Himanshi J.

Salient features of Viruses: (a) They are smaller than bacteria. (b) They can be filterable. (c) May cause infection and diseases like small pox, flu etc. (d) Able to reproduce in host cells. (e) Use enzymes and metabolic machinery of host cell. (f) DNA/RNA is their genetic material. (g) They are obligate parasites, self replicating, non- cellular organisms. (h) Plant viruses mostly have single stranded (ss) RNA. (i) All animal viruses mostly have single or double stranded RNA/DNA. (j) They have protein coat called capsid that protects nucleic acid. (k) They cause diseases in plants like mosaic, leaf curling, leaf role, yellowing, vein clearing, dwarfing as well as stunted growth etc.

S.N. Characters Bacteria Cyanobacteria 1 Size Comparatively smaller. Comparatively larger. 2 Distribution Found every possible places in earth. Only found in presence of sunlight and moisture. 3 Flagella May bear flagella. Flagella always absent. 4 Cell wall 1-2 layered. 4 layered. 5 Composition of cell wall Glycolipids and peptidoglycan. Cellulose and pectin. 6 Nutrition May be autotrophic or heterotrophic. Usually autotrophic. 7 Photosynthetic pigments Photosynthetic pigment is bacteriochlorophyll. Photosynthetic pigments is chlorophyll a. 8 Accessory pigment Absent Accessory pigment like phycocyanin and phycoerythrin are present in dominating form. 9 Reserve food Glycogen Cyanophycean starch 10 Spore formation Is endogenous. Is not endogenous. 11 Hydrogen donor During photosynthesis hydrogen donor is not water; as a result oxygen is not evolved. Thus photosynthesis is anoxygenic. Hydrogen donor is water, oxygen is evolved. Process is oxygenic. 12 Locomotory organ Flagella act as locomotory organ. Lack flagella and other locomotory organ. 13 Heterocyst Absent Present.

Protista Features- 1.These are single celled microscopic organisms. 2.These are eukaryotes. 3.They have membrane bound organells. 4.Some protists have rigid cell wall. 5.Cilia or flagella are useful for locomotion. 6.Nutrition is autotrophic or heterotrophic. 7.They include solitary or colonial forms.

Monera :: 1.They are typically single celled and microscopic. 2.They may have rigid cell wall. 3.DNA is not enclosed by nuclear envelope. 4.Ribosomes are present and they are 70s type. 5.Respiration is aerobic or anaerobic. 6.The mode of nutrients is autotrophic. Protista: 1.These are single celled microscopic organisms. 2.These are eukaryotes. 3.They have membrane bound organells. 4.Some protists have rigid cell wall. 5.Cilia or flagella are useful for locomotion. 6.Nutrition is autotrophic or heterotrophic. 7.They include solitary or colonial forms.

The scientific naming of an organism is called as nomenclature. There are different types of naming systems. Most popularly used naming system is Binomial nomenclature. Binomial nomenclature, introduced by Carolus Linnaeus is the method of naming an organism with the genus name first and species name later. Conventions followed while naming *Name of the genus begins with a capital letter. *Name of the species should begin with a small letter. *Scientific name should be in Italics when printed. *Genus name and the species name should be underlined separately while handwritten.