By Subhash Kumar | Science Educator | UREducator
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Transportation in Animals & Plants
Complete Teaching Resource for CBSE Class 7 Science Chapter 7
Class: VII
Subject: Science
Chapter: 7
Duration: 5 Hours
What Students Will Achieve
Knowledge
- Describe the components and functions of the circulatory system
- Explain the structure and working of the human heart
- Differentiate between arteries, veins and capillaries
- Understand the excretory system in humans
Understanding
- Explain how blood transports substances in the body
- Analyze the importance of xylem and phloem in plants
- Understand the process of transpiration in plants
- Relate pulse rate to heart rate
Skills
- Measure pulse rate and relate to heart rate
- Create a model of the human circulatory system
- Demonstrate water transport in plants
- Identify blood components under microscope
Prior Knowledge Assessment
Starter Questions:
- Why does our heart beat faster when we exercise?
- How do plants transport water from roots to leaves?
- What happens to the waste products produced in our body?
The Body's Transport Network
Components of Blood
Plasma
Liquid component of blood (55%)
- 90% water with dissolved substances
- Transports nutrients, hormones, waste
- Helps regulate body temperature
Red Blood Cells
(Erythrocytes)
- Contain hemoglobin for oxygen transport
- Give blood its red color
- Produced in bone marrow
White Blood Cells
(Leukocytes)
- Part of immune system
- Fight infections and diseases
- Larger than RBCs but fewer in number
Platelets
(Thrombocytes)
- Help in blood clotting
- Prevent excessive bleeding
- Cell fragments without nuclei
Blood Vessels Comparison
| Feature | Arteries | Veins | Capillaries |
|---|---|---|---|
| Wall Thickness | Thick, muscular | Thin | Extremely thin (one cell layer) |
| Pressure | High | Low | Very low |
| Valves | Absent | Present | Absent |
| Blood Type | Oxygenated (except pulmonary) | Deoxygenated (except pulmonary) | Mixed |
Experiment: Measuring Pulse Rate
Objective: Understand the relationship between activity and heart rate
- Locate pulse point on wrist or neck
- Count beats for 30 seconds and multiply by 2
- Record resting pulse rate
- Do 2 minutes of exercise (jumping jacks)
- Measure pulse immediately after
- Continue measuring every minute until normal
- Graph the results
The Human Heart
Structure
- Four chambers: 2 atria (upper), 2 ventricles (lower)
- Size of a fist, weighs 250-350g
- Located slightly left of chest center
- Protected by rib cage
Function
- Acts as a double pump
- Right side: Pumps to lungs (pulmonary)
- Left side: Pumps to body (systemic)
- Valves prevent backflow
Heartbeat
- Average 70-80 beats per minute
- "Lub-dub" sound from valve closure
- Controlled by electrical impulses
- Faster in children, slower in athletes
Activity: Create a Heart Model
Materials: Plastic bottles, balloons, straws, tape, red/blue markers
- Create four chambers using bottles
- Use balloons as valves between chambers
- Show pulmonary and systemic circulation with straws
- Mark oxygenated (red) and deoxygenated (blue) blood
- Demonstrate pumping action
Waste Removal in Animals
Human Excretory System Components
Kidneys (2)
- Bean-shaped, fist-sized organs
- Filter about 180L blood daily
- Produce 1-1.8L urine per day
- Remove urea, excess salts, water
Ureters (2)
- Muscular tubes about 25cm long
- Carry urine from kidneys to bladder
- Use peristalsis (wave-like motions)
Urinary Bladder
- Muscular sac that stores urine
- Can hold 400-600ml when full
- Expands as it fills
Urethra
- Tube that expels urine from body
- About 4cm in females, 20cm in males
- Controlled by sphincter muscles
Other Excretory Mechanisms
| Organ | Waste Product | Notes |
|---|---|---|
| Lungs | Carbon dioxide, water vapor | Byproduct of cellular respiration |
| Skin | Water, salts, urea (sweat) | Also helps regulate body temperature |
| Liver | Bile pigments (in feces) | Breaks down hemoglobin from old RBCs |
Excretion in Different Animals
Aquatic Animals
- Excrete ammonia directly into water
