Class 11 Biology Chapter 5 Enzymes Notes | Punjab Board PDF
Chapter-wise notes covering Active Sites, Cofactors, Lock-and-Key & Induced Fit Models, Environmental Factors, Enzyme Inhibition, and Classification - with solved exercises, MCQs, short questions, and long questions aligned with PCTB / PECTAA syllabus for Class 11 HSSC Part 1 students.
Chapter Overview
Class 11 Biology Chapter 5, "Enzymes", explores biological biocatalysts responsible for regulating metabolic pathways in living cells according to the Punjab Curriculum and Textbook Board (PCTB / PECTAA) curriculum. The chapter outlines the physical and chemical characteristics of enzymes, lowering of activation energy, active site architecture (binding and catalytic sites), and non-protein assistants including cofactors, coenzymes, and prosthetic groups.
Core theoretical models of enzyme action-Emil Fischer's rigid Lock-and-Key hypothesis and Daniel Koshland's flexible Induced Fit Model-are rigorously examined alongside kinetic variables affecting enzymatic velocity (temperature, pH, enzyme concentration, substrate saturation). The chapter also details regulatory mechanisms including competitive and non-competitive enzyme inhibition, allosteric feedback inhibition, and systematic classification based on reaction types and substrate affinities.
Enzymes represents a core scoring chapter in Punjab Board HSSC Part 1 papers, frequently featured in graph interpretations, short definitions (e.g., apoenzyme vs holoenzyme), and descriptive long questions on factors affecting enzyme rate or inhibition mechanisms. These SLO-focused notes include completely solved textbook exercises, objective MCQs, and conceptual exam answers for students across all Punjab educational boards.