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NCERT Solutions for CBSE Class 7 Science Chapter 7: Transportation in Animals and Plants

Transportation in Animals and Plants is a foundational chapter in CBSE Class 7 Science that explains how living organisms move essential substances like oxygen, nutrients, water, and waste products. This chapter introduces students to the human circulatory system — including the four-chambered heart, blood vessels, and blood components — and the excretory system featuring kidneys and nephrons. Equally important is the plant transport system: xylem tissue that carries water upward and phloem tissue that distributes food. These NCERT solutions provide detailed, exam-focused answers to every textbook question, helping students secure full marks in school assessments and build a strong foundation for Class 9 and 10 biology concepts.

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Key takeaways

  • ✓CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants covers circulatory system, blood, heart anatomy, excretion, and vascular tissue in plants
  • ✓The human heart has four chambers (two atria, two ventricles) and pumps oxygenated and deoxygenated blood through separate pathways to prevent mixing
  • ✓Blood consists of plasma, red blood cells (carry oxygen), white blood cells (fight infection), and platelets (clot blood) — each component carries specific exam weightage
  • ✓Excretion in humans occurs via kidneys containing nephrons that filter blood, reabsorb useful substances, and expel urea as urine
  • ✓Xylem transports water and minerals upward from roots using transpiration pull, while phloem moves prepared food bidirectionally through translocation
  • ✓Transpiration — water loss through stomata — creates suction that pulls water up tall trees, a concept tested through diagram-based questions in CBSE exams
  • ✓NCERT Chapter 7 typically contributes 4-6 marks in the Class 7 Science annual exam through short answer (3 marks) and diagram-based questions (2-3 marks)

Understanding the Human Circulatory System (NCERT Question 1-3 Solutions)

The circulatory system in humans is a closed system where blood circulates continuously through blood vessels. The NCERT textbook for CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants explains that this system comprises the heart, arteries, veins, and capillaries. The heart acts as a muscular pump with four distinct chambers: the right atrium receives deoxygenated blood from the body, the right ventricle pumps it to the lungs, the left atrium receives oxygenated blood from the lungs, and the left ventricle pumps it to the entire body. This separation prevents oxygen-rich and oxygen-poor blood from mixing. Questions 1 through 3 in the NCERT exercise ask students to describe the pathway of blood, identify the components of blood, and explain why the heart has valves. When answering these, students must mention that valves prevent backflow of blood, ensuring one-way circulation — a key point in CBSE marking schemes.
  • Right side of heart handles deoxygenated blood; left side handles oxygenated blood
  • Arteries carry blood away from the heart; veins bring blood back to the heart
  • Capillaries are tiny vessels where exchange of gases, nutrients, and waste occurs between blood and body cells
  • The heartbeat sound 'lub-dub' represents closing of valves between atria-ventricles and ventricles-arteries
  • Average human heart beats 72 times per minute at rest, pumping about 5 litres of blood

Blood Components and Their Functions (NCERT Exercise Solution)

CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants dedicates significant content to blood composition, a favourite area for 2-3 mark questions in school exams. Blood consists of a liquid portion called plasma (55% of blood volume) and three types of cells suspended in it. Plasma is a yellowish fluid that transports digested food (glucose, amino acids), hormones, waste products (urea, carbon dioxide), and helps distribute heat. Red blood cells (RBCs or erythrocytes) contain haemoglobin, an iron-rich protein that binds oxygen in the lungs and releases it in tissues — this is why RBCs give blood its red colour. White blood cells (WBCs or leukocytes) are part of the immune system, fighting infections by engulfing bacteria or producing antibodies. Platelets are cell fragments that initiate blood clotting at injury sites, preventing excessive bleeding. Understanding these distinctions helps students answer compare-and-contrast questions accurately.

