Identify the correct statements about biomolecules. A. Lipids are generally water soluble. B. Proteins are polypeptides. C. Polysaccharides are long chains of sugars. D. Adenine and guanine are substituted pyrimidines. E. Almost all enzymes are proteins. Choose the correct answer from the options given below:

Core Logic

Proteins possess hierarchical structural levels:

• Primary: Linear sequence of amino acids.
• Secondary: Local folded structures, most notably the alpha-helix (right-handed coils) and beta-pleated sheets, stabilized by hydrogen bonds.
• Tertiary: 3D overall folding of a single polypeptide chain (hollow ball-like structure).
• Quaternary: Arrangement of multiple polypeptide chains.

Step 1: Final Conclusion

Alpha-helix is a prime example of the secondary structure of proteins.

Pattern Recognition

Alpha-helix and beta-sheet are the two universally taught examples of secondary structure.

Chapter Mix

Class 11 Biology: Biomolecules

Core Logic

• Statement A is correct. Amino acids can be conceptualized as substituted methanes (an alpha-carbon substituted with an amino group, carboxyl group, hydrogen, and an R group).
• Statement B is incorrect. Serine contains a hydroxyl group (alcoholic amino acid). Aromatic amino acids are Tyrosine, Phenylalanine, and Tryptophan.
• Statement C is correct. Valine is a neutral amino acid (one amino group, one carboxyl group).
• Statement D is incorrect. Lysine is a basic amino acid, not acidic. (Glutamic acid and Aspartic acid are acidic).

Step 1: Final Conclusion

Only statements A and C are correct.

Pattern Recognition

Basic amino acids = HAL (Histidine, Arginine, Lysine). Knowing Lysine is basic eliminates D. Aromatic = Phenylalanine, Tyrosine, Tryptophan. Eliminates B.

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Class 11 Biology: Biomolecules

Core Logic

From the secondary metabolites and proteins table in NCERT:

• Trypsin (A) is a classic proteolytic Enzyme. (A-III)
• Morphine (B) is a secondary metabolite classified as an Alkaloid. (B-IV)
• Concanavalin A (C) is a carbohydrate-binding protein known as a Lectin. (C-II)
• Collagen (D) is the most abundant protein in the animal world and serves as an Intercellular ground substance. (D-I)

Step 1: Final Conclusion

The correct matches are A-III, B-IV, C-II, D-I.

Pattern Recognition

Collagen = Intercellular ground substance (D-I) and Trypsin = Enzyme (A-III) are very common. Combining these gives only option 1.

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Class 11 Biology: Biomolecules

Core Logic

Lyases are the enzymes that catalyse the removal of groups from substrates by mechanisms other than hydrolysis, leaving double bonds.

• Transferases are the enzymes that catalyse a transfer of a group between a pair of substrates.
• Isomerases catalyse inter-conversion of optical, geometric or positional isomers.
• Ligases catalyse the linking together of 2 compounds.

Pattern Recognition

Formation of a double bond upon removal of groups without water (non-hydrolytic cleavage) indicates Lyases.

Chapter Mix

Class 11 Biology: Biomolecules