Q.The figure given below is a diagrammatic representation of response of organisms to abiotic factors. What do A, B and C represent respectively ?

A straight diagonal line (internal level tracking external level exactly) represents a conformer; a curve plateauing at the ideal reference level represents a full regulator; a curve plateauing just below that represents a partial regulator.

Organisms respond to changes in abiotic (external) conditions in different ways, conventionally shown on a graph of internal physiological level against external environmental level. A conformer's internal level simply tracks the external level throughout the range shown -- graphically this is a straight, unbroken diagonal line, matching curve A in the figure, since the organism does not regulate its internal environment at all and instead lets it change directly with the surroundings (e.g., many aquatic invertebrates are thermoconformers). A regulator, by contrast, uses homeostatic mechanisms to actively maintain its internal environment relatively constant despite changes in the external environment, at least within tolerable limits -- graphically this shows an initial rise (before regulation is fully effective) followed by a plateau at a …