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Class 7 Science Chapter 7 Transportation in Animals and Plants — Formulas & Key Points

Transportation in Animals and Plants is a core Chapter 7 topic in CBSE Class 7 Science that explains how nutrients, gases, water and wastes move within living organisms. While this chapter is descriptive and diagram-heavy, students still need to memorise key structures, functions and sequences. This formula sheet organises every testable definition, process step and structural detail into tables, provides mnemonics for quick recall, and highlights the top mistakes that cost marks in CBSE term exams.

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Key takeaways

  • ✓Human circulatory system is a closed double-circulation system involving heart, blood vessels and blood with defined composition and functions.
  • ✓Heart has four chambers: two atria (upper) and two ventricles (lower); valves prevent backflow of blood.
  • ✓Excretion in humans occurs primarily through kidneys which filter blood to form urine; sweat glands and lungs are also excretory organs.
  • ✓Xylem transports water and minerals upward from roots to leaves via root pressure and transpiration pull; phloem translocates food (sucrose) bidirectionally.
  • ✓Blood components include plasma (55%), RBCs (oxygen transport), WBCs (immunity) and platelets (clotting); haemoglobin in RBCs binds oxygen.
  • ✓Common exam mistakes include confusing artery-vein structure, mixing xylem-phloem direction, and forgetting valve names or excretory organ functions.
  • ✓Use mnemonics like 'PARV' for heart chambers sequence and 'XU-PD' for xylem-upward, phloem-dual-direction to lock concepts quickly.

Key Definitions and Terminology — Must-Know Terms

CBSE examiners frequently ask 'Define' or 'What is' type questions worth 1-2 marks. The table below lists every critical term from NCERT Class 7 Science Chapter 7 with its exact definition. Memorising these verbatim ensures you do not lose easy marks. Terms like circulatory system, excretion, transpiration and translocation appear in nearly every test. Make sure you can write a two-sentence definition for each term without hesitation, and spell scientific words like haemoglobin and dialysis correctly.

Human Circulatory System — Structure and Function Table

The human circulatory system is a closed double-circulation system. Blood passes through the heart twice in one complete circuit of the body. One circuit is pulmonary (heart to lungs and back), the other is systemic (heart to body tissues and back). Understanding the exact pathway, chamber sequence and vessel names is crucial for diagram labelling and short-answer questions in CBSE exams. The table below maps each component to its structure and function. Remember that arteries always carry blood away from the heart (not necessarily oxygenated), and veins always carry blood toward the heart. The pulmonary artery is the only artery carrying deoxygenated blood, and the pulmonary vein is the only vein carrying oxygenated blood. Valves between atria and ventricles prevent backflow; they are not present in arteries.
  • Heart has four chambers: Right atrium, Right ventricle, Left atrium, Left ventricle (mnemonic: PARV - Please Allow Room Ventilation, reading clockwise from top-right).
  • Septum is the muscular wall separating left and right sides; prevents mixing of oxygenated and deoxygenated blood.
  • Valves between atria and ventricles ensure one-way flow; open when atria contract, close when ventricles contract.
  • Heartbeat rate in resting human adult is approximately 72 beats per minute; one beat = one cardiac cycle.
  • Stethoscope is the instrument used to hear heartbeat sounds ('lub-dub' caused by valve closure).

Blood Components and Their Functions — Composition Table

Blood is a fluid connective tissue making up about seven to eight per cent of total body weight in humans. It consists of a liquid part called plasma (about 55 per cent) and cellular components (about 45 per cent). Plasma is a straw-coloured fluid containing water, proteins, glucose, salts, hormones and waste products. The cellular part includes Red Blood Cells (RBCs or erythrocytes), White Blood Cells (WBCs or leucocytes) and Platelets (thrombocytes). Each component has a specific structure and function. CBSE Class 7 Science exams often ask you to draw and label a diagram of blood components or list the function of each. Haemoglobin content, RBC count and WBC count are measurable parameters in blood tests. Understanding these helps connect biology with real-world health diagnostics.
  • Plasma transports digested food (glucose, amino acids), hormones, carbon dioxide and nitrogenous wastes (urea) throughout the body.
  • RBCs are biconcave disc-shaped cells without nucleus (in mammals); contain haemoglobin which binds oxygen reversibly.
  • WBCs are irregular shaped nucleated cells; act as body's defence by engulfing bacteria (phagocytosis) and producing antibodies.
  • Platelets are cell fragments without nucleus; release clotting factors at injury site to form blood clot and prevent bleeding.
  • Normal RBC count: ~5 million/mm³ in males, ~4.5 million/mm³ in females; WBC count: 6,000-8,000/mm³; low RBC → anaemia.

