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Class 11th Biology MCQ Questions
1. The Living World
This chapter introduces the defining characteristics of **living organisms**, such as growth, reproduction, metabolism, and consciousness. It highlights the immense **biodiversity** on Earth and the need for classifying organisms. Principles and processes of **taxonomy** and **systematics** are discussed, including **nomenclature** (binomial naming) and the hierarchical classification system (species to kingdom). Taxonomic aids like herbarium, botanical gardens, museums, and keys are explained as essential tools for biological studies, providing a framework to understand the vast array of life.
2. Biological Classification
This chapter traces the history of biological classification systems, from early simple groupings to the widely accepted **Five Kingdom classification** proposed by R.H. Whittaker. It provides a detailed overview of the distinct characteristics used to classify organisms into the five kingdoms: Monera (bacteria), Protista (unicellular eukaryotes), Fungi (heterotrophic eukaryotes), Plantae (autotrophic eukaryotes), and Animalia (heterotrophic, multicellular eukaryotes). The chapter also briefly discusses acellular entities like **viruses**, viroids, and prions, highlighting challenges in classifying life and the evolutionary relationships between different groups.
3. Plant Kingdom
This chapter provides a comprehensive classification of the **Plant Kingdom**, covering major divisions: Algae (simplest aquatic plants), Bryophytes (mosses, liverworts - first land plants requiring water for reproduction), Pteridophytes (ferns - first vascular plants), Gymnosperms (naked seeds), and Angiosperms (flowering plants - dominant land plants). It discusses the characteristic features, life cycles (including the concept of **alternation of generations**), and examples of each group. Understanding the diversity and evolution within the Plant Kingdom is essential for appreciating the adaptations and ecological roles of plants.
4. Animal Kingdom
This chapter presents a systematic classification of the **Animal Kingdom**, based on fundamental features like levels of organisation (cellular, tissue, organ, organ system), body symmetry (radial, bilateral), germ layers (diploblastic, triploblastic), presence or absence of a **coelom**, segmentation, and notochord. It details the salient features and examples of major animal phyla, from the simplest ones (Porifera) to the most complex (Chordata), explaining the evolutionary trends and adaptations that have led to the vast diversity of animal forms and functions observed on Earth.
5. Morphology Of Flowering Plants
This chapter focuses on the study of the external form and structure (**morphology**) of flowering plants (**angiosperms**). It describes the characteristic features of different parts: the **root** system (tap root, fibrous root, modifications), the **stem** (types, modifications like underground stems), the **leaf** (venation, phyllotaxy, modifications), the **inflorescence** (arrangement of flowers), the **flower** (structure, parts, floral diagrams), the **fruit**, and the **seed**. Understanding plant morphology is fundamental for plant identification, classification, and appreciating adaptations to various environments.
6. Anatomy Of Flowering Plants
This chapter delves into the internal structure (**anatomy**) of flowering plants, focusing on their tissues and internal organization. It describes different types of **plant tissues**: **meristematic tissues** (responsible for growth) and **permanent tissues** (simple like parenchyma, collenchyma, sclerenchyma, and complex like **xylem** and **phloem**, responsible for transport). The internal structure of dicotyledonous and monocotyledonous root, stem, and leaf is detailed. The process of **secondary growth**, which increases the girth of stems and roots in dicots, is also explained, highlighting the functional significance of these tissues and structures.
7. Structural Organisation In Animals
This chapter examines the levels of structural organisation in multicellular animals, starting from tissues to organs and organ systems. It describes the four main types of **animal tissues**: **epithelial tissue** (covering and lining), **connective tissue** (support, binding - including blood, bone), **muscular tissue** (movement), and **nervous tissue** (control and coordination). Detailed studies of the anatomy and morphology of three representative animals – the earthworm, the cockroach, and the frog – are included to illustrate how tissues are organised into organs and complex organ systems performing specific functions, providing insights into the complexity of animal bodies.
8. Cell - The Unit Of Life
This foundational chapter in cytology focuses on the **cell**, considered the basic structural and functional unit of all living organisms. It discusses the history of cell discovery and the postulates of the **Cell Theory**. The differences between prokaryotic cells (like bacteria) and eukaryotic cells (plants, animals, fungi) are highlighted. The structure and functions of various **cell organelles** within eukaryotic cells are detailed, including the cell membrane, cell wall, nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, mitochondria, chloroplasts, and ribosomes, explaining their specific roles in essential cellular activities, providing a microscopic view of life processes.
