KCET 2020 Biology Solved Paper

The given diagram represents the arrangement of microtubules in 9+2 fashion. This type of arrangement is observed in the cross-section of cilia and flagella. There are nine doublets of microtubules (peripheral microtubules) arranged on the periphery and two microtubules in the centre which are called central microtubules. The peripheral microtubules are connected to the central sheath by radial proteinaceous columns called radial spokes.
Interdoublet bridge is the linker which connects the peripheral microtubules.
The phospholipid layer present outside the cell, which is semi-permeable is called the plasma membrane.