Probiotics	Pathogenic bacteria
Probiotic bacteria are beneficial.	Pathogenic bacteria are harmful.
Probiotic bacteria may be decomposers, photosynthetic and few may be pathogenic.	All are pathogenic and causing diseases.

The practice of naming the animals in which the generic name and species name are the same is called Tautonymy. Eg: Naja naja (The Indian Cobra).

1. Biologists follow universally accepted principles: to provide scientific names to known organisms.
2. Each name has two components, a generic name, and a specific epithet. This system of naming the organism is called Binomial nomenclature which was popularised by Carolus Linnaeus.
Eg: Pavo cristatus (Indian Peafowl)
Pavo - Genus name
cristatus - species name
Classification and grouping were done to facilitate a deeper understanding of the unique characteristics of each organism and its interrelationship among closely related species. It plays a vital role in the arrangement of known species based on their similarities and dissimilarities.

Species is the basic unit of classification in the taxonomic hierarchical system. It is a group of animals having similar morphological features (traits) and is reproductively isolated to produce fertile offspring.

Bacteria	Eukaryotes
1. No defined nuclear, circular DNA seen.	Defined nuclear with nuclear membrane and linear chromosomes.
2. 70s Ribosomes are seen in the cell.	80s Ribosomes are seen in the cell.

R.H. Whittaker (1969) proposed the Five kingdom Classification. The Kingdoms defined by him were Monera, Protista, Fungi, Plantae, and Animalia, based on the cell structure, mode of nutrition, mode of reproduction and phylogenetic relationships.

Based on the presence or absence of red blood he classified the animals into two as Enaima with blood and those without blood as Anaima.

Taxonomy (G. taxis- arrangement; nomos-law) is the science of arrangement of living organisms along with classification, description, identification, and naming of organisms which includes all flora and fauna including microorganisms of the world. The word taxonomy was coined by Augustin Pyramus de Candole (1813).

1. The presence of a large number of species in a particular ecosystem is called 'biological diversity' or in short' biodiversity'.
2. The term biodiversity was first introduced by Walter Rosen (1985), and defined by E.D. Wilson.

Mule is sterile and cannot yield its offsprings because it is born from the cross made between different species like Male Donkey and Female Horse.