Which of the following statements regarding cilia is not correct ? (a) Cilia contain an outer ring of nine doublet microtubules surrounding two singlet microtubules. (b) The organized beating of cilia is controlled by fluxes of Ca 2+ across the membrane. (c) Cilia are hairlike cellular appendages. (d) Microtubules of cilia are composed of tubulin.
Option B Cilia are fine hair like vibratile, cytoplasmic processes borne by certain cell types. Their movement either propel the organism or move the medium past a fixed cell. The cilia are enclosed by a unit membrane which is an extension of the plasma membrane of the cell. Within the membrane, is a fluid matrix having a supporting axial shaft, or axoneme. The microtubules, single as well as double, are composed of the globular units of the protein tubulin. The arms of A microtubules contain a protein dynein. The latter is ATPase enzyme which catalyzes hydrolysis of ATP to ADP, and transfers the free energy released direct to ciliary work.
