Class 9 Science Chapter 7 Transportation in Animals and Plants: 30 MCQs with Answers & Explanations

The revised CBSE Class 9 Science curriculum prioritizes multiple-choice questions because they test both knowledge and application in 60 seconds. A single MCQ forces you to: (1) recall factual knowledge (e.g., haemoglobin carries O₂), (2) compare options logically, (3) avoid trap answers, and (4) apply reasoning to unfamiliar scenarios. Unlike descriptive answers, MCQs demand precision—a single wrong word disqualifies the answer. For Chapter 7, examiners frequently test: structure vs. function (heart chambers, vessel types), numerical relationships (pulse rate ≈ 72 bpm in adults), and mechanism-based reasoning (why xylem transports water upward against gravity). Assertion-reason MCQs (A–R type) have become increasingly common, where both statements must be true AND the reason must explain the assertion. Mastering MCQ strategies—reading all options, identifying keywords, and eliminating distractors—directly improves your exam score. This chapter's MCQs often interweave circulatory system knowledge with plant transport, testing your ability to compare animal and plant mechanisms side by side.

**Q1.** Which of the following is the pumping organ of the circulatory system? A) Lungs B) Heart C) Kidney D) Liver **Answer: B** **Reason:** The heart is a muscular organ that contracts to push blood through arteries and veins. **Q2.** What is the primary function of haemoglobin in red blood cells? A) Carry glucose B) Carry oxygen C) Produce antibodies D) Clot blood **Answer: B** **Reason:** Haemoglobin binds O₂ in lungs and releases it in tissues. **Q3.** Which blood vessels carry blood away from the heart? A) Veins B) Capillaries C) Arteries D) Lymph vessels **Answer: C** **Reason:** Arteries are thick-walled vessels that transport blood under high pressure from the heart. **Q4.** The vascular tissue in plants responsible for transporting water is: A) Phloem B) Xylem C) Cambium D) Cortex **Answer: B** **Reason:** Xylem conducts water and minerals from roots to leaves via capillary action and root pressure. **Q5.** How many chambers does a human heart have? A) 2 B) 3 C) 4 D) 5 **Answer: C** **Reason:** Two atria (upper) and two ventricles (lower) enable efficient two-stage pumping. **Q6.** Which of the following transports nutrients (sugars) in plants? A) Xylem B) Phloem C) Stomata D) Root hair **Answer: B** **Reason:** Phloem is living tissue that moves photosynthetically produced sugars downward from leaves to all plant parts. **Q7.** The normal resting pulse rate in an adult human is approximately: A) 40–50 bpm B) 60–100 bpm C) 120–140 bpm D) 150+ bpm **Answer: B** **Reason:** Healthy adults typically maintain a resting heart rate between 60 and 100 beats per minute. **Q8.** Excretion in humans primarily removes: A) Glucose B) Urea C) Vitamins D) Proteins **Answer: B** **Reason:** Urea is a toxic nitrogenous waste product formed from protein metabolism, filtered by kidneys. **Q9.** Which organ system in humans is mainly responsible for excretion? A) Digestive B) Respiratory C) Urinary D) Nervous **Answer: C** **Reason:** The urinary system (kidneys, bladder, urethra) filters waste from blood and forms urine. **Q10.** Water moves up a plant stem against gravity because of: A) Photosynthesis B) Root pressure and capillary action C) Gravity force D) Chlorophyll absorption **Answer: B** **Reason:** Active uptake by root cells creates root pressure; narrow xylem vessels enable capillary rise of water.

