Q.Structure and function are correlatable in living organisms. Can you justify this by taking plasma membrane as an example?

The plasma membrane is a clear example of how a cell's structure is built precisely to match its function of controlling what enters and leaves the cell.

• Its phospholipid bilayer, with polar heads facing the watery surroundings and hydrophobic tails tucked inward, forms a barrier that keeps the cell's contents separate from its environment.
• Because the lipid is quasi-fluid, embedded proteins can move laterally within it — this fluidity supports functions such as cell growth, secretion, endocytosis and cell division. …

The idea that structure and function go hand in hand is nowhere clearer than in the plasma membrane. Its basic architecture is a bilayer of phospholipid molecules, each oriented with its polar head facing outward, into the watery environment on either side, and its hydrophobic tail pointing inward, away from water. This arrangement is not incidental — it is exactly what allows the membrane to act as a barrier separating the cell's interior from its surroundings while still letting the membrane itself sit comfortably in an aqueous environment on both faces.

Embedded within this bilayer are proteins, occurring either as peripheral proteins on the surface or integral proteins buried partly or wholly within the membrane. Because the lipid bilayer has a quasi-fluid character, these proteins are able to move laterally, and this fluidity underlies processes such as cell growth, the formation of junctions between cells, secretion, endocytosis and cell division — all functions that depend directly on the membrane's structural flexibility. …

Method: Structure-to-Function Mapping, Feature by Feature

For a "justify structure-function correlation" question, the strongest approach is to break the structure into its distinct physical features one at a time, and for each feature immediately state the specific function it enables -- never describe the whole structure first and the whole function second as two separate blocks, since that loses the correlation the question is actually asking you to demonstrate.

Start with the most basic architectural feature (the phospholipid bilayer's polar-head-out, tail-in arrangement) and link it directly to the barrier function it creates. Move to the next feature (the quasi-fluid nature of the lipid, letting embedded proteins move) and link that to the dynamic cellular processes it enables, such as growth, secretion and division. Finally, address the membrane's selective permeability feature by feature -- diffusion/osmosis for small neutral molecule …