Environment and Ecosystem

Overview

Environment and Ecosystem is a foundational topic in the Science section of WB TET Paper II, bridging biology with environmental awareness. This topic tests your understanding of how living organisms interact with each other and their physical surroundings — a concept central to the upper-primary science curriculum (Classes 6–8).

For the exam, expect questions on ecosystem components, energy flow through food chains and food webs, types of biodiversity, and causes and effects of pollution. The topic also connects with pedagogy questions about environmental awareness and sustainable development. Mastering this area requires understanding both the scientific concepts and their real-world applications, particularly in the context of West Bengal's environment.

Questions typically range from straightforward definitions to application-based problems involving food chain analysis or pollution control measures. About 3–5 questions can be expected from this sub-topic.

Key Concepts

• **Environment** comprises all biotic (living) and abiotic (non-living) factors that surround and influence an organism — air, water, soil, temperature, plants, animals and microorganisms.

• **Ecosystem** is a functional unit where living organisms interact with each other and their physical environment; it can be as small as a pond or as large as a forest.

• **Biotic components** include producers (green plants), consumers (herbivores, carnivores, omnivores) and decomposers (bacteria, fungi).

• **Abiotic components** include sunlight, temperature, water, soil, minerals and atmospheric gases.

• **Food chain** represents a linear sequence of energy transfer: Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer.

• **Food web** is an interconnected network of multiple food chains in an ecosystem, showing complex feeding relationships.

• **Biodiversity** refers to the variety of life forms at three levels — genetic diversity, species diversity and ecosystem diversity.

• **Pollution** is the introduction of harmful substances (pollutants) into the environment, classified as air, water, soil and noise pollution.

Formulas / Key Facts

| Concept | Key Fact | |---------|----------| | Energy flow | Only 10% of energy transfers to the next trophic level (10% Law by Lindeman) | | Producers | Also called autotrophs; they convert solar energy to chemical energy through photosynthesis | | Primary consumers | Herbivores that directly feed on plants (e.g., grasshopper, deer, rabbit) | | Secondary consumers | Carnivores that feed on herbivores (e.g., frog, snake, small fish) | | Tertiary consumers | Top predators that feed on secondary consumers (e.g., eagle, tiger, shark) | | Decomposers | Break down dead organic matter and return nutrients to soil (bacteria, fungi) | | Biodiversity hotspots | India has 4 hotspots — Western Ghats, Eastern Himalayas, Indo-Burma, Sundaland | | Endemic species | Species found only in a particular region (e.g., Gangetic dolphin, Bengal tiger) | | Air pollutants | CO, CO₂, SO₂, NO₂, particulate matter, CFCs | | Water pollutants | Industrial effluents, sewage, pesticides, heavy metals | | Greenhouse gases | CO₂, CH₄ (methane), N₂O, water vapour — cause global warming |