Variety of Life, Biodiversity, and Conservation

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Biodiversity and Conservation — Key Facts for Sri Lanka A/L Examination

Three Levels of Biodiversity:

Level	Definition	Sri Lankan Example
Genetic	Variation within a species	Different coconut varieties
Species	Variety of species in an area	~3,150+ plant species in Sri Lanka
Ecosystem	Variety of habitats and communities	Rainforests, mangroves, dry forests

Sri Lanka’s Biodiversity Profile:

• ~21% endemic flowering plants (one of the highest in Asia)
• 26 National Parks, 3 UNESCO World Heritage sites
• Biodiversity hotspot: Western Ghats & Sri Lanka (36 global hotspots)
• Threatened species: Sri Lankan elephant, leopard, freshwater crabs

Conservation Categories (IUCN Red List):

Category	Meaning	Sri Lankan Example
EX	Extinct	Sri Lankan quill pipit (bird)
CR	Critically Endangered	Asian elephant (局部)
EN	Endangered	Leopard, purple-faced langur
VU	Vulnerable	Saltwater crocodile
NT	Near Threatened	Mugger crocodile
LC	Least Concern	Indian peafowl

⚡ A/L Exam Tip: Sri Lanka has extremely high plant endemism — if asked for a biodiversity example, use local Sri Lankan species (e.g., Maha, Na, * Ehela* — local names for trees)!

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Biodiversity and Conservation — Detailed Study Guide

Five Kingdom Classification

Whittaker’s Five Kingdoms (1969):

Kingdom	Cell Type	Nutrition	Cell Wall	Examples
Monera	Prokaryotic	Autotrophic/Heterotrophic	Peptidoglycan	Bacteria, cyanobacteria
Protista	Eukaryotic	Autotrophic/Heterotrophic	Absent/various	Amoeba, Euglena, Paramecium
Fungi	Eukaryotic	Heterotrophic (absorption)	Chitin	Mushrooms, yeast, Penicillium
Plantae	Eukaryotic	Autotrophic (photosynthesis)	Cellulose	Mosses, ferns, flowering plants
Animalia	Eukaryotic	Heterotrophic (ingestion)	Absent	Humans, insects, fish

Three Domains (Woese, 1990):

Domain	Cell Type	Kingdom
Bacteria	Prokaryotic	Monera
Archaea	Prokaryotic	Monera (deep branch)
Eukarya	Eukaryotic	Protista, Fungi, Plantae, Animalia

⚡ A/L PYQ: “State two advantages of the three-domain system over the five-kingdom system.” Answer: (1) It separates Archaea and Bacteria which are fundamentally different at the molecular level. (2) It places all eukaryotes in one domain, reflecting their common ancestry.

Kingdom Plantae in Depth

Plant Divisions:

Division	Vascular	Seeds	Flowers/Fruits	Sri Lankan Example
Bryophyta	❌	❌	❌	Funaria, Marchantia
Pteridophyta	✅	❌	❌	Dryopteris, Pteris
Gymnospermae	✅	✅ (naked)	❌	Pinus, Cycas
Angiospermae	✅	✅ (enclosed)	✅	Coconut, rice, mango

Angiosperm Classification:

Feature	Monocotyledoneae	Dicotyledoneae
Cotyledons	1	2
Leaf venation	Parallel	Reticulate
Flower parts	Usually 3s	Usually 4s or 5s
Vascular bundles	Scattered	Ring
Root system	Fibrous (adventitious)	Tap root
Examples	Rice, coconut, banana, orchid	Mango, rubber, jackfruit, tea

Viruses — A Special Case:

Feature	Description
Size	Nanometres (nm) — much smaller than bacteria
Structure	DNA or RNA genome + protein coat (capsid)
Living?	Debate — obligate intracellular parasites
Examples	Tobacco mosaic virus (TMV), bacteriophage T4, HIV

⚡ A/L Important: Viruses are NOT classified in any kingdom because they are obligate intracellular parasites — they cannot carry out metabolism independently and can only replicate inside host cells.