**Q11.** In the human heart, deoxygenated blood from the body enters the: A) Left atrium B) Right atrium C) Left ventricle D) Right ventricle **Answer: B** **Reason:** Superior and inferior vena cava deliver deoxygenated blood to the right atrium. **Q12.** Which valve prevents backflow of blood into the right atrium? A) Tricuspid B) Mitral C) Aortic D) Pulmonary **Answer: A** **Reason:** The tricuspid valve closes when the right ventricle contracts, preventing reversal into the atrium. **Q13.** Oxygenated blood from the lungs enters the human heart via: A) Superior vena cava B) Inferior vena cava C) Pulmonary veins D) Aorta **Answer: C** **Reason:** Four pulmonary veins bring O₂-rich blood from lungs to the left atrium. **Q14.** The function of the septum in the heart is to: A) Pump blood B) Separate right and left sides C) Conduct electrical impulses D) Produce blood cells **Answer: B** **Reason:** The septum divides the heart into right (deoxygenated) and left (oxygenated) sides, preventing mixing. **Q15.** Transpiration in plants is primarily driven by: A) Root pressure alone B) Evaporation from leaves + root pressure C) Gravity D) Photosynthesis **Answer: B** **Reason:** Water lost from leaves (transpiration) creates tension that pulls water up xylem; root pressure assists during night. **Q16.** Which cells in blood are responsible for fighting infections? A) Red blood cells B) Platelets C) White blood cells D) Plasma proteins **Answer: C** **Reason:** White blood cells (lymphocytes, neutrophils) engulf pathogens and produce antibodies. **Q17.** In the kidneys, selective reabsorption occurs in: A) Glomerulus B) Bowman's capsule C) Proximal convoluted tubule D) Collecting duct **Answer: C** **Reason:** The proximal convoluted tubule actively reabsorbs glucose, amino acids, and ions needed by the body. **Q18.** Phloem tissue in plants differs from xylem because: A) Phloem has living cells; xylem cells lack nuclei B) Phloem carries water; xylem carries sugar C) Phloem requires energy; xylem is passive D) Both A and C **Answer: D** **Reason:** Phloem sieve tubes are living (require ATP for active transport); xylem vessels are dead, lignified tubes for passive water movement. **Q19.** Blood pressure is typically measured as: A) 60/100 mmHg B) 120/80 mmHg C) 80/120 mmHg D) 100/60 mmHg **Answer: B** **Reason:** Normal blood pressure is ~120 mmHg (systolic, heart contraction) / 80 mmHg (diastolic, relaxation). **Q20.** The transpiration-cohesion-tension theory explains water transport in xylem through: A) Osmotic pressure alone B) Continuous water column pulled by leaf transpiration C) Active transport by xylem cells D) Gravity and diffusion **Answer: B** **Reason:** Evaporation from leaves creates negative pressure (tension) that pulls a continuous water column up the xylem against gravity.

**Q21.** **Assertion (A):** Capillaries are the site of exchange of materials between blood and tissue fluid. **Reason (R):** Capillaries have thin, permeable walls and move blood slowly, allowing diffusion. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A true, R false D) A false, R true **Answer: A** **Reason:** Both statements are factually correct, and the slow flow and thin walls of capillaries directly enable the exchange function. **Q22.** **Assertion (A):** Arteries always carry oxygenated blood, and veins always carry deoxygenated blood. **Reason (R):** Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A false, R true D) Both A and R false **Answer: C** **Reason:** The assertion is false because the pulmonary artery is an exception (an artery carrying deoxygenated blood); the reason is true and proves this. **Q23.** **Assertion (A):** Xylem transport requires metabolic energy (ATP), unlike phloem transport. **Reason (R):** Xylem cells are dead and lack mitochondria for ATP synthesis. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A false, R true D) Both A and R false **Answer: A** **Reason:** Xylem's passive transport is enabled by dead cells without ATP; phloem's active transport requires living sieve cells with working mitochondria. **Q24.** **Assertion (A):** The right side of the heart pumps blood at lower pressure than the left side. **Reason (R):** The right ventricle has thinner walls than the left ventricle. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A true, R false D) Both A and R false **Answer: A** **Reason:** The right ventricle's thinner muscle (lower force) generates lower pressure needed only to reach nearby lungs; the left ventricle powerfully pumps to the entire body. **Q25.** **Assertion (A):** Urea concentration is higher in the collecting duct than in the glomerular filtrate. **Reason (R):** Selective reabsorption in the proximal convoluted tubule removes urea. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A true, R false D) A false, R true **Answer: B** **Reason:** The assertion is true (urea concentrates as water is reabsorbed), but the reason is false—urea is NOT reabsorbed; water reabsorption causes relative concentration increase. **Q26.** **Assertion (A):** Sieve tubes in phloem lack nuclei but can still transport sugars actively. **Reason (R):** Companion cells adjacent to sieve tubes provide ATP and regulate transport. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A false, R true D) Both A and R false **Answer: A** **Reason:** Mature sieve tubes are enucleate but functionally sustained by nearby companion cells that generate and supply ATP for active phloem loading. **Q27.** **Assertion (A):** A person with high blood pressure (hypertension) has increased risk of heart disease. A) Sustained high BP damages artery walls and increases workload on the left ventricle, weakening it over time. B) Both A and R true; R does not explain A C) A true, R false D) A false, R true **Answer: A** **Reason:** Chronically elevated BP causes endothelial damage, atherosclerosis, and left ventricular hypertrophy, increasing myocardial infarction risk. **Q28.** **Assertion (A):** Transpiration rate increases during daytime but decreases at night. **Reason (R):** Stomata close at night because photosynthesis stops and turgor pressure in guard cells decreases. A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A true, R false D) A false, R true **Answer: A** **Reason:** Daytime heat and light open stomata for photosynthesis (high transpiration); at night, guard cells lose turgor, stomata close, and transpiration drops. **Q29.** **Assertion (A):** Red blood cell count is higher in people living at high altitudes than at sea level. **Reason (R):** Lower atmospheric oxygen at altitude triggers erythropoietin release, stimulating RBC production (acclimatization). A) Both A and R true; R explains A B) Both A and R true; R does not explain A C) A true, R false D) A false, R true **Answer: A** **Reason:** Hypoxia activates kidneys to release EPO, increasing erythropoiesis; elevated RBC count compensates for thin air. **Q30.** **Assertion (A):** Kidney failure leads to accumulation of urea in blood, causing uremia. A) Damaged nephrons cannot filter waste; urea builds up and poisons cells, affecting nervous system and heart function. B) Both A and R true; R does not explain A C) A true, R false D) Both A and R false **Answer: A** **Reason:** Uremia is clinical toxicity from urea and other nitrogenous wastes; accumulation disrupts cellular metabolism and causes systemic dysfunction, potentially fatal without dialysis.

