CourseCourseConceptConceptDocumentDocument

IB Biology SL B4.1.3 Abiotic Variables Affecting Distribution Questions

Explore how temperature, pH, light, moisture and other abiotic gradients limit organisms and shape distribution, abundance and cover in IB Biology SL B4.1.3.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Explain how temperature, salinity or pH can limit species survival, growth or reproduction.
  • Interpret transect or distribution data to link light, pH or temperature with species abundance.
  • Measure an abiotic gradient along a transect and compare it with species distribution.

IB Biology SL B4.1.3 Abiotic Variables Affecting Distribution Questions question 1

[Maximum number: 2]

The tundra ecosystem in Finnish Lapland has a short growing season and a mean temperature of −2.0∘C-2.0^{\circ} \mathrm{C}. It is also naturally grazed by herbivores such as reindeer (Rangifer tarandus). Different quadrats were set up to include and exclude the reindeer in both normal and warmed temperatures. Open-topped warming chambers were used to heat both the soil and air in the warmed quadrats. The graph shows the changes in plant richness over five years.

Figure for Question IB Biology SL B4.1.3 Abiotic Variables Affecting Distribution Questions question 1 — IB Biology SL

Identify two abiotic limiting factors on plant growth in a tundra ecosystem.

All question bank results loaded