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Question
Select the option that correctly identifies whether the statements (I-III) are true (T) or false (F).
I. Population density is always measured in terms of number only
II. The size of the population can be estimated indirectly without actually counting or seeing the organisms
III. Absolute population densities are considered when the population is very large and counting becomes difficult
Select the option that correctly identifies whether the statements (I-III) are true (T) or false (F).
I. Population density is always measured in terms of number only
II. The size of the population can be estimated indirectly without actually counting or seeing the organisms
III. Absolute population densities are considered when the population is very large and counting becomes difficult
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Solution
The correct option is B I-F, II-T, III-F
Population size is technically called population density. It is generally represented as ‘N’.
Though population density is generally calculated in terms of number, sometimes it is meaningless. For example, in a particular area there are 200 carrot grass plants, but only a single Banyan tree with a large canopy. If population density in terms of number is considered, then the density of carrot grass plants is certainly higher than the Banyan tree, but the ecological role of the Banyan tree in that area cannot be underestimated. Therefore, measuring the number of individuals may not always be apt. In this case, the parameter biomass is more meaningful. The biomass of a single Banyan tree is far more than the 200 carrot grass plants.
Sometimes, when the population is huge and counting is impossible due to some reason or very time-consuming, relative densities are considered instead of absolute population densities. For example, the number of fish caught per trap is a good measure of its total population density in the lake.
The tiger census in our national parks and tiger reserves maintains a count. Population density of tigers in an area can be estimated based on the pugmarks and faecal pellets. This is an indirect method of estimating the population density without actually counting them or seeing them.
Hence, option b is correct.
Population size is technically called population density. It is generally represented as ‘N’.
Though population density is generally calculated in terms of number, sometimes it is meaningless. For example, in a particular area there are 200 carrot grass plants, but only a single Banyan tree with a large canopy. If population density in terms of number is considered, then the density of carrot grass plants is certainly higher than the Banyan tree, but the ecological role of the Banyan tree in that area cannot be underestimated. Therefore, measuring the number of individuals may not always be apt. In this case, the parameter biomass is more meaningful. The biomass of a single Banyan tree is far more than the 200 carrot grass plants.
Sometimes, when the population is huge and counting is impossible due to some reason or very time-consuming, relative densities are considered instead of absolute population densities. For example, the number of fish caught per trap is a good measure of its total population density in the lake.
The tiger census in our national parks and tiger reserves maintains a count. Population density of tigers in an area can be estimated based on the pugmarks and faecal pellets. This is an indirect method of estimating the population density without actually counting them or seeing them.
Hence, option b is correct.
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