Class 9 Science Chapter 10 Living Creatures: Exploring their Characteristics – Previous Year Questions (2020–2025)

Reading your NCERT textbook teaches concepts; solving past papers teaches you how CBSE *tests* those concepts. In Chapter 10, examiners don't just ask 'What is photosynthesis?' — they ask you to label a leaf cross-section, identify the role of chlorophyll, or explain why a plant in a sealed jar wilts. Previous year questions train you to: 1. **Recognize question language patterns** — Words like 'distinguish,' 'explain,' and 'justify' signal different answer depths. A 1-mark question expects a one-line definition; a 5-mark question expects a process breakdown with examples. 2. **Master diagram-labelling skills** — Over 40% of Chapter 10 questions involve root systems, stem anatomy, flower parts, or leaf internal structure. Practising past papers shows exactly which labels appear repeatedly (xylem, phloem, stomata, sepal, anther). 3. **Time your attempts wisely** — In a 3-hour exam, allocating 8 minutes to a 3-mark question vs. 12 minutes to a 5-mark question is critical. PYQ practice builds this intuition. 4. **Anticipate follow-up questions** — If a 2020 paper asked about photosynthesis in shaded leaves, a 2024 paper might ask about adaptation. Solving multiple years reveals these logical progressions. 5. **Reduce exam anxiety** — Familiarity breeds confidence. When you sit the exam and see 'Compare aerobic and anaerobic respiration,' you've already solved three versions of this question.

**Q1. Define photosynthesis.** *Answer:* Photosynthesis is the process by which green plants synthesize carbohydrates (glucose) from carbon dioxide and water in the presence of sunlight and chlorophyll, releasing oxygen as a byproduct. **Q2. Name the part of a plant root responsible for water absorption.** *Answer:* Root hair zone (or region of absorption). Root hairs are extensions of epidermal cells that increase surface area for water and mineral uptake. **Q3. Classify a human as a(n) _____ because it feeds on both plants and animals.** *Answer:* Omnivore. Omnivores have a flexible diet including both herbivorous and carnivorous food sources (e.g., rice, vegetables, chicken, fish). **Q4. What is the primary pigment responsible for light capture in photosynthesis?** *Answer:* Chlorophyll (specifically chlorophyll *a* and *b*). Chlorophyll absorbs photons in the blue and red regions of the visible spectrum and reflects green light. **Q5. Name the tissue in a plant stem that transports water and minerals upward.** *Answer:* Xylem. Xylem vessels and tracheids form a continuous pathway for unidirectional transport of water and dissolved mineral ions from roots to leaves and stems. **Pattern insight:** 1-mark questions test single-concept recall. Answers are ~25–35 words. Practise writing concise, textbook-aligned definitions — avoid over-explanation.

**Q1. Describe the internal structure of a leaf and explain how it is adapted for photosynthesis.** *Answer structure (3 marks):* - 1 mark: Name the three main layers — upper epidermis, mesophyll, lower epidermis. - 1 mark: Explain adaptations — Palisade mesophyll has tightly packed cells rich in chloroplasts for maximum photosynthesis. Spongy mesophyll has air spaces for gas diffusion (CO₂ in, O₂ out). Stomata on the lower epidermis allow CO₂ entry and water loss regulation via guard cells. - 1 mark: Link to function — The arrangement maximizes light absorption while minimizing water loss in terrestrial habitats. **Q2. Distinguish between aerobic and anaerobic respiration in plants.** *Answer structure (3 marks):* - 1 mark: Aerobic respiration uses oxygen; anaerobic respiration occurs without oxygen. - 1 mark: Aerobic: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP). Anaerobic: C₆H₁₂O₆ → Ethanol (or lactic acid) + CO₂ + Energy (small amount). - 1 mark: Energy yield — Aerobic produces ~38 ATP per glucose; anaerobic produces 2 ATP. In flooded soil or low-oxygen conditions, roots undergo anaerobic respiration. **Q3. What are the functions of roots in a plant? Explain with examples.** *Answer structure (3 marks):* - 1 mark: Absorption of water and minerals (root hairs in soil). - 1 mark: Anchoring the plant to soil; storage of food (carrot, potato are modified roots). - 1 mark: Example — A mango tree's root system extends deep into soil for water uptake during drought; a banyan tree produces aerial roots for additional support and water absorption. **Q4. List the parts of a typical flower and state their functions.** *Answer structure (3 marks):* - 1 mark: Male parts — Stamen (anther produces pollen, filament supports anther). - 1 mark: Female parts — Pistil/carpel (stigma receives pollen, style connects stigma to ovary, ovary contains ovules). - 1 mark: Accessory parts — Sepals protect the bud; petals attract pollinators (color, scent). **Q5. Explain the life cycle of a mosquito (or butterfly) with reference to metamorphosis.** *Answer structure (3 marks):* - 1 mark: Four stages — Egg, larva, pupa, adult (complete metamorphosis). - 1 mark: Larval stage undergoes drastic morphological changes in the pupal stage (e.g., mosquito larva in water transforms into adult with wings and proboscis for blood feeding). - 1 mark: Biological significance — Reduces competition between larva and adult for food and habitat; allows life-stage-specific adaptations. **Pattern insight:** 3-mark questions test understanding via comparison, explanation, or structured description. Always show intermediate thinking — don't jump to the final answer.

