How Much Do You Know About the C4 Pathway?

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  • 1/10 Questions

    In which part of the plant does the initial carbon fixation occur in C4 plants?

    • Mesophyll cells
    • Stomata
    • Xylem cells
    • Phloem cells
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About This Quiz

Are you ready to challenge yourself with our C4 Pathway Quiz? This quiz will check how well you know the C4 pathway, an important process in photosynthesis that some plants use. In this quiz, you will learn how C4 plants fix carbon and how they have adapted to different environments.
You will also explore the role of PEPCase and the spatial separation of the C4 and Calvin cycles in different cells. This quiz will help you understand the key aspects and benefits of C4 photosynthesis in plant biology.See how much you know about plant physiology and biochemistry by answering questions on the C4 pathway. This quiz is a great way to enhance your knowledge and interest in this amazing topic of plant biology.

How Much Do You Know About The C4 Pathway? - Quiz

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  • 2. 

    Which enzyme is responsible for catalyzing the initial step of the C4 pathway?

    • Rubisco

    • PEP carboxylase

    • RuBP carboxylase

    • ATP synthase

    Correct Answer
    A. PEP carboxylase
    Explanation
    Phosphoenolpyruvate carboxylase (PEPCase) is responsible for catalyzing the initial step of the C4 pathway by fixing carbon dioxide to phosphoenolpyruvate (PEP) to form oxaloacetate. This enzyme, present in the mesophyll cells of C4 plants, plays a crucial role in carbon assimilation and represents a key adaptation that distinguishes C4 plants from C3 plants. By efficiently capturing atmospheric CO2 in the form of C4 acids, PEPCase helps to minimize photorespiration and optimize carbon fixation under conditions of high light intensity and temperature.

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  • 3. 

    In C4 plants, which cells are responsible for the Calvin cycle?

    • Bundle sheath cells

    • Mesophyll cells

    • Xylem cells

    • Phloem cells

    Correct Answer
    A. Bundle sheath cells
    Explanation
    The Calvin cycle, where carbon fixation occurs, takes place in the bundle sheath cells of C4 plants. Following the initial fixation of CO2 into four-carbon compounds in the mesophyll cells, these C4 acids are transported to the bundle sheath cells, where they release CO2 for use in the Calvin cycle. This spatial separation of initial carbon fixation and the Calvin cycle allows C4 plants to minimize photorespiration and optimize photosynthetic efficiency by concentrating CO2 around the enzyme Rubisco, thereby enhancing carbon fixation rates and biomass production under conditions of high light intensity and temperature.

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  • 4. 

    What is the primary function of phosphoenolpyruvate carboxylase (PEPCase) in the C4 pathway?

    • Fixing carbon dioxide

    • Synthesizing glucose

    • Breaking down ATP

    • Transporting water

    Correct Answer
    A. Fixing carbon dioxide
    Explanation
    The primary function of phosphoenolpyruvate carboxylase (PEPCase) in the C4 pathway is to fix carbon dioxide during the initial steps of photosynthesis. PEPCase catalyzes the carboxylation of phosphoenolpyruvate (PEP) with CO2 to form oxaloacetate, a four-carbon compound. This reaction represents the first step in the C4 pathway, where atmospheric CO2 is assimilated into organic acids in the mesophyll cells of C4 plants. By efficiently capturing CO2 and channeling it into the C4 cycle, PEPCase helps to minimize photorespiration and optimize carbon fixation rates, particularly under conditions of high light intensity and temperature.

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  • 5. 

    What is the primary function of the C4 pathway in plants?

    • Oxygen production

    • Nitrogen fixation

    • Carbon fixation

    • Water absorption

    Correct Answer
    A. Carbon fixation
    Explanation
    The primary function of the C4 pathway is to fix carbon dioxide from the atmosphere into organic molecules during photosynthesis. This process begins with the capture of atmospheric CO2 by phosphoenolpyruvate carboxylase (PEPCase) in the mesophyll cells, leading to the formation of a four-carbon compound. These C4 acids are then transported to the bundle sheath cells, where they release CO2, fueling the Calvin cycle for further carbon fixation. By spatially separating initial CO2 fixation and the Calvin cycle, the C4 pathway enhances photosynthetic efficiency and minimizes photorespiration, particularly under high light and temperature conditions.

