relative to CO₂.
- Photorespiration leads to a reduction in photosynthetic efficiency in C₃ plants.
- C₄ plants have a mechanism to increase CO₂ concentration near RuBisCO, minimizing photorespiration.
- C₄ plants fix CO₂ in mesophyll cells, then transport the fixed carbon to bundle sheath cells.
- This process concentrates CO₂ in the bundle sheath cells, increasing the rate of CO₂ fixation and reducing O₂ competition.
- Concentrating CO₂ in C₄ plants improves productivity and tolerance to higher temperatures.
- Photorespiration does not occur in C₄ plants because they employ a mechanism to increase the concentration of CO₂ at the enzyme site .
CO₂ Fixation in C₄ Plants
- C₄ plants use a two-step process for CO₂ fixation.
- Initially, CO₂ combines with a 3-carbon molecule (PEP) to form a 4-carbon compound.
- This 4-carbon compound is transported to bundle sheath cells, where it releases CO₂.
- CO₂ then enters the Calvin cycle, promoting photosynthesis with high efficiency.
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Description
Explore the intricate mechanisms of photorespiration in C3 and C4 plants. This quiz covers how RuBisCO interacts with CO₂ and O₂, the differences in efficiency, and the strategies C4 plants use to enhance photosynthesis. Test your understanding of these fundamental processes in plant biology.
