Class 9 Science Chapter 10 Living Creatures: Exploring their Characteristics — 30 MCQs with Answers & Explanations

The reformed CBSE assessment structure (2024–25) emphasizes objective testing to measure concept mastery quickly and fairly. MCQs account for 40–50% of Class 9 Science paper marks, with focus on: 1. **Concept Recall**: Direct definitions (e.g., 'Which is the main function of root hair?'). 2. **Application**: Linking concepts to real scenarios (e.g., 'Why do desert plants have thick waxy leaves?'). 3. **Assertion–Reason**: Testing logical connections between statements — highest cognitive demand. Chapter 10 MCQs probe: - Plant tissue function and adaptation (roots absorb water; leaves maximize photosynthesis). - Food relationships (trophic levels; energy flow). - Metabolic processes (photosynthesis in chloroplasts; aerobic respiration in mitochondria). - Life cycle stages (metamorphosis in insects; flowering in plants). Mastering MCQ technique — eliminating wrong options, spotting trap answers, managing time — boosts raw marks by 15–25%. This quiz trains all three skills systematically.

**Q1.** Which of the following is the primary function of roots? (a) Photosynthesis (b) Absorption of water and minerals (c) Transpiration (d) Flower production **Ans:** (b) **Reason:** Root hairs absorb water and dissolved minerals from soil; photosynthesis occurs in leaves. **Q2.** What is the main role of chlorophyll in leaves? (a) Structural support (b) Trapping light energy for photosynthesis (c) Storing starch (d) Producing flowers **Ans:** (b) **Reason:** Chlorophyll (green pigment in chloroplasts) absorbs light wavelengths, initiating photosynthesis. **Q3.** Which type of animal eats only plants? (a) Carnivore (b) Omnivore (c) Herbivore (d) Scavenger **Ans:** (c) **Reason:** Herbivores (cow, goat, deer) have flat molars for grinding plant material. **Q4.** In the life cycle of a butterfly, what is the stage between larva and adult? (a) Pupa (b) Nymph (c) Chrysalis (d) Both (a) and (c) **Ans:** (d) **Reason:** Pupa and chrysalis both refer to the immobile metamorphic stage; chrysalis is the pupa of butterflies. **Q5.** Which organelle is responsible for aerobic respiration in animal cells? (a) Nucleus (b) Ribosome (c) Mitochondrion (d) Golgi apparatus **Ans:** (c) **Reason:** Mitochondria (powerhouse of the cell) break down glucose using oxygen to release energy (ATP). **Q6.** What is the primary function of the stem? (a) Absorption of water (b) Support and transport of water and nutrients (c) Photosynthesis only (d) Storage of food **Ans:** (b) **Reason:** Xylem in the stem transports water upward; phloem transports sugars downward. **Q7.** Which gas is released during photosynthesis? (a) Carbon dioxide (b) Nitrogen (c) Oxygen (d) Methane **Ans:** (c) **Reason:** In photosynthesis, water is split, releasing O₂ as a byproduct: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂. **Q8.** A lion is classified as a: (a) Herbivore (b) Carnivore (c) Omnivore (d) Decomposer **Ans:** (b) **Reason:** Lions hunt and eat meat exclusively; they have sharp canines and no flat molars for grinding plants. **Q9.** In which part of the flower are ovules located? (a) Sepal (b) Petal (c) Ovary (d) Stamen **Ans:** (c) **Reason:** The ovary (female reproductive organ) contains ovules, which develop into seeds after fertilization. **Q10.** What is the primary purpose of respiration in living organisms? (a) To produce glucose (b) To release energy from food (c) To absorb oxygen only (d) To produce chlorophyll **Ans:** (b) **Reason:** Respiration (both aerobic and anaerobic) breaks down nutrients to release energy in the form of ATP.

