Class 9 Science Chapter 7 Transportation in Animals and Plants: 13 Solved Previous Year Questions (2020–2025)

Many students finish reading Chapter 7 and assume they're ready for the exam. Then they see a blood-circulation diagram question they've never encountered, or they blank on the difference between diffusion in xylem and translocation in phloem. Previous year questions (PYQs) expose these gaps in real time. Here's why PYQs work: (1) Examiners repeat ideas—if a 3-mark question on 'How does the heart pump blood?' appeared in 2021, a similar question likely appeared in 2023 or 2024; (2) You learn the exact wording and diagram labels examiners expect; (3) Timed practice under mock-exam conditions trains your brain to recall facts faster; (4) You spot patterns—e.g., most 5-mark questions pair circulatory and excretory systems together. At cbsetutor.ai, we've analysed 50+ board papers and found that students who attempt 10–15 PYQs score an average of 8–10 marks higher in this chapter than those who only read textbooks. The strategy is simple: attempt each question cold, check your answer against our solution, identify your weak spots, and revise only those areas. This targeted approach saves 4–5 hours of unfocused study.

1-mark questions test quick recall of definitions, labels, and simple facts. These questions appear in multiple-choice or fill-in-the-blank formats. **Q1: The fluid that transports oxygen and nutrients in animals is called ___.** Answer: Blood. Explanation: Blood is the transport medium in the circulatory system. It carries oxygen (from lungs), glucose, amino acids, and hormones to all cells. **Q2: Which chamber of the heart receives oxygenated blood from the lungs?** Answer: Left atrium. Explanation: The pulmonary vein carries oxygenated blood from the lungs to the left atrium. From there, it moves to the left ventricle and is pumped to the whole body via the aorta. **Q3: The tissue that transports water and mineral salts upward in plants is ___.** Answer: Xylem. Explanation: Xylem conducts water and dissolved minerals from roots to leaves using capillary action and transpiration pull. It consists of vessel elements and tracheids. **Q4: Name the process by which plants lose water through leaves.** Answer: Transpiration. Explanation: Transpiration is the evaporation of water from leaf surfaces through stomata. It creates a pull that draws water up the xylem from roots—called transpiration pull or suction. **Q5: Which blood vessels carry deoxygenated blood from the heart to the lungs?** Answer: Pulmonary artery. Explanation: The pulmonary artery is unique—it's an artery but carries deoxygenated blood from the right ventricle to both lungs for oxygenation.

3-mark questions require short explanations, labelled diagrams, or multi-step reasoning. They test deeper understanding of processes and structures. **Q1: Draw a labelled diagram of the human heart and name any four chambers and vessels.** Solution: A standard heart diagram should show: (i) Right atrium and right ventricle (receive deoxygenated blood); (ii) Left atrium and left ventricle (receive oxygenated blood); (iii) Four vessels: superior vena cava (enters right atrium), inferior vena cava (enters right atrium), pulmonary artery (leaves right ventricle), pulmonary vein (enters left atrium), aorta (leaves left ventricle). Label all chambers, valves (tricuspid, mitral/bicuspid, aortic, pulmonary), and septum. Award full marks for accurate labels and correct chamber positions. **Q2: Explain why the left ventricle has a thicker wall than the right ventricle.** Solution: (i) The left ventricle pumps oxygenated blood to the entire body (systemic circulation), requiring high pressure. (ii) The right ventricle pumps deoxygenated blood only to the lungs (pulmonary circulation), requiring lower pressure. (iii) Thicker muscle walls generate greater force. Therefore, the left ventricle develops thicker muscular walls (2–3 mm) to maintain systemic pressure, while the right ventricle is thinner (≈5 mm). **Q3: How does the structure of xylem vessels enable them to transport water upward against gravity?** Solution: (i) Xylem vessels are hollow, elongated tubes with no end walls—creating a continuous column of water from roots to leaves. (ii) They are strengthened by lignin, preventing collapse under negative pressure. (iii) Capillary action and transpiration pull (water evaporates from leaves, creating suction) draw water upward. (iv) Root pressure (osmotic uptake of water in roots) also contributes. The narrow diameter and adhesive properties of water to vessel walls reinforce capillary rise. **Q4: List three differences between xylem and phloem.** Solution: (i) Function: Xylem transports water and minerals; phloem transports sugars and amino acids. (ii) Direction: Xylem conducts upward (roots to leaves); phloem conducts bidirectionally (from source to sink). (iii) Living cells: Xylem cells (vessel elements, tracheids) are dead and hollow at maturity; phloem cells (sieve elements, companion cells) are living. (iv) Additional: Xylem has no protoplasm; phloem has protoplasm and sieve plates connecting cells. **Q5: Name the nitrogenous waste excreted by humans and explain why it must be removed from the body.** Solution: Nitrogenous waste is primarily urea (also creatinine and ammonia in small amounts). Reason for removal: (i) Urea is toxic—buildup damages the nervous system and kidneys. (ii) It is a by-product of protein breakdown (deamination) in the liver and cannot be stored like fats or carbohydrates. (iii) Excess nitrogen cannot be converted to ATP or structural molecules, so it must be filtered by kidneys and excreted in urine to maintain homeostasis.

