IB Biology C4.1: Populations and Communities (first exams in 2025)

This PowerPoint contains everything you need to teach the Theme/Unit C4.1 populations and communities in the new IB Biology specification.

**YouTube video is a preview of the full resource (does not include all slides)
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This Powerpoint consists of over 80 slides and contains the followings:

All the information the IB have included in the new spec.

• Clear diagrams
• Student friendly content
• Summary videos
• Student research tasks
• Clearly identified HL and SL content
• Student checklist
• Exam style questions
• Summary

The following content is included:
C4.1.1: Define the term population.
C4.1.2: Outline reasons for estimating population samples.
C4.1.3: Analyse and explain the importance of using random sampling techniques in ecological studies.
C4.1.4: Outline how quadrat sampling is used to estimate the population size for sessile organisms.
C4.1.5: Outline how the capture-mark-release-recapture method and the Lincoln index are implemented to estimate the population size of a motile species. 
C4.1.6: Define carrying capacity and explain why population growth slows down as the carrying capacity is reached.
C4.1.7: Distinguish between density-dependent and density-independent limiting factors.
C4.1.8: Compare and contrast exponential and sigmoidal population growth models.
C4.1.8: Evaluate the use of models as representations of natural phenomena.
C4.1.9: Describe the impact of intraspecific competition and cooperation on the survival and reproduction of a population.
C4.1.10: Define communities as diverse collections of populations that interact and contribute to the functioning of ecosystems.
C4.1.11: Distinguish between multiple interspecific interactions.
C4.1.12: Discuss the ecological significance of interactions between species.
C4.1.13: Outline examples of herbivory, predation, competition, parasitism, pathogenicity and mutualism.
C4.1.14: Evaluate the impact of invasive species on endemic species.
C4.1.15: Outline the role of human activities in the introduction and spread of invasive species.
C4.1.16: Assess the presence of interspecific competition using different testing methods.
C4.1.17: Apply the chi-squared test to determine an association between species.
C4.1.18: Interpret the results of a chi-squared test to generate accurate conclusions.
C4.1.19: Evaluate the validity of the chi-squared test as a statistical method for analysing associations between categorical variables.
C4.1.20:Evaluate the influence of predator–prey interactions on population dynamics using real case studies.
C4.1.21: Discuss the implications of top-down and bottom-up control in population regulation within communities.
C4.1.22: Compare and contrast allelopathy and antibiotic secretion mechanisms of competitive advantage in different organisms