Science: Class 6 — Chapter 2: Diversity in the Living World
2.1 Diversity in Plants and Animals Around Us
Biodiversity: The variety of plants and animals found in a particular region.
Nature walks and direct observations help identify the vast array of living organisms, their unique sounds, smells, and physical features.
2.2 How to Group Plants and Animals?
Grouping makes it easier to understand and study organisms based on their similarities and differences.
2.2.1 How to Group Plants?
Based on Height and Stem Nature:
Herbs: Small plants with soft, green, and tender stems (e.g., Tomato).
Shrubs: Medium-sized plants with hard but thin woody stems branching close to the ground (e.g., Rose).
Trees: Tall plants with hard, thick, brown, and woody stems (trunks) branching higher up (e.g., Mango).
Climbers: Plants with weak stems that require external support to grow upwards (e.g., Money plant).
Creepers: Weak-stemmed plants that spread and creep along the ground (e.g., Pumpkin).
Based on Leaf Venation:
Veins: Thin lines running across a leaf.
Venation: The pattern of veins on a leaf.
Reticulate Venation: A net-like pattern of veins on both sides of a central midrib (e.g., Hibiscus, Sadabahar).
Parallel Venation: Veins running parallel to each other from base to tip (e.g., Grass, Banana, Lemongrass).
Based on Root Systems:
Taproot: A single main primary root with smaller lateral side roots (e.g., Mustard, Radish).
Fibrous Roots: A cluster of thin, similar-sized roots arising directly from the base of the stem (e.g., Grass, Wheat).
Based on Seed Structure (Cotyledons):
Cotyledon: The seed leaf or embryonic leaf within a seed.
Dicotyledons (Dicots): Seeds that easily split into two cotyledons. They typically feature reticulate venation and a taproot system (e.g., Chickpea, Kidney beans).
Monocotyledons (Monocots): Seeds containing a single cotyledon. They typically feature parallel venation and a fibrous root system (e.g., Maize, Wheat).
2.2.2 How to Group Animals?
Animals can be grouped based on their habitats, food habits, and modes of movement (e.g., flying, walking, crawling, swimming).
Janaki Ammal (1897–1984): A pioneering Indian botanist who documented India's rich plant biodiversity and played a key role in the Save Silent Valley movement.
2.3 Plants and Animals in Different Surroundings
Habitat: The natural place where an organism lives, providing food, water, air, and shelter.
Amphibians: Organisms capable of living both on land and in water (e.g., Frogs).
Adaptations: Special physical features or behaviors that enable an organism to survive in its specific environment.
Desert Plants (Cactus): Thick, fleshy stems to store water.
Mountain Trees (Deodar): Conical shape and sloping branches to let snow slide off easily.
Hot Desert Camels: Long legs and wide hooves to walk on sand; single hump to store fat; minimal water loss (dry dung, little urine, no sweat).
Cold Desert Camels (Ladakh): Shorter legs for rocky terrain; two humps; long hair for warmth.
Salim Ali (1896–1987): Known as the 'Birdman of India', he was an influential ornithologist who documented bird diversity and helped establish key sanctuaries.
Sacred Groves: Traditionally protected, undisturbed forest patches conserved by local communities, acting as vital sanctuaries for biodiversity.
Conservation Initiatives: Human activities cause habitat loss, leading to biodiversity decline. Key Indian conservation projects include Project Tiger (1973) and the Cheetah Reintroduction Project (2022).
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