Answer ( 1 )

  1. It promotes Photorespiration.
    The C3 plants fix carbon using the Calvin cycle of photosynthesis in which the RuBP and carbon dioxide react forming two three-carbon molecules known as 3-phosphoglyceric acid (3-PGA). This is the desired reaction for the plant.
    This C3 type of photosynthesis is actually found in more than 80% of plants but it does have some drawbacks. Some of the time the RuBP instead combines with oxygen rather than the carbon dioxide. This process is known as photorespiration and is a wasteful process.
    Temperature and carbon dioxide concentration in cells strongly determines the quantum yield of the C3 plant. This yield is a measure of how effective and efficient photosynthesis is and it relates the number of photons absorbed to the reactions that occur.
    It is when the carbon dioxide level drops that it becomes a problem and the enzyme rubisco starts to combine the oxygen with the RuBP instead of the carbon dioxide.
    In other words, the system shifts to photorespiration. The result of this is that the rate of photosynthesis and the quantum yield can drop dramatically.
    The C3 plant conserves water in hot and dry conditions by closing the stomata. The carbon dioxide needed for photosynthesis enters the leaves via these openings and water vapor exits the plant in the same way.
    This means that when these pores are closed that carbon dioxide drops relative to the oxygen in the plant, resulting in photorespiration occurring.

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