Biology

What is living?

(a) The word living cannot be defined

(b)There are certain characters by which can be distinguishrd from non living.

1-Growth : Increase in the number of cell or mass is called growth

2-Reproduction :Living organism produce young ones of their same kind

3-Metabolism :Chemical reaction occurring inside a living cell

4-Response of stimuli : Living have the ability to sense the condition of their surrounding and respond to these stimuli




(c) Five kingdom classification was proposed in 1969 by R.H whittaker .

The criteria of classifying organism into five kingdoms are its complexity of cell structure complexity of body of organism mode of nutrition life style and phylogenetic relationship .

(a) Mnoera: Itincludes all prokaryoticorganism like bacteria cynobacteria and archiobactera filamentous bacteria also come under this kingdom all organism of this kingdom are microscopic.

(b) Protista : This kingdom includes unicellular form usually found in aquatic habitats on the basis of mode of nutrition they are autotrophic parasitic and saprophytic diatoms flagellates and protozoa come under this kingdom euglena have both heterotrophic and autotrophic mode of nutrition so it is placed between plant and animal



(c) Fungi ; This kingdom includes non -green plants it has saprophytic nutrition and growing on dead and decaying organic matter the cell well is composed of chitin . Example ;Mushroom mucor albugo  etc

(d) Planatae: This kingdom includes all plants except some algae diatoms fungi and member of monera and protista .

(e) Animalia : Almost all animal comes under this kingdom except protozoan .

(d)  Binomial nomenclature : There was the need of uniform internaional naming of organism in biology every organism is given two proper names the first name is genus name always started with capital letter and the second name is species started with small letter for example scientific name of human is homo sapecies started with small letter for example scienpiens homo is the name of genus whose one species is sapiens .