- Ammonia is highly toxic but dissolves easily
- Requires large amounts of water
Birds & Reptiles
- Excrete uric acid as semi-solid paste
- Conserves water (adaptation to land)
- White part of bird droppings
Insects
- Malpighian tubules remove wastes
- Uric acid excreted with feces
- Very water-efficient system
Project: Kidney Function Simulation
Objective: Demonstrate how kidneys filter blood
- Create "blood" mixture: water, red food coloring, salt, coffee grounds
- Use funnel with filter paper as "kidney"
- Pour mixture through - water and salt pass through (urine)
- Red cells and coffee grounds stay (filtered blood)
- Compare to actual kidney nephron function
Transport Systems in Plants
Xylem and Phloem Comparison
| Feature | Xylem | Phloem |
|---|---|---|
| Function | Transports water and minerals upward | Transports food (sap) in all directions |
| Direction of Flow | Unidirectional (roots to shoots) | Bidirectional (source to sink) |
| Components | Tracheids, vessels, fibers, parenchyma | Sieve tubes, companion cells, fibers |
| Cell Status | Dead at maturity | Living cells |
| Mechanism | Transpiration pull, root pressure | Pressure flow hypothesis |
Water Transport Process
Absorption
- Root hairs increase surface area
- Water enters by osmosis
- Minerals absorbed by active transport
Ascent of Sap
- Transpiration creates suction pull
- Cohesion-tension theory
- Water molecules stick together (cohesion)
Transpiration
- Water vapor loss through stomata
- Cools plant (like sweating)
- Creates transpiration pull
Experiment: Colored Water in Celery
Objective: Demonstrate water transport in plants
- Take fresh celery stalk with leaves
- Place in glass with colored water (red/blue)
- Observe after 24 hours
- Cut cross sections to see colored xylem
- Compare with control (plain water)
- Measure rate of water uptake
Factors Affecting Transpiration
Light
- Stomata open in light for photosynthesis
- Increases transpiration rate
Temperature
- Higher temperature increases evaporation
- Each 10°C rise doubles transpiration
Wind
- Removes humid air near leaf surface
- Increases transpiration rate
Humidity
- High humidity decreases transpiration
- Less difference in water vapor concentration
Activity: Transpiration in Bagged Plant
Materials: Potted plant, plastic bag, string, balance
- Water plant thoroughly
- Cover one branch with plastic bag, seal with string
- Weigh plant at start
- Place in sunlight for 2 hours
- Observe water droplets inside bag
- Weigh plant again to measure water loss
Evaluation Strategies
Formative Assessments
- Labeling diagrams of heart and excretory system
- Blood vessel comparison table completion
- Experiment report evaluation
- Classroom quiz on key terms
Summative Assessments
- Chapter test (MCQs, short and long answer)
- Practical exam on pulse measurement
- Project presentation on plant transport
- Case study on importance of blood donation
Extended Learning: Visit a Hospital Lab
Objective: Observe practical applications of circulatory knowledge
- Interview medical staff about blood tests
- Learn about blood typing and compatibility
- Understand ECG and its importance
- Learn about dialysis process
- Prepare a report with photographs
Frequently Asked Questions
Why is the pulmonary artery colored blue in diagrams if it's an artery?
The pulmonary artery is unique because:
- Though technically an artery (carries blood away from heart), it carries deoxygenated blood
- Diagram color conventions use blue for deoxygenated blood, red for oxygenated
- Similarly, pulmonary veins carry oxygenated blood and are colored red
- This exception highlights the special role of pulmonary circulation
How do tall trees like redwoods transport water to their tops?
Redwoods use remarkable adaptations:
- Strong transpiration pull: Continuous water evaporation from leaves creates strong suction
- Cohesion-tension: Water molecules stick together forming unbroken columns
- Narrow xylem vessels: Create capillary action helping water rise
- Root pressure: Active pumping of water into roots at night
- Special adaptations: Thick cell walls prevent collapse under tension