Plant Biodiversity of Sri Lanka

Endemic Plant Species:

• ~500+ endemic plant species in Sri Lanka
• High concentration in montane and lowland rainforests
• Sacred trees: Palu (Manilkara hexandra), Maha (Macaranga spp.), Na (Mesua ferrea)

Important Plant Groups in Sri Lanka:

Group	Sri Lankan Representatives	Conservation Status
Flowering plants	~3,150 species	~21% endemic
Ferns	~200 species	Many endemic
Orchids	~190 species	High endemism (~50%)
Palms	~40 species	Several endemic

Invasive Species:

Species	Origin	Impact
Lantana camara	Central America	Outcompetes native understory
Prosopis juliflora	Americas	Alters dry zone ecosystems
Water hyacinth (Eichhornia)	South America	Clogs waterways, reduces biodiversity

Conservation Biology

Threats to Biodiversity:

Threat	Mechanism	Sri Lankan Example
Habitat destruction	Deforestation, urbanisation	Sinharaja edge effects
Overexploitation	Logging, hunting	Rosewood (Mahogany) depletion
Pollution	Eutrophication, acidification	Temple tank pollution
Invasive species	Competition, predation	Lantana camara invasion
Climate change	Temperature shifts, sea level rise	Coral bleaching, migration shifts

Conservation Strategies:

Strategy	Description	Sri Lankan Example
In-situ conservation	Protect species in natural habitat	National parks (Yala, Wilpattu, Sinharaja)
Ex-situ conservation	Protect outside natural habitat	Peradeniya Botanic Gardens
Legislation	Laws protecting species	Fauna and Flora Protection Ordinance (FFPO)
Community-based	Local community involvement	Vedda traditional conservation knowledge
Seed banks	Store genetic material	National Botanic Gardens, Peradeniya

Sri Lankan Protected Areas:

Category	Number	Example
National Parks	26	Yala, Wilpattu, Udawalawe
Strict Natural Reserves	64	Ritigala, Kanneliya
UNESCO World Heritage	3	Sinharaja, Central Highlands, Polonnaruwa
Ramsar sites	2	Bundala, Vankalai
Biosphere reserves	1	Bundala

⚡ A/L Important: Sinharaja Forest is Sri Lanka’s last viable area of primary tropical rainforest — it is a UNESCO World Heritage Site, a Strict Natural Reserve, and a biodiversity hotspot within the global hotspot.

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Biodiversity and Conservation — Complete Notes for A/L Sri Lanka

Binomial Nomenclature and Taxonomy

Scientific Naming System:

• Binomial nomenclature: Two-part name (Genus + species), e.g., Oryza sativa (rice), Mangifera indica (mango)
• Rules: Italicised (or underlined), Genus capitalised, species lower case
• Author citation: Mangifera L. (L. = Linnaeus)

Taxonomic Hierarchy: $$\text{Domain} \rightarrow \text{Kingdom} \rightarrow \text{Phylum} \rightarrow \text{Class} \rightarrow \text{Order} \rightarrow \text{Family} \rightarrow \text{Genus} \rightarrow \text{Species}$$ Mnemonic: Dear King Phillip Came Over For Good Spaghetti

Example — Coconut Palm:

Domain: Eukarya
Kingdom: Plantae
Phylum: Tracheophyta (vascular plants)
Class: Liliopsida (monocots)
Order: Arecales
Family: Arecaceae (palms)
Genus: Cocos
Species: Cocos nucifera L.

Ecosystem Dynamics

Food Webs and Trophic Interactions:

Sun → Producers (plants, algae)
  → Primary consumers (herbivores: insects, deer)
    → Secondary consumers (small carnivores: frogs, small birds)
      → Tertiary consumers (top predators: snakes, eagles)
        → Decomposers (fungi, bacteria) → nutrients recycled

Ecological Pyramids:

Pyramid	Shows	Pattern	Key Point
Pyramid of numbers	Number of organisms	Usually upright	One tree → many insects
Pyramid of biomass	Dry mass at each level	Usually upright	Can be inverted (insects > trees)
Pyramid of energy	Energy per unit area/time	Always upright	~10% transfer between levels

⚡ A/L Key Point: Energy is always lost between trophic levels (~90%) as heat from respiration, undigested material, and movement — therefore, the pyramid of energy is always upright and tapers.

