IB ESS HL 2.2.4 Photosynthesis Question Bank
Explain how photosynthesis captures light energy and produces chemical energy for ecosystems.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- identify the ecological process or energy relationship
- apply the correct thermodynamic, productivity or trophic concept
- justify the conclusion from evidence and system boundary
2.2.4—Photosynthesis question 1
[Maximum number: 4]
Outline the transfers and transformations of energy as it enters and flows through the first trophic level of a food chain.
Transfers: [3 max]
a. solar/light energy absorbed by leaves/chlorophyll/chloroplasts/plants;
b. stored as chemical energy in glucose/organic compounds/ATP;
c. chemical energy transported around plant/moved from leaves to other plant organs;
d. chemical energy in plant biomass eaten by herbivores/passed on to decomposers;
e. heat energy radiated from plant into atmosphere;
Transformations: [3 max]
f. conversion of light to chemical energy in photosynthesis;
g. conversion of chemical to heat energy in respiration / all metabolic processes release heat (heat loss);
h. conversion of chemical to heat energy through decomposition;
i. conversion of chemical energy to other forms of energy (e.g. kinetic) in various metabolic processes; j. conversion of solar energy to electric energy in the photosynthetic apparatus;
Do not credit reflection of light (albedo), as energy does not enter 1st trophic level.
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