Biomass Measurement: Dry Weight — NEET Biology

Correct answer: C — S1, S2 and S3 only

The pyramid of biomass illustrates the total mass of living organisms (biomass) at each trophic level in an ecosystem. S1: Incorrect. The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area. Measurement of biomass in terms of dry weight is considered more accurate than fresh weight because it eliminates the variable water content. S2: Incorrect. In most terrestrial ecosystems (e.g., grassland), the pyramid of biomass is generally upright, meaning producers have the largest biomass, followed by herbivores, and then carnivores. An inverted pyramid of biomass is an exception, typically found in aquatic ecosystems. S3: Incorrect. An inverted pyramid of biomass in the sea occurs because the biomass of primary producers (phytoplankton) is *less* than the biomass of primary consumers (zooplankton) and higher trophic levels (fishes), causing the base to be narrower than the subsequent levels. The statement says biomass of fishes *exceeding* phytoplankton which is correct but it implies the biomass of phytoplankton is higher than fishes which is false. S4: Correct. This statement accurately describes the characteristics of these two pyramid types. The pyramid of energy is always upright, while the pyramid of biomass can be upright (most terrestrial) or inverted (aquatic). S5: Correct. To ensure an accurate representation of the trophic structure, all organisms at a specific trophic level must be included in the calculation of their total biomass. Therefore, statements S1, S2, and S3 are NOT correct.