| Date | May 2018 | Marks available | 1 | Reference code | 18M.3.HL.TZ1.17 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | State | Question number | 17 | Adapted from | N/A |
Question
In 1911, twenty-five reindeer (Rangifer tarandus) were introduced onto Saint Paul Island in Alaska and the population was recorded for 40 years.
State the type of growth of this population up to 1940.
Suggest one possible cause for the decrease of the number of animals after 1940.
Explain biogeographic factors that increase the effectiveness of nature reserves.
Markscheme
exponential «population growth»
lack of food / disease / hunting / increase of predators
a. large area can support greater range of habitats / longer food chains / higher population numbers
b. low edge effect with circular reserves
OR
reduced edge effect minimises area that is disturbed/competition
c. intact / unbroken areas represent less disturbance on habitats
d. fragmented areas linked by corridors
e. (proximity of fragmented areas) allows for animal movement / genetic exchange
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.
-
16N.3.HL.TZ0.17a:
State two bottom-up factors affecting algal blooms.
- 18M.3.SL.TZ1.12c: State one method that could be used to estimate the isopod population size.
-
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.
- 17M.3.HL.TZ1.17: Discuss the factors affecting population growth that can result in an exponential growth curve.
-
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.
-
17N.3.HL.TZ0.15a.ii:
Suggest factors that could account for the growth curve of the M. gallopavo population.
-
17N.3.HL.TZ0.15c:
Hunting of M. gallopavo is currently regulated. Predict what would happen if the hunting regulations were removed.