**Q1. Explain the process of photosynthesis. Write the word equation and describe the role of each reactant and product.** *Full solution (5 marks):* *Definition (1 mark):* Photosynthesis is the autotrophic process in which green plants capture light energy and convert it into chemical energy in the form of glucose. *Equation (1 mark):* Carbon dioxide + Water + Light energy (chlorophyll) → Glucose + Oxygen *Reactants explained (1.5 marks):* - Carbon dioxide (CO₂): Enters leaves through stomata; provides carbon skeleton for glucose synthesis. - Water (H₂O): Absorbed by roots; provides hydrogen and oxygen atoms; split during light reactions to release electrons and protons. - Light energy: Photons absorbed by chlorophyll in thylakoids; energy excites electrons in photosystem II and I; drives ATP and NADPH synthesis. *Products explained (1 mark):* - Glucose (C₆H₁₂O₆): Primary product; stored as starch; used for respiration and cell growth. - Oxygen (O₂): Released as byproduct; used by plants and animals in aerobic respiration. *Location (0.5 marks):* Light reactions in thylakoid membranes; dark reactions (Calvin cycle) in stroma. --- **Q2. Draw a labelled diagram of a root in cross-section and explain how each tissue is adapted for its function.** *Full solution (5 marks):* *Diagram (1.5 marks):* Concentric zones from outside inward — Epidermis, Cortex, Endodermis, Pericycle, Xylem (central), Phloem (between xylem arms). Include root hair on epidermis. *Tissue adaptations (3.5 marks):* 1. **Epidermis (0.5 marks):** Single layer of protective cells; root hairs increase surface area for water and mineral absorption; cuticle absent for rapid diffusion. 2. **Cortex (0.75 marks):** Parenchyma cells with air spaces; store starch; facilitate diffusion of water and ions toward the endodermis; provide structural support. 3. **Endodermis (0.75 marks):** Casparian strip (suberin band) prevents passive diffusion; ensures selective uptake of mineral ions via active transport into the stele; acts as a checkpoint. 4. **Xylem (0.75 marks):** Vessel elements and tracheids; transport water and minerals acropetally (upward); dead, hollow cells form continuous columns with minimal resistance. 5. **Phloem (0.75 marks):* Sieve tubes and companion cells; transport sugars basipetally and acropetally; companion cells provide ATP for active transport in sieve tubes. --- **Q3. Describe the life cycle of a frog. Explain how each stage is adapted to its environment.** *Full solution (5 marks):* *Stages (1.5 marks):* 1. Eggs (laid in jelly-like clusters in water) 2. Tadpole (aquatic larva) 3. Metamorphosis (gradual development of limbs, loss of tail) 4. Froglet (transitional) 5. Adult frog (terrestrial/semi-aquatic) *Environmental adaptations (3.5 marks):* 1. **Egg stage (0.5 marks):** Jelly coating protects from predators and desiccation; laid in water (oxygen-rich environment for developing embryo). 2. **Tadpole stage (1 mark):** Fishlike body with tail for propulsion in water; gills for aquatic respiration; omnivorous diet (algae, plant matter); absence of limbs reduces drag. Develops in 6–9 weeks depending on temperature. 3. **Metamorphosis (1 mark):** Hindlimbs develop first, followed by forelimbs; tail shortens; lungs replace gills; tympanum (eardrum) forms; diet shifts to carnivory (insects). Thyroid hormone (thyroxine) triggers these changes. 4. **Adult frog (1 mark):** Moist skin for cutaneous respiration; powerful hindlimbs for jumping and swimming; forward-facing eyes for predator detection; external tympanum for hearing; returns to water for breeding (external fertilization). *Significance (0.5 marks):* Complete metamorphosis allows tadpoles and adults to exploit different ecological niches, reducing interspecific competition and maximizing survival. **Pattern insight:** 5-mark questions demand structured answers with diagrams (where applicable), layered explanations, and biological significance. Practice timing: allocate 12–15 minutes per 5-mark question.

