IB Biology HL C4.2 Transfers of Energy and Matter Questions

Practise IB Biology HL C4.2 by tracing energy flow, nutrient cycling, biomass transfer, productivity and carbon fluxes across trophic levels.

Exam points

Define ecosystems as open systems exchanging energy and matter with their surroundings.
Trace chemical energy through producers, consumers and decomposers, and construct or interpret food chains and food webs.
Classify autotrophs and heterotrophs, including consumers, detritivores, decomposers and saprotrophs, by energy/carbon source and digestion.
Explain respiration as chemical-energy release producing ATP and CO2 with heat loss, and deduce trophic levels including omnivory or parasitism.
Construct, calculate and interpret energy pyramids and transfer efficiency using trophic labels, energy units, respiration, heat, uneaten biomass, egestion and excretion.
Explain why respiratory heat cannot be recycled and how inefficient energy transfer limits food-chain length and higher-level biomass.
Distinguish gross and net primary production and calculate or interpret productivity data with units.
Construct and interpret carbon-cycle and carbon-budget evidence, identifying stores, fluxes, sinks, sources and CO2 release from combustion.
Analyse Keeling-curve data to distinguish long-term atmospheric CO2 rise from seasonal photosynthesis and respiration oscillations.
Trace recycling of carbon and other elements through decomposers, inorganic nutrients and producer uptake, distinguishing matter recycling from one-way energy flow.

Covered syllabus points

C4.2.1—Ecosystems as open systems C4.2.2—Sunlight as principal energy source C4.2.3—Chemical energy flow C4.2.4—Food chains and food webs C4.2.5—Supply to decomposers C4.2.6—Autotrophs as self-feeders C4.2.7—Energy sources C4.2.8—Heterotrophs C4.2.9—Energy release C4.2.10—Trophic levels C4.2.11—Energy pyramids C4.2.12—Energy reductions C4.2.13—Heat loss C4.2.14—Restrictions on trophic levels C4.2.15—Primary production C4.2.16—Secondary production C4.2.17—Carbon cycle diagrams C4.2.18—Carbon sinks and sources C4.2.19—CO₂ release during combustion C4.2.20—Keeling Curve analysis C4.2.21—Dependence between respiration and photosynthesis C4.2.22—Recycling of all chemical elements

[Maximum number: 1]

An investigation into food web interactions was conducted in mesocosms in the Mediterranean Sea, off the coast of France. The effects of the addition of soil and fish on bacterial populations were tested.

Each of the mesocosms is an open ecosystem. State the property that makes the mesocosms open ecosystems.

[Maximum number: 4]

The mass of an individual organism can affect its physiology and feeding ecology. The diagram shows the relative mass of carbon (black) and total wet mass (grey) of a marine crustacean, Calanus hyperboreus and a jellyfish, Bathocyroe fosteri.

(a)

State one process that results in the loss of carbon dioxide from a marine organism such as a crustacean or a jellyfish.

[ 1 ]

(b)

Explain how energy enters, flows through and is lost from marine food chains.

[ 3 ]

[Maximum number: 2]

A retreating glacier leaves an environment of lifeless glacial deposits, including sands and gravels. Retreating glaciers often offer suitable sites for primary succession.

Compare and contrast food chains and food webs.

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Covered syllabus points

Question 1

Question 2

Question (a)

Question (b)

Question 3