6.3.1 - Ecosystems Flashcards
What is a population?
A group of organisms of the same species living in the same habitat
What is a habitat?
A part of an ecosystem in which particular organisms live
What is a community?
All the populations of different species in the same area at the same time
What is an ecosystem?
A community and the non-living components of an environment (biotic and abiotic factors)
What is a niche?
An organism’s role within an ecosystem including their position in the food web and habitat
What is carrying capacity?
The maximum population size an ecosystem can support
What are abiotic factors?
Non-living conditions of an ecosystem
What are biotic factors?
Living components of an ecosystem which are an impact of the interactions between organisms
What are abiotic and biotic factors in a rock pool?
Abiotic:
- Water temperature
- pH
- Variation in water depth
- Sunlight
Biotic:
- Plankton food webs
- Seaweeds
- Consumers (crabs)
- External predators (seabirds)
What are abiotic and biotic factors in a playing field?
Abiotic:
- Rainfall
- Temperature
- Light intensity (shade)
- Soil type
- Mineral ions
- Mowing
- Trampling
Biotic:
- Competition between plants
- Pollinators and pest populations
What are abiotic and biotic factors in a large tree?
Abiotic:
- Light intensity and quality
- Water supply
- Soil type
- Mineral ions
Biotic:
- Invertebrates and vertebrates that inhabit the tree
- Surrounding trees
What happens between each trophic level in a food web?
The majority of the energy is lost due to respiration and excretion and the remaining energy is used to form biomass.
What is the amount of biomass remaining in an organism measured in terms of?
The mass of carbon or dry mass of tissue per given area
What is the formula for efficiency?
efficiency = biomass transferred/biomass intake x 100
How can human activities manipulate the transfer of biomass through ecosystems?
They can reduce the energy lost at each trophic level by:
- Restricting the movement and therefore respiration of animals
- Providing animals with higher energy food which increases the energy input
- Keeping animals indoors to reduce the energy transferred as heat
- Removing competition and predators by growing indoors and providing animals and plants with all they need
Which biological molecules contain nitrogen?
Amino acids, proteins, nucleic acids and ATP
What are the 4 key stages of the nitrogen cycle?
- Nitrogen fixation
- Ammonification
- Nitrification
- Denitrification
What is the role of saprobionts in recycling nitrogen?
- Decompose waste and dead matter via extra cellular digestion making inorganic ions available to other organisms
- Carry out process of ammonification (convert nitrogen compounds in waste and dead matter into ammonia which then forms ammonium ions in soil)
What is the role of nitrogen-fixing bacteria in recycling nitrogen?
Convert atmospheric nitrogen gas into nitrogen containing compounds such as ammonia which then forms ammonium ions in soil that can be used by plants
What is the role of nitrifying bacteria in recycling nitrogen?
- Convert ammonium ions in soil into nitrogen compounds that can be used by plants known as nitrates
- Some convert ammonium ions into nitrites and different ones then convert nitrites into nitrates
What is the role of denitrifying bacteria in recycling nitrogen?
Using nitrates during respiration releasing nitrogen gas in the process
What is the role of Mycorrhizal fungi in recycling nitrogen?
Increase surface area of root systems helping plants to absorb water and scarce mineral ions from soil
What are 2 examples of nitrogen fixing bacteria?
- Azotobacter
- Rhizobium
What are 2 examples of nitrifying bacteria?
- Nitrosomonas (ammonium ions to nitrites)
- Nitrobacter (nitrites to nitrates)
What are microorganisms needed for in the nitrogen cycle?
To convert nitrogen gas into nitrogen containing substances that plants and animals can absorb
How does the carbon cycle recycle organic compounds in an ecosystem?
- Decomposition of dead animals and plants by bacteria and fungi releases carbon dioxide
- Respiration by plants and animals releases carbon dioxide from organic compounds
- Photosynthesis by plants absorbs carbon dioxide from the atmosphere
- Combustion of plants and fossil fuels releases carbon dioxide into the atmosphere
What is the imbalance in the carbon cycle caused by?
Deforestation and burning too many fossil fuels so less carbon dioxide is being used in photosynthesis and more is being produced by combustion
What does the imbalance in the carbon cycle lead to?
- Ocean acidification
- Global warming
What is succession?
The change in an ecological community over time
How does a primary succession start?
A pioneer species colonises barren land such as bare rock or sand
What happens after primary succession has started?
- Mosses and smaller plants can now survive and they further increase the depth and nutrient content of soil
- This pattern continues and as the abiotic factors continue to be less harsh larger plants can survive and change the environment further
- Each new species may change the environment in a way that it become less suitable for the previous species so each existing species is outcompeted by a new species colonising
- Biodiversity increases
What is the final stage in succession known as?
Climax community which is dominated by trees and woodland
What are pioneer species?
They are adapted to survive in harsh abiotic factors and through their death and decomposition change the abiotic factors to become less harsh and form a thin layer of soil, humus.
What is an example of a pioneer species?
Lichen
What is secondary succession?
When the succession is disrupted and plants are destroyed so succession starts again but the soil is already created meaning it does not start from the bare rock stage
What is deflected succession?
Preventing the formation of a climax community through controlled burning and removal of vegetation
Why is deflected succession needed?
By maintaining earlier stages in succession and preventing a climax community a greater variety of habitats are conserved and therefore a greater range of species survive
