Topic 4.11: Stability and Change Questions

Stability is referred to as an emergent property of an ecosystem. State what is meant by an emergent property.

Which process was mainly responsible for the rise of oxygen in Earth's atmosphere?

Two genetically identical organisms are raised in different environments and develop different appearances. What is the cause of the difference?

Which statement correctly defines biomagnification?

Which statement best describes a stable ecosystem?

State what is meant by the term phenotypic plasticity.

A fishery removes more fish each year than the population can replace by breeding and growth. How is this harvest best described?

State the process carried out by living organisms that was responsible for raising the level of oxygen in Earth's atmosphere.

Which statement best defines phenotypic plasticity?

Which substances washing into a lake are the usual trigger for eutrophication?

State what is meant by a 'persistent' pollutant.

Over geological time, living organisms changed Earth's atmosphere. Which pair of changes did they cause?

State the two mineral nutrients, usually carried in fertiliser run-off, that trigger eutrophication in a lake.

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.

A species of moth was reared in two groups under identical conditions except for temperature. Moths reared in cooler conditions developed darker wings, while those reared in warmer conditions developed lighter wings. All the moths had the same genotype. Explain these differences in wing colour using the concept of phenotypic plasticity.

Describe how the carbon dioxide removed from the atmosphere by photosynthesis was stored long-term, so that the atmospheric carbon dioxide level stayed low.

Distinguish between the way carbon was stored as fossil fuels and the way carbon was stored as limestone during the long-term fall in atmospheric carbon dioxide.

Two nearby grasslands are studied. One contains many plant and animal species; the other contains only a few. Explain why the grassland with higher biodiversity is likely to be more stable.

A persistent pollutant is measured at 0.04 ppm in plankton and at 32 ppm in the seals that feed at the top of the food chain. (a) Calculate how many times more concentrated the pollutant is in the seals than in the plankton. (b) Name the process responsible for this difference.

After an algal bloom, the dissolved oxygen in a lake falls sharply. Outline why the oxygen level drops.