Practise IB ESS SL 2.1 by identifying species and interactions, designing sampling methods and explaining how resources and feedback shape populations.
Define the term species.
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.
Aquatic-organism context: use the four organisms shown above 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.
Aquatic-organism context: use the four organisms shown above when constructing or evaluating an identification key.
Identify one limitation of using a key to identify an organism.
Figure:Some trees found in the forests of California
Using Figure 3 and the identification key below, identify species A and species B.
Figure:Giant sequoia cones containing seeds
Figure:Long-horned beetle
With reference to Figures 4(b) and 4(c), state the species interaction between the giant sequoia (Sequoiadendron giganteum) and the long-horned beetle (Phymatodes nitidus).
Figure:Habitat preference of Danube fish species
Figure: Habitat preference of Danube fish species
identify the preferred habitat of bream.
compare and contrast the abiotic factors found in the straight part of the river with the abiotic factors found in the meandering part of the river.
| Years | Average sediment flow / tons yr^{-1} |
|---|---|
| 1921-1960 | 67.5 |
| 1971-1980 | 41.3 |
| 1981-1990 | 29.2 |
Table:Changes to sediment flow into the delta
Table: Changes to sediment flow into the delta: Sediment-flow and Danube-delta maintenance context
Table: Changes to sediment flow into the delta data
• 1921–1960 — average sediment flow: 67.5 tons yr⁻¹.
• 1971–1980 — average sediment flow: 41.3 tons yr⁻¹.
• 1981–1990 — average sediment flow: 29.2 tons yr⁻¹.
The Danube River delta is where the Danube flows into the Black Sea and includes UNESCO Biosphere Reserves and a World Natural Heritage site.
A delta is formed by continuous deposition of sediment carried by the river; sediment adds height and helps it extend into the sea.
The delta is a wetland ecosystem rich in plants, birds and fish, including over 1000 plant species, 300 bird species and endangered sturgeon.
Moldova takes nearly 20% of its water supply requirements from a branch of the Danube.
Suggest what effect this change in the sediment flow would have on the maintenance of the Danube River delta.
Figure A:Number of fish species breeding by month
Figure B:River discharge by month in the Danube River delta
Using Figures A and B: Number of fish species breeding by month and River discharge by month in the Danube River delta, outline the relationship between the number of fish species breeding and river discharge.
Define the term species.
Figure:Some trees found in the forests of California
Using Figure 3 and the identification key below, identify species A and species B.
Figure A:Number of fish species breeding by month
Figure B:River discharge by month in the Danube River delta
Using Figures A and B: Number of fish species breeding by month and River discharge by month in the Danube River delta, outline the relationship between the number of fish species breeding and river discharge.
Figure:Habitat preference of Danube fish species
Figure: Habitat preference of Danube fish species
compare and contrast the abiotic factors found in the straight part of the river with the abiotic factors found in the meandering part of the river.
Figure:Habitat preference of Danube fish species
Figure: Habitat preference of Danube fish species
identify the preferred habitat of bream.
Figure:The Eurasian wolf food web
With reference to Figure 6(b), state the ecological relationship between the Eurasian wolf (Canis lupus lupus) and the Eurasian lynx (Lynx lynx).
Outline four ways in which changes in the population of one species may reduce the carrying capacity of an environment for another species.
A new parasite is introduced into an ecosystem and manages to infect a host species. Outline how the host and parasite species may reach an equilibrium over time.
With reference to a named herbivore species, explain why its population growth curve follows an S-shape.
To what extent are natural limiting factors likely to stabilise human population growth?
Outline the difficulties in determining the carrying capacity of the human population.
To what extent can the practical strategies for obtaining data for a pyramid of numbers be made reliable?
Figure:An example of a retreating glacier in the Swiss Alps, 1891 (left) and 2019 (right)
Figure:Average percent cover vegetation near a glacier
Describe a method used to collect the data on percent cover vegetation shown in Figure 4(d).
Outline how the abundance of a motile species in an ecosystem can be measured.
Figure:Map of Algonquin Provincial Park, Canada
Identify one ecosystem in Algonquin Provincial Park.
Figure:Rainforest environmental cartoon
Figure 5 shows an environmental cartoon about rainforests.
The cartoonist has drawn the trees "holding hands". Explain why tropical rainforest ecosystems are more stable when trees remain standing.
| Years | Average sediment flow / tons yr^{-1} |
|---|---|
| 1921-1960 | 67.5 |
| 1971-1980 | 41.3 |
| 1981-1990 | 29.2 |
Table:Changes to sediment flow into the delta
Table: Changes to sediment flow into the delta: Sediment-flow and Danube-delta maintenance context
Table: Changes to sediment flow into the delta data
• 1921–1960 — average sediment flow: 67.5 tons yr⁻¹.
• 1971–1980 — average sediment flow: 41.3 tons yr⁻¹.
• 1981–1990 — average sediment flow: 29.2 tons yr⁻¹.
The Danube River delta is where the Danube flows into the Black Sea and includes UNESCO Biosphere Reserves and a World Natural Heritage site.
A delta is formed by continuous deposition of sediment carried by the river; sediment adds height and helps it extend into the sea.
The delta is a wetland ecosystem rich in plants, birds and fish, including over 1000 plant species, 300 bird species and endangered sturgeon.
Moldova takes nearly 20% of its water supply requirements from a branch of the Danube.
Suggest what effect this change in the sediment flow would have on the maintenance of the Danube River delta.
Figure 3(a): A simplified food web in a kelp forest ecosystem
Figure 3(b): Kelp forest ecosystems with and without the presence of sea otters
The arrows indicate the flow of carbon between the atmosphere and the carbon stored in kelp.
Outline why sea otters are considered a keystone species.
Explain how sea otters contribute to the resilience of the kelp forest ecosystem.