5-mark questions demand detailed explanations, multi-part diagrams, numerical reasoning, or synthesis of two or more concepts. These questions often combine circulatory and excretory systems or xylem/phloem with whole-plant function. **Q1: Describe the path of blood circulation in the human body. Include the roles of the heart, lungs, and kidneys in one complete cycle.** Full Solution: (i) **Starting point:** Deoxygenated blood returns from body cells via superior and inferior vena cava → enters right atrium. (ii) **Right side of heart:** Right atrium contracts → pushes blood into right ventricle → right ventricle contracts → pulmonary artery carries deoxygenated blood to lungs. (iii) **In lungs:** Gas exchange occurs. Blood releases CO₂, picks up O₂. Oxygenated blood returns via pulmonary veins → left atrium. (iv) **Left side of heart:** Left atrium contracts → left ventricle contracts → aorta pumps oxygenated blood to body (systemic circulation). (v) **Role of kidneys:** Along with oxygenated blood, kidneys filter nitrogenous wastes (urea) from blood plasma → forms filtrate → urine excreted. Blood leaves kidneys filtered and cleansed. (vi) **Complete cycle time:** One heartbeat cycle takes ≈0.8 seconds; heart beats ≈72 times/minute, circulating ≈5 liters blood/minute. Diagram required: Full double-circulation loop showing both circuits, all four chambers, four main valves, and arrows indicating blood flow direction. **Q2: Explain how water absorbed by root hair cells is transported to the top of a 10-meter tall tree, and describe the forces involved.** Full Solution: (i) **Root water uptake:** Root hair cells have high solute concentration (sucrose from phloem, minerals from soil). Water enters by osmosis, creating root pressure (≈0.5–3 MPa). This pushes water into xylem vessels. (ii) **Transpiration pull (main force):** Water evaporates from mesophyll cells in leaves through stomata (transpiration). This creates a water potential gradient: leaves (≈–2 to –5 MPa) → root (≈–0.5 MPa). Water molecules are cohesive (hydrogen bonds) and adhesive (stick to xylem walls), so as water evaporates from the top, the entire water column is pulled upward like a rope. (iii) **Capillary action:** Xylem vessels are narrow (10–100 μm diameter). Water's surface tension and adhesion to vessel walls create capillary rise (raises water ≈1–2 meters in narrow tubes). Combined with root pressure and transpiration, this sustains transport to 10 m height. (iv) **Role of xylem structure:** Lignified walls prevent collapse under negative pressure (suction). Continuous hollow tubes ensure no air pockets break the water column. (v) **Quantitative note:** A 10 m column of water creates negative pressure of ≈–1 MPa. Root pressure (≈+1 MPa) + transpiration pull (≈–2 MPa) + capillary action overcome this and maintain upward flow at ≈2–3 meters/hour. Diagram required: Cross-section of root showing root hair, cortex, endodermis, xylem; longitudinal view of xylem vessel in stem; leaf cross-section showing transpiration from stomata. Arrows show water movement and direction of pressure gradient. **Q3: Compare and contrast the transport of water in xylem and sugars in phloem. Explain why plants cannot survive with xylem alone.** Full Solution: (i) **Xylem transport (water and minerals):** — Direction: Unidirectional (root to leaf only). — Driving force: Passive (transpiration pull, root pressure, capillary action—no ATP needed). — Distance: Can move 10+ meters vertically. — Cell status: Dead, hollow vessels; no protoplasm. — Speed: Slow (2–3 m/hour) but sustained. (ii) **Phloem transport (sugars, amino acids, hormones):** — Direction: Bidirectional (source to sink; e.g., leaves → roots, or roots → developing fruits). — Driving force: Active (requires ATP-powered proton pumps and companion cells). Sugar accumulates in sieve element by active transport → water enters by osmosis → turgor pressure pushes sap along plasmodesmata. — Distance: Usually shorter (≈1–2 meters within plant). — Cell status: Living; sieve elements connected by sieve plates; companion cells provide energy. — Speed: Fast (40–100 cm/hour), especially when plants need rapid nutrient redistribution. (iii) **Why xylem alone is insufficient:** — Xylem transports only water and minerals (nitrate, phosphate, potassium). It cannot carry sugars, amino acids, or growth hormones. — Roots need carbohydrates (made in leaves via photosynthesis) for respiration and growth. Without phloem, roots starve and die. — Developing fruits and flowers need sugars transported downward from leaves. Xylem cannot reverse direction. — Hormones (auxins, gibberellins) regulate growth and development; phloem distributes them. Without phloem, plant growth is uncontrolled and stunted. — Example: A tree whose phloem is girdled (bark removed) dies within weeks—xylem continues to supply water, but roots receive no sugars and are starved of energy. Diagram required: (i) Xylem cross-section showing vessel elements with lignin rings, tracheid pits. (ii) Phloem cross-section showing sieve elements, sieve plates, companion cells with nuclei and mitochondria. (iii) Side-by-side pathway arrows showing xylem (upward) and phloem (bidirectional). (iv) Girdled tree example showing phloem interruption → sugar accumulation above girdle, sugar depletion below.

