Practice 4.2 Energy flow with authentic IB Biology exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like cell biology, genetics, and ecology. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
Paper
Level
Question 1
SLPaper 2
The electron micrograph shows palisade mesophyll cells.
1.[1]
State the name of the structures labelled I and III.
2.[2]
Distinguish between autotrophic nutrition and heterotrophic nutrition.
3.[2]
Outline the function of the structure labelled I.
4.[1]
The plant from which this cell was taken is in the group angiospermophyta. State one characteristic that is unique to this group of plants.
5.[3]
Explain how energy and nutrients are transferred in ecosystems.
Question 2
SLPaper 1A
In a woodland ecosystem, each tree provides food for numerous aphids which feed on the sap of the tree. The aphids are eaten by carnivorous beetles, as shown in the food chain.
Oak Tree → Aphids → Beetles
Which pyramid of energy represents this relationship?
Question 3
SLPaper 1A
Animals in the highest trophic level of a food chain will often be the largest in body size but will be few in numbers. What accounts for the small numbers?
Question 4
HLPaper 1A
In the diagram, which of the processes labelled A to D transfers the largest mass of carbon per year in a woodland ecosystem?
Question 5
SLPaper 2
1.[4]
Define habitat, population, community and ecosystem.
2.[6]
Outline how energy flows through an ecosystem.
3.[5]
Discuss the benefits and possible harmful effects of altering species by one example of genetic modification.
Question 6
SLPaper 1A
Assume that an energy pyramid has four levels (producer level plus three consumer levels) and that the energy of the producer level is set at 100%. What percentage of the energy from the producer level will be obtained by the tertiary consumers?
Question 7
HLPaper 1A
The diagram represents a pyramid of energy.
What level does the letter X represent?
Question 8
SLPaper 2
1.[4]
Outline how and where energy is stored in plants.
2.[6]
Ecologists sometimes display data from an ecosystem using a diagram called a pyramid of energy. Describe what is shown in pyramids of energy.
3.[8]
Explain the control of body temperature in humans.
Question 9
SLPaper 2
The diagrams below show different organisms (not drawn to scale). 
1.[3]
State all the organisms shown above that belong to the following phyla.
Filicinophyta:
Arthropoda:
Mollusca:
2.[2]
Construct a possible food chain using three of the organisms shown opposite, stating the trophic level to which they belong.
3.[1]
State the initial energy source of the food chain constructed in (i).
Question 10
SLPaper 1A
The following statements refer to a pyramid of energy.
I. Some material is not assimilated by each trophic level. II. Energy transformations are never 100% efficient. III. Heat is lost during photosynthesis.
Which of the statements give the reason why a pyramid of energy is narrower at the top than at the bottom?