Biology · Ecosystems · NEET
Biomass is the mass of living organisms present at a trophic level in a unit area at one point in time. It is living material only, like plants at the producer level or animals at the consumer level. In NCERT this mass of living material is called the standing crop, and biomass is how we measure that standing crop.
Biomass can be given as fresh weight or dry weight, but dry weight is more accurate. This is because water content changes a lot and adds weight that is not real living material. NEET often tests that dry weight is the better, more accurate measure.
Standing crop is the total living material at a trophic level at a given time. Biomass is one way to measure that standing crop, as mass in a unit area. So standing crop is the idea, and biomass (or number of organisms) is the measurement. They are closely linked and often used together.
No. NCERT says the standing crop can be measured as biomass (mass of living organisms) OR as the number in a unit area. Number counts how many organisms there are; biomass weighs how much living material there is. A pond may have millions of tiny phytoplankton (high number) but a small biomass.
No. Biomass is only living material. Dead organic matter is called detritus, and the pool of soil nutrients at a given time is called the standing state. Do not confuse standing state (nutrients) with standing crop (living biomass) - NEET sets this exact trap.
Biomass is expressed as weight per unit area, such as g m-2 (grams per square metre) or kg m-2. Note there is no time in the unit. If you see a per-year unit like g m-2 yr-1, that is productivity (the RATE of biomass production), not biomass itself.
Which ecosystem has the maximum biomass?
The amount of nutrients such as carbon, nitrogen, phosphorus and calcium present in the soil at any given time, is referred to as the
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Because fresh weight includes water, which varies and is not real living material. Dry weight removes this error, so NCERT states dry weight measurement is more accurate.
At every trophic level - producers, primary consumers, secondary consumers and so on. Each level has its own standing crop, and the pyramid of biomass compares these values.
Yes, in some aquatic systems. In a sea, the biomass of fishes can be greater than the small standing crop of phytoplankton, giving an inverted pyramid of biomass. This is a common NEET point.
No. Biomass is the standing mass of living material at one time (unit g m-2). Productivity is the RATE at which biomass is produced (unit g m-2 yr-1). The time term (per year) is the clue for productivity.
