| Date | May 2018 | Marks available | 1 | Reference code | 18M.3.SL.TZ1.12 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | State | Question number | 12 | Adapted from | N/A |
Question
Isopods are a group of organisms belonging to the arthropods and include woodlice (slaters) and other species, some of which live on land and others in water. A study was carried out on the diversity of isopod species living in a bog (site B), the edge zone separating the bog and forest (site E) and adjacent forest (site F).
Data collected for the three sites are summarized in the table:
Outline what is meant by the edge effect.
Analyse the differences in biodiversity seen in the three sites.
State one method that could be used to estimate the isopod population size.
Markscheme
a. occurs at the boundary between two ecosystems/habitats
b. gradient of abiotic conditions at the edge
c. (as a result) community differs at the edge
d. community at the edge is more diverse than adjacent communities
a. number of individuals differs more than number of species between the zones
b. zone E has lowest diversity / zone F has highest diversity
c. zone B has higher diversity than zone E
d. edge effect is evident
capture-mark-release-recapture
OR
quadrat / transect
Examiners report
Syllabus sections
- 17N.3.HL.TZ0.15b: State how the population of M. gallopavo may have been determined.
- 19M.3.SL.TZ1.11c: Suggest one way in which depth may act as a limiting factor for coral.
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16N.3.HL.TZ0.17a:
State two bottom-up factors affecting algal blooms.
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19M.3.HL.TZ2.16a:
Explain the factors that can contribute to the exponential growth phase in a sigmoid population curve.
- 16N.3.HL.TZ0.16a: Describe one method that could have been used to estimate the population size of a given tree...
- 17N.3.HL.TZ0.15a.i: State the range of years when exponential growth of the M. gallopavo population occurred.
- 18M.3.HL.TZ1.17a.ii: Suggest one possible cause for the decrease of the number of animals after 1940.
- 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.TZ2.15e: Explain how an excessive growth of algae on coral reefs can be controlled by top-down factors.
- 18M.3.HL.TZ2.15c: Explain how nutrients can have a positive or negative bottom-up effect on seagrass.
- 18M.3.HL.TZ1.17a.i: State the type of growth of this population up to 1940.
- 17M.3.HL.TZ1.17: Discuss the factors affecting population growth that can result in an exponential growth curve.
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19N.3.HL.TZ0.18:
Explain the technique used to estimate the population size of a named species of organism that is able to move.
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19M.3.HL.TZ1.19:
The garden snail, Helix aspersa, is a herbivore.
[Source: Sinan Önder /https://www.pexels.com/photo/animal-close-up-crawling-garden-243128/]
Explain how the population of snails in an ecosystem could be estimated by capture-mark-release-recapture, identifying the limitations in the method.
- 16N.3.HL.TZ0.17b: Explain how top-down factors control algal blooms.
- 19M.3.HL.TZ2.16b: Outline the effect of carrying capacity on the growth of a population.
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17N.3.HL.TZ0.15a.ii:
Suggest factors that could account for the growth curve of the M. gallopavo population.
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17N.3.HL.TZ0.15c:
Hunting of M. gallopavo is currently regulated. Predict what would happen if the hunting regulations were removed.