Biogeochemical Cycles:

Cycle	Key Reservoirs	Human Impact
Carbon	Atmosphere, oceans, fossil fuels	CO₂ from burning fossil fuels → global warming
Nitrogen	Atmosphere, soils, oceans	Fertiliser run-off → eutrophication
Phosphorus	Rocks, soils, oceans	Phosphate mining, detergent pollution
Water	Oceans, glaciers, freshwater	Over-extraction, pollution

Nitrogen Cycle:

N₂ (atmosphere, 78%) → [N₂ fixation by Rhizobium] → NH₃ → [nitrification by Nitrosomonas/Nitrobacter] → NO₃⁻ → plants absorb
                                                              ↓
  ← [denitrification by Pseudomonas] ← NO₃⁻ ← decomposition ← organic N (dead matter)

⚡ A/L Important: Eutrophication — excess nitrogen/phosphorus from agricultural fertilisers washes into waterways → algal bloom → algae die → decomposers multiply → consume all oxygen → fish kill (anoxic conditions).

Sri Lankan Ecosystem Case Studies

Tropical Rainforest (Sinharaja):

Feature	Description
Canopy	Multi-layered, 35-40m tall
Biodiversity	Highest in Sri Lanka
Endemism	~64% endemic plants, many endemic birds, butterflies
Threats	Edge effects, illegal gem mining, encroachment
Conservation	UNESCO World Heritage, strict protection

Dry Zone Forest (Wilpattu, Yala):

Feature	Description
Climate	Monsoon, 1500-2000mm rain annually
Vegetation	Deciduous trees, scrub jungle
Key species	Leopard, sloth bear, spotted deer
Adaptations	Drought-deciduous leaves, thick bark

Mangrove Ecosystems (Kalpitiya, Trincomalee):

Feature	Description
Plants	Rhizophora, Avicennia, Sonneratia
Adaptations	Pneumatophores (aerial roots), vivipary
Functions	Nursery for fish, coastal protection, carbon sequestration
Threats	Shrimp farming, coastal development

⚡ A/L Strategy: Sri Lanka A/L questions frequently use local ecosystems — always include specific Sri Lankan examples: Sinharaja for rainforest, Wilpattu for dry forest, Bundala for wetlands, mangroves of the west coast for coastal ecosystems.

GCE A/L Sri Lanka Past Paper Tips

Common Structured Questions:

1. “What is meant by biodiversity? Describe the three levels of biodiversity with examples” (10 marks)
2. “Explain why Sri Lanka is considered a biodiversity hotspot” (10 marks)
3. “Describe the nitrogen cycle, mentioning the role of named microorganisms” (12 marks)
4. “Discuss the threats to biodiversity in Sri Lanka and conservation measures” (15 marks)
5. “Compare in-situ and ex-situ conservation methods” (8 marks)

Diagram Questions:

1. Draw and label a pyramid of energy (6 marks)
2. Draw a food web from a named Sri Lankan ecosystem (8 marks)
3. Draw and label the nitrogen cycle (10 marks)
4. Draw LS of a mangrove propagule (viviparous germination) (6 marks)

Case Study Questions:

• Sinharaja Forest conservation challenges
• Bundala National Park as a Ramsar wetland
• Threatened endemic plants of Sri Lanka (e.g., Isachne spp., Ruellia)
• Effect of Lantana camara invasion on native biodiversity

⚡ A/L Strategy: When asked about conservation in Sri Lanka, mention specific legislation (Fauna and Flora Protection Ordinance), specific protected areas (Sinharaja, Yala, Wilpattu), and the IUCN Red List categories — this demonstrates depth of local knowledge.

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