Structure and Function of the Human Heart (Diagram-Based NCERT Questions)

One of the most tested topics in CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants is the structure of the human heart. Students are frequently asked to draw a labelled diagram showing the four chambers, major blood vessels, and valves. The heart is roughly the size of a human fist, located slightly left of the chest centre, and protected by the rib cage. The muscular wall separating the left and right sides (septum) is crucial — it ensures that oxygenated and deoxygenated blood never mix. The right atrium receives deoxygenated blood from the superior and inferior vena cava. This blood moves through the tricuspid valve into the right ventricle, which contracts to push blood through the pulmonary artery to the lungs for oxygenation. Oxygen-rich blood returns via pulmonary veins to the left atrium, passes through the bicuspid (mitral) valve to the left ventricle, and is pumped through the aorta to the body. The left ventricle has the thickest muscular wall because it must generate enough pressure to send blood throughout the entire body.
  • Always label: superior vena cava, inferior vena cava, right atrium, tricuspid valve, right ventricle, pulmonary artery, pulmonary veins, left atrium, bicuspid valve, left ventricle, aorta, septum
  • Use blue shading or arrows for deoxygenated blood pathways, red for oxygenated blood in exam diagrams
  • Valves prevent backflow: tricuspid and bicuspid between atria and ventricles; semilunar valves at artery exits
  • The 'double circulation' system means blood passes through the heart twice in one complete circuit: heart → lungs → heart → body → heart

Arteries, Veins, and Capillaries: Structural Differences (NCERT Compare-and-Contrast Questions)

CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants requires students to distinguish between the three types of blood vessels. Arteries carry blood away from the heart and must withstand high pressure generated by ventricular contraction; therefore, they have thick, elastic muscular walls that can expand and recoil with each heartbeat. The pulse you feel at your wrist or neck is the rhythmic expansion of arteries. Except for the pulmonary artery (which carries deoxygenated blood to the lungs), all arteries carry oxygen-rich blood. Veins, in contrast, carry blood toward the heart under much lower pressure. Their walls are thinner with less muscle tissue. To prevent backflow of blood due to gravity (especially in limbs), veins contain one-way valves at intervals. Most veins carry deoxygenated blood, except pulmonary veins which bring oxygenated blood from lungs to the heart. Capillaries are microscopic vessels with walls only one cell thick, facilitating efficient exchange of oxygen, carbon dioxide, nutrients, and wastes between blood and surrounding tissues.

Excretion in Humans: Kidneys and Nephrons (NCERT Questions 7-9)

The second major component of CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants is excretion — the removal of metabolic waste products from the body. Humans have two bean-shaped kidneys located on either side of the spine, just below the rib cage. Each kidney contains about one million microscopic filtering units called nephrons. Blood enters each nephron through a cluster of capillaries called the glomerulus, housed in a cup-shaped structure called Bowman's capsule. High pressure forces water, glucose, salts, urea, and other small molecules out of the blood into the nephron tubule (filtration). As this filtrate moves through the tubule, useful substances like glucose, amino acids, and most water are reabsorbed back into surrounding blood capillaries (reabsorption). The remaining waste — mainly urea, excess salts, and water — forms urine, which flows through collecting ducts to the ureter, then to the urinary bladder for temporary storage, and is finally expelled through the urethra. Students must emphasise that urea (produced in the liver from breakdown of proteins) is toxic and must be removed continuously.
  • Kidneys filter approximately 180 litres of blood daily, producing about 1.5 litres of urine
  • Nephron has distinct regions: glomerulus, Bowman's capsule, proximal tubule, loop of Henle, distal tubule, collecting duct
  • Filtration occurs at glomerulus; reabsorption occurs along the tubule; secretion adds more wastes into tubule
  • Urine composition: water (95%), urea (2%), salts, uric acid, creatinine — no glucose or proteins in normal urine
  • Dialysis is an artificial method to filter blood when kidneys fail

Transport of Water and Minerals in Plants: Xylem (NCERT Questions 10-12)

