CBSE Class 11 Biology Important Questions with Solutions for 2025-26 exams

Biology in Class 11 is where science becomes more detailed and fascinating, but also a bit challenging for many students. It lays the foundation for your Class 12 board exams and for competitive exams like NEET.

That’s why practising important questions from Class 11 Biology is a smart way to revise , they highlight exactly what examiners love to ask and help you strengthen tricky concepts.

These CBSE Class 11 Biology Important Questions with Solutions (2025-26) are carefully framed according to the NCERT syllabus and exam trends. With these, you’ll:

• Revise the most crucial NCERT-based concepts chapter by chapter.
• Get familiar with frequently asked and expected questions.
• Practise clear, step-by-step solutions to improve your writing style in exams.
• Boost confidence by solving a mix of short answer and long answer questions.

So, let’s get started with chapter-wise important questions and answers.

Chapter-wise CBSE Class 11 Biology Important Questions PDF

Stop wasting time on scattered notes - here’s a clear, chapter-wise table of Class 11 Biology Important Questions for quick and smart revision.

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Some Important Questions for Class 9 Maths 2025-26 Exams

Here are some of the most important questions you must know for your Class 11 Biology exam. These questions cover key concepts and will help you prepare effectively for CBSE.

Chapter 1: The Living World

Q1. Define taxonomy. Why is it important?

Ans. Taxonomy is the science of naming, describing, and classifying organisms into groups based on shared characteristics. It helps in identification, provides universal names, and establishes evolutionary relationships.

Q2. Long Question: Explain the need for a system of classification. How did early systems evolve into the modern five-kingdom system?

Ans. Early systems classified organisms into plants and animals, which was insufficient. With scientific progress, more detailed systems like two-kingdom, three-kingdom, and four-kingdom classifications were proposed. Finally, Whittaker’s five-kingdom system (Monera, Protista, Fungi, Plantae, Animalia) was accepted as it considered cell structure, body organization, mode of nutrition, and reproduction.

Chapter 2: Biological Classification

Q1. What are the five kingdoms of classification proposed by Whittaker?

Ans. Monera, Protista, Fungi, Plantae, and Animalia.

Q2. Long Question: Describe the characteristics of Kingdom Protista with suitable examples.

Ans. Protists are unicellular eukaryotes with a well-defined nucleus and cell organelles. They can be autotrophic (e.g., diatoms) or heterotrophic (e.g., amoeba). Some are parasitic (Plasmodium). Locomotion is by cilia, flagella, or pseudopodia. They reproduce both sexually and asexually.

Chapter 3: Plant Kingdom

Q1. Differentiate between bryophytes and pteridophytes.

Ans. Bryophytes lack vascular tissues; pteridophytes have xylem and phloem.

Q2. Long Question: Describe the life cycle of a fern with emphasis on alternation of generations.

Ans. The fern shows alternation of generations with dominant sporophyte producing spores in sporangia. These germinate into gametophytes (prothallus), which produce gametes. Fertilisation produces zygote, developing into sporophyte again. Thus, both haploid and diploid stages alternate.

Chapter 4: Animal Kingdom

Q1. Differentiate between diploblastic and triploblastic animals.

Ans. Diploblastic animals have two germ layers (ectoderm and endoderm), while triploblastic animals have three germ layers (ectoderm, mesoderm, and endoderm).

Q2. Long Question: Explain the basis of classification of animals into phyla with suitable examples.

Ans. Animals are classified based on body symmetry (radial/bilateral), germ layers, body cavity (acoelomate, coelomate, pseudocoelomate), segmentation, and notochord. Example: Porifera (asymmetry), Cnidaria (diploblastic), Annelida (segmented coelomates), Chordata (with notochord).

Chapter 5: Morphology of Flowering Plants

Q1. Define phyllotaxy and name its types.

Ans. Phyllotaxy is the arrangement of leaves on a stem. Types: alternate, opposite, and whorled.

Q2. Differentiate between tap root and fibrous root systems.

Ans. Tap root arises from radicles, while fibrous roots arise from the base of stem. Tap roots are common in dicots, fibrous in monocots.

Q3. Long Question: Explain the structure of a dicotyledonous flower with a labelled diagram.

