Question

Flagellum of Astasia/Euglena is:
A. Pantoematic
B. Acronematic
C. Pentachronematic
D. Stichonematic

Answer 1

Flagellum is a thin thread-like structure which helps in the locomotion of protozoans. They are classified into many types. The flagellum is primarily a motility organelle that enables the movement and helps in chemotaxis. Bacteria that can contain one flagellum or several, can be either polar or peritrichous.

Complete answer: The flagellum is a hair-like structure that acts primarily as an organelle of locomotion in the cells of many living organisms. The flagella are the characteristic feature of the protozoan group Mastigophora. It also occurs on the gametes of the algae, fungi, mosses, slime moulds, and animals. The flagella are used not only for the movement but also for aiding in the cell feeding and eukaryotic reproduction. The flagella use intraflagellar transport, which is the transport of a complex of proteins required for the signalling molecules that provide the mobility to the flagella.
There are two types of flagella:

1. Whiplash or achromatic type: Flagella which possesses a smooth surface.
2. Tinsel or Pleuronematic type: These are covered by fine filamentous appendages called mastigonemes or flimmers. (Hairy flagella)
   Tinsel type is divided into three types according to the arrangement of mastigonemes.
   a) Pantonematic: in these mastigonemes arranged in two opposite rows or radially. Example: Pyronema.
   b) Pantocronematic: Pantonematic flagellum with a terminal fibril. Example: Mercilus.
   c) Stichonematic: the mastigonemes develop only on one side of the flagellum. Example: Euglena and Astasia.
   Therefore, the correct answer is option D.

Note: There are many organ of locomotion in protozoans:
• By pseudopodia; with the help of this structure, they show amoeboid movement. Example: Sarcodina and few sporozoans.
• By flagella; they help in flagellar movement: Example: Mastigophora.
• By cilia; they help in ciliary movement. Example: Ciliophora.