Comprehensive notes, solved MCQs, and short questions for Class 9 Biology Chapter 2 Biodiversity. Covers classification systems, five kingdoms, binomial nomenclature, and conservation.
Biodiversity is a measure of the variety of living organisms present in different ecosystems including terrestrial, marine, and desert ecosystems. Ideally, it refers to the degree of variation within species, between species, and of ecosystems.
Importance of Biodiversity: Biodiversity provides many essential services for humans and the planet. Some key benefits include:
Classification is the process of organizing and classifying living organisms based on their similarities and differences. Biologists have identified and described about 2 million kinds of organisms. Out of these, 0.5 million are plants and 1.5 million are animals.
Aims of Classification:
Taxonomy vs Systematics:
The groups into which organisms are classified are known as taxonomic ranks or taxa. The Swedish botanist Carolus Linnaeus devised the system of taxonomic ranks. The hierarchy is as follows:
Aristotle (384-322 BC): Classified organisms into two groups: Plants and Animals.
Abu Usman Umer Al-Jahiz (781-869 AD): Described characteristics of 350 species of animals and wrote about the life of ants.
Andrea Caesalpinio (1519-1603): Divided plants into fifteen groups and called them genera.
John Ray (1627-1705): Published important works on plant classification.
Augustus Rivinus (1652-1723): Introduced the category of order.
Tournefort (1656-1708): Introduced the taxa of class and species.
Carolus Linnaeus (1707-1778): Grouped species into genera, orders, and classes. He is known as the father of Taxonomy.
The oldest system, classifying organisms into Plantae (autotrophs, bacteria, fungi) and Animalia (heterotrophs). Drawbacks: Euglena (plant-like and animal-like features) was difficult to classify. It did not distinguish between prokaryotes and eukaryotes.
Proposed by Ernst Haeckel in 1866. He created Protista for Euglena-like organisms and bacteria. Fungi were still in Plantae.
Proposed by Robert Whittaker in 1967. Based on cellular organization (prokaryotic, unicellular eukaryotic, multicellular eukaryotic) and mode of nutrition (photosynthesis, absorption, ingestion).
Binomial Nomenclature is the system of giving scientific names to living organisms. Introduced by Carolus Linnaeus. Each name has two parts:
Names are printed in italics or underlined when handwritten.
Examples: