To solve the question regarding which group has the highest proportion of assimilated energy consumed in respiration, we can follow these steps:
### Step-by-Step Solution:
1. **Understanding Trophic Levels**:
- In an ecosystem, organisms are categorized into different trophic levels based on their feeding relationships. The primary levels include producers (plants), herbivores (primary consumers), carnivores (secondary consumers), and decomposers.
2. **Role of Producers**:
- Producers, such as plants, are the first trophic level. They convert sunlight into chemical energy through photosynthesis, assimilating the highest amount of energy in the ecosystem.
3. **Energy Transfer**:
- As energy moves up the trophic levels (from producers to herbivores to carnivores), there is a loss of energy at each level due to metabolic processes, including respiration. Typically, only about 10% of the energy is transferred to the next trophic level, while the rest is lost, primarily through respiration and heat.
4. **Respiration in Different Trophic Levels**:
- Decomposers break down dead organic matter and recycle nutrients back into the ecosystem. They also respire, but they do not assimilate energy in the same way that producers do.
- Herbivores consume producers and respire a portion of the energy they assimilate.
- Carnivores consume herbivores and also respire energy.
5. **Comparing Energy Consumption**:
- Among these groups, decomposers typically have a lower proportion of energy consumed in respiration compared to producers, as they primarily recycle energy rather than assimilate it from sunlight.
- Producers, while they assimilate the most energy, also utilize a significant portion for their own respiration.
6. **Conclusion**:
- After considering the roles and energy dynamics of each trophic level, it is evident that the proportion of assimilated energy consumed in respiration is highest in **producers**.
### Final Answer:
The proportion of assimilated energy consumed in respiration is highest in **producers**.
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