Environment and Ecology

Overview

Environment and Ecology forms a critical component of the KTET Category II/III Science section, testing your understanding of how living organisms interact with each other and their physical surroundings. This topic bridges biology with real-world environmental concerns, making it both conceptually important and practically relevant.

For KTET, expect questions on ecosystem components and functions, food chains and webs, types of biodiversity, major pollutants and their effects, and conservation strategies. Kerala's unique ecological features—Western Ghats biodiversity hotspot, backwater ecosystems, and coastal environments—often appear in context-based questions. Mastering this topic requires understanding interconnections rather than memorising isolated facts.

Key Concepts

• **Ecosystem** is a functional unit comprising living organisms (biotic) and non-living environment (abiotic) interacting as a system. Examples: pond ecosystem, forest ecosystem, Kerala backwaters.

• **Biotic components** include producers (green plants), consumers (herbivores, carnivores, omnivores), and decomposers (bacteria, fungi). Abiotic components include sunlight, temperature, water, soil, and minerals.

• **Food chain** shows linear transfer of energy from producers to consumers. Food web is interconnected food chains showing complex feeding relationships in an ecosystem.

• **Ecological pyramid** represents trophic levels graphically—pyramid of numbers, pyramid of biomass, and pyramid of energy. Energy pyramid is always upright (10% law: only 10% energy transfers to next level).

• **Biodiversity** refers to variety of life at three levels: genetic diversity (within species), species diversity (between species), and ecosystem diversity (variety of habitats).

• **Biogeochemical cycles** are pathways through which elements like carbon, nitrogen, and water circulate between living organisms and environment.

• **Pollution** is introduction of harmful substances into environment. Types: air, water, soil, and noise pollution.

• **Conservation** includes in-situ (national parks, sanctuaries) and ex-situ (zoos, seed banks) methods of protecting biodiversity.

Formulas / Key Facts

| Concept | Key Fact | |---------|----------| | Energy flow | Only 10% energy passes from one trophic level to next (Lindeman's 10% Law) | | Oxygen in atmosphere | 21% of atmospheric composition | | CO₂ in atmosphere | Approximately 0.04% (increasing due to human activities) | | India's biodiversity | 12 mega-biodiversity countries; India is one of them | | Western Ghats | UNESCO World Heritage Site; one of 36 global biodiversity hotspots | | Silent Valley | Kerala's only national park with tropical rainforest; saved from hydroelectric project | | Periyar Tiger Reserve | Located in Idukki and Pathanamthitta districts of Kerala | | Ramsar Sites in Kerala | Vembanad-Kol wetland and Ashtamudi wetland | | Ozone layer | Found in stratosphere; protects from UV radiation | | BOD (Biochemical Oxygen Demand) | Higher BOD indicates more polluted water |

Worked Examples

**Example 1: Food Chain Construction**

*Question*: Construct a food chain in a pond ecosystem with four trophic levels.

*Solution*:

• First trophic level (Producer): Phytoplankton (algae)
• Second trophic level (Primary consumer): Zooplankton
• Third trophic level (Secondary consumer): Small fish
• Fourth trophic level (Tertiary consumer): Large fish

Food chain: Phytoplankton → Zooplankton → Small fish → Large fish

Energy available at each level (if producer has 10000 J):

• Zooplankton receives: 10000 × 10% = 1000 J
• Small fish receives: 1000 × 10% = 100 J
• Large fish receives: 100 × 10% = 10 J

**Example 2: Identifying Pollution Type**

*Question*: A factory releases untreated effluents containing heavy metals into a river. Fish start dying, and people drinking river water develop health issues. Identify the pollution type and explain the impact.

*Solution*:

• Pollution type: Water pollution
• Pollutant: Heavy metals (like mercury, lead, cadmium)
• Impacts:
• Reduced dissolved oxygen (increases BOD)
• Bioaccumulation in fish tissues
• Biomagnification through food chain
• Health hazards in humans: kidney damage, neurological disorders
• Prevention: Effluent treatment plants, strict industrial regulations

**Example 3: Conservation Classification**

*Question*: Classify the following into in-situ and ex-situ conservation: Periyar Wildlife Sanctuary, Seed bank, National park, Botanical garden, Biosphere reserve, Zoo.

*Solution*:

• In-situ (on-site, natural habitat): Periyar Wildlife Sanctuary, National park, Biosphere reserve
• Ex-situ (off-site, artificial conditions): Seed bank, Botanical garden, Zoo

Common Mistakes

• **Confusing food chain with food web** → Food chain is a single linear pathway; food web is multiple interconnected chains. Questions often ask specifically for one.

• **Thinking decomposers are consumers** → Decomposers (saprotrophs) form a separate category; they break down dead organic matter, not consume living organisms.

• **Reversing the energy pyramid concept** → Students sometimes think energy increases at higher levels. Remember: energy always decreases (10% rule), which is why top predators are fewer in number.

• **Mixing up in-situ and ex-situ conservation** → In-situ means "in the original place" (protected areas). Ex-situ means "outside original habitat" (zoos, gene banks). The Latin roots help: situ = site/place.

• **Assuming all ecological pyramids are upright** → Pyramid of numbers can be inverted (one tree supporting many insects). Pyramid of biomass can be inverted in aquatic ecosystems. Only energy pyramid is always upright.

Quick Reference

• Ecosystem = Biotic (living) + Abiotic (non-living) components interacting together

• 10% Law: Energy transfer between trophic levels is only 10% efficient

• Three levels of biodiversity: Genetic → Species → Ecosystem

• Western Ghats and Eastern Himalayas are India's two biodiversity hotspots

• In-situ = conservation in natural habitat; Ex-situ = conservation outside natural habitat

• Higher BOD = More organic pollution = Less dissolved oxygen = Unhealthy water