Which of the following statements about the energy flow in ecosystems are correct?
1. Energy flow in an ecosystem is always unidirectional.
2. In a food web, energy is transferred between trophic levels with 100% efficiency.
3. The energy available to tertiary consumers is lower than that available to primary consumers.
4. The 10% energy transfer law is applicable in all ecosystems.
1
1, 2, and 4 only
2
1, 3, and 4 only
3
1 and 3 only
4
2, 3, and 4 only