What are the different levels of organisation in an ecosystem from individual organisms to the whole ecosystem?
There are 4 levels of ecological organisation. It starts at the lowest level: individual organisms, then populations, then communities, then finally to the whole ecosystem. Individual species of living organisms include every single plant and animal species that can be found on our planet
What is the importance of interdependence and competition in a community?
All organisms in an ecosystem depend upon each other. If the population of one organism rises or falls, then this can affect the rest of the ecosystem. If the foxes in the food chain above were killed, the population of rabbits would increase because they are no longer prey to the foxes.
To survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there.
Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil.
Animals often compete with each other for food, mates and territory.
Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community. This is called interdependence. A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
What is an eco-system?
An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment
Suggest the factors for which organisms are competing in a given habitat
To survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there.
Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil.
Animals often compete with each other for food, mates and territory
Suggest how organisms are adapted to the conditions in which they live
Animals adapt in three different types of ways:
- Behavioural
- Physiological
- Structural
What is a behavioural response?
Responses made by an organism that help it to survive/reproduce
What is a physiological response?
A body process that helps an organism to survive/reproduce
What is a structural response?
A feature of an organism’s body that helps it to survive/reproduce
Note:
AQA says that students should be able to extract and interpret information from charts, graphs and tables relating to the interaction of organisms within a community.
(Check page 83 on CGP)
What are the abiotic (non-living) factors which can affect a community?
- Light intensity
- Temperature
- Moisture levels
- Soil pH and mineral content
- Wind intensity and direction
- Carbon dioxide levels for plants
- Oxygen levels for aquatic animals
How does a change in an abiotic factor would affect a given community given appropriate data or context?
- Abiotic factors can have a significant impact on the food chain in an ecosystem
- For example, changes in temperature or water levels can alter the populations of certain species, which can in turn affect the species that depend on them for it
Note:
AQA says that students should be able to extract and interpret information from charts, graphs and tables relating to the effect of abiotic factors on organisms within a community
(Check CGP page 84)
What are the biotic (living) factors which can affect a community
- Availability of food
- New predators arriving
- New pathogens
- One species outcompeting another so the numbers are no longer sufficient to breed.
How does a change in a biotic factor might affect a given community?
The abundance and distribution of organisms in an ecosystem are affected by biotic factors, which involve living organisms. the arrival of new predators : in balanced ecosystems, predators and prey have evolved together. the arrival of a new predator will disrupt numbers of prey and other organisms.
Note:
AQA says thats students should be able to extract and interpret information from charts, graphs and tables relating to the effect of biotic factors on organisms within a community
(Check page 84)
How organisms are adapted to live in their natural environment,given appropriate information
- Organisms have features (adaptations) that enable them to survive in the conditions in which they normally live
- These adaptations may be structural, behavioural or functional
What are organisms called if they live in environments that are extreme?
- Some organisms live in environments that are very extreme, such as at high temperature, pressure, or salt concentration
- These organisms are called extremophiles
- Bacteria living in deep sea vents are extremophiles
What are photosynthetic organisms?
The producers of biomass for life on Earth
How are feeding relationships within a community represented by?
- Feeding relationships within a community can be represented by food chains
- All food chains begin with a producer which synthesises molecules
- This is usually a green plant or alga which makes glucose by photosynthesis
What do ecologists use to determine the distribution and abundance of species in an ecosystem?
A range of experimental methods using transects and quadrats
Note:
In relation to abundance of organisms students should be able to:
• understand the terms mean, mode and median
• calculate arithmetic means
• plot and draw appropriate graphs selecting appropriate scales for the axes.
(Check page 87)
State the food chain cycle
- Producer: food chains always begin with a producer.
- Primary consumer: producers are eaten by primary consumers (herbivores/omnivores)
- Secondary consumer: primary consumers are eaten by secondary consumers (carnivores/omnivores)
- Tertiary consumer: secondary consumers are eaten by tertiary consumers (carnivores/omnivores)
- Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers.
What are consumers that eat and kill other animals called?
Predators
What are consumers that gets killed and eaten by other animals called?
Prey