Ans. A dicot flower consists of four whorls – calyx, corolla, androecium, and gynoecium. Calyx (sepals) protects the bud; corolla (petals) attracts pollinators; androecium (stamens) produces pollen; gynoecium (carpels) bears ovules. Example: Hibiscus.

Chapter 6: Anatomy of Flowering Plants

Q1. Differentiate between monocot and dicot stems.

Ans. Dicot stems have vascular bundles arranged in a ring, with secondary growth, while monocot stems have scattered bundles with no secondary growth.

Q2. What are annual rings? How are they formed?

Ans. Annual rings are formed due to seasonal variation in cambial activity. In spring, vessels are larger (spring wood), while in winter, they are smaller (autumn wood).

Q3. Long Question: Describe secondary growth in dicot stems with the help of a diagram.

Ans. Secondary growth occurs by activity of vascular cambium and cork cambium. Cambium forms secondary xylem and phloem, increasing stem thickness. Annual rings appear due to seasonal variation in xylem activity. Cork cambium produces periderm for protection.

Chapter 7: Structural Organisation in Animals

Q1. Name the four types of tissues in animals.

Ans. Epithelial, connective, muscular, and nervous tissue.

Q2. Long Question: Describe the structure of epithelial tissues and their types with examples.

Ans. Epithelial tissue covers body surfaces. Types include squamous (lung alveoli), cuboidal (kidney tubules), columnar (intestine lining), ciliated (trachea), and glandular (glands). Each type has specialised functions like protection, absorption, secretion, or movement.

Chapter 8: Cell: The Unit of Life

Q1. What is the difference between prokaryotic and eukaryotic cells?

Ans. Prokaryotic cells lack nucleus and membrane-bound organelles, while eukaryotic cells have both.

Q2. What is the function of mitochondria?

Ans. Mitochondria are the powerhouse of the cell. They produce ATP through cellular respiration.

Q3. Long Question: Describe the structure of a eukaryotic cell with functions of major organelles.

Ans. A eukaryotic cell has nucleus, mitochondria (ATP synthesis), endoplasmic reticulum (transport), Golgi apparatus (packaging), lysosomes (digestion), chloroplasts (photosynthesis in plants), and ribosomes (protein synthesis). These organelles coordinate for cell functioning.

Chapter 9: Biomolecules

Q1. What are macromolecules? Give examples.

Ans. Large molecules with high molecular weight like proteins, nucleic acids, and polysaccharides.

Q2. Long Question: Explain the structure and functions of proteins.

Ans. Proteins are polymers of amino acids linked by peptide bonds. They have primary (sequence), secondary (α-helix/β-sheet), tertiary (3D folding), and quaternary structures. Functions include enzymatic activity, structural support, transport, and hormonal action.

Chapter 10: Cell Cycle and Cell Division

Q1. Differentiate between mitosis and meiosis.

Ans. Mitosis produces two identical diploid cells, while meiosis produces four non-identical haploid cells.

Q2. In which phase of cell cycle does DNA replication occur?

Ans. DNA replication occurs in the S phase of interphase.

Q3. Long Question: Describe the stages of mitosis with diagrams.

Ans. Mitosis has four stages: prophase (chromosome condensation, spindle formation), metaphase (alignment on equator), anaphase (separation of chromatids), and telophase (reformation of nuclear membrane). Cytokinesis completes division into two daughter cells.

Chapter 11: Transport in Plants

Q1. What is transpiration pull?

Ans. It is the suction force created by transpiration that pulls water upward through the xylem vessels.

Q2. Define apoplast and symplast pathways.

Ans. Apoplast: movement through cell walls and intercellular spaces. Symplast: movement through cytoplasm connected by plasmodesmata.

Q3. Long Question: Explain the mechanism of ascent of sap in tall trees.

Ans. Cohesion-tension theory explains the ascent of sap. Water molecules stick together (cohesion) and to xylem walls (adhesion). Transpiration pull creates tension, drawing water upward.

Chapter 12: Mineral Nutrition

Q1. What are essential elements? Give examples.

Ans. Elements required for plant growth and metabolism. Examples: N, P, K, Ca, Mg, Fe, Zn.

Q2. What is biological nitrogen fixation?

Ans. Conversion of atmospheric N₂ into ammonia by microbes like Rhizobium.

Q3. Long Question: Explain the role of nitrogen, phosphorus, and potassium in plant growth.