Excretion in Humans — Organs and Waste Products Table

Excretion is the biological process of removing metabolic waste products from the body. The main excretory organ in humans is the kidney, but lungs, skin and liver also play excretory roles. Kidneys filter blood to remove urea, excess salts and water, forming urine. Each kidney contains about one million nephrons, the functional filtration units. Urine passes from kidneys to the urinary bladder via ureters, and is expelled through the urethra. When kidneys fail, waste accumulates in blood, requiring dialysis or transplant. The table below lists all excretory organs and the wastes they remove. CBSE examiners often ask you to name organs and wastes, or explain dialysis in 2-3 sentences. Make sure you can draw and label a diagram of the human excretory system showing kidneys, ureters, urinary bladder and urethra.
  • Kidneys are bean-shaped organs located on either side of the backbone in the abdomen; each about 10 cm long.
  • Nephron is the structural and functional unit of the kidney; performs filtration, reabsorption and secretion.
  • Urine composition: water (95%), urea (2%), salts and other wastes (3%); yellow colour due to pigment urochrome.
  • Dialysis is done by a machine that filters blood when kidneys fail; patient's blood is passed through dialysis machine containing dialysing fluid.
  • Urinary bladder is a muscular sac that stores urine temporarily; capacity ~400-500 mL; urge to urinate felt at ~150 mL.

Transportation in Plants — Xylem and Phloem Comparison

Plants have two types of vascular tissues for transportation: xylem and phloem. Xylem conducts water and dissolved minerals unidirectionally from roots to stems and leaves. Phloem translocates food (mainly sucrose prepared during photosynthesis) bidirectionally from leaves to all parts of the plant. The movement of water in xylem is driven by root pressure (push from below) and transpiration pull (suction from above due to water loss from stomata). Translocation in phloem requires energy and occurs in sieve tubes assisted by companion cells. CBSE diagrams often ask you to label xylem and phloem in a cross-section of stem or root. Remember: Xylem = X = eXit water upward; Phloem = Food transport. The table below compares the two tissues side by side to help you avoid mixing them up in exams.
  • Xylem tissue is made of tracheids and vessels (dead cells with lignified walls); provides mechanical support as well as conduction.
  • Phloem tissue is made of sieve tubes (living cells with perforated end walls) and companion cells (help in metabolism).
  • Transpiration is the loss of water vapour from stomata in leaves; creates a suction force (transpiration pull) that pulls water upward in xylem.
  • Root pressure is the pressure developed in roots due to active absorption of minerals which draws water into root xylem; contributes to upward push.
  • Translocation in phloem can be upward (to growing shoots, fruits) or downward (to roots, storage organs like tubers); requires metabolic energy (ATP).

Common Mistakes and Correct Usage — Avoid These Errors

Students often lose marks in CBSE Class 7 Science Chapter 7 questions due to small conceptual or terminology errors. Mixing up the functions of xylem and phloem, confusing artery-vein definitions, writing incorrect chamber sequences, and using wrong units or terms are frequent pitfalls. Examiners specifically look for precision in definitions and diagram labels. For example, writing 'xylem transports food' is a direct error; xylem transports water and minerals only. Similarly, stating 'all arteries carry oxygenated blood' is wrong because the pulmonary artery carries deoxygenated blood. The table below lists the top mistakes seen in answer scripts and the correct statements. Review this section carefully before your exam to ensure you do not repeat these errors. Parents can quiz their child using this table to catch misconceptions early.
  • Do NOT write 'RBCs have nucleus' — mammalian RBCs lose nucleus during maturation; only WBCs have nucleus among blood cells.
  • Do NOT say 'heart has three chambers' — human heart has four chambers; three-chambered hearts are found in amphibians and most reptiles.
  • Do NOT mix 'excretion' with 'egestion' — excretion removes metabolic wastes from cells; egestion removes undigested food from the digestive tract.
  • Do NOT write 'veins have thick walls' — veins have thin walls and valves; arteries have thick elastic walls without valves (except semilunar valves in heart).
  • Do NOT state 'phloem transports water' — phloem transports food; xylem transports water and minerals.