Plant transport is the second half of CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants and is equally important for exams. Plants absorb water and dissolved minerals from the soil through root hairs — tiny extensions of root epidermal cells that increase surface area for absorption. This water enters xylem tissue, a complex tissue made of dead cells with thick, lignified walls arranged end-to-end to form continuous tubes running from roots through stems to leaves. Xylem transports water and minerals in one direction only: upward. The mechanism involves root pressure (push from below due to active pumping of minerals into xylem) and transpiration pull (suction from above due to water loss through stomata). Transpiration pull is the dominant force: when water evaporates from leaf stomata, it creates a negative pressure that pulls water molecules upward through xylem tubes — like sucking liquid through a straw. Cohesion (water molecules sticking to each other) and adhesion (water molecules sticking to xylem walls) allow this pull to extend hundreds of feet in tall trees.
  • Root hairs increase surface area 5-20 times for efficient water absorption
  • Xylem vessels are dead at maturity; lignin provides strength and prevents collapse under negative pressure
  • Transpiration accounts for 90-95% of water absorbed by plants; only 5-10% is used in photosynthesis and metabolism
  • Rate of transpiration increases with higher temperature, lower humidity, wind, and more light
  • Xylem also transports dissolved minerals like nitrogen, phosphorus, potassium, calcium, magnesium upward

Transport of Food in Plants: Phloem and Translocation (NCERT Exercise Solutions)

While xylem moves water upward, phloem is the living tissue responsible for transporting food in plants, a key concept in CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants. Food (mainly sucrose, a sugar) is produced during photosynthesis in green leaves and must be transported to non-photosynthetic parts like roots, stems, flowers, and fruits that cannot make their own food. Phloem consists of sieve tube cells (living cells with perforated end walls) and companion cells (which provide metabolic support). Unlike xylem, phloem can transport substances in multiple directions — upward to growing shoots and downward to roots — depending on where food is needed. This process is called translocation. Translocation requires energy (ATP) and involves active loading of sugars into phloem at source tissues (leaves) and unloading at sink tissues (roots, fruits). The pressure-flow hypothesis explains that high sugar concentration in phloem at the source creates osmotic pressure, pushing the solution toward regions of lower concentration (sinks).

Stomata and Transpiration: How Plants Lose Water (Diagram Questions)

Stomata are tiny pores, mostly on the undersides of leaves, surrounded by two specialised guard cells that regulate their opening and closing. Each stoma (singular of stomata) allows exchange of gases: carbon dioxide enters for photosynthesis, oxygen exits as a by-product, and water vapour escapes in a process called transpiration. This water loss is essential for creating the transpiration pull discussed in CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants. Guard cells control stomatal opening through changes in turgor pressure — when guard cells absorb water and swell, they curve outward, opening the pore; when they lose water, they become flaccid and close the pore. Stomata typically open during the day (when photosynthesis occurs) and close at night to conserve water. Environmental factors like light, humidity, temperature, and wind affect transpiration rate. Excessive transpiration can cause wilting, so plants balance the need for gas exchange with water conservation.
  • A single leaf may contain 100 to 500 stomata per square millimetre
  • Guard cells contain chloroplasts (unlike other epidermal cells) and photosynthesise to produce sugars that affect osmotic balance
  • Transpiration cools the plant (similar to sweating in animals) and helps distribute minerals throughout the plant
  • Desert plants (xerophytes) have fewer stomata, sunken stomata, or waxy coatings to reduce water loss
  • Students must be able to draw and label a stoma showing two guard cells, pore, and adjacent epidermal cells

Comparing Circulation in Animals: Open vs Closed Systems (Beyond NCERT, Exam-Relevant)

While CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants focuses primarily on humans, students benefit from understanding that not all animals have closed circulatory systems like humans. In a closed system, blood flows entirely within vessels and does not directly bathe tissues. This allows for higher pressure, faster circulation, and more efficient oxygen delivery — essential for active, warm-blooded animals. In contrast, many invertebrates like insects and most molluscs have open circulatory systems where a fluid called haemolymph is pumped into open spaces (sinuses) surrounding organs, directly bathing tissues before returning to the heart. Open systems operate at lower pressure and are sufficient for smaller, less active organisms. Fish have a single-loop circulation (heart → gills → body → heart), while mammals and birds have double circulation (heart → lungs → heart → body → heart), which is more efficient. This comparative understanding helps students appreciate why humans evolved a four-chambered heart.
  • Closed system advantages: higher pressure, faster nutrient/oxygen delivery, precise control of blood flow to specific organs
  • Open system advantages: lower metabolic cost, simpler structure, adequate for organisms with low oxygen demands
  • Amphibians and reptiles have three-chambered hearts (two atria, one ventricle) with partial mixing of oxygenated and deoxygenated blood
  • Complete separation in four-chambered hearts allows warm-blooded animals to maintain high, constant body temperatures

Common Mistakes Students Make in CBSE Class 7 Science Chapter 7 Exams

Based on analysis of past CBSE Class 7 Science exam papers and school assessment patterns for Transportation in Animals and Plants, several errors recur frequently. First, students often confuse the functions of arteries and veins, forgetting that the pulmonary artery carries deoxygenated blood and pulmonary veins carry oxygenated blood — exceptions to the general rule. Second, in diagrams of the heart, students mix up the positions of chambers or forget to draw and label valves, losing 1-2 marks. Third, when explaining transpiration pull, students write vague statements like 'water moves up' instead of clearly describing the suction created by water loss from stomata and the cohesive properties of water molecules. Fourth, students sometimes state that xylem transports food or that phloem is made of dead cells — both incorrect. Fifth, in questions about excretion, students forget to mention that glucose should NOT be present in urine and that its presence indicates diabetes. Careful review of these points ensures students avoid easy mark deductions.
  • Always specify direction of blood flow in circulatory diagrams with arrows
  • Remember: arteries carry blood AWAY from heart (A for Away); veins carry blood TOWARD heart
  • Xylem = water upward; Phloem = food in multiple directions — never mix these
  • Transpiration is water loss, not absorption or transport (common vocabulary confusion)
  • Nephrons filter blood to form urine; they do not filter urine from blood
  • In 3-mark answers, always provide three distinct points; one-line answers receive only 1 mark even if correct

Practical Activities from NCERT Chapter 7: Demonstrating Plant Transport

CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants includes hands-on activities that often appear in practical exams or internal assessments. Activity 11.1 asks students to place a leafy twig in coloured water (food dye or ink) and observe after a few hours. The coloured water travels up the stem through xylem vessels, and when the stem is cut open, the xylem appears coloured while surrounding tissues remain uncoloured — demonstrating that xylem specifically conducts water. Activity 11.2 involves covering a potted plant with a transparent plastic bag. After a few hours, water droplets appear on the inner surface of the bag, demonstrating transpiration. Activity 11.3 measures the rate of transpiration by placing a leafy shoot in a graduated cylinder of water and marking the water level; the decrease in water level over a set time period quantifies transpiration rate. These activities help students understand abstract concepts through direct observation and are excellent revision tools before practicals.

How CBSE Class 7 Science Chapter 7 Connects to Future Biology Topics

Transportation in Animals and Plants is not an isolated chapter; it lays the foundation for multiple topics students will encounter in higher classes. In Class 9, the chapter on Tissues explores xylem and phloem structure in much greater detail, including different types of xylem elements (tracheids vs vessels) and phloem elements (sieve tubes vs companion cells). Class 10 Life Processes dedicates extensive content to nutrition, respiration, transportation, and excretion in organisms, building on the Class 7 circulatory and excretory system basics. In Class 11 Biology (NEET/JEE stream), students study Transport in Plants with advanced concepts like water potential, Munch hypothesis for translocation, and mineral uptake mechanisms. The human circulatory system is revisited in Class 11 with details of cardiac cycle, blood pressure regulation, and lymphatic system. Even in Class 12, topics like immunology require understanding of white blood cell function introduced here. Strong conceptual clarity in CBSE Class 7 Science Chapter 7 therefore pays dividends throughout secondary and senior secondary education.
  • Class 9 Tissues: detailed anatomy of xylem vessels, tracheids, sieve tubes, companion cells
  • Class 10 Life Processes: expanded coverage of double circulation, nephron functioning, transportation in plants
  • Class 11 Transport in Plants: Munch hypothesis, water potential, mycorrhizal associations, active vs passive transport
  • Class 11 Circulation: cardiac cycle, ECG, blood pressure, atherosclerosis, blood groups
  • Class 12 Human Health: immune system, role of WBCs (lymphocytes, phagocytes), vaccination

