| Science NCERT Exemplar Solutions (Class 6th to 10th) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6th | 7th | 8th | 9th | 10th | ||||||||||
| Science NCERT Exemplar Solutions (Class 11th) | ||||||||||||||
| Physics | Chemistry | Biology | ||||||||||||
| Science NCERT Exemplar Solutions (Class 12th) | ||||||||||||||
| Physics | Chemistry | Biology | ||||||||||||
Class 11th Biology NCERT Exemplar Solutions
1. The Living World
This introductory chapter defines what constitutes a 'living' organism by examining definitive characteristics like metabolism, cellular organisation, and consciousness. It explores the immense biodiversity on our planet and establishes the need for a structured system of classification. The chapter delves into the principles of taxonomy and systematics, explaining the universal system of binomial nomenclature proposed by Carolus Linnaeus for naming organisms. It details the taxonomic hierarchy, a framework for classifying organisms into successive levels from species to kingdom. Finally, it describes essential taxonomic aids such as herbaria, botanical gardens, and museums, which are crucial for the identification and study of species.
2. Biological Classification
This chapter presents the scientific approach to classifying the vast array of living organisms. It traces the evolution of classification systems, culminating in R.H. Whittaker's widely accepted Five Kingdom Classification. This system categorizes organisms based on criteria like cell structure, mode of nutrition, and body organisation into five distinct kingdoms: Monera (all prokaryotes like bacteria), Protista (unicellular eukaryotes), Fungi (heterotrophic organisms with chitinous cell walls), Plantae (multicellular, autotrophic producers), and Animalia (multicellular, heterotrophic consumers). The chapter also discusses organisms that do not fit neatly into this scheme, such as viruses, viroids, and lichens, highlighting the complexity and ongoing refinement of biological classification.
3. Plant Kingdom
This chapter provides a detailed survey of the Plant Kingdom, outlining the characteristics and evolutionary progression of its major groups. It begins with the simplest plants, Algae, followed by Bryophytes (the amphibians of the plant kingdom). It then moves to Pteridophytes, the first terrestrial plants to possess vascular tissues (xylem and phloem). The chapter further explores seed-bearing plants, distinguishing between Gymnosperms (which have naked seeds) and the highly evolved Angiosperms (flowering plants with seeds enclosed in fruits). A central concept discussed is the alternation of generations, the life cycle pattern involving both haploid (gametophyte) and diploid (sporophyte) stages, which varies across these plant groups.
4. Animal Kingdom
This chapter offers a comprehensive classification of the immensely diverse Animal Kingdom. It explains the fundamental criteria used for classification, such as levels of organisation, symmetry, number of germ layers (diploblastic/triploblastic), and the nature of the body cavity or coelom. The chapter systematically describes the salient features and provides characteristic examples for each major phylum, starting from the simplest invertebrates like Porifera and Coelenterata, and progressing through Platyhelminthes, Annelida, Arthropoda (the largest phylum), Mollusca, Echinodermata, and finally to the phylum Chordata. This systematic approach reveals the evolutionary relationships and increasing complexity among animal groups.
5. Morphology Of Flowering Plants
This chapter focuses on the external structure, or morphology, of flowering plants (angiosperms). It provides a detailed description of the various parts of a plant and their modifications, which are adaptations for specific functions. The chapter covers the root system (tap and fibrous), the stem, the leaf (including venation and phyllotaxy), the inflorescence, the flower, the fruit, and the seed. It elaborates on how these structures can be modified for functions like storage, support, protection, and reproduction. Understanding morphology is essential for identifying plants and appreciating their adaptations to diverse environments.
6. Anatomy Of Flowering Plants
This chapter shifts the focus from external form to the internal structure, or anatomy, of flowering plants. It describes the different types of tissues and their organisation. It classifies plant tissues into meristematic tissues (apical, lateral, intercalary) responsible for growth, and permanent tissues. Permanent tissues are further divided into simple tissues (parenchyma, collenchyma, sclerenchyma) and complex tissues—xylem and phloem—which form the vascular system for transport. The chapter details the anatomical differences between dicot and monocot roots, stems, and leaves, and also explains the process of secondary growth, which increases the girth of dicot stems and roots.
7. Structural Organisation In Animals
This chapter examines how cells are organised into tissues, organs, and organ systems in animals. It provides a detailed account of the four primary types of animal tissues: epithelial tissue, which forms coverings and linings; connective tissue, which provides support and includes diverse types like bone, cartilage, and blood; muscular tissue, responsible for movement; and nervous tissue, which facilitates communication and control. To illustrate how these tissues work together, the chapter presents a detailed study of the morphology and anatomy of three representative animals: the earthworm (an annelid), the cockroach (an arthropod), and the frog (an amphibian).
