Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

3. Acids and Bases

Organic Chemistry Reactions

Organic Chemistry

3. Acids and Bases

Organic Chemistry Reactions

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Multiple Choice

Which of the following mechanisms do C4 plants use to minimize photorespiration?

They increase the concentration of oxygen in the chloroplasts.

They utilize a specialized enzyme called PEP carboxylase to initially fix CO2.

They use CAM pathway to fix carbon dioxide.

They perform photosynthesis only at night to avoid oxygen interference.

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Verified step by step guidance

Understand the problem: The question is about the mechanism C4 plants use to minimize photorespiration, which is a process that can reduce the efficiency of photosynthesis.

Identify the key concept: C4 plants have evolved a mechanism to efficiently fix carbon dioxide (CO2) even under conditions where oxygen (O2) might interfere, such as high temperatures and light intensities.

Recognize the role of PEP carboxylase: C4 plants utilize an enzyme called phosphoenolpyruvate (PEP) carboxylase, which has a higher affinity for CO2 and does not react with O2, unlike the enzyme RuBisCO used in C3 plants.

Explain the initial fixation process: In C4 plants, CO2 is initially fixed into a four-carbon compound (hence the name C4) by PEP carboxylase in mesophyll cells. This compound is then transported to bundle-sheath cells where CO2 is released for the Calvin cycle.

Clarify the advantage: By concentrating CO2 in bundle-sheath cells, C4 plants effectively reduce photorespiration and increase photosynthetic efficiency, especially in hot and dry environments.