Chapter 6 Biomolecules Notes - Class 9 Biology Punjab Board

This page provides Class 9 Biology Chapter 6, Biomolecules, notes for Punjab Board students following the PCTB syllabus for the 2026-2027 session. It includes solved exercises, important MCQs, and short and long questions on carbohydrates, proteins, lipids, nucleic acids, and the working of DNA and RNA, and can be read online by SSC Part 1 and Matric Part 1 students.

Chapter 6 of Class 9 Biology, Biomolecules, introduces students to the chemical building blocks that make up all living organisms. The chapter opens with an overview of biomolecules and explains why these large organic molecules are essential for the structure and function of cells. Students are then taken through the four major classes of biomolecules — carbohydrates, proteins, lipids, and nucleic acids — with each class explained in terms of its composition, types, and biological role. Carbohydrates are studied as sources of energy and structural materials, with attention to monosaccharides, disaccharides, and polysaccharides.

Proteins are covered in terms of their amino acid composition, peptide bonds, and the diversity of functions they perform — from enzymes and hormones to structural components of cells. Lipids are examined as energy-storage molecules, membrane components, and chemical messengers. The chapter then turns to nucleic acids, explaining the structure of DNA and RNA, the difference between the two types, and the role each plays in storing and transmitting genetic information. The section on the working of DNA and RNA walks students through how genetic information is stored in DNA and how RNA uses that information during protein synthesis.

This chapter is important for Punjab Board exams because biomolecules underpin the content of the enzyme and bioenergetics chapters that follow. Punjab Board papers regularly include short questions on the functions of carbohydrates, proteins, and lipids, and concept questions on the structure and working of DNA and RNA. These solved notes are organized to help SSC Part 1 students build a clear understanding of each biomolecule class and revise efficiently before their annual Biology exams.