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IB Biology HL C4.1 Populations and Communities Question Bank

Practise IB Biology HL C4.1 with population and community data questions on growth, carrying capacity, competition, niches, succession and biodiversity.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • analyse population data using carrying capacity, limiting factors, growth curves and competition
  • explain community interactions and biodiversity using niches, succession and sampling evidence
  • evaluate population-change hypotheses from abundance, distribution and ecological data

Covered syllabus points

C4.1.1—PopulationsC4.1.2—Population size estimationC4.1.3—Random quadrat samplingC4.1.4—Capture-mark-release-recaptureC4.1.5—Carrying capacityC4.1.6—Negative feedback controlC4.1.7—Population growth curvesC4.1.8—Modelling sigmoid growthC4.1.9—Competition vs. cooperationC4.1.10—CommunityC4.1.11—Interspecific relationshipsC4.1.12—Mutualism as interspecific relationshipC4.1.13—Endemic vs. invasive speciesC4.1.14—Tests for interspecific competitionC4.1.15—Chi-squared testC4.1.16—Predator-prey relationshipsC4.1.17—Top-down vs. bottom-up controlC4.1.18—Allelopathy and antibiotics

C4.1 Populations and communities question 1

[Maximum number: 3]

The photograph shows Japanese knotweed, Reynoutria japonica, which is native to Japan, China and Korea. It has been introduced into other regions of the world and is now an invasive alien species in parts of Europe and North America. Dense groups of stems often develop with a height of up to 3 metres, which prevent other plants from growing.

Figure for Question C4.1 Populations and communities question 1 — IB Biology HL

Question (a)

(a)

State the biological term for a group of organisms of the same species living in an area.

[ 1 ]

Question (b)

(b)

Suggest two ways in which a plant such as Reynoutria japonica could prevent the growth of other plants.

[ 2 ]

C4.1 Populations and communities question 2

[Maximum number: 2]

The Atlantic cod is considered in many countries to be endangered due to overfishing. Describe two methods that could be used to estimate the cod population.

C4.1 Populations and communities question 3

[Maximum number: 4]

White sage (Salvia apiana) is a native Californian shrub. Slender oat (Avena barbata) is a grass, originally from the Mediterranean, which was introduced to California. The map shows the distribution of the two species in relation to one another in an area near Santa Ynez, California.

Figure for Question C4.1 Populations and communities question 3 — IB Biology HL

Question (a)

(a)

Using the scale bar, determine the area of quadrat A1, giving the units.

[ 1 ]

Question (b)

(b)

Outline how chi-squared can be used to test for an association between the distributions of the two species.

[ 3 ]
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