Chapter 23- Ecosystems Flashcards
definition of population
group of organisms of the same species living in the same habitat at the same time
definition of habitat
part of an ecosystem in which particular organisms live
definition of community
all the populations of different species living in the same area at the same time.
Ecosystem definition
The community of organisms (biotic) and non living (abiotic) components of an area and their interactions.
ecosystems can range in size from very small to very large.
niche definition
an organisms role within an ecosystem, including their position in the food web and habitat. each species occupies their own niche governed by adaptation to both abiotic and biotic conditions.
carrying capacity
the maximum population size that an ecosystem can maintain sustainably.
abiotic factors definition
the non living aspects of an ecosystem
list examples of abiotic factors
light
temperature
water availability
oxygen content
soil ph
biotic factors definition
living components of an ecosystem
biotic factors examples
food availability
breeding partners
pathogens
predators
list examples of three varying sizes of ecosystem
rock pool-small
large tree- bigger than rock pool
playing field- bigger than large tree
biomass definition
the total mass of organic material, measured in a specific area over a set time period. this can be calculated as dry mass.
biomass is transferred through an ecosystem.
what are the producers in a food web and how do they produce their own food
plants are the producers in a food web and they are able to produce their own carbohydrates from carbon dioxide in the atmosphere or in the water (co2 dissolved in water)
explain what happens to energy between trophic levels in the food web
-majority of energy is lost through respiration and excretion between each trophic level in the food web.
the remaining energy is used to form biomass.
how can biomass be measured
measured as mass of carbon or as dry mass of tissue per given area.
how productive an ecosystem is depends on abiotic and biotic factors. plenty of water, light, warmth and green plants will maximise the rate of photosynthesis and therefore results in more carbohydrates being produced by plants
efficiency of biomass formula
efficiency- biomass transferred/ biomass intake x 100
how can humans manipulate the transfer of biomass through ecosystems by reducing energy lost at each trophic level.
1) restricting movement (therefore respiration) of animals
2)providing animals with high energy food, (increasing energy input)
3)keeping animals indoors reduces energy transferred as heat.
4) Removing competition and predators (growing indoors and providing animals and plants with all they need)
why is the nitrogen cycle important
-air is 78% nitrogen however plants and animals cannot obtain nitrogen through gaseous exchange because nitrogen has a triple bond between nitrogen atoms N—N.
microorganisms are needed to convert nitrogen gas into nitrogen containing substances that plants and animals can absorb.
which biological molecules contain nitrogen
proteins
ATP
nucleic acid
list the four stages of the nitrogen cycle
1) Nitrogen fixation
2) Ammonification
3) Nitrification
4) Denitrification
Outline process of nitrogen fixation and state the names of the nitrogen fixing bacteria
nitrogen (from atmosphere N2) + 3h2——–> 2NH3 (ammonia)
nitrogenases from nitrogen fixing bacteria (rhizobium and azotobacter) found in legume root nodules)
Outline process of Ammonification and state the microorganisms needed
NO3/NO2- ————> NH4+ (NH3)
decomposers- aerobic and anaerobic bacteria and fungi
saprobiotic nutrition- bacteria and fungi (microbes) release enzymes that break down larger products into smaller absorb-able nutrients.
Outline the process of nitrification and state the names of nitrifying bacteria
NH4+———–> NO2- ———–> NO3- (oxidation reactions)
from ammonia to nitrites- nitrosamonas
from nitrites to nitrate ions- nitrobacter
nitrates are then actively absorbed into soil, plant will use those nitrates to make atp, proteins and DNA
Outline process of Denitrification and state the name of the bacteria needed
NO3- ——-> N2
nitrogen enters the atmosphere and used for nitrogen fixation
denitrifying bacteria- pseudomonas
requires anaerobic condition, occurs in waterlogged soil.
Describe the carbon cycle
Plants photosynthesise, to fix carbon from the atmosphere (carbon dioxide) into carbohydrates which can be ingested by animals.
All organisms respire and this converts the carbon in carbohydrates back into carbon dioxide in the atmosphere or oceans. When organisms die or excrete, the carbon is broken down to carbon dioxide by decomposers that respire using the carbohydrates within dead or waste matter.
An imbalance in this cycle leads to ocean acidification and global warming . imbalance is caused by deforestation and burning too many fossil fuels this means less co2 being used in photosynthesis and more being produced by combustion of fossil fuels.
what can an imbalance in the carbon cycle lead to
-too much co2 could lead to ocean acidification and global warming
what is an imbalance in the carbon cycle caused by
- deforestation and burning of too many fossil fuels
deforestation- less co2 being used in photosynthesis
burning too many fossil fuels- more co2 being produced by combustion of fossil fuels.
Definition of succession
change in an ecological community over time
definition of pioneer species
first species to colonise a new area, examples are lichen which are adapted to harsh abiotic conditions
Describe process of primary succession
starts with pioneer species colonising bare rock or sand.
the pioneer species are adapted to survive harsh abiotic factors and with their death and decomposition, they change the abiotic conditions to become less harsh and form a thin layer of soil called humus.
mosses and smaller plants can now survive, they further increase the depth and nutrient content of the soil. this pattern continues and as the abiotic factors become lass harsh and so larger plants can survive and change environment further.
each new species changes the environment in a way that makes it less suitable for existing species, newer species outcompete the pioneer species
increased biodiversity and a more stable environment as abiotic factors less harsh.
how does succession change biodiversity
increases biodiversity and so more a stable environment formed
species richness and number of organisms increases.
what is the final stage of succession known as
the climax community- this is dominated by trees
what is secondary succession
succession is disrupted and plants and animals may be destroyed
succession starts again but soil is already formed, succession does not start at bare rock seral stage
as succession occurs larger animals and plants can…
colonise the area
what is deflected succession, give examples
deflected succession is when human activities can disrupt the progress of succession
a climax community cannot be reached if animals are grazing or grass is being trampled on by humans
controlled burning or removal of vegetation can also prevent a climax community from being formed.
what human activities can prevent a climax community from forming
-vegetation removed
-trampling on grass by humans
-animals grazing
-controlled burning
why would we want deflected succession to occur
by maintaining earlier stages of succession and preventing a climax community, a greater variety of habitats can be conserved and therefore a greater range of species can survive.
there can be conflict between human needs and conservation in order to maintain the sustainability of natural resources.
what is an example of a compromise made in order to manage this conflict
forests can be coppiced to provide timber for fuel and furniture while still allowing the tree to survive.
why might an ecologist want to measure the size of a population
to measure the impact of changing environments and to protect plants and animals.
what are a few common aspects of taking population sizes
for the sampling to provide an accurate estimate that is representative of the population size. many samples 30+ need to be taken and sampling should be random to avoid bias.
