Unit 4: Continuity and Change

Topic 4.11: Stability and Change Questions

Practice 20 exam-style questions for IB Biology Topic 4.11. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.

1State1 mark
Stability is referred to as an emergent property of an ecosystem. State what is meant by an emergent property.
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2Identify1 mark
Two genetically identical organisms are raised in different environments and develop different appearances. What is the cause of the difference?
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3Identify1 mark
Over geological time, living organisms changed Earth's atmosphere. Which pair of changes did they cause?
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4Identify1 mark
Which substances washing into a lake are the usual trigger for eutrophication?
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5Identify1 mark
Which process was mainly responsible for the rise of oxygen in Earth's atmosphere?
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6Identify1 mark
Which statement best defines phenotypic plasticity?
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7State1 mark
State the process carried out by living organisms that was responsible for raising the level of oxygen in Earth's atmosphere.
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8Identify1 mark
Which statement correctly defines biomagnification?
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9Identify1 mark
A fishery removes more fish each year than the population can replace by breeding and growth. How is this harvest best described?
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10State1 mark
State what is meant by a 'persistent' pollutant.
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11State1 mark
State the two mineral nutrients, usually carried in fertiliser run-off, that trigger eutrophication in a lake.
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12State1 mark
State what is meant by the term phenotypic plasticity.
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13Identify1 mark
Which statement best describes a stable ecosystem?
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14Identify1 mark
Which best describes Earth's atmosphere before photosynthesising organisms had evolved?
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15Distinguish3 marks
Distinguish between a difference in phenotype caused by phenotypic plasticity and a difference caused by a heritable genetic change (such as one produced by natural selection).
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16Identify1 mark
In the eutrophication chain, what is the immediate effect of the thick algal bloom on the plants living below the water surface?
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17Identify1 mark
Why must an ecosystem receive a continuous supply of energy, even though it does not need a continuous supply of new nutrient elements?
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18Identify1 mark
Which statement best describes a tipping point in an ecosystem?
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19Predict4 marks
Nitrogen-rich fertiliser leaches from farmland into a nearby lake over several weeks, disrupting the lake's ecosystem. Predict, with reasons, the changes that will occur in the lake.
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20Outline4 marks
An ecosystem is described as stable when it can resist change and recover after a disturbance. Outline the conditions an ecosystem needs in order to remain stable.
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