Question

The variation in pattern of 9+2 in cilium or flagellum is shown by

• A. Flatworm
• B. Eel
• C. Sporozoan protozoan
• D. All of the above

Answer 1

The correct option is D All of the above

The 9+2 arrangement of fibrils is characteristics of eukaryotes being comprised of 9 peripheral doublet and 2 central singlet fibrils. Although the 9 + 2 pattern is the fundamental pattern of virtually all cilia and flagella, the axonemes of certain sporozoan protozoans and some insect sperm show some interesting variations. The spermatozoids of flatworms are also atypical. The eel sperm shows 9+0 arrangement. These atypical cilia and flagella, which are all motile, show that the central pair of singlet microtubules is not necessary for axonemal beating and that fewer than nine outer doublets can sustain motility, but at a lower frequency.