Question

The given diagram represents the relationships between organisms in a remote pond ecosystem. From this information, which of the following is the most likely to be correct?

• A. $DDT$ present in the ecosystem would accumulate to the highest concentrations in the tissues of detritivore $1$.
• B. The introduction of consumer $4$ individuals from an external population would lead to a temporary increase in numbers of producer $2$
• C. Disease in the producer $1$ population would lead to an increase in the producer $3$ population
• D. Extermination of consumer $3$ would cause a sustained increase in the population of consumer $2$

Answer 1

Answer: (B)

$DDT$ present in ecosystem would accumulate to the highest concentration in the tissues of consumer 4 due to the phenomenon of biomagnification. If consumer $4$ is introduced from an external population it would cause a decrease in consumer $2$. This will lead to a temporary increase in producer $2$ on which consumer $2$ was feeding. If there is disease in the producer $1$, consumer $2$ will have one less option to eat, so it will be more dependent on producer $2$ and $3$, hence decreasing their populations. Extermination of consumer $3$ would lead to more dependence of consumer $4$ on consumer $2$, thereby decreasing its number.