The Living World Class 11 Notes Biology Chapter 1 - CBSE
Chapter : 1
What Are The Living World ?
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Unique Characteristics Of Living Organisms
Growth
- Living organisms grow in mass and number (Internal growth).
- Plants show continuous growth.
- Non-living organism show external growth.
Reproduction
Production of progeny possessing features more or less similar to those of parents.
Sexual
Involves two parents
Asexual
Involves single parents, e.g. Fission, Regeneration, Fragmentation, Budding etc.
Growth
- Sum total of chemical reactions occurring in the body.
- Defining feature of all living organisms.
Cellular Organisms
Consciences
Diversity In The Living World
Occurrence of variety of life form differing in morphology, size, colour, anatomy, habitat and habits. 1.07-1.8 million living organisms are known today.
Systematics
Branch of Biology that deals with cataloging plants, animals and other organism into categories that can be named, compared and studied.
Need For Classification
To organize the vast number of microorganisms, Plants and animals into categories that can be named, remembered, studied and understood.
Nomenclature
Process of standardize naming of living organism.
Binomial Nomenclature
Given by Carolus Linnaeus. Each name has two components: Generic Name and Specific epithet.
Taxonomic Categories
- Classification involves hierarchy of step where each step represents a taxonomic category (rank).
- All category together constitutes a taxonomic hierarchy.
- Each category represents a unit classification.
Kingdom ⇒ Phylum ⇒ Class ⇒ Order ⇒ Family⇒ Genus ⇒ Genus⇒ Species
Three Domains Of Life
- The three-domain system is a biological classification introduced by Carl Woese, Otto Kandler, and Mark Wheelis in 1990.
- This system divides cellular life forms into three domains, namely Archaea, Bacteria, and Eukaryota.
- The key difference from earlier classifications such as the two-empire system and the five-kingdom classification is the splitting of Archaea from bacteria as completely different organisms. It has been challenged by the two-domain system that divides organisms into Bacteria and Archaea only, as Eukaryotes are considered as one group of Archaea.
