The Question is from neet-botany , and it was created by the author Mr. NARESH KUMAR K

Question

In the context of photorespiration, what are the immediate products formed when RuBisCo acts as an oxygenase?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: Option B
## CONCEPT FRAMEWORK
 **Primary Concept**: Photorespiration and RuBisCo's dual functionality
 **Related Topics**: Calvin cycle, photosynthesis, C3 plants, glycolate pathway
 **Prerequisites**: Understanding of RuBisCo's active site and its interaction with both CO2 and O2.
## SOLUTION PATHWAY
**Given Information**:
  RuBisCo acts as an oxygenase.
  We need to identify the immediate products.
**Method & Steps**:
 1. Understand RuBisCo's dual function:
  Reasoning: Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) is an enzyme crucial in the Calvin cycle.  It catalyzes the first major step of carbon fixation in photosynthesis. However, RuBisCo can also bind to oxygen instead of carbon dioxide, leading to photorespiration.
  Formula/Rule:  None explicitly needed, but understanding the reaction is key.
 2. Analyze the oxygenase reaction:
  Working: When RuBisCo acts as an oxygenase, it reacts with RuBP (ribulose-1,5-bisphosphate) and O2. This reaction yields one molecule of 2-phosphoglycolate and one molecule of 3-phosphoglycerate.
  Key Point: The reaction is not symmetrical like the carboxylase reaction. One product is a 2-carbon compound (phosphoglycolate), while the other is a 3-carbon compound (phosphoglycerate).
 3. Identify the immediate products:
  Result: One molecule of 3-phosphoglycerate and one molecule of 2-phosphoglycolate are the immediate products.
  Verification: This aligns with the established understanding of RuBisCo's oxygenase activity and the initiation of the photorespiration pathway.
 ## OPTION ANALYSIS
A :x: Two molecules of phosphoglycerate are produced when RuBisCo acts as a carboxylase, not an oxygenase.
B ✓: One molecule of phosphoglycerate and one molecule of phosphoglycolate accurately reflect the products of RuBisCo's oxygenase activity.
C :x: Two molecules of phosphoglycolate are not formed; only one is a product of the oxygenase reaction.
D :x: Phosphoglyceraldehyde is a product of the later stages of the Calvin cycle, not a direct product of RuBisCo's oxygenase activity.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the products of RuBisCo's carboxylase and oxygenase activities: Remember that the oxygenase activity leads to a different set of immediate products.
  2.Forgetting that the products are not in equal amounts: It's one molecule of each, not two of one and one of the other.
 **Quick Tips**:
  1.Remember that photorespiration is a wasteful process resulting from RuBisCo's affinity for oxygen.
  2.Visualize the reaction: Imagine RuBP breaking down into a 2-carbon and a 3-carbon compound.

Mr. NARESH KUMAR K · Answer

Two molecules of phosphoglycerate

Mr. NARESH KUMAR K · Answer

The correct Option is "One molecule of phosphoglycerate and one molecule of phosphoglycolate"

Mr. NARESH KUMAR K · Answer

Two molecules of phosphoglycolate

Mr. NARESH KUMAR K · Answer

One molecule of phosphoglyceraldehyde and one molecule of phosphoglycolate

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