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IB Biology SL B4.2 Ecological Niches Question Bank

Practise IB Biology SL B4.2 by comparing niches, habitats, resource use, nutrition and environmental requirements with evidence.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • distinguish a niche from a habitat by including resource use, interactions and environmental requirements
  • compare niches using food, feeding time, microhabitat, predators, nesting sites or tolerance conditions
  • classify autotrophic, holozoic, saprotrophic or mixotrophic nutrition from organism evidence
  • use competition or predation evidence to explain why species occupy different parts of an ecological niche

Covered syllabus points

B4.2.1—Ecological nicheB4.2.2—Oxygen toleranceB4.2.3—Photosynthesis as nutrition modeB4.2.4—Holozoic nutritionB4.2.5—Mixotrophic nutritionB4.2.6—Saprotrophic nutritionB4.2.7—Diversity in archaeaB4.2.8—Dentition and diet in Family HominidaeB4.2.9—Herbivore and plant adaptationsB4.2.10—Predator and prey adaptationsB4.2.11—Plant form for light harvestingB4.2.12—Fundamental vs. realized nicheB4.2.13—Competitive exclusion

B4.2 Ecological niches question 1

[Maximum number: 6]

12. Ecologists studied the distribution of five species of insectivorous wood warblers of the genus Dendorica living on different parts of coniferous trees in mature forests.

Figure for Question B4.2 Ecological niches question 1 — IB Biology SL

Question (a)

(a)

Outline the principle of competitive exclusion

[ 2 ]

Question (b)

(b)

Other than position in the tree, suggest two ways in which the niches of the warblers in the ecosystem may differ.
1:
2:

[ 2 ]

Question (c)

(c)

The diagram shows the realized niches of the five species of warbler. Suggest how the fundamental niche of D. castanea might differ from its realized niche.

[ 2 ]

B4.2 Ecological niches question 2

[Maximum number: 1]

A student set up a 20 -metre transect line along a rocky shore and measured the abundance of seven species of seaweeds (A-G) at 21 different sampling stations at fixed distances. The kite diagram represents the species abundance data across the 20 metres.

Figure for Question B4.2 Ecological niches question 2 — IB Biology SL

Seaweeds are obligate aerobes. Describe an environmental condition required for seaweed survival.

B4.2 Ecological niches question 3

[Maximum number: 3]

There is evidence that prokaryotes were responsible for changes in the atmospheric gases 3.5 billion years ago. Outline the role of bacteria in producing an oxygen-rich atmosphere.

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