8. Cell - The Unit Of Life
This chapter reinforces the concept of the cell as the fundamental structural and functional unit of life, as stated in the Cell Theory. It provides an overview of cell diversity and distinguishes between simple prokaryotic cells (lacking a nucleus) and more complex eukaryotic cells. The chapter then takes a detailed tour of a eukaryotic cell, explaining the structure and function of its various membrane-bound organelles. This includes the endomembrane system (endoplasmic reticulum, Golgi complex, lysosomes), mitochondria (the powerhouse), plastids (like chloroplasts), and the nucleus, which houses the cell's genetic material. The roles of the cytoskeleton, cilia, and flagella are also described.
9. Biomolecules
This chapter explores the chemistry of life, focusing on the organic molecules, or biomolecules, that make up living cells. It details the structure, properties, and biological roles of the four major classes of macromolecules. These are carbohydrates (for energy and structure), proteins (which perform a vast array of functions, with their structure described at four levels), lipids (for energy storage and membranes), and nucleic acids (DNA and RNA), which store and transmit genetic information. The chapter also provides a crucial introduction to enzymes, the protein catalysts that speed up biochemical reactions, explaining their mechanism of action and the factors that regulate their activity.
10. Cell Cycle And Cell Division
This chapter describes the life of a cell, known as the cell cycle, which includes a period of growth and DNA replication (Interphase) followed by cell division (M phase). It explains the two main types of cell division in eukaryotes. Mitosis is an equational division where a parent cell produces two genetically identical daughter cells, essential for growth and repair. Meiosis is a reductional division that occurs in germ cells to produce four genetically unique haploid gametes, a process crucial for sexual reproduction and creating genetic diversity through crossing over. The chapter details the distinct stages of both mitosis and meiosis (Prophase, Metaphase, Anaphase, Telophase) and their biological significance.
11. Transport In Plants
This chapter explains the physiological processes involved in the movement of water, minerals, and food within a plant. It covers short-distance transport mechanisms like diffusion and active transport, as well as the principles of water potential and osmosis. The long-distance transport of water and minerals from the roots to the leaves through the xylem is explained by the cohesion-tension-transpiration pull theory. The chapter also details the translocation of sugars (food) from the leaves to other parts of the plant through the phloem, primarily explained by the pressure-flow hypothesis. This highlights the intricate vascular system that sustains plant life.
12. Mineral Nutrition
This chapter focuses on the inorganic nutrients that plants require for healthy growth. It outlines the criteria for an element to be considered essential and categorizes them into macronutrients and micronutrients based on the required quantities. The specific physiological roles of various essential minerals and the visible symptoms caused by their deficiency are discussed. A significant portion of the chapter is dedicated to nitrogen metabolism, a critical process for all life. It explains the biological nitrogen fixation, where atmospheric nitrogen is converted into ammonia by certain microbes, making it available for plants to synthesize vital compounds like proteins and nucleic acids.
13. Photosynthesis In Higher Plants
This chapter provides a detailed molecular and biochemical understanding of photosynthesis, the process that converts light energy into chemical energy. It describes the structure of the chloroplast, the site of photosynthesis, and the roles of various photosynthetic pigments. The mechanism is broken down into two stages: the light-dependent reactions, which capture light energy to produce ATP and NADPH, and the light-independent reactions (Calvin cycle), which use these products to fix CO2 into sugars. The chapter also discusses alternative carbon fixation pathways like the C4 pathway and analyzes the various external and internal factors that affect the rate of photosynthesis.
14. Respiration In Plants
This chapter details the process of cellular respiration in plants, the metabolic pathway that breaks down glucose to release energy in the form of ATP. It covers the stages of aerobic respiration, a process that requires oxygen. This includes glycolysis (the initial splitting of glucose in the cytoplasm), the link reaction, the Krebs cycle (citric acid cycle) occurring in the mitochondrial matrix, and the electron transport system (ETS) on the inner mitochondrial membrane, which culminates in oxidative phosphorylation. The chapter also discusses anaerobic respiration (fermentation) and the respiratory balance sheet, illustrating the cell's efficient energy-harvesting machinery.