Based on recent CBSE notifications and pilot schemes, expect these changes in Chapter 10 questions: **1. Increased emphasis on case-based and scenario questions (20% of marks):** Examiners will present real-world scenarios — e.g., 'A farmer observes yellowing leaves in a shaded orchard. Explain the physiological reason and suggest remedies based on photosynthesis principles.' These test application over rote recall. **2. Graphical data interpretation (15% of marks):** Graphs showing CO₂ absorption rates at different light intensities, or respiration rates at varying temperatures, will be included. You'll need to read data, calculate gradients, and interpret biological meaning. **3. Reduced emphasis on memorized diagrams, increased focus on functional explanation:** Rather than 'Label the parts of a stamen,' expect 'Explain how the structure of a stamen ensures pollen viability.' This rewards conceptual understanding over artistic skill. **4. Integration of ecology and evolution (new for 2026–27):** Questions linking herbivore-carnivore relationships to food chains, or life-cycle adaptations to natural selection, will appear. For instance: 'Why do most plants have stomata on the lower epidermis? Explain in terms of water conservation and evolutionary fitness.' **5. Practical-skill questions (10% of marks):** 'Outline an experiment to measure the rate of photosynthesis in an aquatic plant using oxygen bubbles.' Short experimental design questions will test your lab familiarity. **Preparation strategy:** Supplement your PYQ practice with NCERT Exemplar problems (especially the 'Application' and 'High Order Thinking Skills' sections). Watch CBSE sample videos on experimental procedures. Practice writing explanations with 'because' and 'therefore' connectives to build causal reasoning.

**Before the exam (preparation phase):** 1. **Solve at least 2–3 past papers end-to-end in timed conditions** (full 3-hour session). This trains your speed and identifies weak areas before exam day. 2. **Create a diagram checklist** — Root cross-section, stem cross-section, leaf anatomy, flower parts, life cycle stages. Practise drawing each 5–10 times until you can do it in under 3 minutes without reference. 3. **Memorize key equations and define boundary terms:** - Photosynthesis: C₆H₁₂O₆ + 6O₂ ← 6CO₂ + 6H₂O (know direction of arrows; reactants vs. products) - Aerobic respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ~38 ATP - Anaerobic respiration: C₆H₁₂O₆ → 2 Ethanol + 2 CO₂ + 2 ATP (or lactic acid in animals) 4. **Build a glossary of comparison keywords:** herbivore vs. carnivore vs. omnivore; aerobic vs. anaerobic; complete vs. incomplete metamorphosis; xylem vs. phloem; sepal vs. petal. Write one-line differences. **During the exam (execution phase):** 1. **Read all questions in the first 5 minutes.** Identify easy 1-mark questions and harder 5-mark questions. Allocate time: 1-mark = 1.5–2 min, 3-mark = 6–8 min, 5-mark = 12–15 min. 2. **Start with 1-mark questions** to build confidence and rack up quick marks. These are low-risk, high-certainty. 3. **For diagram questions, draw lightly in pencil first, then ink after labelling.** Avoid erasing — it wastes time and looks messy. 4. **For explanation questions, use this structure:** - **What?** Define the term or process in 1–2 sentences. - **How?** Describe the mechanism or sequence of steps. - **Why/Where?** Explain the biological purpose or location. - **Example?** Cite a real example from the NCERT (e.g., 'Spinach leaf has more palisade cells than underwater plant Hydrilla because....'). 5. **Check your equations one last time.** A reversed arrow in a photosynthesis equation costs 0.5 marks in a 1-mark question. 6. **Leave 10 minutes for review.** Revisit 3-mark and 5-mark answers; correct spelling errors (e.g., 'chlorophyll' not 'chlorophil'); add missing units (e.g., ATP, not just 'energy'). **If stuck:** - On a 1-mark question: Move on. Return if time permits. - On a 3-mark question: Write what you know (partial credit = 1–2 marks). Diagram + one sentence often earns 1.5–2 marks. - On a 5-mark question: Attempt the definition and one detailed point. This secures 2–3 marks, leaving time for other questions. Practise this strategy with at least 5 full mock papers. Consistency builds exam-day muscle memory. Start a 3-day free trial at cbsetutor.ai to access AI-guided revision, live doubt sessions, and unlimited mock tests tailored to your pace.

