The correct option is A.
Explanation
Ecological processes govern the movement of energy and matter through various trophic levels in an ecosystem. These processes follow specific thermodynamic and biological principles that dictate the efficiency and direction of flow.
- Energy flow (Unidirectional): Correct. Energy enters the ecosystem primarily through solar radiation and is captured by primary producers. It flows through the food chain from producers to consumers and finally to decomposers. According to the Second Law of Thermodynamics, energy is lost as heat at each transfer and cannot be recycled back to the sun or previous trophic levels.
- Matter accumulation (Progressive across levels): Incorrect. While certain non-biodegradable pollutants may accumulate (biomagnification), organic matter itself does not progressively accumulate across trophic levels. In fact, due to metabolic demands and energy loss, the total biomass generally decreases at higher trophic levels, often represented by a pyramid of biomass.
- Solar energy capture (Reversible to solar input): Incorrect. Solar energy capture via photosynthesis is an irreversible process in ecological terms. Once light energy is converted into chemical energy (glucose), it cannot be converted back into solar radiation within the biological system.
- Trophic energy availability (Increasing at higher levels): Incorrect. According to Lindeman’s 10% Law, only about 10% of the energy available at one trophic level is transferred to the next. Consequently, energy availability decreases significantly at higher trophic levels, limiting the number of levels an ecosystem can support.
Key Takeaway: Energy in an ecosystem follows a unidirectional flow and decreases at each successive trophic level due to metabolic heat loss, whereas matter is recycled but its biomass typically diminishes at higher levels.