Class 11 Biology

An introduction to the diversity of life on Earth, what makes organisms 'living', the need for classification systems, the foundational concepts of taxonomy including nomenclature, identification, the hierarchical system of taxonomic categories, and a practical walkthrough applying the full hierarchy to four familiar organisms

The history and evolution of classification systems from Aristotle's earliest attempts through the Two Kingdom system to Whittaker's Five Kingdom framework, covering Kingdom Monera, Kingdom Protista, Kingdom Fungi, Kingdom Plantae, Kingdom Animalia, and the unique world of viruses, viroids, prions, and lichens

A detailed tour of the plant kingdom covering the evolution of classification systems from artificial to phylogenetic, the diversity of algae across Chlorophyceae, Phaeophyceae and Rhodophyceae, the land-pioneering bryophytes, vascular pteridophytes, seed-bearing gymnosperms, and the flowering angiosperms, along with the alternation of generations and plant life cycles

A comprehensive tour of the animal kingdom covering the basis of animal classification through levels of organisation, body symmetry, germ layers, coelom types, segmentation, and the notochord, followed by a systematic study of major non-chordate phyla from Porifera through Hemichordata, and a detailed look at chordate classes from jawless fish to mammals, with a final comparative overview of key features across all phyla

A detailed study of the external form and structure of flowering plants covering root systems, stems, leaves, flowers, fruits and seeds, along with descriptions of important plant families

A detailed study of the internal structure and tissue organisation of higher plants, covering the three tissue systems, internal anatomy of dicot and monocot roots, stems, and leaves, and the process of secondary growth

A study of how cells organise into tissues, tissues into organs, and organs into organ systems in multicellular animals, illustrated through the detailed morphology and anatomy of the frog

From cell discovery to cell theory, the reductionist approach to molecular biology, a deep dive into cell structure and organelles, prokaryotic cell organisation including bacterial shapes, plasmids, mesosomes, and the cell envelope, eukaryotic cells with plant versus animal cell differences, the detailed structure and function of the plasma membrane (fluid mosaic model, transport mechanisms) and plant cell wall, the endomembrane system (ER, Golgi apparatus, lysosomes, vacuoles), mitochondria (double-membrane structure, cristae, matrix, ATP production, semi-autonomous nature), plastids (chloroplasts with thylakoids and grana, chromoplasts, leucoplasts and their storage subtypes), ribosomes (80S and 70S, subunit architecture, Svedberg unit), the cytoskeleton (microtubules, microfilaments, intermediate filaments), cilia and flagella (axoneme with 9+2 microtubule array, basal bodies), centrosomes and centrioles (cartwheel organisation, triplet fibrils, spindle apparatus formation), the nucleus (nuclear envelope with double membrane and pores, perinuclear space, nucleoplasm, chromatin, nucleolus as rRNA factory), chromosomes (chromatin composition with DNA and histones, centromere and kinetochores, four chromosome types by centromere position, secondary constrictions and satellites), and microbodies (membrane-bound enzyme-containing vesicles in plant and animal cells)

How scientists analyse the chemical composition of living tissues, the acid-soluble pool and acid-insoluble fraction, the relative abundance of carbon and hydrogen in living matter, biomolecules, inorganic constituents, destructive analysis (wet weight, dry weight, ash), the structure and properties of amino acids including the zwitterionic form, lipids from fatty acids to phospholipids, the hierarchy of nitrogen bases to nucleosides to nucleotides that build DNA and RNA, the distinction between primary metabolites (universal across life) and secondary metabolites (unique to plants, fungi, and microbes), biomacromolecules versus micromolecules including the lipid exception and the average chemical composition of a cell, proteins as heteropolymers of amino acids with diverse biological roles including enzymes, hormones, transporters, and structural support, the four levels of protein structure from primary sequence through secondary helices and sheets to tertiary 3D folding and quaternary multi-subunit assembly with haemoglobin as a key example, polysaccharides including cellulose, starch, glycogen, inulin, and chitin, nucleic acids as polynucleotides with five nitrogenous bases classified as purines and pyrimidines and how ribose versus deoxyribose determines whether the polymer is RNA or DNA, enzymes as biological catalysts with active sites, the distinction between physical changes and chemical reactions, reaction rates and temperature effects, the staggering catalytic power of carbonic anhydrase, how metabolic pathways channel glucose into different end products depending on aerobic or anaerobic conditions, how enzymes lower activation energy to speed up reactions through the transition state and the four-step catalytic cycle from enzyme-substrate complex to product release, how temperature pH and substrate concentration shape enzyme performance with optimum conditions and saturation kinetics, competitive inhibition by substrate-mimicking chemicals, the six-class international system for naming and organising enzymes, and the role of non-protein co-factors (prosthetic groups, co-enzymes, and metal ions) that many enzymes need for catalytic activity