9. Biomolecules
This chapter explores the complex molecules that constitute living organisms, known as **biomolecules**. It discusses the chemical composition of cells and the structure and function of major classes of organic biomolecules: **carbohydrates** (energy sources, structural components), **proteins** (diverse roles like enzymes, structural components), **lipids** (energy storage, cell membranes), and **nucleic acids** (**DNA** and **RNA** - carriers of genetic information). The chapter also introduces **enzymes** as biological catalysts, explaining their mechanism of action and factors affecting their activity, providing a biochemical perspective on the chemistry of life.
10. Cell Cycle And Cell Division
This chapter explains the sequence of events by which a cell grows, duplicates its genome, and divides to form two daughter cells – the **cell cycle**. It describes the different phases of the cell cycle: Interphase (G1, S, G2, where DNA replication occurs) and M Phase (Mitosis or Meiosis). **Mitosis** (equational division for growth, repair) and **Meiosis** (reductional division for sexual reproduction, reducing chromosome number and creating genetic variation) are explained in detail, including their stages (Prophase, Metaphase, Anaphase, Telophase) and significance for the organism.
11. Transport In Plants
This chapter explores the mechanisms by which substances move within plants, from short-distance transport within cells to long-distance transport throughout the plant body. It discusses passive and active transport, diffusion, and osmosis. **Water transport** from roots to leaves through the **xylem** is explained, focusing on the **transpiration pull theory**. Uptake and translocation of **mineral nutrients** are also covered. The transport of organic nutrients (sugars produced during photosynthesis) through the **phloem** by the **mass flow hypothesis** is detailed, highlighting the plant's efficient transport systems.
12. Mineral Nutrition
This chapter focuses on the essential inorganic nutrients, or **mineral elements**, required by plants for their growth and development. It discusses the methods for identifying essential elements (like hydroponics), criteria for essentiality, and the roles of **macronutrients** (needed in large amounts, e.g., N, P, K, S) and **micronutrients** (needed in small amounts, e.g., Fe, Mn, Zn, Cu). Deficiency symptoms caused by lack of specific elements are described. The mechanisms of absorption of these elements and the process of **nitrogen metabolism**, including nitrogen fixation (converting atmospheric nitrogen into usable forms), are also explained, emphasizing the critical role of minerals.
13. Photosynthesis In Higher Plants
**Photosynthesis** is the process by which green plants use light energy to synthesize organic food ($\textsf{C}_6\textsf{H}_{12}\textsf{O}_6$) from carbon dioxide ($\textsf{CO}_2$) and water. This chapter delves into the detailed mechanism in higher plants. It covers the site (chloroplasts), the role of pigments, the **light-dependent reactions** (photophosphorylation, electron transport), and the **light-independent reactions** or Calvin cycle (C3 pathway) where $\textsf{CO}_2$ is fixed. The C4 pathway is also discussed. Factors affecting the rate of photosynthesis are analyzed, highlighting this vital energy-producing process that sustains most life on Earth.
14. Respiration In Plants
**Respiration** is the process by which living organisms break down organic molecules to release usable energy in the form of ATP. This chapter explains respiration in plants, covering both **aerobic respiration** (requiring oxygen) and **anaerobic respiration** (fermentation). Key metabolic pathways involved in aerobic respiration – **glycolysis** (in cytoplasm), the **Krebs cycle** or citric acid cycle (in mitochondria), and **oxidative phosphorylation** via the electron transport system (in mitochondria) – are detailed. The chapter discusses the overall process of energy release and the **Respiratory Quotient (RQ)**, illustrating how plants obtain energy for their various life activities.
15. Plant - Growth And Development
This chapter explores the complex processes of **growth**, **differentiation**, and **development** in plants, which are influenced by both genetic factors and environmental cues. It discusses the characteristics of plant growth and various stages of development from seed germination to flowering and senescence. The roles of different **plant growth regulators** or phytohormones (Auxins, Gibberellins, Cytokinins, Abscisic acid, Ethylene) in controlling processes like cell division, elongation, flowering, fruiting, and dormancy are explained. Concepts like **photoperiodism** (response to day length for flowering) and **vernalisation** (cold requirement for flowering) are also covered, highlighting the intricate regulation of plant life cycles.