Using CBSETUTOR.ai for CBSE Class 7 Science Chapter 7 Mastery

Parents seeking comprehensive support for CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants often find that textbook solutions alone are not enough for deep understanding, especially when students struggle with diagram labelling or application questions. CBSETUTOR.ai provides a 24×7 AI tutor that has ingested every NCERT book for Classes 6 through 12, making it uniquely capable of answering chapter-specific doubts. Students can upload a photo of any diagram question from their worksheet — say, 'label the parts of the human heart' — and receive step-by-step guidance on correct labels and functions. The AI tutor explains concepts like transpiration pull or double circulation through multiple examples and analogies until the student demonstrates understanding. Unlike generic tutoring apps, CBSETUTOR.ai is trained specifically on the CBSE curriculum, so its answers match the terminology and depth expected in exams. At a flat ₹999 per month covering all subjects and all classes from 6 to 12, with a 3-day free trial and no credit card required to start, it offers exceptional value for families wanting to ensure their child is never stuck on a homework question or exam preparation challenge.
  • Photo upload feature allows instant help with diagram questions, labelling, and numerical problems
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Chapter 7 Exam Strategy: How to Score Full Marks in Transportation Questions

CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants typically yields one 3-mark question, one 2-mark diagram question, and two to three 1-mark objective questions in the annual examination, totalling 6-8 marks. To maximise scores, students should master five key diagrams: human heart with labels, human excretory system, structure of a nephron, xylem and phloem tissue cross-sections, and stomatal apparatus. For 3-mark descriptive answers, always structure the response with three distinct, complete sentences — examiners allocate one mark per valid point. When comparing arteries and veins or xylem and phloem, present the answer as a table with at least three points of difference; this format is easier for examiners to evaluate and ensures full marks. For 1-mark MCQs, common traps include statements like 'arteries always carry oxygenated blood' (incorrect due to pulmonary artery) or 'xylem is living tissue' (incorrect). Practice previous years' CBSE question papers to familiarise yourself with question phrasing. Time management is crucial: allocate 5-6 minutes for a 3-mark question, 3-4 minutes for a diagram, and 30 seconds for MCQs.
  • Underline key terms in your answers: transpiration pull, reabsorption, translocation, double circulation
  • In diagram questions, use a sharp pencil, draw neat lines, and place labels outside the diagram with ruled lines pointing to parts
  • For 'Explain the function of...' questions, describe both what the structure does and why it is important
  • Avoid writing more than required; a 2-mark answer should have two clear points, not a full-page essay
  • Review NCERT in-text questions and 'Think and Answer' sections — exam questions are often adapted from these

