Biology · Ecosystems · NEET
It is a diagram shaped like a pyramid that shows how organisms at different trophic levels relate to each other. You draw a bar for each trophic level. The base bar is the widest (producers), and each higher bar is usually smaller, so the shape looks like a pyramid. The bars can measure number of organisms, biomass, or energy. This is a key NEET topic from NCERT Chapter 12 (Ecosystem).
There are three: (a) pyramid of number, (b) pyramid of biomass, and (c) pyramid of energy. Number counts how many organisms are at each level. Biomass measures the mass of living material at each level. Energy shows the amount of energy at each level. NEET often asks which type is upright or inverted, so learn all three.
The base of every ecological pyramid represents the producers, that is the first trophic level. The apex (top) represents the tertiary or top-level consumer. So energy and food always start from producers at the bottom and move up to the top consumer at the tip.
The concept of ecological pyramids was given by Charles Elton, so they are also called Eltonian pyramids. NCERT itself does not stress the name, so for NEET focus more on the three types and which one is always upright (energy).
No. The pyramid of energy is always upright because energy is lost as heat at each trophic level. But the pyramid of number and the pyramid of biomass can sometimes be inverted. For example, the pyramid of biomass in a sea is inverted, because the small standing crop of phytoplankton supports a larger biomass of fish. This exact point is asked repeatedly in NEET.
Standing crop is the mass of living material (biomass) or the number of organisms present at a trophic level at a particular time. Biomass is expressed in fresh or dry weight; dry weight is more accurate. Standing crop is what you measure to draw the pyramid of number and pyramid of biomass.
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.
Because the base is the producers (first trophic level), and producers have the most number, biomass, or energy in most ecosystems. Energy and food both start from producers, so this level supports everything above it.
The pyramid of energy is always upright and can never be inverted, because energy is lost as heat at every trophic level (10% law). Number and biomass pyramids can sometimes be inverted.
Pyramid of number counts how many organisms are at each trophic level. Pyramid of biomass measures the mass of living material at each level. A single big tree is one organism (small number) but has huge biomass, which is why the two pyramids can look different.
Yes, very important. NEET has asked about ecological pyramids almost every year, especially about which pyramid is upright or inverted (sea biomass inverted, energy always upright). It is a high-scoring, direct NCERT topic.