16. Digestion And Absorption
This chapter focuses on how the human body obtains nutrients from food through the processes of **digestion** and **absorption**. It describes the structure of the **human digestive system**, including the alimentary canal (mouth, pharynx, oesophagus, stomach, small intestine, large intestine, anus) and associated digestive glands (salivary glands, liver, pancreas). The mechanical and chemical breakdown of food (carbohydrates, proteins, fats) into simpler molecules is explained, detailing the action of various enzymes. The chapter then covers the process of **absorption** of these digested products, primarily in the small intestine, and their assimilation into the body. Common disorders of the digestive system are also discussed, highlighting the importance of a healthy gut.
17. Breathing And Exchange Of Gases
This chapter explains the vital process of **respiration** in animals, focusing on **breathing** (ventilation) and the **exchange of gases**. It describes the respiratory organs in various animals and provides a detailed account of the structure of the **human respiratory system**. The mechanism of breathing (inhalation and exhalation), involving the lungs and diaphragm, is explained. The process of **exchange of oxygen ($\textsf{O}_2$) and carbon dioxide ($\textsf{CO}_2$)** occurs across the thin membranes in the alveoli of the lungs and at the tissue level. Transport of gases by blood and common respiratory disorders are also covered, highlighting the efficiency of gas exchange systems.
18. Body Fluids And Circulation
This chapter explores the internal transport system in animals, focusing on **body fluids** like **blood** and **lymph**, and the **circulatory system** responsible for their movement. It describes the composition of blood (plasma and formed elements - RBCs, WBCs, platelets), different **blood groups** (ABO and Rh) important for transfusions, and blood coagulation. The structure and working of the **human heart** are detailed, explaining the cardiac cycle. The chapter covers the types of blood vessels (arteries, veins, capillaries) and the pathway of blood circulation (**pulmonary** and **systemic** circulation), along with the structure and function of the lymphatic system, crucial for transport and defense.
19. Excretory Products And Their Elimination
This chapter focuses on the process of **excretion**, the removal of metabolic wastes, particularly nitrogenous wastes, from the body. It discusses different types of nitrogenous wastes (ammonia, urea, uric acid) produced by animals and their modes of elimination. The structure and function of the **human excretory system**, particularly the **kidney**, are detailed. The complex process of **urine formation** in the nephrons, involving **glomerular filtration**, **tubular reabsorption**, and **tubular secretion**, is explained. The roles of other organs in excretion and common disorders of the excretory system are also covered, highlighting the body's mechanism for maintaining homeostasis.
20. Locomotion And Movement
This chapter explores the various types of **movement** and **locomotion** (movement from place to place) exhibited by living organisms. It discusses movement at the cellular level (amoeboid, ciliary, flagellar). The focus then shifts to the **human musculoskeletal system**, describing the **skeleton** (axial and appendicular bones), different types of **joints** allowing various movements, and the structure and function of **muscles** (skeletal, smooth, cardiac). The mechanism of **muscle contraction** based on the sliding filament theory is explained. Common disorders of the muscular and skeletal systems are also discussed, highlighting how bones, joints, and muscles work together to enable motion and maintain posture.
21. Neural Control And Coordination
This chapter introduces the **nervous system**, the primary system for rapid control and coordination in animals. It describes the basic structural and functional unit, the **neuron** (nerve cell), explaining the generation and conduction of nerve impulses (**action potential**) and transmission across **synapses**. The organisation of the **human nervous system** is detailed, including the Central Nervous System (brain and spinal cord) and the Peripheral Nervous System. **Reflex action** is explained as an involuntary response. The structure and functioning of sensory organs like the eye and ear are also covered, highlighting how the nervous system receives, processes, and responds to information from the environment.
22. Chemical Coordination And Integration
This chapter complements neural control by exploring the **endocrine system**, which provides slower, long-lasting coordination through chemical messengers called **hormones**. Various **endocrine glands** in the human body (pituitary, pineal, thyroid, parathyroid, thymus, adrenal, pancreas, gonads) are discussed, along with the specific hormones they secrete and their diverse physiological roles in regulating processes like growth, metabolism, reproduction, and maintaining **homeostasis**. The chapter explains how hormones act on target cells and the concept of feedback mechanisms regulating hormone secretion, illustrating the integrated nature of control systems in the body.