Transportation in Animals and Plants: The Circulatory Dance of Life
Chapter 11 of NCERT’s Grade 7 Science textbook provides a detailed insight into the fascinating world of transportation mechanisms in animals and plants. These systems, while varying significantly between organisms, are universally crucial to ensuring the efficient distribution of nutrients, oxygen, and other vital substances.
Circulatory System in Animals
The circulatory system in animals, particularly vertebrates, is primarily composed of the heart, blood, and an intricate network of vessels.
1. Blood
- Components: Plasma, Red Blood Cells, White Blood Cells, and Platelets.
- Functions: Transports nutrients, oxygen, hormones, and waste products. Protects against diseases and helps in clotting.
2. Heart
- Chambers: Four chambers in mammals (two atria and two ventricles) ensure that oxygen-rich and oxygen-poor blood doesn’t mix.
3. Blood Vessels
- Arteries: Carry oxygen-rich blood away from the heart (except pulmonary artery).
- Veins: Bring oxygen-poor blood back to the heart (except pulmonary vein).
- Capillaries: Tiny vessels where the exchange of oxygen, nutrients, and waste occurs with cells.
Excretory System in Animals
To maintain homeostasis, waste products must be efficiently removed.
Human Excretory System
- Kidneys: Filter blood, removing waste products to form urine.
- Ureters: Tubes transporting urine from kidneys to the bladder.
- Bladder: Stores urine until it’s excreted.
- Urethra: The duct through which urine is discharged.
Transport in Plants
Unlike animals, plants employ a simpler yet effective transport system, primarily consisting of the xylem and phloem.
1. Xylem
- Function: Transports water and minerals from the soil (taken by roots) to different parts of the plant.
2. Phloem
- Function: Distributes the food produced by photosynthesis in leaves to the entire plant.
Transpiration in Plants
The loss of water in the form of vapor from aerial parts of the plant, mainly leaves, is termed as transpiration. It’s vital for:
- Cooling: Helps in cooling the plant.
- Water Uptake: Creates a suction force that aids in water uptake from the soil.
Guttation
At times, you might observe droplets at the edges of leaves. This is guttation, a process where plants exude water droplets, especially during high soil moisture levels.
Transport Mechanism in Lower Organisms
Simple organisms have straightforward transport mechanisms:
- Amoeba: Simple diffusion moves nutrients and oxygen in and out.
- Hydra: Body wall is two-cell thick, ensuring efficient diffusion of substances.
Significance of Transportation Systems
Transport systems, both in plants and animals, ensure:
- Efficient Distribution: Nutrients, oxygen, hormones, and other vital substances are evenly distributed.
- Waste Removal: Efficiently disposes of waste products, preventing toxicity.
- Homeostasis: Maintains internal equilibrium despite external environmental changes.
Concluding Thoughts: The Symphony of Life
Chapter 11 of NCERT’s Grade 7 Science paints the portrait of a meticulously orchestrated symphony. Every beat of the heart, every pulsation in plant vessels, is a testament to nature’s genius. As these systems transport the essence of life throughout organisms, we’re reminded of the interconnected dance of existence, where each element plays its part seamlessly.