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  • 6. 

    Which environmental condition is most favorable for C4 plants?

    • High temperature

    • Low light intensity

    • High humidity

    • Low carbon dioxide concentration

    Correct Answer
    A. High temperature
    Explanation
    C4 plants are most favorable in high-temperature environments, where they exhibit better photosynthetic efficiency compared to C3 plants. Due to their specialized anatomy and biochemical adaptations, C4 plants are well-suited to thrive in hot and dry conditions, where they can maintain optimal photosynthetic rates and water use efficiency. By concentrating CO2 around the enzyme Rubisco in bundle sheath cells, C4 plants minimize photorespiration and enhance carbon fixation rates, allowing them to outperform C3 plants in environments characterized by high temperatures and limited water availability. As a result, C4 plants are commonly found in tropical and subtropical regions, where they play crucial roles in ecosystem dynamics and agricultural productivity.

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  • 7. 

    What is the main role of malate or aspartate in the C4 pathway?

    • Transporting electrons

    • Transporting carbon dioxide

    • Transporting glucose

    • Transporting water

    Correct Answer
    A. Transporting carbon dioxide
    Explanation
    Malate or aspartate is involved in transporting carbon dioxide from the mesophyll cells to the bundle sheath cells in C4 plants. These C4 acids serve as carriers of fixed carbon, facilitating the transport of CO2 from the site of initial fixation in the mesophyll cells to the site of Calvin cycle activity in the bundle sheath cells. This spatial separation of carbon fixation and assimilation allows C4 plants to minimize photorespiration and optimize photosynthetic efficiency, particularly under conditions of high light intensity and temperature. By effectively shuttling CO2 to the Calvin cycle, malate and aspartate contribute to the enhanced water use efficiency and productivity of C4 plants in diverse environmental conditions.

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  • 8. 

    Which type of plants primarily utilize the C4 pathway?

    • Trees

    • Cacti

    • Grasses

    • Mosses

    Correct Answer
    A. Grasses
    Explanation
    Grasses, such as corn and sugarcane, primarily utilize the C4 pathway for photosynthesis due to their adaptation to hot and dry environments. Unlike C3 plants, which dominate in temperate climates, C4 plants have evolved this pathway to optimize carbon fixation and minimize water loss through transpiration. This specialized biochemical pathway enables C4 plants to thrive in conditions of high light intensity and limited water availability, making them essential crops in agriculture.

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  • 9. 

    What is the ultimate product of the C4 pathway in plants?

    • Oxygen

    • Glucose

    • Water

    • Carbon dioxide

    Correct Answer
    A. Glucose
    Explanation
    The ultimate product of the C4 pathway in plants is glucose, which is synthesized through the Calvin cycle following carbon fixation. After atmospheric CO2 is initially fixed into four-carbon compounds in the mesophyll cells, these C4 acids are transported to the bundle sheath cells, where they release CO2 for use in the Calvin cycle. Through a series of enzymatic reactions in the stroma of chloroplasts, CO2 is assimilated into triose phosphates, which are then converted into glucose and other carbohydrates. This glucose serves as the primary source of energy and carbon for the plant, fueling various metabolic processes and providing the building blocks for growth and development.

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  • 10. 

    What is the primary advantage of the C4 pathway over the C3 pathway?

    • Higher water use efficiency

    • Higher light utilization

    • Lower energy requirement

    • Lower carbon dioxide fixation rate

    Correct Answer
    A. Higher water use efficiency
    Explanation
    One of the primary advantages of the C4 pathway over the C3 pathway is its higher water use efficiency, making C4 plants more drought-resistant. By spatially separating initial carbon fixation and the Calvin cycle between mesophyll and bundle sheath cells, respectively, C4 plants can minimize photorespiration and conserve water under conditions of high light intensity and limited water availability. This adaptive mechanism allows C4 plants to maintain optimal photosynthetic rates and biomass production even in arid and semi-arid environments, making them essential components of ecosystems and agricultural systems in regions prone to drought stress.

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Quiz Review Timeline (Updated): Feb 8, 2024 +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Feb 08, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Feb 06, 2024
    Quiz Created by
    Surajit Dey
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