Question

In peritrichous bacteria flagella occurs in
A. At one end
B. At both ends
C. All over the body
D. Absent

Answer 1

Hint: A long whip like structure, uniform distributed of flagella over the body surface. The bacteria possess multiple flagella that can grow essentially any point on the cell body surface. Such as Escherichia coli.

Complete answer:
 Flagellum or flagella is a whip like structure that helps some single celled organisms to move. Flagella are unbranched, long, thread like structures. They are about 12-30nm in diameter and 5-16 in length. Flagella are projections from the cell. The flagella has three basic parts : a filament, a hook, and a basal body.
The filament : the filament of flagellum is a hollow tube made of a flagellar protein called flagellin.
The hook : at the base of the filament is a flexible hook, that couples the filament to the base and acts as a universal joint.
The basal body: the basal body is made up of a rod and a series of rings that anchor the flagellum to the cell wall and the plasma membrane.
Types and examples of flagella:
> Monotrichous: Mono means single. It is single polar flagellum
Example: Vibrio cholera
> Amphitrichous :
It has single flagellum on both sides
Example: Alkaligens faecalis
> Lophotrichous:
Tufts of flagella at one or both sides.
Example: Spirillum
> Peritrichous:
Peri means around. Numerous flagella all over the body
Example : Salmonella typhi and Eschericia coli
>Atrichous:
A means absent. So flagella is absent.
Nonmotile bacteria without flagella are called atrichous.
> Functions of flagella :
Movements
Sensation
Signal transduction
Adhesion

Note: The primary function of a flagellum is that of locomotion but it often functions as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. Motility plays an important role in survival and the ability of certain bacteria to cause disease.