Bioknowledgy
questioning, investigating and understanding
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  • IB Biology
    • Syllabus
    • General Resources
    • Practical scheme of work >
      • Practical activities (Labs)
      • Individual investigation
      • IB Write
      • Group 4 project
  • Core
    • 1. Cell biology >
      • 1.1 Introduction to cells
      • 1.2 Ultrastructure of cells
      • 1.3 Membrane structure
      • 1.4 Membrane transport
      • 1.5 The origin of cells
      • 1.6 Cell division
    • 2. Molecular biology >
      • 2.1 Molecules to metabolism
      • 2.2 Water
      • 2.3 Carbohydrates and lipids
      • 2.4 Proteins
      • 2.5 Enzymes
      • 2.6 Structure of DNA and RNA
      • 2.7 DNA replication, transcription and translation
      • 2.8 Cell respiration
      • 2.9 Photosynthesis
    • 3. Genetics >
      • 3.1 Genes
      • 3.2 Chromosomes
      • 3.3 Meiosis
      • 3.4 Inheritance
      • 3.5 Genetic modification and biotechnology
    • 4. Ecology >
      • 4.1 Species, communities and ecosystems
      • 4.2 Energy flow
      • 4.3 Carbon cycling
      • 4.4 Climate change
    • 5. Evolution and biodiversity >
      • 5.1 Evidence for evolution
      • 5.2 Natural selection
      • 5.3 Classification of biodiversity
      • 5.4 Cladistics
    • 6. Human physiology >
      • 6.1 Digestion and absorption
      • 6.2 The blood system
      • 6.3 Defence against infectious disease
      • 6.4 Gas exchange
      • 6.5 Neurons and synapses
      • 6.6 Hormones, homeostasis and reproduction
  • Additional higher level (AHL)
    • 7. Nucleic acids >
      • 7.1 DNA structure and replication
      • 7.2 Transcription and gene expression
      • 7.3 Translation
    • 8. Metabolism, cell respiration and photosynthesis >
      • 8.1 Metabolism
      • 8.2 Cell respiration
      • 8.3 Photosynthesis
    • 9. Plant biology >
      • 9.1 Transport in the xylem of plants
      • 9.2 Transport in the phloem of plants
      • 9.3 Growth in plants
      • 9.4 Reproduction in plants
    • 10. Genetics and evolution >
      • 10.1 Meiosis
      • 10.2 Inheritance
      • 10.3 Gene pools and speciation
    • 11. Animal physiology >
      • 11.1 Antibody production and vaccination
      • 11.2 Movement
      • 11.3 The kidney and osmoregulation
      • 11.4 Sexual reproduction
  • Options
    • A. Neurobiology and behaviour >
      • A.1 Neural development
      • A.2 The human brain
      • A.3 Perception of stimuli
      • A.4 Innate and learned behaviour (AHL)
      • A.5 Neuropharmacology (AHL)
      • A.6 Ethology (AHL)
    • B. Biotechnology and bioinformatics
    • C. Ecology and conservation >
      • C.1 Species and communities
      • C.2 Communities and ecosystems
      • C.3 Impacts of humans on ecosystems
      • C.4 Conservation of biodiversity
      • C.5 Population ecology (AHL)
      • C.6 Nitrogen and phosphorus cycles (AHL)
    • D. Human physiology
  • BISV Revision
  • Giving back - BioKQQAnswers

Essential idea: Community structure is an emergent property of an ecosystem.

The image above shows savannah grassland. The community of animals (here grazing Antelope, Zebra and Wildebeest) are present only due to the grassland environment, which in itself is a function of the grazing animals. Grazing is a key element along with fire and soil fertility that maintains the savannah. Without these elements in balance the savannah would either be succeeded by bush and forest or deteriorate into desert. A good example of how a community can be an emergent property of an ecosystem, whilst still being a critical part of the ecosystem.

Understandings, Applications and Skills

C.1.U1 The distribution of species is affected by limiting factors.
C.1.U2 Community structure can be strongly affected by keystone species.
C.1.U3 Each species plays a unique role within a community because of the unique combination of its spatial habitat and interactions with other species.
C.1.U4 Interactions between species in a community can be classified according to their effect.
C.1.U5 Two species cannot survive indefinitely in the same habitat if their niches are identical.
C.1.A1 Distribution of one animal and one plant species to illustrate limits of tolerance and zones of stress.
C.1.A2 Local examples to illustrate the range of ways in which species can interact within a community.
C.1.A3 The symbiotic relationship between Zooxanthellae and reef-building coral reef species.
C.1.S1 Analysis of a data set that illustrates the distinction between fundamental and realized niche.
C.1.S2 Use of a transect to correlate the distribution of plant or animal species with an abiotic variable.
[Text in square brackets indicates guidance notes]

Starters

What are keystone species? Learn by watching the video below.
Bees again - bees are a good example of the importance of a keystone species. Bees are under threat in many parts of the world. Learn more about their role in ecosystems and what their disappearance could mean to us.

Presentation and notes

The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.


Vocabulary

Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
Use the Cornell style template to collate your own notes for Topic C.1 Species and communities.


Quick Quiz

Use the BioK Quick Quiz on C.1 Species and communities (as directed) to check your understanding of the topic

Weblinks

Keystone Species
Keystone Species by National Geographic
Keystone Species by Sctiable (Nature)
Keystone Species Presentation by Washington University

Niches and Competitive Exclusion
Niches (includes
competitive exclusion) by Bozeman Science
Competitive Exclusion by LiweiCoastline
Sampling Methods
Using quadrats by The Woodland Education Centre
Quadrats by Intel Education Resources
Rocky Shore Transect by the British Ecological Society

Nature of science

Use models as representations of the real world—zones of stress and limits of tolerance graphs are models of the real world that have predictive power and explain community structure. (1.10)

Shelford's law of tolerance is a useful tool to understand the relative abundance of a species and hence predict community structure. It plots the range of a biotic or abiotic factor that is tolerated by a species,. Because their is variability but within a population the limits of tolerance and where the zones of stress start is not always easy to measure.
Picture
http://www.anselm.edu/homepage/bpenney/teaching/BI320/elements/Krohne_Shelfords.jpg

Theory of knowledge

Random samples are taken in studies involving large geographical areas or if limited time is available. Is random sampling a useful tool for scientists despite the potential for sampling bias?
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