What is an ecosystem?
The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of the environment
What do organisms need to survive and reproduce?
A supply of materials from their surroundings and from other living organisms.
What do plants compete for?
• Light and space
• Water and mineral ions from the soil
What do animals compete for?
Within a community what does each species depend on other species for?
Food, shelter, pollinations, seed dispersal etc…
What happens if one species is removed from a community?
The whole community can be affected (known as interdependence)
What is a stable community?
One where all the species and environmental factors are in balance so that population size remains fairly constant
List abiotic (non-living) factors which can affect a community
• Light intensity
• Moisture levels
• Soil pH and mineral content
• Wind intensity and direction
• CO2 levels for plants
• O2 levels of aquatic animals
List biotic (living) factors which can affect a community
• Availability of food
• New predators arriving
• New pathogens
• One species outcompeting another (so numbers are no longer sufficient to breed)
What are adaptations?
Features of an organism enabling it to survive in the conditions in which it normally lives
How can adaptations be characterised?
What are extremophiles and what examples of habitat may they live in?
Organisms which live in habitats which are extreme e.g. high temperature, pressure or salt concentration
Bacteria living in deep sea vents would be classified as what?
For life on Earth, what are the producers of biomass?
How can feeding relationships in a community be represented?
In a food web.
Describe a simple food chain.
Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers.
What are predators?
Consumers that kill and eat other animals
What are prey?
Animals eaten by consumers
In a stable community, what may happen to the numbers of predators and prey?
It may rise and fall in cycles
What happens to all materials in the living world?
They are recycled to provide the building blocks for future organisms
What does the carbon cycle return to the atmosphere?
Carbon dioxide - which is then used by plants for photosynthesis.
What does the water cycle provide
Fresh water for plants and animals on land, before draining into the seas (water is continuously evaporated and precipitated)
What role do microorganisms provide in an ecosystem?
They cycle materials through an ecosystem by returning carbon to the atmosphere and mineral ions to the soil
What is biodiversity?
The variety of all the different species of organisms on Earth (or within an ecosystem)
What does a great biodiversity ensure?
The stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment
What can impact biodiversity?
Waste, deforestation and global warming
How are most human activities impacting biodiversity?
Human activities are reducing biodiversity (impacting the future of the human species)
What does rapid growth in human population and increasing living standards lead to?
More resources are used and more waste produced (including pollution when not handled properly)
Where can pollution occur?
• Water (sewage, fertilisers or toxic chemicals)
• Air (smoke and acidic gases)
• Land (landfill and toxic chemicals)
What can pollution cause?
A reduction in biodiversity as plants and animals can be killed