Topic 9 - Ecosystems and Material Cycles
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Define a species
A group of similar organisms that can reproduce with one another to make fertile offspring
Define a population
All the members of the same species within the same habitat
Define a niche
An organism’s role
Define an ecosystem
The interaction of abiotic and biotic factors
Define a community
All the different populations within a habitat
Define a habitat
A place where an organism lives
Define an organism
An individual living thing
Explain how communities can be affected by the abiotic factor of temperature
Temperature affects the rate of photosynthesis. Living things have evolved to grow healthily at their optimum temperature and could not survive in different conditions.
Explain how communities can be affected by the abiotic factor of water
Living things require water to survive. If plant roots are waterlogged they are unable to respire, they rot and the plant dies. Plants vary in the mositure levels that they require.
Explain how communities can be affected by the abiotic factor of light
Light is required for photosynthesis. The rate of photosynthesis affects the rate at which the plant grows. Plants can be food sources or shelter for many organisms. Some plants have evolved for optimum growth in certain light intensity.
Explain how communities can be affected by the abiotic factor of pollutants
Air pollutants such as sulfur dioxide are released from the burning of fossil fuels. Lichens cannot survive if the concentration of sulfur dioxide is too high.
Explain how communities can be affected by the biotic factor of competition
If one species is better adapted to the environment than another, then it will outcompete it until the numbers of the lesser adapted species are insufficient to breed.
Explain how communities can be affected by the biotic factor of predation
New predators can upset the balance of the habitat of a balanced ecosystem where predator and prey have evolved together.
Describe interdependence in a community
Interdependence describes how organisms in a community depend on other organisms for vital services. This could include food, shelter or reproduction.
Describe parasitism
A parasite is an organism that lives and feeds on another organism, called its host. The host is harmed in the relationship while the parasite benefits.
Describe mutualism
Both species in a relationship benefit
Describe the core practical to investigate the relationship between organisms and their environment using field-work techniques, including quadrats and belt transects
-Divide a field into a numbered grid with equally sized squares. -Place a quadrat in a random square -Count the number of the object/plants there are within the quadrat -Repeat this with other random squares (5-15) -Compare results by calculating a mean. -Multiply the mean by how many squares there are to discover how many of the object/plants there are in the whole grid
What is the calculation for population size based on quadrats?
Population size = mean number of organisms in quadrant x total size of area where organism lives/total area of quadrats
Define a producer
An organism that makes its own food
Define a primary consumer
A herbivorous organism that eats plants for energy
Define a secondary consumer
A carnivorous or omnivorous organism that eats primary consumers for energy
Define a decomposer
An organism that breaks down or eats decaying material as its energy source
Explain energy transfers between trophic levels
The stages in a food chain or web are called trophic levels. Energy/biomass is transferred between each trophic level. It transfers into less useful forms at each trophic level, which affects the number of organisms at each level and limits the length of the food chain.
What are the reasons for energy loss between trophic levels?
-Energy lost as heat to the environment -Energy used as metabolism -Energy lost in faeces/urine