Q.8 Which of the following statement is incorrect ?
I. Ramachandran plot is related to protein structure.
2. Watson and Crick discovered the stmcture of DNA. proteins and RNA
3. Calvin cycle inccnporates all the carbon backbone of biomolecules.
4. Both 2 and 3
Ramachandran plot relates to protein backbone angles, while statements about Watson-Crick and the Calvin cycle contain inaccuracies. The incorrect statements are 2 and 3.
Option Analysis
Statement 1: Ramachandran Plot
The Ramachandran plot visualizes allowed phi (φ) and psi (ψ) dihedral angles in protein polypeptide chains, helping validate 3D structures. It is exclusively linked to protein secondary structure analysis, not nucleic acids or lipids. This statement is correct.
Statement 2: Watson and Crick Discovery
James Watson and Francis Crick discovered the double-helix structure of DNA in 1953, using X-ray data from Rosalind Franklin and Maurice Wilkins. They did not discover structures of proteins or RNA; protein structures (e.g., alpha helix by Pauling) and RNA details emerged separately. This statement is incorrect.
Statement 3: Calvin Cycle Role
The Calvin cycle (dark reactions of photosynthesis) fixes atmospheric CO₂ into glyceraldehyde-3-phosphate (G3P), a 3-carbon sugar. G3P forms glucose and other carbohydrates, but not the full carbon backbone of all biomolecules like proteins (amino acid-derived), lipids (acetyl-CoA derived), or nucleic acids (from ribose/phosphate pathways). This statement is incorrect.
Statement 4: Both 2 and 3
Since both 2 and 3 are incorrect, this identifies the combined inaccuracies. Thus, 4 is the answer.
The incorrect statement Ramachandran plot Watson Crick Calvin cycle question tests core molecular biology concepts vital for exams like NEET and GATE Life Sciences. This MCQ evaluates knowledge of protein structure tools, DNA history, and photosynthesis pathways, helping students pinpoint common misconceptions.
Ramachandran Plot in Protein Structure
Ramachandran plots map φ and ψ angles to predict stable conformations in proteins, excluding nucleic acids. Useful for validating PDB models.
Watson and Crick’s DNA Breakthrough
Watson and Crick unveiled DNA’s double helix in 1953, not proteins or RNA structures. Key for genetics but limited to DNA.
Calvin Cycle Limitations
It assimilates CO₂ into sugars, not all biomolecule backbones like amino acids or fatty acids.
| Aspect | Correct Fact | Common Error |
|---|---|---|
| Ramachandran Plot | Proteins only | Applies to RNA/DNA |
| Watson-Crick | DNA double helix | Includes proteins/RNA |
| Calvin Cycle | C3 sugars from CO₂ | All biomolecules |
Mastering these distinctions boosts accuracy in competitive biology exams.