Ans. Nitrogen is essential for proteins and nucleic acids; phosphorus for ATP and nucleic acids; potassium for enzyme activation and stomatal regulation.

Chapter 13: Photosynthesis in Higher Plants

Q1. Differentiate between C3 and C4 pathways.

Ans. C3 pathway produces a 3-carbon compound (PGA), occurs in mesophyll cells; C4 produces a 4-carbon compound (OAA), occurs in mesophyll and bundle sheath cells.

Q2. Write the equation for photosynthesis.

Ans. 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O.

Q3. Long Question: Describe the light reaction of photosynthesis.

Ans. Light reaction occurs in thylakoid membranes. It involves absorption of light by chlorophyll, photolysis of water, release of O₂, production of ATP and NADPH via electron transport chain.

Chapter 14: Respiration in Plants

Q1. What are the three stages of aerobic respiration?

Ans. Glycolysis, Krebs cycle, and Electron Transport Chain.

Q2. Differentiate between glycolysis and Krebs cycle.

Ans. Glycolysis occurs in cytoplasm, anaerobic, breaks glucose into pyruvate. Krebs cycle occurs in mitochondria, aerobic, produces CO₂, NADH, FADH₂.

Q3. Long Question: Explain the process of glycolysis.

Ans. Glycolysis occurs in cytoplasm. Glucose (6C) breaks into two molecules of pyruvate (3C) through 10 enzyme-catalysed steps. Produces 2 ATP (net) and 2 NADH.

Chapter 15: Plant Growth and Development

Q1. What are plant growth regulators?

Ans. Hormones that regulate plant growth. Examples: auxins, gibberellins, cytokinins, ethylene, abscisic acid.

Q2. Differentiate between photoperiodism and vernalisation.

Ans. Photoperiodism is a response to the light period for flowering. Vernalisation is promotion of flowering by low temperature treatment.

Q3. Long Question: Explain the role of auxins and gibberellins in plant growth.

Ans. Auxins promote cell elongation, apical dominance, root initiation. Gibberellins promote stem elongation, seed germination, and flowering.

Chapter 16: Digestion and Absorption

Q1. Name the enzymes secreted by the pancreas.

Ans. Trypsin, chymotrypsin, pancreatic amylase, and lipase.

Q2. What is emulsification of fats?

Ans. Breakdown of large fat globules into smaller droplets by bile salts.

Q3. Long Question: Explain the process of protein digestion in humans.

Ans. Protein digestion begins in the stomach with pepsin breaking proteins into peptones. In the small intestine, trypsin and chymotrypsin break them into peptides. Peptidases convert peptides into amino acids, which are absorbed.

Chapter 17: Breathing and Exchange of Gases

Q1. Define tidal volume.

Ans. Volume of air inspired or expired during normal breathing (~500 ml).

Q2. What is the role of hemoglobin in respiration?

Ans. Hemoglobin transports oxygen from lungs to tissues by binding O₂.

Q3. Long Question: Describe the mechanism of breathing in humans.

Ans. Inspiration: diaphragm contracts, thoracic cavity expands, pressure decreases, air enters lungs. Expiration: diaphragm relaxes, thoracic cavity reduces, pressure increases, air moves out.

Chapter 18: Body Fluids and Circulation

Q1. What are the components of human blood?

Ans. Plasma, red blood cells, white blood cells, and platelets.

Q2. Differentiate between open and closed circulatory systems.

Ans. Open: blood flows in open spaces (arthropods). Closed: blood flows in vessels (vertebrates).

Q3. Long Question: Explain the double circulation in humans with a diagram.

Ans. Double circulation involves systemic and pulmonary circulation. The right side pumps deoxygenated blood to the lungs, the left side pumps oxygenated blood to the body. Ensures efficient oxygen supply.

Chapter 19: Excretory Products and Their Elimination

Q1. What is the functional unit of the kidney?

Ans. Nephron.

Q2. Differentiate between ureotelic and uricotelic organisms.

Ans. Ureotelic excrete urea (humans), uricotelic excrete uric acid (birds).

Q3. Long Question: Explain the process of urine formation.

Ans. Urine formation involves three steps: (i) Glomerular filtration – ultrafiltration of blood in Bowman’s capsule, (ii) Tubular reabsorption – reabsorption of essential substances, (iii) Tubular secretion – secretion of waste substances into filtrate.

