If plant gene alterations cause the plants to be deficient in photorespiration, what would most...

Question:

If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur?

A) Cells would carry on more photosynthesis.

B) Cells would carry on the Calvin cycle at a much slower rate.

C) Less ATP would be generated.

D) There would be more light-induced damage to the cells.

E) More sugars would be produced.

Photorespiration:

Photorespiration is a process in which the RUBISCO oxidizes the RUBP using atmospheric oxygen. The resultant molecule of this reaction is 2-phosphoglycerate which cannot enter into the Calvin cycle.

Answer and Explanation: 1

The correct answers areA) Cells would carry on more photosynthesis, D) There would be more light-induced damage to the cells, E) More sugars would be produced.

RUBISCO can use both oxygen and carbon dioxide and undergoes oxidation or carboxylation of RUBP respectively. If the RUBISCO utilise carbon dioxide, RUBP undergoes carboxylation that produces the product 3-phosphoglyceric acid which can enter into the Calvin cycle. If the RUBISCO utilises oxygen and RUBP undergoes oxidation, results in the product 2-phosphoglycolate (photorespiration) that cannot enter into the Calvin cycle. If plant gene alterations cause the plants to be deficient in photorespiration, that may increase the cellular photosynthesis as the RUBISCO can use carbon dioxide completely and oxygen cannot interfere. There would be more light-induced damage to the cell because photorespiration utilizes the excessive redox potential of the cell under high light that may protect the photosystem from the photo damage This mechanism is called photoinhibition. More sugars can be produced if the photorespiration is stopped as the RUBISCO give 3-phosphoglycerate which can enter the Calvin cycle results in the more sugar production.

Explanation to incorrect options:

The cell will not carry on the Calvin cycle at a much slower rate as it is acquiring more 3-phosphoglycerate which is an initial product of the Calvin cycle. ATP wasting is reduced if the photorespiration has defected so the ATP generated in the light reaction is efficiently utilized for the carbon fixation.


Learn more about this topic:

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The Role of Photosynthesis in the Life of Animals

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Chapter 5 / Lesson 4
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Learn what photosynthesis is and what it does. Explore why photosynthesis is important. Understand the benefits of photosynthesis for both humans and animals.


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