**Q11.** A plant placed in a dark cupboard for 5 days showed yellowing of leaves. What is the most likely reason? (a) Root rot (b) Absence of light for photosynthesis, preventing chlorophyll synthesis (c) Excess water (d) Pest infestation **Ans:** (b) **Reason:** Chlorophyll synthesis requires light; without photosynthesis, new leaves lack pigment and appear yellow (etiolation). **Q12.** In a food chain: Grass → Grasshopper → Bird → Snake, how much energy (approx.) is available to the snake? (a) 100% of the energy in grass (b) 10% of the energy in grass (c) 50% of the energy in grass (d) 1% of the energy in grass **Ans:** (d) **Reason:** Energy transfer between trophic levels is ~10%; snake receives 10% of 10% of 10% = 0.1% ≈ 1%. **Q13.** A plant's leaf shows brown, papery texture and curled edges in summer. What adaptation is NOT evident? (a) Reduced surface area (b) Waxy coating (cuticle) (c) Increased transpiration (d) Minimized water loss **Ans:** (c) **Reason:** Curling and browning reduce transpiration (water loss), not increase it; this is a drought adaptation. **Q14.** A frog undergoes complete metamorphosis from egg to tadpole to adult frog. At which stage does the frog begin to breathe air? (a) Egg (b) Tadpole (aquatic, gills) (c) Metamorphlet (developing lungs) (d) Adult frog **Ans:** (c)/(d) — most likely **(d)** **Reason:** As the frog metamorphoses, gills are resorbed and lungs develop; air-breathing begins late in tadpole stage or early adulthood. **Q15.** In photosynthesis, the light-dependent reactions occur in the: (a) Stroma (b) Thylakoid membranes (grana) (c) Nucleus (d) Mitochondrial matrix **Ans:** (b) **Reason:** Thylakoids trap light and split water; stroma hosts the Calvin cycle (light-independent reactions). **Q16.** A student observes a plant with simple, oval leaves alternately arranged on the stem. The leaf has a single central vein. This plant likely has: (a) Parallel venation; monocot (b) Reticulate (net-like) venation; dicot (c) Parallel venation; dicot (d) Reticulate venation; monocot **Ans:** (a) **Reason:** Single midrib with parallel side veins and alternate leaf arrangement indicates monocot (e.g., grass, banana); reticulate (net) venation suggests dicot. **Q17.** During anaerobic respiration in muscles during intense exercise, lactic acid accumulates. Why do muscles feel fatigue? (a) Lactic acid buildup lowers pH, inhibiting enzyme function (b) Excess oxygen is produced (c) Mitochondria are destroyed (d) Glucose is completely converted to CO₂ **Ans:** (a) **Reason:** Lactate fermentation produces lactic acid (C₃H₆O₃), which acidifies muscle tissue, causing pain and fatigue. **Q18.** In a flower, the stamen (male reproductive organ) produces: (a) Seeds (b) Ovules (c) Pollen grains (d) Fruit **Ans:** (c) **Reason:** Stamen comprises anther (produces pollen) and filament; pollen contains male gametes. **Q19.** A herbivore's digestive system is longer than a carnivore's. Why? (a) Herbivores eat more food by mass (b) Plant cellulose requires longer breakdown; more chambers (ruminants) aid fermentation (c) Carnivores have stronger stomach acids (d) Herbivores have larger livers **Ans:** (b) **Reason:** Cellulose digestion is slow; herbivores (especially ruminants) possess multiple stomach chambers for microbial fermentation. **Q20.** A seedling grown indoors near a window shows bending toward the light source. This response is called: (a) Geotropism (gravity response) (b) Phototropism (light response) (c) Hydrotropism (water response) (d) Chemotropism (chemical response) **Ans:** (b) **Reason:** Phototropism is directional growth toward light, driven by auxin (plant hormone) redistribution away from the light source.