How cells reproduce through a tightly controlled cycle of growth, DNA duplication, and division, the distinct phases of interphase and M phase, the four stages of mitosis from prophase through telophase and the splitting of cytoplasm in cytokinesis, the significance of mitosis in growth and repair, how meiosis halves the chromosome number through two successive divisions with crossing over and genetic recombination, the five sub-stages of prophase I including synapsis and chiasmata formation, the events of meiosis II that resemble mitosis, and the role of meiosis in maintaining chromosome number across generations and generating genetic variation

How green plants capture light energy and convert it into chemical energy, the photosynthetic machinery of chloroplasts and pigment systems, the light reactions that split water and produce ATP and NADPH, the Calvin cycle that fixes carbon dioxide into sugar, photorespiration and C4 pathways, and the factors that influence the rate of photosynthesis

How plants break down food molecules within cells to release energy, the step-wise oxidation of respiratory substrates, glycolysis, fermentation under anaerobic conditions, the TCA cycle, the electron transport chain, ATP as the universal energy currency of the cell, the amphibolic nature of the respiratory pathway, and the respiratory quotient as a measure of the type of substrate being respired

How plants grow from a single zygote into complex organisms, the characteristics and phases of growth, arithmetic and geometric growth rates, differentiation and dedifferentiation, the concept of development as the sum of growth and differentiation, plasticity, plant growth regulators including auxins, gibberellins, cytokinins, ethylene, and abscisic acid, their discovery, physiological effects, and roles in plant development, photoperiodism and vernalisation

How the human respiratory system brings oxygen into the body and removes carbon dioxide, covering respiratory organs, the mechanics of breathing, lung volumes and capacities, gas exchange at the alveolar and tissue level, oxygen and carbon dioxide transport in blood, neural and chemical regulation of breathing, and common respiratory disorders

How blood and lymph transport nutrients, gases, and waste products throughout the body, covering the composition of plasma and formed elements, blood groups, coagulation, the structure and working of the human heart, the cardiac cycle, the electrocardiogram (ECG), double circulation through pulmonary and systemic loops, the vascular system, and common circulatory disorders

How animals produce and get rid of metabolic waste, covering the three main nitrogenous wastes (ammonia, urea, uric acid), the classification of animals based on their excretory strategy (ammonotelic, ureotelic, uricotelic), the diverse excretory structures found across the animal kingdom, the organs of the human urinary system, the detailed internal architecture of the kidney, the structure and types of nephrons, how the kidneys form urine through glomerular filtration, reabsorption, and tubular secretion, the specialised function of each tubular segment from the PCT through Henle's loop and DCT to the collecting duct, how the counter current mechanism involving Henle's loop and vasa recta builds the medullary osmolarity gradient to concentrate urine, how hormonal feedback systems involving ADH, the renin-angiotensin mechanism, and atrial natriuretic factor regulate kidney function, the micturition reflex and urine characteristics, excretory roles of the lungs, liver, and skin, and disorders including uremia, hemodialysis, kidney transplantation, renal calculi, and glomerulonephritis

How living organisms move and travel from place to place, covering the difference between movement and locomotion, the three types of cellular movement (amoeboid, ciliary, and muscular), the structure and types of skeletal muscles including the organisation of muscle fibres, myofibrils, sarcomeres, and contractile proteins (actin and myosin), the mechanism of muscle contraction explained through the sliding filament theory and the role of calcium ions, the human skeletal system with its 206 bones divided into the axial skeleton (skull, vertebral column, sternum, ribs) and the appendicular skeleton (limb bones and girdles), the classification of joints into fibrous, cartilaginous, and synovial types, and common disorders of the muscular and skeletal system including myasthenia gravis, muscular dystrophy, tetany, arthritis, osteoporosis, and gout

How the neural system coordinates body functions through specialised cells called neurons, covering the organisation of the neural system from simple nerve nets in Hydra to the complex brain and spinal cord of vertebrates, the structure and types of neurons, the central and peripheral divisions, the anatomy of the human brain and spinal cord, the generation and conduction of nerve impulses, synaptic transmission, reflex arcs, and the sensory organs including the eye and ear

How hormones produced by endocrine glands act as chemical messengers to coordinate body functions, covering the human endocrine system from the hypothalamus and pituitary to the thyroid, parathyroid, adrenal, pancreas, and gonads, the structure and function of each gland, the hormones they secrete, the disorders caused by their over- or under-secretion, hormones from non-endocrine tissues, and the mechanisms by which hormones act on target cells