Question

(i) State, what does "standing crop" of a trophic level represent.

(ii) List any two ways of measuring the standing crop of a trophic level.

Hint:

Standing crop is the amount of living matter in a trophic level at a given moment. Measure it as dry weight or as number per unit area.

Answer 1

Step 1: Meaning of a trophic level:
A trophic level is a feeding level in a food chain, such as producers, herbivores or carnivores.
Each level holds some living organisms at any given moment.

Step 2: Part (i): What standing crop means:
The standing crop of a trophic level is the mass of living organisms (the biomass) present in that level at a given time.
It is a stock at one moment, unlike productivity, which is a rate over time.
It is usually shown per unit area, for example \( \mathrm{g\,m^{-2}} \).

Step 3: Part (ii): Ways of measuring it:
Way 1: Find the mass of the living organisms, that is the biomass, per unit area. Dry weight is better than fresh weight because water content changes.
Way 2: Count the number of organisms per unit area (population number).

Final Answer:
(i) Standing crop = the mass of living organisms (biomass) present in a trophic level at a given time. (ii) It is measured as biomass (dry weight) per unit area, or as number of organisms per unit area.