Look around you — a crow on a branch, a mango tree in the garden, a mushroom on a log, moss on a wall. Life on Earth exists in an astonishing variety of shapes, sizes, colours, and habits. This variety is called biodiversity.
What is Biodiversity?
Biodiversity refers to the variety of living organisms found on Earth — from microscopic bacteria to giant blue whales. Scientists have identified and named over 1.8 million species, and millions more are yet to be discovered.
Characteristics of Living Organisms
All living things share certain basic characteristics that distinguish them from non-living things:
- Nutrition — All living organisms obtain and use food for energy.
- Respiration — Living organisms break down food to release energy.
- Growth — Living organisms increase in size over time.
- Movement — Living organisms can move (even plants show slow movement).
- Response to stimuli — Living organisms react to changes in their environment.
- Reproduction — Living organisms produce offspring of their own kind.
- Excretion — Living organisms remove waste products from their bodies.
Classification of Living Organisms
To study the vast variety of life, scientists group organisms with similar features together — this is called classification. The father of modern classification is Carl Linnaeus.
The main kingdoms of life (as per the NCERT framework) include:
- 1.Monera — Single-celled organisms without a true nucleus (e.g., bacteria).
- 2.Protista — Single-celled organisms with a true nucleus (e.g., Amoeba, Paramecium).
- 3.Fungi — Organisms that feed on dead matter; includes mushrooms and moulds.
- 4.Plantae — All plants; make their own food through photosynthesis.
- 5.Animalia — All animals; obtain food by eating other organisms.
Plants: A Closer Look
- Plants are classified as:
- Flowering plants (Angiosperms) — produce flowers and fruits (e.g., mango, rose).
- Non-flowering plants — do not produce flowers (e.g., ferns, mosses, pine trees).
Plants can also be grouped by their habitat: terrestrial (land), aquatic (water), or desert plants. Desert plants like the cactus store water in their thick stems.
Animals: A Closer Look
- Animals are broadly divided into:
- Vertebrates — animals with a backbone (fish, amphibians, reptiles, birds, mammals).
- Invertebrates — animals without a backbone (insects, worms, crabs, jellyfish).
Importance of Biodiversity
Biodiversity keeps ecosystems healthy. Plants produce oxygen, bees pollinate crops, earthworms enrich soil, and bacteria decompose dead matter. Losing species through extinction disrupts these processes and affects human survival.
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A mango tree is a flowering plant (Angiosperm). It belongs to Kingdom Plantae. It grows in soil, makes food through photosynthesis, and produces fruits containing seeds — all characteristics of living organisms.
A mushroom looks like a plant but does NOT make its own food. Instead, it absorbs nutrients from dead organic matter. This places it in Kingdom Fungi, not Plantae.
Amoeba is a single-celled organism visible only under a microscope. It moves, eats, reproduces, and responds to stimuli — all living characteristics — but it belongs to Kingdom Protista.
A butterfly is an insect (invertebrate). A sparrow is a bird (vertebrate). Both are in Kingdom Animalia, but they differ in structure — the butterfly has no backbone while the sparrow does.
A cactus lives in a desert. Its leaves are modified into spines (to reduce water loss), and its stem is thick and green (to store water and perform photosynthesis). This is an example of adaptation — how organisms develop features suited to their environment.
Carl Linnaeus introduced a two-name system called binomial nomenclature. For example, the scientific name for humans is · Homo sapiens · — · Homo · is the genus and · sapiens · is the species. This system is used worldwide so scientists everywhere refer to the same organism.
Bacteria in the soil break down dead leaves and animal waste into simpler substances, returning nutrients to the soil. Without these decomposers, dead matter would pile up and nutrients would not be recycled — showing the ecological importance of even microscopic organisms.
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Common mistakes
Common mistakes
Students often think that all living things must move visibly. Plants also move — sunflowers turn toward the sun (a movement called phototropism) — but the movement is very slow. Movement does not always mean walking or running.
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Summary
- Biodiversity is the variety of life on Earth, with millions of identified species.
- All living organisms share characteristics: nutrition, respiration, growth, movement, response to stimuli, reproduction, and excretion.
- Organisms are classified into five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia.
- Plants can be flowering or non-flowering; animals can be vertebrates or invertebrates.
- Biodiversity is essential for healthy ecosystems and human survival.