Class 9 Biology Chapter 3 BiodiversityClassification Aims and Principles

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Class 9 Biology Chapter 3 Biodiversity Classification, Aims and Principles • 9 Class Biology Chapter 3 Biodiversity Classification, Aims and Principles • Biology Class 9 Chapter 3 Biodiversity Classification, Aims and Principles • Punjab Board • Federal Board • aims of classification • aims and principles of classification • two kingdom classification system • aims and principles of classification class 9 • aims of classification class 9 • classification aims and principles class 9 • matric • classification aims and principle of biodiversity • biology classification aim and principal • biodiversity • grade 9 • biology • biology class 9 chapter 3 classification aims and principles • class 9 biology chapter 3,9 class biology chapter 3 • eLearning • Slides will be sent to you on request. • Biodiversity • The term “biodiversity” has been derived from ‘bio’ and ‘diversity’. “Diversity” means variety within a species and among species. Biodiversity is a measure of the variety of organisms present in different ecosystems. • The diversity of plants’ (flora) and animals’ (fauna) in a region depends on climate, altitude, soils and the presence of other species. Biodiversity is not distributed evenly on Earth. It is richest in the tropics. Temperate regions also have many species while there are fewer species in the polar regions. Biodiversity found on Earth today is the result of 4 billion years of evolution. The origin of life is not well known to science, though limited evidence suggests that until 600 million years ago, all life consisted of bacteria and similar unicellular organisms. • Importance of biodiversity • Biodiversity provides food for humans. A significant proportion of drugs are derived, directly or indirectly, from biological sources. • Classification - Aims And Principles • There is a large collection of very dissimilar forms of organisms, found on Earth. Over 1.5 million types of animals and over 0.5 million types of plants are known to biologists and these are only a small percentage of the total types estimated to live on Earth. • Aims of Classification • The branch of biology which deals with classification is called taxonomy and the branch which deals with classification and also traces the evolutionary history of organisms is known as systematics. • The main aims of both these branches are; • • To determine similarities and differences among organisms so that they can be studied easily. • • To find the evolutionary relationships among organisms. • Basis of Classification • Classification is based on relationship amongst organisms and such relationship is got through similarities in characteristics. These similarities suggest that all organisms are related to one another at some point in their evolutionary histories. However, some organisms are more closely related than others. For example sparrows are more closely related to pigeons than to insects. It means that the former two have common evolutionary • histories. When biologists classify organisms into groups and subgroups, the similarities are seen in external and internal structures and stages of development. Modern genetics provides another type of information to taxonomists. The similarities and differences in the DNA of two studied • organisms can be used for getting idea about similarities and differences in their structures and functions. • Taxonomic Hierarchy • The groups into which organisms are classified are known as taxonomic categories or taxa (singular “taxon”). The taxa form a ladder, called taxonomic hierarchy. All organisms are divided into five • kingdoms. So kingdom is the largest taxon. On the basis of similarities, each kingdom is further divided into smaller taxa in the following way: • • Phylum (Division: for plants and fungi): A phylum is a group of related classes. • • Class: A class is a group of related orders. • • Order: An order is a group of related families. • • Family: A family is a group of related genera. • • Genus: A genus is a group of related species. • • Species: A species consists of similar organisms. • Species - The Basic Unit of Classification • Species is the basic unit of classification. “A species is a group of organisms which can interbreed freely among them and produce fertile offspring, but are reproductively isolated from all other such groups in nature.” Each species possesses its own distinct structural, ecological and behavioural characteristics. • In the definition of species we must emphasize “in nature” because two organisms related to two different but closely related species can cross-breed under artificial conditions. In such unnatural crosses they produce infertile offspring. For example, a cross between a male donkey and a female horse produces an infertile offspring i.e. mule. • #biology #science #9thclassbiology #lecture #educational #educationalvideo #education #viral #viralvideo #foryou #trending #biodiversity #classification #aims #principles

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