Chapter 20: Locomotion and Movement

Q1. Name the three types of muscles.

Ans. Skeletal, smooth, and cardiac muscles.

Q2. Differentiate between actin and myosin.

Ans. Actin is thin filament, myosin is thick filament of muscle fibres.

Q3. Long Question: Explain the mechanism of muscle contraction.

Ans. Sliding filament theory: During contraction, myosin heads attach to actin, pull actin filaments inward using ATP. Sarcomere shortens, causing contraction.

Chapter 21: Neural Control and Coordination

Q1. Draw and label a neuron.

Ans. Neurons have cell body, dendrites, axon, and synaptic terminals.

Q2. What is synapse?

Ans. A junction between two neurons where transmission of impulses occurs.

Q3. Long Question: Explain the structure and functions of the human brain.

Ans. The brain has three regions: forebrain (cerebrum for intelligence, hypothalamus for regulation), midbrain (vision and hearing reflexes), hindbrain (cerebellum for balance, medulla for involuntary activities). Protected by skull and meninges.

Chapter 22: Chemical Coordination and Integration

Q1. What is the role of insulin?

Ans. Insulin lowers blood glucose by stimulating uptake of glucose by cells.

Q2. Differentiate between endocrine and exocrine glands.

Ans. Endocrine secrete hormones directly into blood, exocrine secrete via ducts.

Q3. Long Question: Describe the functions of the pituitary gland. Why is it called the master gland?

Ans. Pituitary secretes growth hormone, TSH, ACTH, LH, FSH, oxytocin, vasopressin. It regulates other endocrine glands like thyroid, adrenal, and gonads, hence called master gland.

Benefits of Solving Important Questions Class 11 Biology

Practising the right CBSE Class 11 Biology Important Questions can make a huge difference in how well you perform in exams. Here’s why these questions matter:

1. Stronger Concept Clarity

‍These questions help you understand complex biological processes and terms better, instead of just memorising them from the textbook.

2. Better Application of Knowledge

‍The CBSE Class 11 Biology Question Bank includes short, long, and diagram-based questions. Solving them trains you to explain concepts clearly - just like in board exams.

3. Exam Pattern Familiarity

‍Regular practice helps you get used to the CBSE-style questions, weightage, and answer format - so you know exactly what to expect in the exam.

4. Improved Time Management

‍Answering a mix of one-mark, short, and long questions helps you learn how to manage your time efficiently during exams.

5. Boosted Confidence

‍As you practise more important questions, your confidence in writing detailed, diagram-supported answers increases - helping you stay calm and perform better in exams.

Pro Tips to Score High in Class 11 Biology

Here are some practical tips to help you boost your marks in Biology, along with practising the CBSE Class 11 Biology Important Questions:

• Solve previous years’ question papers

This helps you understand the type of questions often asked and familiarises you with the CBSE exam pattern and marking scheme.

• Revise diagrams and definitions regularly

Biology is all about clear concepts and visuals. Make short notes and label diagrams daily so you can recall them quickly during exams.

• Practice timed mock tests

Set a timer while solving questions to improve your speed and accuracy, and to ensure you can complete long answers within the exam time.

• Focus on weaker chapters

Identify which chapters (like Human Physiology or Plant Kingdom) you find tough, and revise them more often to strengthen your preparation.

• Clear your doubts immediately

Don’t delay! Ask your teacher, friends, or use trusted study resources to clear concepts early - this helps you avoid confusion before exams.

FAQs

Q1. How many marks are usually asked from Class 11 Biology in boards?

Ans. Around 25–30% of the Class 12 board exam Biology paper is based on Class 11 concepts.

Q2. Are diagrams compulsory in long answers?

Ans. Not always, but drawing diagrams where relevant improves your score.

Q3. How should I practise these questions for exams?

Ans. Write answers in your own words, stick to NCERT terminology, and practise diagrams.

Q4. Which chapters are most important in Class 11 Biology?

Ans. Cell cycle & division, Human physiology chapters (digestion, breathing, circulation, excretion, neural control), and Plant physiology chapters (photosynthesis, respiration, transport).

Q5. Will practising only these important questions be enough?

Ans. These cover exam-focused areas, but for complete preparation, read NCERT thoroughly.