Class 11 Biology Notes

About the Class 11 Biology Notes

Class 11 Biology is the foundation of the CBSE syllabus and NEET, and it is where most of the theory-heavy scoring sits. These chapter-wise notes follow the NCERT order exactly, so you can revise in sequence or jump straight to the chapter that needs work. Each page carries the key facts, the few equations that matter, exam pointers and solved examples.

Diversity in the Living World (Chapters 1–4)

• The Living World — characteristics of living organisms and the need for classification, taxonomy, taxonomical aids and binomial nomenclature.
• Biological Classification — the five-kingdom system, Monera, Protista, Fungi, Plantae and Animalia, plus viruses, viroids, prions and lichens.
• Plant Kingdom — algae, bryophytes, pteridophytes, gymnosperms and angiosperms, with their life cycles.
• Animal Kingdom — the basis of classification and the major phyla from Porifera to Chordata.

Plant and Animal Forms (Chapters 5–7)

• Morphology of Flowering Plants — root, stem and leaf and their modifications, inflorescence, flower, placentation, fruit and seed, plus the families.
• Anatomy of Flowering Plants — meristematic and permanent tissues, tissue systems, and dicot versus monocot anatomy including secondary growth.
• Structural Organisation in Animals — epithelial, connective, muscular and neural tissues, and the frog as a representative animal.

Cell Biology and Biomolecules (Chapters 8–10)

• Cell: The Unit of Life — prokaryotic and eukaryotic cells, the organelles, and the nucleus.
• Biomolecules — carbohydrates, proteins, lipids, nucleic acids, enzymes and the metabolites in living systems.
• Cell Cycle and Cell Division — interphase, mitosis, meiosis and the significance of each.

Plant Physiology (Chapters 11–13)

• Photosynthesis in Higher Plants — the light reactions (Z-scheme), the Calvin cycle, the C4 pathway and photorespiration.
• Respiration in Plants — glycolysis, the Krebs cycle, the electron transport chain and oxidative phosphorylation.
• Plant Growth and Development — growth phases, plant hormones, photoperiodism and vernalisation.

Human Physiology (Chapters 14–16)

• Breathing and Exchange of Gases — the respiratory system, mechanism of breathing, respiratory volumes, gas exchange and transport.
• Body Fluids and Circulation — blood, blood groups, coagulation, the cardiac cycle and double circulation.
• Excretory Products and their Elimination — the human excretory system, nephron, urine formation and hormonal regulation.

Solved Examples

Two representative questions you are likely to meet, worked through in full.

Example 1: State the rules for writing a scientific name, using Mangifera indica as the example.

Solution: The scientific name is written with the genus first (capitalised) and the species second (lowercase), both italicised or underlined when handwritten, and followed by the abbreviating author — Mangifera indica is the mango. The same format holds whatever the language of the name.

Example 2: How many ATP (net) and NADH molecules does one molecule of glucose produce during glycolysis in a plant cell?

Solution: Glycolysis breaks glucose into two pyruvate molecules, giving a net 2 ATP (4 produced minus 2 consumed in the energy-investment phase) and 2 NADH per glucose. The pyruvate then enters the Krebs cycle, so glycolysis is only the first stage of aerobic respiration.