| Date | May 2017 | Marks available | 3 | Reference code | 17M.3.SL.TZ2.14 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Explain | Question number | 14 | Adapted from | N/A |
Question
Paramecium aurelia and Paramecium caudatum are single cell organisms. They were grown separately and together. The population growth curves are shown.
Explain the results shown in this experiment.
Markscheme
a. when they are alone they both show a greater population than when together
b. two species cannot survive indefinitely in the same habitat if their niches are identical
OR
competitive exclusion
c. Paramecia compete for food/space
d. P. caudatum starts to disappear/decrease after day 6–8 days «whereas P. aurelia reaches a plateau» Vice versa
OR
the population of P.caudatum decreases much more than the population of P.aurelia
e. P. aurelia is better suited/fitted than P. caudatum
Examiners report
[N/A]
Syllabus sections
Option C: Ecology and conservation » Option C: Ecology and conservation (Core topics) » C.1 Species and communities
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