15. Plant - Growth And Development
This chapter covers the entire life journey of a plant, from seed germination to senescence. It defines and differentiates between growth, differentiation, and development. The key players in regulating these processes, the plant growth regulators or phytohormones, are discussed in detail. These include growth promoters (Auxins, Gibberellins, Cytokinins) and growth inhibitors (Abscisic acid, Ethylene). The chapter also explains how plants respond to environmental cues, covering topics like photoperiodism (the effect of light duration on flowering) and vernalisation (the promotion of flowering by a period of low temperature).
16. Digestion And Absorption
This chapter explains the human nutritional process, beginning with the structure and function of the human digestive system. It traces the journey of food through the alimentary canal—from the mouth, through the oesophagus, stomach, small intestine, and large intestine. It details the process of digestion, where complex food molecules (carbohydrates, proteins, fats) are broken down into simpler, absorbable units by the action of various digestive enzymes. Subsequently, the chapter explains the mechanism of absorption of these nutrients into the bloodstream and lymph, primarily in the small intestine, and concludes with a discussion of common digestive disorders.
17. Breathing And Exchange Of Gases
This chapter focuses on the physiological process of gaseous exchange in humans. It details the anatomy of the human respiratory system, from the nasal passage to the alveoli in the lungs. The mechanics of breathing (inspiration and expiration) are explained, involving the coordinated action of the diaphragm and intercostal muscles. The chapter provides a deep dive into the exchange of gases (O2 and CO2) at the alveolar surface and in the tissues, driven by differences in partial pressures. It also covers the transport of these gases in the blood and the neural regulation of respiration, along with common respiratory disorders.
18. Body Fluids And Circulation
This chapter details the internal transport system of the human body. It describes the composition and functions of blood and lymph. A key focus is the human circulatory system, with a detailed explanation of the structure and pumping action of the four-chambered heart. The chapter explains the cardiac cycle, electrocardiogram (ECG), and the concept of double circulation (pulmonary and systemic circuits). It also covers the different types of blood vessels, blood groups (ABO and Rh), the mechanism of blood coagulation, and common circulatory disorders, highlighting the system's role in transporting substances and maintaining homeostasis.
19. Excretory Products And Their Elimination
This chapter explains how the body eliminates metabolic wastes, a process crucial for maintaining internal balance. It describes the structure of the human excretory system, focusing on the kidneys. The functional unit of the kidney, the nephron, is described in detail. The chapter elaborates on the three key steps of urine formation: glomerular filtration, selective reabsorption, and tubular secretion. It also discusses the role of hormones like ADH in regulating kidney function (osmoregulation) and briefly covers other excretory organs and common disorders of the excretory system, such as kidney failure.
20. Locomotion And Movement
This chapter explores how animals move, focusing on the human body. It begins by describing the three types of muscle tissue: skeletal, visceral, and cardiac. The main focus is on the mechanism of skeletal muscle contraction, explained by the sliding filament theory, which involves the interaction of actin and myosin filaments. The chapter also provides a detailed overview of the human skeletal system, categorizing it into the axial and appendicular skeletons. It describes the different types of joints that permit movement and discusses common disorders of the muscular and skeletal systems, like arthritis and osteoporosis.
21. Neural Control And Coordination
This chapter details the structure and function of the nervous system, the body's rapid communication network. It explains the structure of a neuron and the generation and propagation of a nerve impulse (action potential). The chapter then provides a comprehensive overview of the human nervous system, dividing it into the Central Nervous System (brain and spinal cord) and the Peripheral Nervous System. It also explains the mechanism of a reflex arc. A significant portion is dedicated to sensory reception, detailing the anatomy and physiology of the eye and the ear, our windows to the external world.
22. Chemical Coordination And Integration
This chapter explains the role of the endocrine system, which uses chemical messengers called hormones for slower, long-term regulation of body functions. It describes the location and function of the major endocrine glands in the human body, including the hypothalamus, pituitary (the master gland), thyroid, adrenal glands, pancreas, and gonads. The chapter details the specific hormones secreted by each gland, their target organs, and their roles in processes like growth, metabolism, and stress response. The concept of feedback mechanism in regulating hormone levels is also explained, illustrating the integration between the nervous and endocrine systems.
Sample Paper
This entry provides a comprehensive Sample Paper specifically designed for Class 11 Biology students. It serves as an essential tool for self-evaluation, containing a mix of questions that cover the entire syllabus from all 22 chapters. By attempting this paper, students can practice time management, understand the question patterns, and assess their grasp of key biological concepts. It is an invaluable resource for thorough revision, helping students to identify areas of weakness and build confidence before their final examinations.