Chapter 29, Problem 1MC

Which trophic level(s) must be present to sustain any ecosystem?

1. producers only

2. producers and consumers

3. producers, detritivores, and decomposers

4. producers, consumers, detritivores, and decomposers

Summary Introduction

Introduction:

The ecosystem is sustained by the interaction of biotic (living organisms) and abiotic components (like climate, environment, water, and soil). Each organism in the biotic component is categorized in various trophic levels through which energy passes. To sustain an ecosystem, a healthy interaction among different components present in the ecosystem is necessary. The members of biotic component seek their nutritional support from the abiotic component of the ecosystem and return the nutrients back into the abiotic pool at each trophic level. Thus, the nutrients and energy keep recycling in the ecosystem.

Answer to Problem 1MC

Correct answer:

To sustain an ecosystem producers, consumers, detritivores, and decomposers must be present. All tropic levels are necessary to keep the nutrient cycle going.

Explanation of Solution

Explanation for the correct answer:

Option (d) is given as producers, consumers, detritivores, and decomposers. All these are required to sustain an ecosystem. This statement is true because in any ecosystem, the energy flows from one trophic level to the next. Every trophic level has its own purpose in an ecosystem. The first trophic level is producers or autotrophs that are capable of producing food themselves. Consumers are organism that obtains food by feeding on producers or other organisms. Detritivores and decomposers are responsible for the decomposition of dead and waste material. Thus, all tropic levels maintain the ecosystem. Therefore, option (d) is a correct answer.

Explanation for incorrect answers:

Option (a) is given that producers only are able to uphold any ecosystem. This is false because if only producers would be present, their number would increase tremendously and no organism would be present to eat or decompose them. This would cease the nutrient flow and eventually ecosystem would collapse. So, it is an incorrect answer.

Option (b) is given that only producers and consumers can support any ecosystem. This statement is false as the energy will flow from producers to consumers but without detritivores and decomposers, dead and waste material would accumulate. The absence of decomposition would terminate the availability of nutrients for the producers. Thus, their growth would cease, resulting in their death, hence disintegration of the ecosystem would occur. So, it is an incorrect answer.

Option (c) is given as producers, detritivores, and decomposers. Consumers are organism that obtains food by feeding on other organisms or organic matter due to lack of the ability to manufacture own food from inorganic sources. Absence of any of these levels disrupts the energy flow, due to which the ecosystem would collapse. So, it is an incorrect answer.

Hence, options (a), (b), and (c) are incorrect.

Conclusion

Thus, it can be concluded that all trophic levels hold a unique place in an ecosystem. It is through each trophic level that the energy travels in the ecosystem in the form of nutrients, thus maintaining nutrient cycle and supporting the ecosystem.