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Zorluk: ZorPlant Biology and Photosynthesis

During an extended drought, a terrestrial plant keeps its leaf stomata tightly closed during daylight hours to conserve water. Which consequence directly explains why the plant's rate of glucose production drops significantly during this period?

  1. A
    The plant depletes internal oxygen (O2O_2), preventing the synthesis of carbohydrates in the light-independent reactions.
  2. The plant cannot take in carbon dioxide (CO2CO_2), starving the Calvin cycle of the carbon source needed for sugar synthesis.Cevap
  3. C
    The plant's cell walls lose the ability to capture photons in the absence of continuous water transpiration.
  4. D
    The mitochondria cease cellular respiration due to an overaccumulation of atmospheric water vapor in the mesophyll.

Cevap

The plant cannot take in carbon dioxide (CO2CO_2), starving the Calvin cycle of the carbon source needed for sugar synthesis.
Stomata are microscopic pores on plant leaves that facilitate the uptake of atmospheric carbon dioxide (CO2CO_2) and the release of oxygen and water vapor. When a plant closes its stomata to conserve water during drought conditions, CO2CO_2 can no longer diffuse into the leaf mesophyll. Because CO2CO_2 is the carbon source fixed by RuBisCO in the stroma during the Calvin cycle, its depletion directly halts the production of glucose (C6H12O6C_6H_{12}O_6).

Adım Adım Çözüm

1
Analyze the physiological function of stomata in plant leaves.
Stomata are epidermal pores that regulate both water loss via transpiration and gas exchange between the leaf interior and the atmosphere.
Understanding the anatomical role of stomatal opening and closing establishes what substances enter or leave the leaf.
2
Determine the biochemical requirements for sugar synthesis in photosynthesis.
The synthesis of glucose occurs in the stroma via the Calvin cycle, which requires atmospheric CO2CO_2 as the raw carbon donor.
Identifying the chemical equation (6CO2+6H2O→lightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2) pinpoints the limiting factor when gas exchange is halted.
3
Connect stomatal closure to the reduction in photosynthetic yield.
Closed stomata block CO2CO_2 diffusion into the mesophyll, halting the Calvin cycle despite available sunlight.
Without carbon fixation, glucose synthesis stops even if light-dependent energy carriers were briefly available.

Anahtar Kavram

Stomatal Regulation of Carbon Dioxide Intake for Photosynthetic Sugar Synthesis
Tahmini Süre:1m 5s
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Konular

Plant Biology and Photosynthesis

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