Diversity in the Living World 🌿 Official Notes By AI BIOLOGY CLASS 11 Chapter1 NEET

 

Diversity in the Living World 🌿

Definition of Biology

Biology is the science of life forms and living processes. The living world comprises an amazing diversity of living organisms.

Early Perception of Living Organisms

Early man could easily perceive the difference between inanimate matter and living organisms. Early man deified some of the inanimate matter (wind, sea, fire, etc.) and some among the animals and plants. A common feature of all such forms of inanimate and animate objects was the sense of awe or fear that they evoked.

Importance of Systematic Description

Societies which indulged in anthropocentric view of biology could register limited progress in biological knowledge. Systematic and monumental description of life forms brought in, out of necessity, detailed systems of identification, nomenclature, and classification.

Ernst Mayr (1904-2004)

Ernst Mayr, the Harvard University evolutionary biologist, was one of the 100 greatest scientists of all time. He pioneered the currently accepted definition of a biological species and made significant contributions to ornithology, taxonomy, zoogeography, evolution, systematics, and the history and philosophy of biology.

1.1 Diversity in the Living World

The living world is home to a wide range of living types, from cold mountains to hot springs, and from deciduous forests to oceans and deserts. The beauty of a galloping horse, migrating birds, or a valley of flowers evokes awe and wonder.

What is Life?

The question "what is life?" has two implicit questions within it. The first is a technical one and seeks an answer to what living is as opposed to non-living, and the second is a philosophical one, and seeks an answer to what the purpose of life is.

Biodiversity

Biodiversity refers to the number and types of organisms present on earth. There are approximately 1.7-1.8 million known species, and new organisms are continuously being identified.

Need for Standardized Naming

Local names for organisms vary from place to place, even within a country. To facilitate communication and study, scientists have established procedures to assign a scientific name to each known organism.

Binomial Nomenclature

Binomial nomenclature is a system of providing a name with two components: the generic name and the specific epithet. This system was given by Carolus Linnaeus and is practiced by biologists worldwide.

Example: Mango (Mangifera indica)

Component	Description
Mangifera	Genus
indica	Specific epithet

Universal Rules of Nomenclature

• Biological names are generally in Latin and written in italics.
• The first word in a biological name represents the genus, while the second component denotes the specific epithet.
• Both words in a biological name, when handwritten, are separately underlined, or printed in italics to indicate their Latin origin.
• The first word denoting the genus starts with a capital letter, while the specific epithet starts with a small letter.

Example: Mangifera indica Linn.

• Mangifera (genus)
• indica (specific epithet)
• Linn. (author's abbreviation)## Systematics and Taxonomic Categories 🌿

Systematics is the branch of study that focuses on knowing more about different kinds of organisms and their diversities, as well as the relationships among them. The word systematics is derived from the Latin word systema, which means systematic arrangement of organisms.

Taxonomic Categories

Classification is not a single step process but involves a hierarchy of steps, in which each step represents a rank or category. Since the category is a part of overall taxonomic arrangement, it is called the taxonomic category, and all categories together constitute the taxonomic hierarchy.

Taxonomic Hierarchy

Category	Description
Species	A group of individual organisms with fundamental similarities
Genus	A group of related species which has more characters in common
Family	A group of related genera with still less number of similarities
Order	An assemblage of families which exhibit a few similar characters
Class	A category that includes related orders
Phylum/Division	A category that includes classes with a few similar characters
Kingdom	The highest category that includes all animals or plants from various phyla or divisions

Species

"A group of individual organisms with fundamental similarities"

• Mangifera indica, Solanum tuberosum (potato), and Panthera leo (lion) are examples of species

Genus

"A group of related species which has more characters in common"

• Panthera is a genus that includes species like Panthera leo (lion), Panthera tigris (tiger), and Panthera pardus (leopard)
• Solanum is a genus that includes species like Solanum tuberosum (potato) and Solanum melongena (brinjal)

Family

"A group of related genera with still less number of similarities"

• Solanaceae is a family that includes genera like Solanum, Petunia, and Datura
• Felidae is a family that includes genera like Panthera (lion, tiger, leopard) and Felis (cats)

Order

"An assemblage of families which exhibit a few similar characters"

• Polymoniales is an order that includes families like Convolvulaceae and Solanaceae (plant families)
• Carnivora is an order that includes families like Felidae (lions, tigers, leopards) and Canidae (dogs)

Class

"A category that includes related orders"

• Mammalia is a class that includes orders like Primata (monkeys, gorillas, gibbons) and Carnivora (lions, tigers, leopards)

Phylum/Division

"A category that includes classes with a few similar characters"

• Chordata is a phylum that includes classes like Mammalia, Aves (birds), and Reptilia (reptiles)
• Plantae is a kingdom that includes divisions like Angiospermae (flowering plants) and Gymnospermae (conifers)

Kingdom

"The highest category that includes all animals or plants from various phyla or divisions"

• Animalia is a kingdom that includes all animals from various phyla like Chordata, Arthropoda, and Mollusca
• Plantae is a kingdom that includes all plants from various divisions like Angiospermae and Gymnospermae