Individuals, Populations, Communities & Ecosystems (DP IB Environmental Systems & Societies (ESS): SL): Exam Questions

Outline the role of abiotic factors and how they influence ecosystems, providing examples to illustrate their impact.

Outline the role of biotic factors and how they influence ecosystems, providing examples to illustrate their impact.

With reference to a named species, distinguish between the terms habitat and niche.

Compare and contrast predation and competition.

Define the term carrying capacity.

Outline four factors that contribute to the difficulty in estimating carrying capacity.

At least two of these factors should be specific to human populations.

The figure below shows how the dominant vegetation changes with altitude in the Alps mountain range in Europe.

Identify three limiting factors likely to be affecting alpine vegetation above 2 500 m.

Explain the role of limiting factors in shaping S and J population curves.

Define the term ecosystem.

The figure below shows the data for a wolf population and the amount of suitable habitat that is available to the wolves.

Suggest one possible method for estimating the wolf population size.

Outline two reasons why collecting this type of data on wolves might be challenging.

Lichens are organisms that grow well on stone walls in unpolluted air. Lichens grow less well in polluted air.

Car exhaust fumes contain sulfur dioxide that pollutes air.

A scientist investigates the effect of pollution by cars in a city.

This is their method:

• Measure the percentage area of a stone wall in the city centre covered by lichen

• Repeat this measurement at different distances from the city centre

The table shows their results.

Explain the results shown in the table.

Describe a method to measure the percentage of a stone wall covered by lichen.

Use the dichotomous key provided to identify the organisms below.

Identify three limitations of using dichotomous keys for identifying organisms.

A group of students compares the distribution of plant species in two fields using the following method:

• Use random sampling

• Use a 0.5 m × 0.5 m quadrat

• Count the number of each species in a quadrat

• Repeat this method for five quadrats in each field

The tables below show the students’ results.

Describe how the students would obtain random samples from each field.

Calculate the mean number of dandelions per quadrat in field B.

Calculate the number of dandelions per m² in field B.

Describe the differences in species distribution in field A and field B.

Explain why estimating carrying capacity is problematic for human populations and how it differs from other species.

Distinguish between the terms ecological footprint and carrying capacity of a human population and describe the relationship between them.

When plotted on a graph, the population growth of a particular population often takes on an 'S' shape, sometimes known as an S-population curve.

Explain how the interactions that a species has with its environment can result in this curve.

Discuss the role of carrying capacity in determining population size in humans and other species.