IB Biology HL C4.2.12 Energy Reductions Questions

Energy availability decreases at each transfer between trophic levels. In IB Biology HL C4.2.12, trace losses through respiration, heat, egestion, excretion and uneaten biomass, and use these losses to explain why less energy reaches higher levels.

Exam points

Explain why less energy is available at each successive trophic level, including losses through respiration, heat, egestion, excretion and uneaten biomass.
Explain how limited energy transfer between trophic levels restricts food-chain length.
Calculate or compare energy transferred or lost between named trophic levels using supplied data, including conversion efficiency.

[Maximum number: 3]

Outline how the energy flow through food chains limits their length.

a. only a small proportion/20 \%/10\% «of energy» can pass from one trophic level to the next

OR large proportion/80 \%/90\% lost between one trophic level and the next

b. energy released by respiration AND lost as heat

c. energy losses due to uneaten parts/undigested parts/feces/egestion

d. not enough energy for $4^{\text {th }} / 5^{\text {th }} /$ later stages of a food chain

OR

more energy available if feeding at an earlier stage in a food chain

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IB Biology HL C4.2.12 Energy Reductions Questions question 1