Question : In some cases, population density is measured in terms of biomass rather than in terms of number because

it is a more meaningful measure when the CONSIDERED organisms vary greately in size
it is more convenient when population is huge and counting is impossible or very time consuming
it is a relatively constatn measure
both (a) and (B)

Solution :Although the total number is most appropriate measure of population density, but in some cases it is difficult to determine. In a forest area, suppose there are 200 Parthenium plants but only a single huge BANYAN tree with a LARGE canopy. Stating that the population density of banyan is low relative to that of Parthenium, amounts to underestimating the great role of the banyan in that forest community. In such cases, the percent cover or BIOMASS is a more meaningful measure of the population size. if the population is huge and counting is impossible or very time-consuming, the total number is not easily measured. e.g., for a dense laboratory culture of bacteria in a petri dish, only the biomass can be used as a measure of its density.