Question

Which among the following has arrangement?
A. Flagella
B. Ribosome
C. Mitochondria
D. Golgi apparatus

Answer 1

The $9 + 2$ arrangement refers to how the microtubules are organised in structure. This arrangement has 9 pairs of microtubules situated on the outside that are bound together and 2 microtubules pairs in the middle that are not bound together.

Complete step by step answer:
An axoneme is a microtubule based cytoskeletal structure that forms the core of a cilium or flagellum. Cilia and flagella are present on the cells, organisms and microorganisms to provide motility. Axoneme serves as the skeleton of these organelles and it provides the support to the structure and ability to bend.
A eukaryotic flagellum is a bundle of nine fused pairs of microtubule doublets surrounding two central single microtubules. The $9 + 2$ structure is the characteristic of the core of the eukaryotic flagellum called an axoneme. At the base of the flagellum is a basal body which is structurally identical to the centrioles. Flagella is the helical shaped structure which allows the cell to move. It works through rotational motion of the filament.
Classification based upon arrangement:
1. Monotrichous- one flagellum.
2. Amphitrichous- single flagellum at both ends.
3. Lophotrichous- numerous flagella as a tuft.
4. Peritrichous- flagella distributed all over the cell.
So, the correct answer is Flagella.

So, the correct answer is “Option A”.

Note:
Flagella are of three types: Archaeal flagella (non-homologous), bacterial flagella are thread-like and consist of rotary motion at its base, Eukaryotic flagella are cellular projections and composed of a protein called tubulin. The flagellar structure is divided into basal body, hook and filament.