Question

When flagella are distributed all around a bacterial cell, the arrangement is called as
a. Polar
b. Random
c. Peritrichous
d. Encapsulated

Answer 1

Hint: Flagella is an organelle defined by function rather than structure. Flagella vary greatly. A flagella is a microscopic hair-like organelle employed by cells and microorganisms for movement. The word flagella in Latin means whip, a bit like the whipping motion.

Complete answer:
- Flagellum could also be a lash-like appendage that protrudes from the cell body of certain bacteria and eukaryotic cells termed as flagellates. A flagellate can have one or several flagella. This is a locomotory structure in bacteria. The number and site of flagella are distinctive for each genus. Flagella is often used for locomotion.

There are four sorts of flagellar arrangement:
- Monotrichous: A single polar flagella that extends from one end of the cell. This arrangement is called Monotrichous. e.g., Vibrio cholera.
- Amphitrichous: A single flagellum or many flagella extend from both ends of the cell. This arrangement is called Amphitrichous. e.g., Alcaligenes faecalis.
- Lophotrichous: Several flagella (means tuft of flagella) extend from one end or both ends of the cell. The arrangement is called Lophotrichous. e.g., Spirilla.
- Peritrichous: Multiple flagella randomly distributed over the whole bacterial cell. The arrangement is called Peritrichous. e.g., Typhoid bacilli.

Hence, the correct answer is option (C).

Note: Flagellum is singular while flagella are plural which is frequently used for locomotion. A flagellate could also be a cell or organism with one or more whip-like appendages called flagella. Cilia and flagella are cell organelles that are structurally similar but different within the length and functions. Cilia are present in organisms like paramecium while flagella are often found in bacteria and sperm cells.