Biology · Ecosystems · NEET
It can be both. The pyramid of biomass is UPRIGHT in most land ecosystems like forest and grassland, where producers (plants) have the largest biomass. It is INVERTED in the sea and pond, where the biomass of fish is larger than the biomass of the tiny phytoplankton that feed them. So there is no single fixed answer — it depends on the ecosystem. For NEET, remember the sea (aquatic) is the classic inverted example.
In the sea, the producers are phytoplankton — very tiny plants that live for a very short time. At any one moment their standing crop (total living mass present) is small. But they reproduce and grow so fast that they can feed a much larger mass of zooplankton and fish. So when you measure biomass at a single point in time, the fish biomass on top is larger than the phytoplankton biomass at the base. This makes the pyramid inverted. NCERT states: 'The pyramid of biomass in sea is generally inverted.'
Upright. A forest has huge trees as producers. These trees hold a very large biomass (standing crop) at the base. The mass of animals (herbivores, then carnivores) is much smaller at each level above. So the pyramid narrows towards the top and is clearly upright. Forest also has the maximum biomass of any ecosystem — a common NEET fact.
Upright. In grassland, the grass (producers) forms the largest biomass at the base, herbivores are smaller, and carnivores are smallest. NEET note: the pyramid of NUMBERS in grassland is also upright, but the pyramid of numbers can become inverted in a big tree ecosystem — do not mix these two up.
Biomass is the total mass of living material (living organisms) present at a trophic level at a particular time. NCERT calls this the standing crop. It is measured as mass per unit area, for example grams per square metre (g/m2). The pyramid of biomass compares this living mass at each trophic level.
The pyramid of numbers counts how MANY individual organisms are at each level. The pyramid of biomass measures the total MASS of living material at each level. A single large tree is ONE number but a HUGE biomass. That is why a tree ecosystem gives an inverted pyramid of numbers but an upright pyramid of biomass. They measure different things, so they can point in opposite directions.
Which of the following statements is not correct?
What type of ecological pyramid would be obtained with the following data? Secondary consumer: 120 g; Primary consumer: 60 g; Primary producer: 10 g
Which of the following ecological pyramids is generally inverted?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The pyramid of biomass in the sea (and pond) is inverted. Producers there are tiny, fast-growing phytoplankton with a small standing crop that supports a larger fish biomass.
No. Only the pyramid of energy is always upright. The pyramid of biomass is upright on land (forest, grassland) but inverted in aquatic ecosystems like the sea.
The forest ecosystem has the maximum biomass, because large woody trees store a huge amount of living material. This is a direct NEET 2017 fact.
Standing crop is the mass of living material (biomass) present at a trophic level at a particular time. It is measured as mass per unit area, for example g/m2. Do not confuse it with standing state, which is the amount of nutrients in the soil.
Generally no. On land, producers (plants and trees) always hold the largest biomass, so the land pyramid of biomass stays upright. Inversion is seen mainly in aquatic ecosystems.
