| Date | May 2019 | Marks available | 2 | Reference code | 19M.3.SL.TZ1.11 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 11 | Adapted from | N/A |
Question
The table shows the distribution of four coral reef species along a transect as a function of depth.
[Source: © International Baccalaureate Organization 2019]
From the data, identify the depth along the transect where the greatest species richness is observed.
Outline the relationship between Zooxanthellae and reef-building coral reef species.
Suggest one way in which depth may act as a limiting factor for coral.
Markscheme
6.5 m ✔
Unit required
a. a symbiotic/mutualistic relationship ✔
b. Zooxanthellae obtain shelter/habitat/exposure to light ✔
c. coral obtains energy/food through photosynthesis of the Zooxanthellae ✔
low light levels/lower temperatures cannot support growth/metabolism ✔
Requires the explanation for the mark
Examiners report
Richness appeared well understood but the depth unit was sometimes omitted.
This was a well-answered question with many candidates knowing the term symbiosis or mutualism. Protection provided by coral was often stated but the role of Zooxanthellae in providing nutrients from photosynthesis was less often seen.
The reduction in light or temperature with greater depth was recognized but not often linked to growth or photosynthesis.
Syllabus sections
- 17N.3.SL.TZ0.14c: Outline how deforestation can affect the richness of biodiversity in an ecosystem.
- 17N.3.SL.TZ0.14b: State one reason mammals can continue to survive even if they are extinct in the wild.
- 17M.3.SL.TZ1.16a: Calculate the diversity of site C. Working should be shown.
-
17N.3.HL.TZ0.14b.i:
State the role of an indicator species.
- 18N.3.SL.TZ0.13b: State the name given to organisms whose presence or absence reflects an environmental condition.
- 18M.3.SL.TZ2.12a: Determine how far from the forest edge an increase in disturbance-adapted beetles would be...
- 20N.3.SL.TZ0.14a.i: Two components of biodiversity are richness and evenness. Deduce which of the two pools was...
- 19M.3.SL.TZ2.12d: State one abiotic factor that could have determined the distribution of barnacles.
-
17N.3.HL.TZ0.14b.ii:
Identify possible approaches to maintain the population of P. sandwichensis.
- 17N.3.SL.TZ0.14a: Calculate how many species are classified as endangered due to hunting and trapping.
- 19N.3.SL.TZ0.15a: State the impact of environmental disturbance on biodiversity.
- 18M.3.SL.TZ1.12b: Analyse the differences in biodiversity seen in the three sites.
- 17M.3.HL.TZ1.15b: Discuss two advantages of ex situ conservation measures.
- 18M.3.SL.TZ2.12b: With respect to the example of disturbance-adapted beetles, explain what is meant by an...
-
17N.3.SL.TZ0.14d:
Explain the impact of plastic waste on Laysan albatrosses (Phoebastria immutabilis).
- 18N.3.HL.TZ0.15c: Outline how organisms in Group V could be used to measure pollution in an environment.
-
18N.3.SL.TZ0.13a:
State which species could be found in mildly polluted water.
- 20N.3.SL.TZ0.14a.ii: Two components of biodiversity are richness and evenness. Deduce which of the two pools was...
- 17M.3.SL.TZ2.18: Explain the use of indicator species to assess the condition of the environment.
- 18N.3.SL.TZ0.13d: Explain how edge effects can influence biodiversity in a region.
- 17M.3.HL.TZ1.15c: State the two components needed to calculate the biodiversity of an area.
- 17M.3.HL.TZ1.14b: Define indicator species.
- 16N.3.SL.TZ0.14a: Outline the trend in the number of people with malaria during the period when the use of...
- 17M.3.HL.TZ2.15c: When coral is bleached, certain organisms become more common in the ecosystem such as the...
-
16N.3.SL.TZ0.13b:
A calculation of Simpson’s reciprocal index was undertaken on each field with the following results.
Evaluate these results.
-
18M.3.SL.TZ1.12a:
Outline what is meant by the edge effect.
- 18N.3.SL.TZ0.13c: Distinguish between richness and evenness as components of biodiversity.
-
19M.3.SL.TZ2.12a:
Outline how the data could have been obtained.
- 19M.3.SL.TZ1.11a: From the data, identify the depth along the transect where the greatest species richness is...
- 19N.3.HL.TZ0.16a: State one advantage of this in situ conservation method.
- 19N.3.HL.TZ0.15c: Describe the use of indicator species in monitoring environmental change.
- 17M.3.SL.TZ1.16c: Discuss the advantages and disadvantages of in situ conservation methods.
- 18N.3.HL.TZ0.15b.ii: Deduce the meaning of ai in this formula.
- 18N.3.HL.TZ0.15a: Identify the group that is most intolerant to pollution.
- 19M.3.HL.TZ1.16b: Distinguish between ex situ and in situ conservation of endangered species.
-
19M.3.SL.TZ2.12e:
Barnacles are sensitive to pollution. Outline how it might be possible to use these organisms as indicator species.
- 19M.3.SL.TZ2.14b: Explain the likely effects on biodiversity if a forest becomes fragmented.
- 19M.3.SL.TZ2.14a: State two abiotic factors that are increased in the fragmented forest with respect to the...
-
19M.3.SL.TZ2.12c:
E. modestus is an invasive barnacle while the others are native species. Analyse the data to show how it supports this statement.
- 16N.3.SL.TZ0.13a: Compare and contrast the richness and the evenness of the two fields.
-
17M.3.HL.TZ1.14c:
Indicator species may be affected by biomagnification. Discuss biomagnification using a named example of a pollutant.
- 20N.3.SL.TZ0.14b: Calculation of Simpson’s reciprocal diversity index for both rockpools gives the following...
-
20N.3.SL.TZ0.14c:
The graph shows how the number of ant species found on isolated islands near New Guinea depends on the size of the island.
[Source: University of Windsor, The Theory of Island Biogeography. Available at:
http://web2.uwindsor.ca/courses/biology/macisaac/55-437/lecture9.htm.]Explain the relationship between island size and number of ant species.
- 18M.3.SL.TZ2.12c: Outline how reserve size and shape can impact edge effects.
- 19M.3.SL.TZ1.12: Outline one example of an active management strategy employed in the context of in situ...
-
19M.3.HL.TZ2.17:
Outline a named example of the captive breeding and reintroduction of an endangered animal species.
-
19M.3.SL.TZ2.12b:
Describe the distribution of C. montagui and S. balanoides barnacles in Butter Lump Bay.
- 16N.3.HL.TZ0.16b: Outline how the edge effect can affect diversity in forests.
- 16N.3.HL.TZ0.16c: The number of plants in two fields of approximately the same size was counted. Compare and...
- 17M.3.SL.TZ1.16b: Site A has a higher Simpson’s reciprocal index than Site B showing that its diversity is...
- 19N.3.HL.TZ0.16c: State what a high value of Simpson’s reciprocal index of diversity suggests about an ecosystem.
-
18M.3.HL.TZ1.17b:
Explain biogeographic factors that increase the effectiveness of nature reserves.
- 18N.3.HL.TZ0.15b.i: Deduce the meaning of ni in this formula.
