Biology Chapter 1: The Living World

The Living World

• The living world comprises an amazing diversity of living organisms, with diverse habitats, and ecological conflicts and cooperation among populations.

Biology and Classification

• Biology is the science of life forms and living processes.
• Early man could distinguish between inanimate matter and living organisms.
• Classification of living organisms is necessary to understand the diversity of life.
• The process of classification involves identification, nomenclature, and taxonomy.

Ernst Mayr

• Ernst Mayr (1904-2004) was an evolutionary biologist and ornithologist who made significant contributions to the field of biology.
• He is considered the "Darwin of the 20th century" and was awarded the Balzan Prize, International Prize for Biology, and the Crafoord Prize.

Diversity in the Living World

• There are approximately 1.7-1.8 million known species of living organisms on Earth.
• New species are continuously being identified, and classification is necessary to understand the diversity of life.

Nomenclature

• Nomenclature is the process of assigning scientific names to living organisms.
• The scientific name of an organism is a unique combination of generic and specific epithets.
• Binomial nomenclature is the system of providing a scientific name with two components, a generic name and a specific epithet.
• This system was developed by Carolus Linnaeus.

Taxonomic Categories

• Taxonomic categories are hierarchical and include Kingdom, Phylum, Class, Order, Family, Genus, and Species.
• Each category is a unit of classification and represents a rank or level of organization.
• The categories become more specific as you move from Kingdom to Species.

Characteristics of Taxonomic Categories

• Species: a group of individual organisms with fundamental similarities.
• Genus: a group of related species with more characteristics in common.
• Family: a group of related genera with still fewer similarities.
• Order: a group of related families with fewer similarities.
• Class: a group of related orders.
• Phylum: a group of related classes (in animals) or divisions (in plants).
• Kingdom: the highest category, comprising all animals (Kingdom Animalia) or plants (Kingdom Plantae).

Importance of Taxonomic Categories

• Taxonomic categories help in identifying and understanding the relationships among different organisms.
• They provide a framework for classification and understanding the diversity of life.
• They help in recognizing the similarities and differences among organisms.

Figure 1.1 and Table 1.1

• Figure 1.1 shows the hierarchical arrangement of taxonomic categories from Species to Kingdom.

• Table 1.1 provides examples of common organisms and their taxonomic categories.### Taxonomic Categories

• Organisms can be classified into different categories, including Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

• The taxonomic categories are hierarchical, with each category becoming more specific.

Characteristics of Living Organisms

• Living organisms exhibit a wide range of characteristics, including size, color, habitat, physiological features, and morphological features.
• These characteristics are used to identify and classify organisms.

Taxonomy

• Taxonomy is the branch of biology that deals with the identification, naming, and classification of organisms.
• Taxonomic studies are useful in agriculture, forestry, industry, and for understanding bio-resources and their diversity.

Binomial System of Nomenclature

• The binomial system of nomenclature is used to assign scientific names to organisms.
• Each scientific name consists of two words: a genus name and a species name.
• The binomial system is universally accepted and follows international codes.

Taxonomic Hierarchy

• The taxonomic hierarchy is a system of classification that consists of multiple categories.
• Each category represents a level of classification, with each level becoming more specific.
• The categories include Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Examples of Organisms and Their Taxonomic Categories

• Human (Homo sapiens): Kingdom - Animalia, Phylum - Chordata, Class - Mammalia, Order - Primata, Family - Hominidae, Genus - Homo
• Housefly (Musca domestica): Kingdom - Animalia, Phylum - Arthropoda, Class - Insecta, Order - Diptera, Family - Muscidae, Genus - Musca
• Mango (Mangifera indica): Kingdom - Plantae, Phylum - Angiospermae, Class - Dicotyledonae, Order - Sapindales, Family - Anacardiaceae, Genus - Mangifera
• Wheat (Triticum aestivum): Kingdom - Plantae, Phylum - Angiospermae, Class - Monocotyledonae, Order - Poales, Family - Poaceae, Genus - Triticum