Memory Tricks and Mnemonics — Lock Concepts Fast

Mnemonics are powerful tools to remember sequences, lists and comparisons quickly. For CBSE Class 7 Science Chapter 7, you need to recall chamber names in order, differences between xylem and phloem, excretory organs, and blood components. The memory tricks below have been tested by thousands of students across India and consistently help in scoring full marks in definitional and labelling questions. Use these mnemonics during revision, write them on flashcards, and quiz yourself until recall becomes instant. Mnemonics work best when you create a mental image or story around them. For example, visualise a room (atrium) on the right side of your house being ventilated (ventricle) to remember the right chambers of the heart. Associating abstract terms with everyday objects makes retention stronger and exam recall faster under time pressure.
  • Heart chambers sequence (clockwise from top-right): PARV — Please Allow Room Ventilation → Right Atrium, Right Ventricle, Left Ventricle, Left Atrium.
  • Xylem vs Phloem direction: XU-PD → Xylem Upward only; Phloem Dual-direction (both up and down).
  • Blood components: PRWP → Plasma, RBCs, WBCs, Platelets (in decreasing order of volume proportion).
  • Excretory organs: KLSS → Kidneys, Lungs, Skin, (Liver indirectly) — remember as 'Class' without 'C' for organs removing waste.
  • Artery vs Vein: Arteries = Away (from heart); Veins = Toward (toward heart) — both start with same letter pair A-A, V-T.
  • Functions of WBCs: FBI → Fight infection, Body defence, Immunity (produce antibodies and engulf pathogens).

Important Values and Constants — Numbers to Remember

While NCERT Class 7 Science Chapter 7 does not involve numerical problem-solving like physics or chemistry, certain quantitative facts and reference values are frequently asked in fill-in-the-blank, MCQ and short-answer questions. Knowing the average heartbeat rate, blood volume percentage, number of nephrons, RBC count range, and kidney dimensions can fetch you direct marks. CBSE examiners use these values to frame questions like 'How many times does a human heart beat per minute at rest?' or 'What percentage of blood is plasma?'. Memorise the table below and practice writing these values in proper units. Incorrect units or wildly wrong numbers can make an otherwise correct answer lose marks. For example, writing heartbeat as 720 per minute instead of 72 per minute shows lack of attention to detail.
  • Normal resting heartbeat in adult human: approximately 72 beats per minute (can range 60-100 bpm depending on age and fitness).
  • Blood composition: Plasma ~55%, Cellular components (RBCs, WBCs, platelets) ~45% by volume.
  • RBC count: ~5 million per cubic millimetre (mm³) in males; ~4.5 million/mm³ in females.
  • WBC count: 6,000 to 8,000 per mm³ of blood; increase indicates infection or inflammation.
  • Each human kidney contains approximately 1 million nephrons (functional filtration units).
  • Average adult blood volume: about 5 to 6 litres; represents 7-8% of body weight.

Three Solved Mini-Examples — Apply the Concepts

While this chapter is primarily descriptive, examiners often frame application-based or reasoning questions worth 2-3 marks. These require you to apply your understanding of circulatory, excretory and plant transport systems to new situations or explain why certain phenomena occur. The three worked examples below mirror typical CBSE question styles and model answers. Practice writing these answers in your own words within the word limits specified in your exam. Notice how each answer begins with a definition or statement, followed by reasoning or mechanism, and ends with a conclusion. This structure maximises marks. Use technical terms from the chapter (like 'transpiration pull', 'sieve tubes', 'nephron', 'haemoglobin') to show conceptual clarity. Parents can use these examples to simulate exam conditions at home by asking the question and timing the child's written response.

One-Glance Last-Minute Revision Box — 5 Minutes Before Exam

Use this ultra-condensed checklist in the final five minutes before your CBSE Class 7 Science exam. Cover the page and try to recall each point. If you can mentally tick all items below, you are ready to score full marks in Chapter 7 questions. This box is also ideal for quick morning revision on exam day or during travel to the exam centre. Parents can read out the left column and ask the child to complete the fact or definition. Flashcard-style rapid-fire recall builds confidence and ensures no silly mistakes under exam pressure. Print this box, laminate it, and keep it handy in your school bag throughout the term for micro-revision sessions between classes or during breaks.
  • **Circulatory system type in humans:** Closed, double circulation (blood passes through heart twice per circuit).
  • **Four chambers of heart (sequence):** Right Atrium → Right Ventricle → Lungs → Left Atrium → Left Ventricle → Body.
  • **Artery vs Vein:** Artery = away from heart, thick walls, no valves (except at heart exit); Vein = toward heart, thin walls, valves present.
  • **Blood components (4):** Plasma (~55%), RBCs (oxygen transport via haemoglobin), WBCs (immunity), Platelets (clotting).
  • **Excretory organs & wastes:** Kidneys (urea, salts, water → urine); Lungs (CO₂); Skin (sweat: water, salts); Liver (bile pigments).
  • **Nephron:** Functional unit of kidney; ~1 million per kidney; filters blood to form urine.
  • **Dialysis:** Artificial blood filtration when kidneys fail; uses dialysis machine with semi-permeable membrane.
  • **Xylem:** Transports water & minerals upward (root → leaf); made of tracheids & vessels (dead cells); driven by root pressure + transpiration pull.
  • **Phloem:** Transports food (sucrose) bidirectionally; made of sieve tubes & companion cells (living); process called translocation.
  • **Transpiration:** Loss of water vapour from stomata; creates transpiration pull; helps in upward water movement and cooling.
  • **Key numbers:** Heartbeat ~72/min, Blood volume ~5-6 L, RBC ~5 million/mm³, WBC ~6,000-8,000/mm³, Nephrons ~1 million/kidney.
  • **Common mistakes to avoid:** Don't say 'all arteries carry oxygenated blood'; don't confuse xylem (water) with phloem (food); don't write RBCs have nucleus.

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Memorising definitions, structures and processes in Transportation in Animals and Plants can feel overwhelming when you are juggling ten subjects. CBSETUTOR.ai gives your child a 24×7 AI tutor that answers every 'Why?', 'What?' and 'How?' question instantly. Snap a photo of any diagram — heart, kidney, xylem-phloem cross-section — and get immediate labelled explanations, mnemonic tips and even voice-based walkthroughs. Whether your child is stuck understanding the difference between artery and vein at 10 p.m. or needs a last-minute recap of excretory organs before the morning exam, CBSETUTOR.ai is always ready. The platform covers all NCERT chapters for Classes 6 to 12 at a single flat fee of ₹999 per month — no hidden charges, no per-subject billing. A 3-day free trial lets you and your child explore chapter-wise formula sheets, solved examples, practice MCQs and diagram-based questions risk-free. Thousands of students across India use CBSETUTOR.ai to convert descriptive chapters into high-scoring opportunities by mastering terminology and application in half the time traditional coaching takes.
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Frequently asked questions

What is the main function of the circulatory system in humans?+
The circulatory system transports oxygen, nutrients, hormones and other essential substances to all body cells, and carries away carbon dioxide and metabolic wastes for excretion. It also helps regulate body temperature and fight infections through white blood cells.
Why are there valves in veins but not in arteries?+
Veins carry blood at low pressure toward the heart, often against gravity (e.g. from legs upward). Valves prevent backflow and ensure unidirectional movement. Arteries carry blood at high pressure away from the heart, so backflow does not occur and valves are not needed (except semilunar valves at the heart exits).
What is the difference between excretion and egestion?+
Excretion is the removal of metabolic waste products (like urea, CO₂) produced inside body cells. Egestion is the removal of undigested food materials (faeces) from the digestive system. Kidneys, lungs and skin perform excretion; the anus performs egestion.
How does dialysis work when kidneys fail?+
In dialysis, blood is taken from the patient's body and passed through a dialysis machine containing a semi-permeable membrane and dialysing fluid. Waste products like urea diffuse from blood into the fluid, while essential substances are retained. The cleaned blood is returned to the body. This process mimics the kidney's filtration function.
Why is xylem made of dead cells and phloem of living cells?+
Xylem vessels and tracheids are dead at maturity because their thick lignified walls provide mechanical support and unobstructed hollow tubes for efficient water transport without metabolic interference. Phloem sieve tubes are living cells because translocation of food requires active metabolic processes, energy (ATP) and assistance from companion cells.
What creates transpiration pull in plants?+
Transpiration pull is created by the loss of water vapour from stomata in leaves. This loss reduces water potential in leaf cells, creating a suction force that pulls water upward from roots through the xylem. The cohesive and adhesive properties of water molecules maintain a continuous water column during this upward movement.
Why is the left ventricle wall thicker than the right ventricle?+
The left ventricle pumps oxygenated blood to the entire body through the systemic circulation, requiring high pressure to overcome long distances and resistance. The right ventricle only pumps blood to the lungs (short distance), needing lower pressure. Hence, the left ventricle has a thicker muscular wall to generate the necessary force.
Can you explain the pathway of blood through the heart in one sentence?+
Deoxygenated blood enters the right atrium from the body via vena cava, moves to the right ventricle, is pumped to lungs via pulmonary artery, returns oxygenated to the left atrium via pulmonary veins, passes to the left ventricle, and is pumped to the body via the aorta.
What happens if platelets are absent in the blood?+
If platelets are absent, blood clotting will not occur at injury sites, leading to continuous bleeding even from minor cuts. This condition can be life-threatening as the body cannot seal wounds or stop haemorrhage. Platelets are essential for initiating and maintaining the clotting process.
How are water and food transported differently in plants?+
Water and minerals are transported upward from roots to leaves through xylem using root pressure and transpiration pull (passive, no energy required). Food (sucrose) is transported from leaves to all plant parts in all directions through phloem by translocation, an active process requiring energy (ATP) and living sieve tube cells.

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