Q.67 Match List I with List II
| LIST I Metabolic Cycles |
LIST II Organelle(s) involved |
|---|---|
| A. Glyoxylate Cycle B. Citric acid cycle C. Calvin Cycle D. C₂ oxidative Photosynthesis cycle |
I. Chloroplast II. Glyoxysome III. Mitochondria, Chloroplast, Peroxisome IV. Mitochondria |
Choose the correct answer from the options given below:
Correct Answer: Option 4 (A-II, B-IV, C-I, D-III)
The Glyoxylate Cycle occurs in glyoxysomes, the Citric Acid Cycle (TCA cycle) takes place in mitochondria, the Calvin Cycle happens in chloroplasts [known biology fact, standard textbook knowledge], and the C₂ oxidative photosynthesis cycle (photorespiration) involves mitochondria, chloroplasts, and peroxisomes [standard plant physiology].
Matching Explanation
Each metabolic cycle links to specific organelles based on their biochemical roles in plants.
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A. Glyoxylate Cycle → II. Glyoxysome: This cycle allows plants to convert fatty acids into carbohydrates during seed germination. Key enzymes like isocitrate lyase and malate synthase operate in glyoxysomes, specialized peroxisomes.
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B. Citric Acid Cycle → IV. Mitochondria: Also called the Krebs or TCA cycle, it generates energy via acetyl-CoA oxidation in the mitochondrial matrix.
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C. Calvin Cycle → I. Chloroplast: This light-independent photosynthesis phase fixes CO₂ into sugars using stroma enzymes in chloroplasts [standard].
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D. C₂ oxidative Photosynthesis Cycle → III. Mitochondria, Chloroplast, Peroxistome: Photorespiration (C₂ cycle) salvages 2-phosphoglycolate, shuttling metabolites across chloroplasts (Rubisco oxygenation), peroxisomes (glycolate oxidase), and mitochondria (glycine decarboxylation) [standard plant biology].
Option Analysis
| Option | A (Glyoxylate) | B (Citric Acid) | C (Calvin) | D (C₂ Cycle) | Correct? |
|---|---|---|---|---|---|
| 1 | II (Correct) | I (Wrong) | II (Wrong) | IV (Wrong) | No |
| 2 | IV (Wrong) | II (Wrong) | III (Wrong) | I (Wrong) | No |
| 3 | I (Wrong) | III (Wrong) | IV (Wrong) | II (Wrong) | No |
| 4 | II (Correct) | IV (Correct) | I (Correct) | III (Correct) | Yes |
Only option 4 matches all correctly.
Introduction to Metabolic Cycles and Organelles
In plant cell biology, metabolic cycles like Glyoxylate Cycle, Citric Acid Cycle, Calvin Cycle, and C₂ oxidative photosynthesis cycle occur in specific organelles such as glyoxysomes, mitochondria, chloroplasts, and peroxisomes. This NEET-style matching question tests precise localization knowledge.
Key Metabolic Cycles Breakdown
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Glyoxylate Cycle: Bypasses CO₂ loss in TCA for gluconeogenesis from fats in germinating seeds. Glyoxysomes house it.
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Citric Acid Cycle: Aerobic respiration core in mitochondria matrix.
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Calvin Cycle: CO₂ fixation in chloroplast stroma.
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C₂ Oxidative Photosynthesis Cycle (Photorespiration): Wasteful O₂ fixation pathway spanning chloroplasts, peroxisomes, mitochondria [III].
Why Option 4 is Correct
A-II (Glyoxysome), B-IV (Mitochondria), C-I (Chloroplast), D-III (Multi-organelle). Others mismatch, e.g., option 1 wrongly places Citric Acid in chloroplasts.
Exam Tips for Organelle Matching
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Recall: Glyoxysomes unique to plants for fat-to-sugar conversion.
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Visualize shuttles in photorespiration.
