1. What is Biodiversity?

Definition: Biodiversity is the variety of living organisms found on Earth — including plants, animals, fungi and microorganisms — and the ecosystems in which they live.

Explanation: Biodiversity includes diversity at the genetic level, species level and ecosystem level. It supports ecosystem services such as food production, oxygen supply, climate regulation and nutrient cycling. High biodiversity increases resilience against environmental changes.

Example: A forest ecosystem contains many species of trees, shrubs, insects, birds and mammals; each plays a role in energy flow and nutrient cycles.

2. Levels of Biodiversity

Biodiversity is studied at three main levels:

Why each level matters: Genetic diversity allows adaptation, species diversity maintains stable food webs, and ecosystem diversity provides different services and habitats.

3. Classification of Organisms

Definition: Classification is the process of grouping organisms based on shared characteristics.

Explanation: Classification helps scientists organize and study millions of organisms. Scientific classification uses standardized Latin names to avoid confusion caused by different local names.

Aims of Classification:

1. To arrange organisms logically and make them easier to study.
2. To show relationships and evolutionary history between organisms.
3. To standardize names and avoid confusion from common names.
4. To help identify organisms correctly.

Example: Domestic dog — Canis lupus familiaris. Scientific name shows exact species and genus.

4. Taxonomic Hierarchy (Ranks)

Definition: A hierarchical system of categories used to classify organisms from most general to most specific.

1. Kingdom
2. Phylum (Division for plants)
3. Class
4. Order
5. Family
6. Genus
7. Species

Species: The basic unit of classification. Members of a species can interbreed and produce fertile offspring.

Example (Human):

5. Systems of Classification

Two‑Kingdom System

Proposed by Linnaeus — only Plants and Animals. This system could not accommodate microorganisms and fungi properly.

Three‑Kingdom System

Proposed by Ernst Haeckel — added Protista for unicellular organisms with a true nucleus.

Five‑Kingdom System (Whittaker)

Widely used modern system dividing life into five kingdoms:

6. Binomial Nomenclature

Definition: A universal system of naming species using two names: the Genus name and the species name (binomial).

Rules & format:

• Genus name is capitalized, species name is lowercase.
• Both names are italicized (or underlined when handwritten).
• Introduced by Carolus Linnaeus.

Examples: Homo sapiens, Allium cepa (onion), Mangifera indica (mango).

Importance: Provides a standard, universal name for each organism and avoids confusion created by local names.

7. Importance and Conservation of Biodiversity

Importance

• Food: Crops, fruits, fish and livestock.
• Medicine: Many medicines and pharmaceutical compounds come from plants and microbes.
• Ecosystem services: Pollination, water purification, soil formation, climate regulation.
• Economic value: Timber, tourism, fisheries and agriculture.
• Scientific value: Research, discovery of genes and compounds.

Conservation

Definition: Conservation means protecting and managing natural resources to prevent destruction and loss of biodiversity.

Methods of conservation:

1. Establishing protected areas: National parks, wildlife sanctuaries and reserves.
2. Legal protection: Laws to prevent hunting, logging and trade of endangered species.
3. Ex-situ conservation: Zoos, botanical gardens and seed banks.
4. In-situ conservation: Protecting species within their natural habitats.
5. Public awareness and education.

8. Human Impact on Biodiversity

Negative impacts

• Deforestation: Habitat loss for many species.
• Pollution: Chemical, plastic and oil pollution kills organisms and damages habitats.
• Over-exploitation: Overfishing and hunting reduce populations.
• Introduction of invasive species: Non-native species can outcompete native species.
• Climate change: Alters habitats and migration patterns.

Positive actions

• Reforestation and afforestation.
• Protected area creation and management.
• Wildlife laws and international treaties (e.g., CITES).
• Community-based conservation and sustainable use.

9. Important Terms

10. Long Questions & Detailed Answers

Q1: Define biodiversity and explain its levels with examples.

Answer: Biodiversity is the variety of life forms on Earth across all levels. The three levels are:

1. Genetic diversity: Variation within species; e.g., different rice varieties with different tolerance to drought.
2. Species diversity: Variety of species present; e.g., many species in a tropical rainforest.
3. Ecosystem diversity: Different habitats like deserts, forests and wetlands, each supporting different life communities.

These levels together ensure ecosystem stability and services for humans and other organisms.

Q2: What are the aims and advantages of classification?

Answer: The aims are to organize biological diversity, to identify organisms, to show evolutionary relationships and to avoid ambiguity in naming. Advantages include easier study, clear communication among scientists, predictable grouping of organisms and facilitation of biological research and conservation planning.

Q3: Describe the five-kingdom system of classification.

Answer: Whittaker’s five-kingdom system includes Monera (prokaryotes), Protista (unicellular eukaryotes), Fungi (non-green absorptive organisms), Plantae (photosynthetic multicellular organisms) and Animalia (multicellular heterotrophs). Each kingdom groups organisms with shared fundamental features and cellular organization.

Q4: Explain binomial nomenclature and its importance.

Answer: Binomial nomenclature gives every species a two-part Latin name: Genus and species (e.g., Homo sapiens). It provides a universal and stable way to name organisms, avoids confusion with local names and reflects relationships between organisms.

Q5: How do humans affect biodiversity and how can we protect it?

Answer: Humans affect biodiversity negatively through habitat destruction, pollution and over-exploitation. Protection measures include legal protection, creating reserves, ex-situ conservation (zoos, seed banks), public education and sustainable resource use. International agreements (e.g., CITES) and national policies also play a critical role.