Class 11 Biology - ISC
Biomolecules
The chapter Biomolecules in Class 11 ISC Biology explores the chemical building blocks of living organisms. Students will study the structure, classification, and biological roles of carbohydrates, proteins, lipids, nucleic acids, and enzymes. A major focus is placed on enzyme action, factors affecting enzyme activity, and metabolic pathways like anabolism and catabolism. This chapter is vital for board exams as it forms the chemical foundation for physiology chapters. Examiners frequently test structural differences between polysaccharides, peptide bond formation, nucleic acid components, and the Lock-and-Key hypothesis of enzyme action through direct and application-based questions.
Start Learning FreeKey Concepts
Carbohydrates
Polyhydroxy aldehydes or ketones classified into monosaccharides, oligosaccharides, and polysaccharides that serve as primary energy sources and structural components.
Proteins and Amino Acids
Polymers of amino acids linked by peptide bonds, possessing primary, secondary, tertiary, and quaternary structures critical for structural and functional roles in cells.
Nucleic Acids
Polynucleotides comprising DNA and RNA formed by nitrogenous bases, pentose sugars, and phosphate groups, responsible for genetic information storage and transfer.
Enzymes
Biological catalysts, mostly proteins, that lower activation energy to speed up biochemical reactions, characterized by active sites and substrate specificity.
Lipids
Diverse hydrophobic molecules including triglycerides, phospholipids, and steroids that provide long-term energy storage and form cellular membranes.
Important Formulas
Board Exam Info
In the ISC Class 11 Biology examination, Biomolecules typically carries around 6 to 8 marks. Questions usually include objective MCQs, short-answer questions defining specific structures like zwitterions or glycosidic bonds, and structural differentiation problems such as comparing DNA and RNA or reducing and non-reducing sugars.
Frequently Asked Questions
Reducing sugars have free aldehyde or ketone groups that can reduce copper(II) ions (e.g., glucose and maltose), whereas non-reducing sugars lack free reactive groups because their anomeric carbons are involved in glycosidic bonds (e.g., sucrose).
Why are enzymes considered specific in their action?
Enzymes have a uniquely shaped active site that complements the specific substrate molecule, much like a lock and key, allowing only particular substrates to bind and undergo a reaction.
What is a zwitterion?
A zwitterion is a dipolar form of an amino acid that carries both a positive charge (on the amino group) and a negative charge (on the carboxyl group) simultaneously, resulting in a net charge of zero.
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