Which of the following statements are correct regarding amino acids? A. They are substituted methanes. B. Serine is an aromatic amino acid. C. Valine is a neutral amino acid. D. Lysine is an acidic amino acid. Choose the correct answer from the options given below:

Core Logic

Let's check each statement:

• Statement A is false: Lipids are generally water-insoluble.
• Statement B is true: Proteins are heteropolymers made of amino acids, known as polypeptides.
• Statement C is true: Polysaccharides are long polymeric chains of monosaccharides (sugars).
• Statement D is false: Adenine and guanine are substituted purines, not pyrimidines. (Cytosine, Uracil, and Thymine are pyrimidines).
• Statement E is true: Almost all enzymes are proteins (with some exceptions like ribozymes).

Step 1: Final Conclusion

Statements B, C, and E are correct.

Pattern Recognition

Knowing Purines = Adenine, Guanine (Pure As Gold) instantly marks D as incorrect. Eliminating D removes options 1 and 3. Knowing Lipids are non-polar (insoluble) eliminates A, leaving only option 2.

Chapter Mix

Class 11 Biology: Biomolecules

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

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.

Chapter Mix

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