Intramembranous Ossification is the formation of bone from within fibrous membranes.
The other method of bone formation, Endochondral Ossification, is the formation of bone from preexisting hyaline cartilage models.
Darwin’s Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources. This illustration shows the beak shapes for four species of ground finch: 1. Geospiza magnirostris (the large ground finch), 2. G. fortis (the medium ground finch), 3. G. parvula (the small tree finch), and 4. Certhidea olivacea (the green-warbler finch) the Grants measured beak sizes in the much-reduced population, they found that the average bill size was larger. This was clear evidence for natural selection of bill size caused by the availability of seeds. The Grants had studied the inheritance of bill sizes and knew that the surviving large-billed birds would tend to produce offspring with larger bills, so the selection would lead to evolution of bill size. Subsequent studies by the Grants have demonstrated selection on and evolution of bill size in this species in response to other changing conditions on the island. The evolution has occurred both to larger bills, as in this case, and to smaller bills when large seeds became rare.

<h3>Answer:</h3>
The Fluid Mosaic Model declares that membranes are formed of a Phospholipid Bilayer with several protein molecules drifting about inside it. The ‘Fluid’ section describes how any components of the membrane can run nearby loosely if they are not connected to different components of the cell. The ‘mosaic’ section explains the ‘patchwork’ of proteins that are detected in the Phospholipid Bilayer.
<h3>Explanation:</h3>
There is a lipid bilayer in which the protein molecules are embedded. The lipid bilayer gives fluidity and elasticity to the membrane. Carbohydrates are also found in a cell membrane. The plasma membrane is said to be two-dimensional structure or liquid we can say which does not allow the lateral diffusion of membrane components. The plasma membrane has the texture of vegetable oil at body temperature, because of which the proteins and other substances move across it. That's why the plasma membrane is described as using the fluid-mosaic model.