IB ESS SL 2.1 Populations and Ecosystems Question Bank

Practise IB ESS SL 2.1 by identifying species and interactions, designing sampling methods and explaining how resources and feedback shape populations.

Exam points

Identify species and biotic interactions from figures, keys and case-study evidence.
Design quadrat or capture–mark–recapture sampling and evaluate reliability.
Explain how competition and resource limits alter population size, niches and resilience.

Covered syllabus points

2.1.1—Biosphere composition 2.1.2—Species definition 2.1.3—Classification of organisms 2.1.4—Taxonomist tools 2.1.5—Population definition 2.1.6—Distribution factors 2.1.7—Abiotic factors examples 2.1.8—Niche 2.1.9—Population interactions 2.1.10—Carrying capacity 2.1.11—Density-dependent regulation 2.1.12—Population growth curves 2.1.13—Human population limiting factors 2.1.14—Human carrying capacity 2.1.15—Estimating population abundance 2.1.16—Quadrat sampling 2.1.17—Capture-mark-release-recapture 2.1.18—Community definition 2.1.19—Habitat definition 2.1.20—Ecosystems as open systems 2.1.21—Ecosystem sustainability 2.1.22—Human impacts on stability 2.1.23—Keystone species 2.1.24—Biosphere integrity boundary 2.1.25—Reversing biosphere integrity loss

[Maximum number: 3]

(a)

Define the term species.

[ 1 ]

(b)

Figure:Aquatic organism image A

Figure:Aquatic organism image B

Figure:Aquatic organism image C

Figure:Aquatic organism image D

The organisms shown below (not drawn to scale) were found in an aquatic ecosystem.

[ 2 ]

(i)

Aquatic-organism context: use the four organisms shown in the protected the four aquatic organisms shown above visual when constructing or evaluating an identification key.

Suggest two visible characteristics of the organisms shown above which could be used to construct an identification key.

[ 1 ]

(ii)

Aquatic-organism context: use the four organisms shown in the protected the four aquatic organisms shown above visual when constructing or evaluating an identification key.

Identify one limitation of using a key to identify an organism.

[ 1 ]

[Maximum number: 3]

(a)

Figure:Some trees found in the forests of California

Using Figure: Some trees found in the forests of California and the identification key below, identify species A and species B.

[ 2 ]

(b)

Figure:Giant sequoia cones containing seeds

Figure:Long-horned beetle

With reference to Figures: Giant sequoia cones containing seeds and Long-horned beetle, state the species interaction between the giant sequoia (Sequoiadendron giganteum) and the long-horned beetle (Phymatodes nitidus).

[ 1 ]

[Maximum number: 6]

Figure:Four species of the family Leporidae

Figure:A dichotomous key for species A to D

Figure:Sagebrush ecosystem without invasive cheatgrass

Figure:Sagebrush ecosystem with invasive cheatgrass

The family Leporidae includes hares and rabbits. The figures show four species that can be found in western North America.

(a)

Use Figures: Four species of the family Leporidae and A dichotomous key for species A to D to identify Species B and Species C.

[ 2 ]

(b)

The sagebrush ecosystem provides a habitat for pygmy rabbits. Suggest one reason why there might be a greater number of pygmy rabbits in the ecosystem shown in Figure: Sagebrush ecosystem without invasive cheatgrass than in the ecosystem shown in Figure: Sagebrush ecosystem with invasive cheatgrass.

[ 1 ]

(c)

Describe one method to determine the impact of invasive cheatgrass on sagebrush density.

[ 3 ]

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Covered syllabus points

2.1 Individuals, populations, communities, and ecosystems question 1

Question (a)

Question (b)

Question (i)

Question (ii)

2.1 Individuals, populations, communities, and ecosystems question 2

Question (a)

Question (b)

2.1 Individuals, populations, communities, and ecosystems question 3

Question (a)

Question (b)

Question (c)