Q. An organelle with an internal cross-section showing characteristic $"9 \, + \, 2"$ array is the
NTA AbhyasNTA Abhyas 2022
Solution:
Cilia and flagella are long, motile, cylindrical projections of the cell membrane. The core of the cilia and flagella is called as axoneme. Axoneme of Both cilia and flagella, in a cross-section exhibit, a structure of $\left(\right.9+2\left.\right)$ , i.e., $9$ microtubules doublets on the periphery and $2$ central microtubules. In eukaryotes, it is composed of tubulin protein. Both cilium and flagellum are covered with a layer of plasma membrane.
Diagram showing axoneme of cilia and flagella
They arise from centriole like structures called basal bodies which, possess a number of microtubules running parallel to the long axis, in an arrangement of $\left(\right.9+0\left.\right)$ , i.e., nine triplets in the periphery without any microtubules in the centre, unlike the $\left(\right.9+2\left.\right)$ arrangement found in cilia and flagella.
Diagram showing axoneme of cilia and flagella
They arise from centriole like structures called basal bodies which, possess a number of microtubules running parallel to the long axis, in an arrangement of $\left(\right.9+0\left.\right)$ , i.e., nine triplets in the periphery without any microtubules in the centre, unlike the $\left(\right.9+2\left.\right)$ arrangement found in cilia and flagella.