**Q21.** **Assertion (A):** Roots can absorb water and minerals from soil even in the dark. **Reason (R):** Root absorption requires light energy for photosynthesis. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is true; R is false. (d) A is false; R is true. **Ans:** (c) **Reason:** Roots absorb water by osmosis (passive, no light needed); roots lack chlorophyll and cannot photosynthesize. **Q22.** **Assertion (A):** Leaves with a waxy cuticle lose more water by transpiration than leaves without one. **Reason (R):** The waxy cuticle prevents water loss by reducing the surface area available for evaporation. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is false; R is true. (d) A is true; R is false. **Ans:** (c) **Reason:** The assertion is backwards; waxy cuticle *reduces* water loss, not increases it. **Q23.** **Assertion (A):** Omnivores occupy a higher trophic level than herbivores in all food chains. **Reason (R):** Omnivores consume both primary and secondary consumers, receiving energy from multiple sources. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is false; R is true. (d) Both A and R are false. **Ans:** (c) **Reason:** Omnivores occupy *variable* trophic levels depending on what they eat in a given chain; an omnivore eating plants is at trophic level 2, eating herbivores at level 3. **Q24.** **Assertion (A):** During aerobic respiration, glucose is completely oxidized to CO₂ and H₂O in the mitochondrial matrix alone. **Reason (R):** Glycolysis (initial glucose breakdown) occurs in the cytoplasm; the Krebs cycle and electron transport occur in mitochondria. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is false; R is true. (d) A is true; R is false. **Ans:** (c) **Reason:** Glucose oxidation is split between cytoplasm (glycolysis) and mitochondria; not all oxidation occurs in the matrix. **Q25.** **Assertion (A):** The life cycle of a frog includes both aquatic (tadpole) and terrestrial (adult) stages. **Reason (R):** This transition from tadpole to frog involves complete metamorphosis, including gill-to-lung transition and limb development. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is true; R is false. (d) Both A and R are false. **Ans:** (a) **Reason:** Both statements are accurate; metamorphosis explains the habitat shift due to physiological transformation. **Q26.** **Assertion (A):** In photosynthesis, the Calvin cycle (light-independent reactions) can occur in complete darkness if ATP and NADPH are supplied externally. **Reason (R):** The light-dependent reactions produce ATP and NADPH, which are then used in the Calvin cycle to fix CO₂. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is true; R is false. (d) Both A and R are false. **Ans:** (a) **Reason:** If ATP and NADPH are provided, the Calvin cycle proceeds without direct light; light is needed to generate these energy carriers. **Q27.** **Assertion (A):** A carnivore's stomach acid is weaker than a herbivore's because meat is easier to digest than plant fibre. **Reason (R):** Carnivores secrete high concentrations of pepsin (protease) to break down protein; herbivores rely on microbial fermentation in multiple stomach chambers. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is false; R is true. (d) A is true; R is false. **Ans:** (c) **Reason:** Carnivores have *stronger* (more acidic) stomach acid (pH 1.5–2) to denature proteins; the assertion is reversed. **Q28.** **Assertion (A):** Flowers are reproductive structures that produce seeds and ensure genetic diversity through sexual reproduction. **Reason (R):** Pollination and fertilization within a flower lead to the fusion of male (pollen) and female (ovule) gametes, forming seeds. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is true; R is false. (d) Both A and R are false. **Ans:** (a) **Reason:** Both are correct; sexual reproduction via pollination and fertilization explains genetic diversity and seed formation. **Q29.** **Assertion (A):** Respiration in plants always occurs in the dark, while photosynthesis occurs only in light. **Reason (R):** Photosynthesis requires light energy; respiration in mitochondria and cytoplasm is independent of light and occurs 24/7. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is false; R is true. (d) A is true; R is false. **Ans:** (c) **Reason:** Plants respire continuously in light *and* dark; photosynthesis during the day outpaces respiration, creating net O₂ release. **Q30.** **Assertion (A):** Root hair cells have a large surface area and high mitochondrial density to maximize water and mineral absorption. **Reason (R):** Root hair cells absorb ions against the concentration gradient via active transport, requiring ATP energy from mitochondria. (a) Both A and R are true; R explains A. (b) Both A and R are true; R does NOT explain A. (c) A is true; R is false. (d) Both A and R are false. **Ans:** (a) **Reason:** Root hairs use active transport (mitochondrial ATP) to absorb ions; large surface area and abundant mitochondria are structural/metabolic adaptations for this function.

CBSE question-setters deliberately craft plausible distractors to test depth of understanding. Watch for these recurring traps: **1. Reversing Function–Structure Links** - **Trap:** "Thick waxy leaves *increase* transpiration in deserts." - **Reality:** Cuticle *reduces* water loss. The assertion is backwards. **2. Confusing Organelle Roles** - **Trap:** "Photosynthesis occurs in mitochondria; respiration in chloroplasts." - **Reality:** Inverse — chloroplasts do photosynthesis; mitochondria do respiration. **3. Overgeneralizing Trophic Levels** - **Trap:** "An omnivore is always at trophic level 3." - **Reality:** Trophic level depends on what the omnivore eats in a specific food chain. A human eating salad is at level 2; eating chicken is at level 3. **4. Misinterpreting Life Cycle Terminology** - **Trap:** "Tadpoles breathe air via lungs from the egg stage." - **Reality:** Tadpoles use *gills* for aquatic respiration; lungs develop during metamorphosis. **5. Partial Truths in Assertion–Reason** - **Trap:** "A is true; R is true" but R *doesn't logically explain* A. Students miss the second clause. - **Example:** A: "Leaves are green." R: "Chlorophyll contains magnesium." Both true, but R doesn't fully explain A's greenness. **6. Confusing Light-Dependent & Light-Independent Reactions** - **Trap:** "The Calvin cycle requires direct light." - **Reality:** Calvin cycle is light-*independent* but needs ATP/NADPH from light reactions. **7. Anaerobic vs. Aerobic Respiration** - **Trap:** "Lactic acid fermentation releases more ATP than aerobic respiration." - **Reality:** Anaerobic respiration (2 ATP) yields ~95% less energy than aerobic respiration (~30–32 ATP per glucose). **8. Root Absorption Misconception** - **Trap:** "Roots absorb water and minerals because they have chlorophyll to photosynthesize sugars." - **Reality:** Roots lack chlorophyll; they absorb via osmosis (passive) and active transport (ions), fueled by sugar made in leaves. Read each option and ask: *Is this literally true? Does it explain the statement? Or is it a half-truth?*