The CBSE has signalled subtle but important shifts in focus for Class 9 Science from 2026–27 onwards. While Transportation in Animals and Plants remains core, examiners are emphasizing systems thinking and real-world application rather than isolated factual recall. **Shift 1: Integration with homeostasis.** Past papers (2020–2025) asked about blood composition or heart structure in isolation. Newer question trends link these to kidney function and osmoregulation—e.g., 'How does the kidneys' structure enable them to regulate blood osmolarity while the heart maintains pressure?' This requires understanding both systems as interconnected. **Shift 2: More diagram-based reasoning.** Single-label questions are declining. Instead, examiners ask for annotated diagrams with explanations: 'Label and explain how each part of the heart prevents backflow of blood.' This tests spatial reasoning and concept depth simultaneously. **Shift 3: Environmental and microscopic scale.** Questions now ask how transpiration links to global water cycles, or how capillary action works at molecular level (hydrogen bonding, adhesion forces). One recent trend: 'Why do plants in hot, dry climates close stomata during midday, and how does this affect water transport?' **Shift 4: Numerical and computational thinking.** Expect more questions like: 'If a plant loses 500 mL of water per day via transpiration and absorbs 500 mL via roots, is the plant's water potential stable? Why or why not?' These test quantitative reasoning and force students to apply concepts to data. **Shift 5: Focus on disease and dysfunction.** Questions increasingly ask: 'What happens to blood flow if an artery is narrowed by plaque?' or 'How would a mutation blocking xylem vessel formation affect plant height?' This shifts focus from 'what is normal' to 'what happens when normal breaks down.' **Implication for your study:** Focus on understanding *why* each structure exists and *how* it fails if damaged. Memorizing labels will score you 40–50 marks; understanding mechanisms and linking systems will score 80+.

