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Zorluk: Çok zorPlant Biology and Photosynthesis

An aquatic plant is submerged in a sealed test tube containing water and a chemical indicator. The indicator is initially green, but it turns yellow in environments with high carbon dioxide (CO2CO_2) concentrations and blue in environments with low CO2CO_2 concentrations. If the sealed tube is placed in a completely dark room for 24 hours, which of the following best describes the resulting color of the indicator and the primary biological reason for this change?

  1. The indicator will turn yellow because the plant performs cellular respiration, which releases CO2CO_2 while photosynthesis is halted.Cevap
  2. B
    The indicator will turn blue because the plant continues to perform photosynthesis, drawing residual CO2CO_2 out of the water.
  3. C
    The indicator will remain green because plant cells lack mitochondria and completely cease gas exchange when light is removed.
  4. D
    The indicator will turn yellow because the chloroplasts reverse the process of photosynthesis to generate energy in the dark, releasing CO2CO_2.

Cevap

The indicator will turn yellow because the plant performs cellular respiration, which releases CO2CO_2 while photosynthesis is halted.
Although plants are best known for photosynthesis (which consumes carbon dioxide in the presence of light), they also possess mitochondria and must perform cellular respiration continuously to survive. In complete darkness, photosynthesis is halted, meaning carbon dioxide is no longer consumed. However, cellular respiration continues to break down glucose, resulting in a net release of carbon dioxide into the water. This accumulation of carbon dioxide causes the indicator to turn yellow.

Adım Adım Çözüm

1
Analyze the environmental conditions inside the sealed tube.
The plant is isolated in complete darkness for 24 hours.
Identifying the lack of light is crucial because it immediately dictates which metabolic pathways can function.
2
Determine the status of photosynthesis.
Photosynthesis halts entirely.
Photosynthesis requires solar energy to split water and fix carbon dioxide. Without light, CO2CO_2 consumption stops.
3
Determine the active metabolic processes in the plant cells.
Cellular respiration continues uninterrupted.
Like animals, plants contain mitochondria and must continuously burn glucose to produce ATP for survival, a process that consumes oxygen and releases CO2CO_2.
4
Evaluate the net change in gas concentrations.
Carbon dioxide (CO2CO_2) accumulates in the water.
Because respiration is releasing CO2CO_2 and photosynthesis is no longer consuming it, the net concentration of CO2CO_2 rises.
5
Relate the gas concentration to the chemical indicator.
The indicator shifts from green to yellow.
The stem states that the indicator turns yellow in high CO2CO_2 environments.

Anahtar Kavram

Plant Cellular Respiration and Gas Exchange
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Konular

Plant Biology and Photosynthesis

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