CBSE examiners deliberately craft distractor options that exploit common misconceptions. Awareness of these traps will save you marks. **Trap 1: Artery vs. Vein Confusion** Wrong: "Veins carry all deoxygenated blood." Right: Pulmonary veins carry oxygenated blood from lungs. The keyword is NOT the name—it's the direction (away from heart = artery; toward heart = vein). **Trap 2: Xylem vs. Phloem Function Reversal** Wrong: "Xylem transports sugars downward." Right: Phloem (living, requires energy) transports sugars bidirectionally; xylem (dead tubes) transports water and minerals upward only. Examiners often swap these to test depth. **Trap 3: Excretion vs. Elimination Conflation** Wrong: "Excretion is removing all waste from the body." Right: Excretion removes metabolic waste (urea, uric acid); defecation is elimination of undigested food. Kidney-related MCQs test this fine line. **Trap 4: Pressure Direction in Heart** Wrong: "Right atrium receives oxygenated blood." Right: Right atrium receives deoxygenated blood from the body; left atrium receives oxygenated blood from lungs. Flipping left/right is a frequent error. **Trap 5: Root Pressure vs. Capillary Action** Wrong: "Root pressure alone pulls water 100+ meters up a tree." Right: Root pressure is weak (~2 atm); capillary action + transpiration-cohesion tension dominates. MCQs test which mechanism is primary. **Trap 6: Assertion-Reason Pitfall** Wrong: Choosing "Both true" without checking if R actually explains A. A statement can be factually correct yet logically unrelated. Always verify causation, not just truth. **Trap 7: Valve Direction Confusion** Wrong: "Aortic valve prevents backflow into the left atrium." Right: Aortic valve closes between left ventricle and aorta. Students confuse which valve guards which chambers—memorize each valve's exact location. **Trap 8: Cell Count Misconception** Wrong: "Red blood cells are the most numerous, so they are most important." Right: RBCs carry O₂ (essential for energy), but WBCs are infection-fighters, and platelets prevent bleeding. MCQs test functional importance, not abundance. **Strategy:** Before submitting, ask: "Is this the mechanism, not just a name?" "Does the reason logically explain the assertion?" "Am I confusing similar structures (left vs. right, xylem vs. phloem)?" This metacognitive check eliminates ≈80% of trap answers.