**Photosynthesis:** - Equation: 6CO₂ + 6H₂O + Light (Chlorophyll) → C₆H₁₂O₆ + 6O₂ - Site: Chloroplast (thylakoid membranes for light reactions; stroma for dark reactions/Calvin cycle) - Pigments: Chlorophyll *a*, *b*; carotenoids; xanthophyll (absorption spectrum peaks in blue and red regions) **Respiration in Plants:** - Aerobic: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ~38 ATP - Anaerobic: C₆H₁₂O₆ → 2 Ethanol + 2 CO₂ + 2 ATP (in flooded roots or low O₂ conditions) - Occurs in mitochondria (cristae house electron transport chain) **Respiration in Animals:** - Aerobic: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ~30–32 ATP - Anaerobic (lactic acid fermentation): C₆H₁₂O₆ → 2 Lactic Acid + 2 ATP (muscles during intense exercise) **Plant Transport:** - Xylem: Water and mineral ions, unidirectional (root → stem → leaf), passive transport, dead cells - Phloem: Sugars (sucrose) and amino acids, bidirectional (source ↔ sink), active transport, living cells (sieve tubes + companion cells) **Leaf Anatomy (layers from top to bottom):** - Upper epidermis (cuticle + transparent cells) - Palisade mesophyll (tightly packed, high chloroplast density, 70–80% of photosynthesis) - Spongy mesophyll (loose cells, air spaces, gas exchange) - Lower epidermis (stomata, guard cells regulate opening) **Animal Classification:** - Herbivores: Feed on plants only (deer, rabbit, cow). Teeth: flat molars for grinding. - Carnivores: Feed on meat only (tiger, eagle, shark). Teeth: sharp incisors and canines for tearing. - Omnivores: Feed on plants and meat (human, bear, pig). Teeth: mixed morphology (incisors, canines, molars). **Life Cycles:** - **Complete metamorphosis:** Egg → Larva → Pupa → Adult (butterfly, mosquito, beetle). Four distinct stages; drastic morphological change. - **Incomplete metamorphosis:** Egg → Nymph → Adult (cockroach, grasshopper, dragonfly). Three stages; nymph resembles adult but lacks wings and sexual maturity. - **Amphibian (frog):** Egg → Tadpole (aquatic) → Froglet → Adult (semi-aquatic). Involves metamorphosis triggered by thyroxine. **Flower parts and functions:** - **Calyx:** Sepals (protective, usually green) - **Corolla:** Petals (attractive, often colorful) - **Androecium:** Stamens (anther produces pollen; filament supports anther) - **Gynoecium:** Carpels (stigma receives pollen; style connects stigma to ovary; ovary contains ovules) Use this reference during your final revision 48 hours before the exam. Memorize formulas exactly — even a misplaced coefficient or wrong coefficient can cost marks.