Correct option is B
The correct answer is (b).
Energy flow in an ecosystem strictly follows a unidirectional path dictated by the laws of thermodynamics, starting from an external energy source.
Solar energy is initially captured by primary producers (green plants) through photosynthesis, which is then sequentially transferred to primary consumers (herbivores) when they consume the plants.
Information Booster
- Ecosystem energetics is primarily governed by the First and Second Laws of Thermodynamics, ensuring energy transformation and inevitable loss as heat.
- Primary producers utilize only about 1-2% of the photosynthetically active radiation (PAR) to synthesize organic compounds.
- Energy transfer between trophic levels is highly inefficient, largely explained by Lindeman's Ten Percent Law.
- Approximately 90% of energy is lost at each trophic level through respiration, metabolic activities, and unassimilated waste.
- Due to continuous energy degradation, food chains are rarely longer than 4 to 5 trophic levels in natural ecosystems.
- The unidirectional nature of energy flow implies that energy cannot be recycled back to the sun or to the producers once utilized by consumers.
- Ecological pyramids of energy are invariably upright, accurately reflecting this progressive decrease in available energy at successive trophic stages.
- Option A: This sequence skips the crucial intermediate trophic level of herbivores. Carnivores do not typically consume producers directly, making this pathway ecologically invalid.
- Option C: This indicates a reverse and impossible flow where carnivores derive energy directly from the sun, and herbivores eat carnivores, contradicting all biological principles.
- Option D: This sequence incorrectly places herbivores as the initial capturers of solar energy, bypassing the indispensable role of autotrophic green plants.
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