Frequently asked questions

Why does the left ventricle have a thicker wall than the right ventricle in the human heart?+
The left ventricle must pump oxygenated blood to the entire body through the systemic circulation, requiring much higher pressure than the right ventricle, which only pumps blood the short distance to the lungs through pulmonary circulation. The thicker muscular wall generates the force needed to push blood through thousands of kilometres of blood vessels throughout the body, while the right ventricle's thinner wall is adequate for the low-resistance pathway to the lungs. This structural difference directly reflects functional demand — a principle of anatomy.
What happens if glucose appears in urine, and how do kidneys normally prevent this?+
Glucose in urine (glycosuria) indicates diabetes mellitus, where blood sugar levels are abnormally high and exceed the kidney's reabsorption capacity. Normally, during filtration in the nephron, glucose passes from blood into Bowman's capsule along with water and other small molecules. However, as the filtrate moves through the proximal tubule, all glucose is actively reabsorbed back into the blood capillaries surrounding the tubule. This reabsorption is so efficient that healthy urine contains zero glucose. When blood sugar exceeds approximately 180 mg/dL (the renal threshold), the transport proteins become saturated and cannot reabsorb all glucose, causing it to appear in urine. This is why urinalysis is a quick diabetes screening test taught in CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants.
Can plants survive without transpiration, and is transpiration wasteful?+
While transpiration results in loss of 90-95% of absorbed water, it is not wasteful but essential for plant survival. Transpiration creates the transpiration pull that drives water and mineral movement from roots to leaves through xylem — without it, tall plants could not transport water to upper leaves. Transpiration also cools the plant through evaporative cooling (similar to sweating in animals), preventing heat damage on hot days. Additionally, the continuous water flow distributes dissolved minerals throughout the plant. While plants can temporarily survive with closed stomata (reducing transpiration), they cannot photosynthesize without CO₂ entry through open stomata, making some water loss unavoidable and functionally linked to carbon fixation and growth.
How is the human circulatory system different from that of fish or frogs?+
Fish have a single-loop circulatory system: heart (2 chambers) → gills (oxygenation) → body → heart. Blood passes through the heart only once per complete circuit, and pressure drops significantly after passing through gill capillaries, resulting in slower circulation. Frogs and most amphibians have a three-chambered heart (2 atria, 1 ventricle), leading to partial mixing of oxygenated and deoxygenated blood in the single ventricle, reducing efficiency. Humans, along with birds and mammals, have a four-chambered heart enabling complete double circulation: deoxygenated blood travels heart → lungs → heart, and oxygenated blood travels heart → body → heart, with no mixing. This allows us to maintain high blood pressure, rapid circulation, and constant high body temperature (endothermy), supporting our high metabolic rate.
Why do veins appear blue if blood is red, and do veins carry blue blood?+
This is a common misconception. Veins do not carry blue blood — all human blood is red due to haemoglobin, though deoxygenated blood is darker red (maroon) than bright red oxygenated blood. Veins appear blue when viewed through skin because of how light interacts with skin layers and blood. Blue light wavelengths penetrate skin and reflect back to our eyes more effectively than red wavelengths from blood vessels located just beneath the skin surface. The optical effect creates a blue appearance, but if you drew blood from a vein (as during a blood test), it would be dark red, not blue. This concept corrects a persistent myth and reinforces that colour perception depends on light physics, not actual blood colour.
Why do CBSE exams ask to draw the human heart, and what are the key labelling requirements?+
Diagram-based questions test whether students truly understand three-dimensional structure, spatial relationships between parts, and functional anatomy — concepts that cannot be assessed through text-only questions. The human heart diagram typically carries 2-3 marks in CBSE Class 7 Science Chapter 7 exams. Mandatory labels include: superior vena cava, inferior vena cava, right atrium, right ventricle, pulmonary artery, pulmonary veins, left atrium, left ventricle, aorta, septum, and valves (tricuspid, bicuspid). Marks are deducted for incorrect spellings, missing arrows showing blood flow direction, failure to distinguish oxygenated (red) from deoxygenated (blue) pathways, or poor diagram quality (faint lines, cramped labels). Practising this diagram 10-15 times before exams ensures accuracy and speed under time pressure.
How does root pressure work, and is it sufficient to move water up tall trees?+
