IB ESS SL 2.2.8 Second Law and Energy Loss Question Bank
Explain why energy quality decreases and energy is lost as heat during transfers.
- Syllabus
- First assessment 2026
- Course
- ESS SL
- Level
- SL
Explain why energy quality decreases and energy is lost as heat during transfers.

Figure:Savanna food chain

Figure:Biting flies in the savanna

Figure:Biting flies in the savanna
Figure: Savanna food chain: Savanna food chain. Figure: Biting flies in the savanna: Biting flies in the savanna.
Explain how the second law of thermodynamics applies to this food chain.
Biting flies bite and drink the blood of zebras. They commonly carry diseases that can be fatal to zebras.
Explain how the second law of thermodynamics applies to this food chain.
i. second law of thermodynamics states that the entropy/disorder of a system increases over time / conversions/transformations in energy aren't 100\% efficient;
ii. available energy is lost to environment between trophic levels;
iii. energy is lost as heat from cell respiration;
iv. often only 10 % of available energy is passed on / 90 % lost between trophic levels / ecological efficiency is limited;
v. not all parts of the grass/zebra are consumed/absorbed;