Question

The amount of living matter present in the ecosystem at a given time is called
(a)Biomass
(b)Standing crop
(c)Standing state
(d)Productivity

Answer 1

Hint: It is measured as the mass of organisms or biomass or a number of organisms per unit area. The biomass is expressed in terms of dry matter and wet matter.

Complete answer:
When an organism is dead it is converted into biomass or debris that serves as a source of energy for saprotrophs also called decomposers. For the source of energy, the organism at each trophic level depends upon those at lower trophic level organisms. A certain mass of living material in each trophic level at a particular time is called ‘standing crop’.

Additional Information:
1. For every organism, synthesizing new molecules requires a constant supply of energy.
2. The transfer of energy through the food chain is known as energy flow.
3. The amount of energy decreases at each trophic level.
4. When an organism dies it becomes debris that serves as an energy source for the lower trophic level organisms called decomposers or saprotrophs.
5. Each trophic level has a certain mass of living material at a particular time, it is known as the standing crop.
6. Number of organisms or biomass of organisms present in the unit area is measured as a standing crop.
7. Biomass of an organism is measured in terms of fresh weight and dry weight.
8. Dry weight is more accurate as it does not contain any water.
9. The amount of inorganic nutrients present in the ecosystem is called the standing state.
10. The rate of production of biomass is called productivity. It is further divided into primary productivity and secondary productivity.
So, the correct answer is ‘standing crop’

Note: The amount of organic matter produced by plants via photosynthesis per unit area over a period of time is called primary productivity and the rate of formation of new organic matter by consumers is called secondary productivity.