Root pressure is created when root cells actively pump mineral ions into the xylem using metabolic energy (ATP). This increases solute concentration in xylem sap, causing water from surrounding soil to enter xylem by osmosis, creating positive pressure that pushes water upward. Evidence of root pressure includes guttation (water droplets exuded from leaf edges early morning) and xylem sap flow from cut stems. However, root pressure is relatively weak (typically 1-2 atmospheres) and can only push water up a few metres, making it insufficient for tall trees that may exceed 100 metres. For such heights, transpiration pull is the dominant mechanism. Root pressure mainly contributes during early morning or when transpiration is low, and helps refill xylem vessels after air bubbles (cavitation) form. Both mechanisms complement each other in the overall water transport system.
What is the difference between filtration and reabsorption in the nephron?+
Filtration and reabsorption are two distinct stages of urine formation in nephrons, both critical in CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants. Filtration occurs in the Bowman's capsule, where high blood pressure in the glomerulus forces water, glucose, amino acids, salts, urea, and other small molecules out of blood into the nephron tubule — this is non-selective; all small molecules pass through. The resulting liquid is called filtrate. Reabsorption occurs in the tubule (especially proximal convoluted tubule), where useful substances like glucose, amino acids, and 99% of water are selectively transported back into blood capillaries surrounding the tubule, conserving essential nutrients. The remaining liquid, now concentrated with wastes (urea, excess salts), becomes urine. Filtration is passive (pressure-driven), while reabsorption is active (requires energy) and selective.
Why do plants need two separate transport systems (xylem and phloem)?+
Plants require two transport systems because they move two fundamentally different types of materials in different directions with different mechanisms. Xylem transports water and dissolved minerals absorbed from soil upward from roots to leaves, driven by transpiration pull (a passive, physical process). This unidirectional flow supplies water for photosynthesis, maintains cell turgor, and transports mineral nutrients. Phloem transports sugars produced by photosynthesis in leaves to all non-photosynthetic parts (roots, stems, flowers, fruits, growing tips), requiring bidirectional flow — upward to growing shoots, downward to roots — and active transport mechanisms using ATP. The two systems have different structures (xylem: dead cells; phloem: living cells) suited to their functions. Having separate dedicated systems allows simultaneous, independent transport of water and food without interference, maximising plant efficiency.
Will my child's understanding of this chapter be tested in competitive exams like Olympiads?+
Yes, CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants forms the basis for numerous questions in Science Olympiads (NSO), NSTSE, and other competitive exams, though at a higher difficulty level than school exams. Olympiad questions often test application and analysis: for example, 'If a ring of bark (containing phloem) is removed from a tree trunk, what will happen to roots?' (Answer: roots will eventually die due to lack of food supply, though water transport via xylem continues). Other questions may involve interpreting experimental data on transpiration rates under different conditions, or identifying circulatory system disorders based on symptoms. Strong conceptual clarity from NCERT Chapter 7, combined with practice of higher-order thinking questions, prepares students well for these competitive assessments.
How can students remember the difference between xylem and phloem for exams?+
Multiple mnemonic devices help students distinguish xylem from phloem in CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants. Memory trick 1: 'Xylem' contains 'X' (like eXit) — water eXits roots going upward; 'Phloem' contains 'F' (like Food) — transports Food. Memory trick 2: Xylem = 'Xtra strong' (thick, lignified, dead) vs Phloem = 'Flexible' (living, softer). Memory trick 3: In alphabetical order, X comes before P, and in the plant, xylem tissue is typically located toward the inside while phloem is toward the outside in vascular bundles. Additionally, creating a comparison table (as shown in these solutions) and copying it multiple times helps kinesthetic learners retain the distinctions. Regular self-quizzing — 'What does xylem transport?', 'Is phloem living or dead?' — strengthens recall.
Are there any common diseases related to circulatory and excretory systems students should know?+
While CBSE Class 7 Science Chapter 7 Transportation in Animals and Plants does not mandate disease knowledge, awareness enriches understanding and appears in application questions. Circulatory disorders include: hypertension (high blood pressure damaging blood vessels and heart), atherosclerosis (plaque buildup narrowing arteries, causing heart attacks), anaemia (insufficient haemoglobin reducing oxygen transport), and thrombosis (blood clots blocking vessels). Excretory system disorders include: kidney stones (crystallised minerals blocking ureters, causing pain), kidney failure (requiring dialysis or transplant), and urinary tract infections. Additionally, diabetes affects both systems — high blood glucose damages blood vessels (circulatory) and overwhelms nephron reabsorption capacity (excretory). Understanding these connections helps students appreciate why maintaining healthy circulatory and excretory systems through proper diet, exercise, and hydration is important, motivating better health habits.

Related resources

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