IB ESS HL 2.2.12 Food Chain Energy Losses Questions
Explain why energy is lost between trophic levels through respiration, waste and uneaten material.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- explain how respiration, heat loss and thermoregulation reduce energy transferred between successive trophic levels
- explain how uncaptured, uneaten, undigested or unabsorbed food—including faeces—reduces organic-matter transfer
IB ESS HL 2.2.12 Food Chain Energy Losses Questions question 1
[Maximum number: 7]
Explain the ways in which energy is lost as it moves through an ecosystem.
a. The second law of thermodynamics indicates that energy is "lost"/becomes less useful from a system when transformed / entropy increases from a system in any transformation;
b. Not all sunlight is captured by plants for photosynthesis / light can be reflected or absorbed by surfaces/land/water;
c. Plants use sugars/fixed energy for respiration which is lost as heat;
d. Some chemical energy ingested by animals is lost as heat due to respiration;
e. Mammals/birds use considerable energy for thermoregulation/homeostasis;
f. Not all parts of plants/animals can be consumed/digested by a consumer;
g. Undigested material is lost as feces;
h. Decomposers use energy for respiration, causing its loss as heat;
i. Extreme temperatures/water scarcity/nutrient availability can stress organisms, increasing energy used in respiration;
j. Generally only 10 % of the energy is passed between trophic levels;
Note to examiners: Allow these points in diagram only if it is clearly annotated.
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