CBSE Class 9 Science papers (total 80 marks over 3 hours) typically allocate 30–40 minutes to MCQs. Chapter 10 questions constitute ~8–12 marks. Optimize your approach: **Before the Exam (Practice Phase)** - Time yourself on 10–15 mixed-difficulty MCQs. Average: 1.5–2 min per easy, 2–3 min per medium, 3–4 min per assertion–reason. - Identify *your* weak topics (e.g., photosynthesis biology vs. plant anatomy). Pre-study those heavily. **During the Exam (Time Allocation)** 1. **First Pass (Easy): 10–12 min** — Scan all easy MCQs (Q1–Q10 type). Answer those you recognize instantly. Mark doubtful ones with a pencil dot. 2. **Second Pass (Medium): 12–15 min** — Work through application-based questions. Re-read the scenario; eliminate 2–3 clearly wrong options; choose between last 2. 3. **Third Pass (Hard/Assertion–Reason): 15–18 min** — Read assertion first. Then reason. Check if R logically supports A. Use elimination: *both true but unrelated → (b); A false, R true → (d),* etc. 4. **Review (5–7 min)** — Revisit marked questions. Do not second-guess unless you have fresh reasoning. **Elimination Technique (Saves 20–30 sec per Q)** - **Step 1:** Eliminate any option contradicting textbook facts (e.g., "roots photosynthesize" — crossed out immediately). - **Step 2:** Eliminate overgeneralizations (e.g., "always," "never," "all"). - **Step 3:** Check remaining 2 options against the *exact* wording of the question. **Assertion–Reason Fast-Track (Cuts 45 sec)** - If R is clearly *false* → answer is (d) or (c) (depending on A). - If A is *obviously false* but R is true → answer is always (d). - If both A and R are true, re-read R: Does it *directly explain* A's cause? If yes → (a). If no → (b). **Red Flags (Questions to Skip Initially)** - Unfamiliar organism names → Skip; revisit later if time permits. - Assertion–reason with 3+ clauses → Read twice; high error rate. - Numerical calculations (energy transfer) → Flag; solve last. **Mark Confidence** - Confident answers: tick ✓ - Guesses (70% sure): dot • - Blind guesses (50%): cross ✗ - Review order: ✗ → • → ✓ (never second-guess confident answers). With structured practice using this quiz, students typically improve MCQ accuracy from 65% → 82–88% in 2–3 weeks. Start a 3-day free trial at cbsetutor.ai to access adaptive AI-powered MCQ sessions that track weak topics and adapt difficulty in real-time.

**Plant Biology** - Photosynthesis: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ - Chlorophyll location: Thylakoid membranes (grana) in chloroplasts. - Root hair function: Osmotic water uptake + active transport of minerals (K⁺, NO₃⁻, PO₄³⁻). - Leaf venation: Monocots (parallel); Dicots (reticulate/net-like). **Animal Nutrition & Respiration** - Aerobic respiration (mitochondrial): C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ~30–32 ATP - Anaerobic respiration (lactic fermentation): C₆H₁₂O₆ → 2C₃H₆O₃ + 2 ATP (muscles, RBCs) - Energy transfer in food chains: ~10% per trophic level. - Herbivore stomach pH: 7–8 (neutral to slightly alkaline); Carnivore: 1.5–2 (highly acidic). **Life Cycles** - **Amphibian (frog):** Egg → Tadpole (aquatic, gills) → Metamorphlet → Adult (terrestrial/aquatic, lungs). Complete metamorphosis. - **Insect (butterfly):** Egg → Larva → Pupa/Chrysalis → Adult. Complete metamorphosis. - **Insect (grasshopper):** Egg → Nymph (resembles adult, wingless) → Adult (winged). Incomplete metamorphosis. **Flower Structure** - Male: Stamen (anther + filament) → pollen. - Female: Carpel/Pistil (stigma + style + ovary) → ovule → seed. - Pollination: Transfer of pollen to stigma (abiotic or biotic). - Fertilization: Fusion of pollen nucleus + ovule nucleus → zygote → embryo → seed. Use this table as a revision checklist 2–3 days before the exam.