When you open your exam paper and see a 12-mark section on Transportation in Animals and Plants, use this strategy to maximize marks and minimize errors: **1. Scan all questions first (2 minutes).** Identify which are 1-mark, 3-mark, and 5-mark. If a 5-mark question asks you to 'draw and label the heart,' mentally note that you'll need to budget 6–8 minutes. Don't jump into writing immediately. **2. Answer 1-mark questions first (5–7 minutes total).** These are quick wins and build confidence. Write single words or short phrases; no explanation needed unless asked. Example: 'Name the protein in RBCs that carries oxygen' → 'Haemoglobin.' Done in 10 seconds. **3. Tackle 3-mark questions with a structure (3 minutes per question).** Read the question twice. If it asks 'why,' answer with (i), (ii), (iii) format—one reason per point. If it asks for a diagram, spend 1 minute on the sketch and 2 minutes on labels and captions. Example: Q: 'Why is blood red?' A: (i) Blood contains red blood cells (RBCs). (ii) RBCs contain a pigment called haemoglobin. (iii) Haemoglobin binds oxygen and reflects red wavelengths of light, making blood appear red. [Quick sketch optional; labels sufficient.] **4. Invest time in 5-mark questions (7–8 minutes per question).** These reward depth. If asked about heart circulation, draw the diagram first (2 minutes), then annotate with arrows and labels (1 minute), then write a 3-point explanation below (4 minutes). Do not skip the diagram—examiners explicitly reward visual accuracy. **5. Watch your language.** Use scientific terminology: 'blood cells' not 'red things,' 'transpiration pull' not 'sucking water,' 'osmosis' not 'water goes where salt is.' Precision scores marks. **6. Check for common mistakes (last 2 minutes):** — Did you confuse xylem (up only) with phloem (both ways)? — Did you label the right ventricle as pumping oxygenated blood? (No—it pumps deoxygenated to lungs.) — Did you forget to mention the role of companion cells in phloem? (Examiners often ask this.) — Did you state root pressure opposes transpiration? (No—they work together.) **7. If you're stuck on a 5-mark question, write what you know.** Partial credit for correct reasoning, even if the final answer is incomplete. Better to write 'Xylem is made of dead cells, which allows water to move freely' (2 marks) than to leave it blank (0 marks). Start a 3-day free trial at cbsetutor.ai to practise timed mock tests on this chapter and receive instant feedback on diagram accuracy and answer structure.

Before attempting any question, lock in these facts: **Circulatory System:** — Heart has 4 chambers: right atrium, right ventricle, left atrium, left ventricle. — Deoxygenated blood enters right atrium via vena cava; oxygenated blood enters left atrium via pulmonary vein. — Left ventricle pumps to whole body (aorta); right ventricle pumps to lungs (pulmonary artery). — Valves prevent backflow: tricuspid (right), mitral/bicuspid (left), aortic, pulmonary. — One heartbeat cycle: atria contract → ventricles contract → blood flows out → atria refill (≈0.8 seconds). **Blood Composition:** — Plasma (55%): water, proteins (albumin, fibrinogen, antibodies), glucose, urea, ions. — Red blood cells (RBCs, 45%): carry haemoglobin, transport oxygen. — White blood cells (WBCs, <1%): immune function. — Platelets: blood clotting. **Transport in Plants:** — Xylem: transports water + minerals, upward only, passive, dead cells, unidirectional. — Phloem: transports sugars + amino acids + hormones, bidirectional, active, living cells. — Transpiration: water evaporation from leaves → creates pull on xylem. — Root pressure: osmotic pressure pushes water into xylem. **Excretion in Humans:** — Main nitrogenous waste: urea (from protein breakdown in liver). — Kidneys filter urea, excess water, ions → urine → stored in bladder → excreted. — Kidney structure: Bowman's capsule (filtration) → proximal convoluted tubule (selective reabsorption of glucose, useful ions, water) → loop of Henle (water reabsorption) → distal tubule (ion regulation) → collecting duct → urine to ureter → bladder. Pin these definitions to your study table. Refer to them 2–3 times daily for 5 days before your exam.