Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species)
-If Figure 42.2 represents a terrestrial food web,the combined biomass of 3 + 4 would probably be
A)greater than the biomass of 1.
B)less than the biomass of 8.
C)greater than the biomass of 2.
D)less than the biomass of 1 + 2.
E)less than the biomass of 6.

Question

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species)
-If Figure 42.2 represents a terrestrial food web,the combined biomass of 3 + 4 would probably be
A)greater than the biomass of 1. 
B)less than the biomass of 8. 
C)greater than the biomass of 2. 
D)less than the biomass of 1 + 2. 
E)less than the biomass of 6.

Quizplus · Accepted Answer

In a food web, the biomass tends to decrease as you move up trophic levels. 
Option 1 includes only plants (primary producers) and so has the highest biomass among all other options. 
Option 8 is a tertiary predator that feeds on both herbivores (Option 3) and secondary predators (Option 7), hence it has relatively lower biomass compared to primary consumers (Options 2, 3, and 4) and secondary predators (Option 7). 
Options 2 and 6 have the same trophic position and so cannot be compared. 
Therefore, the combined biomass of Options 1 and 2 (primary producers and primary consumers) would be greater than the biomass of Options 3 and 4 (herbivores and primary carnivores) but less than the biomass of Option 1 alone. Thus, the correct answer is Option D (less than the biomass of 1 + 2).

Figure 422 Diagram of a Food Web (Arrows Represent Energy Flow