6.3 Ecosystems, Populations and Sustainability Flashcards
What are some biotic factors experienced by a rock pool?
- Food competition
What are some abiotic factors experienced by a rock pool?
- Tides: pH, salinity, temperature
What are some biotic factors experienced by a playing field?
- Food
What are some abiotic factors experienced by a playing field?
- Rainfall
- Sunlight
What are some biotic factors experienced by a large tree?
- Deformation (removal of leaves)
What are some abiotic factors that can be experienced by large trees?
- Low rainfall
What is the main way that energy enters an ecosystem?
Through photosynthesis
What do plants store energy as?
Biomass
What is biomass?
The mass of living material
How is energy transferred through the living organisms of an ecosystem?
By the organisms eating other organisms
What do food chains and webs show?
How energy is transferred through an ecosystem
Why isn’t all energy transferred to the next trophic level?
Because around 90%of available energy is lost in various ways
How is energy lost in trophic levels?
- some energy isn’t taken in
- Some energy is lost via respiration
Why is some of the available energy not taken in by organisms?
- Plants can’t use all the light energy that reaches their leaves. Some is the wrong wavelength, some is reflected, and some passes straight through the leaves.
- Some sunlight can’t be used because it hits parts of the plant that can’t photosynthesise I.e the bark.
- Some parts of food aren’t eaten by organisms so the energy isn’t taken in
- Some parts of food are indigestible so pass through organisms and come out as waste
What is the net productivity?
The amount of energy that is available for the next trophic level
What is the gross productivity?
The energy that is taken in
Net productivity =
Gross productivity- respiratory loss
Efficiency =
Biomass transferred/ biomass intake X 100
What is the carbon cycle?
How carbon moves through living organisms and the non-living environment
Give the 8 stages of the carbon cycle
1) Photosynthesis
2) Respiration by plants
3) Feeding
4) Death and waste
5) Respiration by animals
6) Decomposition of dead animals
7) No Decomposition after death , leading to the formation of fossil fuels.
8) Combustion of fossil fuels
What is called when decompsoers feed on dead organic matter?
Saprobiontic nutrition
What are rocks such as limestone and chalk mainly composed of ?
Calcium carbonate
what do plants and animals need nitrogen to make?
proteins and nucleic acids
what does the nitrogen cycle show?
how nitrogen is converted into a useable form and then passed on between different living organisms and the non-living environment
What are the 4 main processes of the nitrogen cycle?
- Nitrogen fixation
- Ammonification
- Nitrification
- Denitrification
what is nitrogen fixation?
where nitrogen gas is turned into Ammonium(NH4+) by bacteria Rhizobium and Azotobacter
where is rhizobium found?
in root nodules of legumous plants
where is azotobacter found?
in the soil
what is ammonification?
when nitrogen compounds from dead organisms are turned into ammonia by decomposers, which go on to form ammonium ions
what is nitrification?
- when ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants as nitrates.
- first nitrifying bacteria called Nitrosomonas change ammonium ions into nitriles.
- then nitrobacter change nitrites into nitrates
what is denitrification?
when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria. this happens under anaerobic conditions
what are some other ways that nitrogen enters the atmosphere?
- Lightning
- artificial fertilisers
what is succession?
the process by which an ecosystem changes over time
what re the 2 types of succession?
primary succession and secondary sucession
where does primary succession happen?
on land that’s been newly formed or exposed
where does secondary succession happen?
on land that’s been cleared of all the plants, but where the soil remains
what’s an example of a type of land that undergoes primary succession?
where a volcano has erupted to form a new rock surface, or where the sea level has dropped, exposing a new areas of land
what’s an example of a type of land that undergoes secondary succession?
after a forest fire, or where a forest has been cut down by humans
Give some examples of biotic factors
- Predation
- Competition (inter-specific) for space, food, water, light etc.
- ## Disease
Give some examples of abiotic factors
Availability of water
Light
Temperature
Turbidity (‘cloudiness’) of water
Humidity
pH
Salinity
Soil composition
what do saprobionts do?
they secrete enzymes onto their food (dead organisms and waste material), which then digest the material externally
what are the stages of primary succession?
- Pioneer species colonise the new land
- The pioneer species change the abiotic conditions by dying and decomposing. This forms a basic soil
- New organisms can move in and grow. When they die and decompose, the soil becomes deeper and richer in minerals.
- Larger plants, like shrubs, grow in the deeper soil.
- As more plants move in they create more habitats, so more animals move in.
what happens after primary succession is complete?
a climax community is created
what is a climax community?
where the ecosystem is supporting the largest and most complex community of plants and animals it can, and the community won’t change very much
Give an example of primary succession (bare rock to woodland)
- Pioneer species, such as lichens, colonise the rocks.
- The lichens dies and decompose, helping to form a thin soil. This allows species such as mosses to grow
- Larger plants that need more water can move in as the soil deepens. i.e small trees and shrubs. The soil continues to deepen as the larger plants die and are decomposed.
- Shrubs, ferns, and small trees begin to grow and they outcompete the smaller plants
- The soil finally becomes deep and rich in nutrients enough to support large trees. These become the dominat species and a climax community is formed
what is a plagioclimax?
when successon is stopped artificially
what is deflected succession?
when succession is prevented by human activity
what are some ways succession can be deflected?
- through mowing
- grazing
- managed burnings
Populations and Sustainability
what is the population size?
the total number or organisms of one species in a habitat
what causes the population size to vary?
both biotic and abiotic factors
what is the carrying capacity?
the maximum stable population size of a species that an ecosystem can support
what is predation?
where a predator kills and eats prey
what are the population sizes of predators and prey controlled by?
negative feedback
is it true that limiting factors stop the population size of a species from increasing?
yes
do limiting factors determine the carrying capacity of an ecosystem?
yes
what is conservation?
conservation is the protection and management of ecosystems so that natural resources can be used without them running out
for what reasons is the conservation of ecosystems important?
- Economic reasons
- Social reasons.
- Ethical reasons
what are the economic reasons for why conservation of ecosystems is important?
- Ecosystems provide resources for a lot of things humans need i.e drugs and food.
- These resources are economically important and so if these ecosystems aren’t conserved, the resources will be lost and this will result in a loss of money
what are the social reasons for why conservation of ecosystems is important?
- Looking at certain ecosystems makes people happy because they’re attractive to look at
what are the social reasons for why conservation of ecosystems is important?
- Some people think it’s morally right to conserve ecosystems
what is preservation?
the protection of ecosystems so that they’re kept exactly as they are
how can fishing provide resources in a sustainable way?
- Using fishing quotas
- Controlling mesh size or nets
what are fishing quotas?
- limits to the amount of certain fish species that fishermen are allowed to catch
what does the eu common fisheries policy state?
it regulates the amount of fish each country can take and where they’re allowed to take them from
Define ‘producer’
Photosynthesises and produces its own food
Define consumer
Feeds on other ogranisms
Define trophic level
A stage in a food chain
