2.1 Individuals, populations, communities and ecosystemsIB Environmental Systems and Societies HL: Flashcards
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Define a population.
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- Define a population.
- A group of organisms of the same species living in the same area at the same time and capable of interbreeding.
- Define a community.
- A collection of interacting populations within an ecosystem.
- Name four abiotic factors that affect species distribution.
- For example temperature, sunlight, pH, salinity, dissolved oxygen, soil texture.
- What is a niche?
- The set of abiotic and biotic conditions and resources upon which an organism or population depends.
- List the six ways populations interact.
- Herbivory, predation, parasitism, mutualism, disease and competition.
- What is carrying capacity?
- The maximum population size determined by competition for limited resources.
- How is population size regulated?
- By density-dependent factors and negative feedback mechanisms.
- Which organisms are sampled with random quadrats?
- Non-mobile organisms such as plants.
- Write the Lincoln index.
- N = (n1 × n2) ÷ m2.
- What is a keystone species?
- A species with an effect on ecosystem sustainability far greater than its abundance, such as the sea otter.
- What does the planetary boundaries model say about biosphere integrity?
- Changes to biosphere integrity have passed a critical threshold and loss needs to be reversed.
- (HL) Define fundamental and realized niche.
- Fundamental: the full range of conditions a species could use without competition. Realized: the narrower range occupied when competition and other interactions apply.
- (HL) What is an advantage of classifying organisms into clades?
- A clade shows evolutionary relationships (shared ancestry), usually using evidence such as DNA.
- (HL) Why are life cycles useful when assessing human impact?
- Reproductive behaviour and lifespan show how fast a species can recover from losses, and so how vulnerable it is.
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).