In a 3-hour CBSE exam with 40+ MCQs across all chapters, efficient time allocation is critical. This strategy applies directly to Chapter 7 questions. **Rule 1: The 60-Second Rule per MCQ** Allocate ~60 seconds per MCQ in your mind. If you read the stem + options and cannot identify the answer within 45 seconds, mark it for review and move on. Spending 3 minutes on one MCQ costs you 2–3 others. In practice: Read the question in 10 seconds → eliminate 2 obviously wrong options in 15 seconds → decide between remaining 2 in 25 seconds. **Rule 2: Assertion-Reason MCQs Require a Two-Step Check** Step 1 (15 sec): Is A true? (Yes/No) Step 2 (15 sec): Is R true? (Yes/No) Step 3 (20 sec): Does R explain A logically? (Yes/No/N/A) If you spend >60 seconds, skip and return after completing all single-statement MCQs. A–R questions often trip up students who rush. **Rule 3: Keyword Scanning for Plant vs. Animal Transport** When you see "xylem," "phloem," "sieve," "vessel," "roots," immediately recall their definitions. For circulatory questions, keywords are "atrium," "ventricle," "artery," "vein," "deoxygenated," "oxygenated." This 5-second keyword scan prevents reading errors. **Rule 4: Flag & Review Strategy** During first read-through: Mark questions you're 100% sure about (skip in review); mark questions you're unsure about (return later). Typically, 60–70% of Chapter 7 MCQs should feel straightforward (easy + medium difficulty). Focus review time on hard/assertion-reason MCQs where you had doubt. **Rule 5: Numerical Questions—Double-Check Units** If an MCQ provides numbers (e.g., "pulse rate ≈ X bpm," "blood pressure = Y mmHg"), pause 5 seconds to verify units match NCERT-given norms. A student choosing 120 bpm instead of 60–100 bpm loses a mark due to careless unit misread. **Rule 6: Elimination-by-Contrast** When stuck between two options, ask: "What is the OPPOSITE of what I'm asked?" If one option describes the opposite (e.g., phloem vs. xylem), eliminate it. Examiners often place contrasting distractors next to the correct answer to test reading precision. **Practical Exam Flow for Chapter 7 Batch (assume 8–10 Chapter 7 MCQs mixed in a 40-MCQ paper):** 1. First pass (12 min): Scan all 40 MCQs, answer 6–7 Chapter 7 questions you're confident in (easy + medium). 2. Second pass (8 min): Tackle Chapter 7 assertion-reason MCQs (harder focus). 3. Third pass (remaining time): Return to flagged MCQs; use elimination and educated guesses if needed. This phased approach ensures you don't lose marks on easy Chapter 7 MCQs due to time panic, while preserving mental energy for assertion-reason complexity. Practice this flow using mock papers to internalize the rhythm—speed comes from repeated exposure, not cramming.

Solving 30 MCQs once is not enough. For mastery, integrate MCQ practice into your weekly study rhythm: **Week 1:** Study NCERT Chapter 7 thoroughly (all subsections on circulatory system, blood, kidney, plant transport). Take notes on definitions, structures, and mechanisms. **Week 2:** Solve the 10 easy MCQs (above). If accuracy < 80%, re-read corresponding NCERT sections. **Week 3:** Solve the 10 medium MCQs. These test application—if you miss >2, you need deeper conceptual work (draw diagrams of the heart, label vessels; sketch xylem and phloem structure). **Week 4:** Solve the 10 hard/assertion-reason MCQs. These demand precise language and logical reasoning. Time yourself strictly (60 sec/MCQ). Review every wrong answer to identify whether the error was factual or logical. **Ongoing:** Mix Chapter 7 MCQs with MCQs from other chapters in mock exams. This trains your brain to switch between topics fluidly under exam pressure. **Spaced Repetition:** Revisit all 30 MCQs 2–3 weeks before your exam. Aim for 95%+ accuracy. Any question you miss should trigger a 5-minute deep-dive into that specific concept. **Study Buddy Strategy:** Exchange Chapter 7 MCQ results with a classmate. Discuss trap options and reasoning together—explaining a concept to someone else cements your understanding and reveals gaps. The goal is not to memorize answers, but to internalize the **underlying biology**. If you can explain WHY each option is right or wrong, you've truly mastered the chapter. This depth automatically carries you through board exams and competitive entrance tests in biology.