Question

Peritrichous bacteria have flagella-
A. All over the body
B. At one end
C. At both ends
D. None

Answer 1

flagella are locomotory organs present in bacteria. We have to memorise the classification of bacteria based on the number and arrangement of flagella.

Complete answer: Flagella are appendages present in both prokaryotic as well as eukaryotic organisms that protrudes from the cell body. A cell can have one or several flagella. The main function of a flagellum is locomotion but it also doubles as a sensory organelle, it is chemically and thermally sensitive.
On the basis of number and arrangement of flagella, bacteria can be of following types-
Monotrichous bacteria- such bacteria have a single flagellum. e.g., Vibrio cholera
Lophotrichous bacteria- these bacteria have multiple flagella present at the same spot on the bacterial surfaces which helps the bacteria to move in a single direction. A specialized region of the cell membrane called the polar organelle may also be present.
Amphitrichous bacteria- they have a single flagellum present on each of the two ends out of the two, only one flagellum operates at a time, allowing the bacterium to move bidirectionally.
Peritrichous bacteria- peritrichous bacteria have flagella projected in all directions. The movement occurs in a counterclock manner, which causes the appearance of a left handed helix. eg.- E. coli.

Thus, the correct option is- A. all over the body.

Note: Flagella serves two functions, locomotion as well as sensing the surrounding environment. Peritrichous bacteria have flagella present all over the body.