6.23 - Ecosystems Flashcards
(66 cards)
1
Q
ecosystem
A
made up of all the living organisms that interact with one another in a defined area (varying in size)and the physical factors present in that region
2
Q
habitat
A
A place where organisms live, where all of their needs can be met
3
Q
biodiversity
A
the variety of living organisms within an area
4
Q
population
A
all of the individuals of a species in a given area/habitat
5
Q
community
A
all of the species in an area/habitat
6
Q
intraspecific
A
within a species
7
Q
interspecific
A
between species
8
Q
the effect of light availability on plants
A
- the greater the availability of light, the greater the success of plants as light is required for photosynthesis
- plants can develop strategies to cope with different light intensities (e.g. larger leaves, different photosynthetic pigments)
9
Q
the effect of light availability on animals
A
- low availabilities of light affect the whole animal food chain due to being indirectly affected by a lack of plants
- affects cell mutation (vitamin D)
- influences metabolic rate so affects movement and reproduction
10
Q
the effect of temperature on plants
A
- affects enzymes controlling metabolic reactions
- plants will develop more rapidly in warmer temperatures
- changes in temperature can trigger leaf abscission, dormancy and flowering
11
Q
the effect of temperature on animals
A
- affects enzymes controlling metabolic reactions
- ectothermic animals will develop more rapidly in warmer temperatures
- changes in temperature can trigger migration and hibernation
12
Q
effect of water availability on plants
A
- severe water stress can lead to death
- lack of water will cause most plants to wilt
- water is required for photosynthesis
- waterlogged soil can lead to a lack of oxygen availability
- xerophytes adapted to low levels of water
13
Q
effect of water availability on animals
A
- severe water stress can lead to death
- water stress can trigger migration
- aquatic organisms will die or migrate if habitats dry out
14
Q
effects of oxygen availability on plants
A
- waterlogged soils affects aerobic respiration and active transport as air spaces between the soil particles are saturated with water
15
Q
effects of oxygen availability on aquatic animals
A
- water becoming too warm or flow rate too slow can lead to a drop in oxygen concentration, suffocating aquatic organisms
16
Q
clay soil
A
- fine particles
- easily waterlogged
- forms clumps when wet
- fewer plants can survive in waterlogged soil due to reduction in aerobic respiration
- roses, geraniums, earthworms, nematodes, microbes
17
Q
loam soil
A
- different sized particles
- retains water but does not become waterlogged
- ideal conditions for plants as sufficient water and sufficient ai spaces
- high levels of minerals and decaying matter
- wisteria, delphinium, earthworms, nematodes, microbes
18
Q
sandy soil
A
- coarse, well-separated particles that allow for free draining
- does not retain water
- easily eroded
- does not retain water well enough for many plants to survive
- low levels of minerals, acidic
- plants adapted to retain moisture with large root systems such as cacti and lavender
- termites, nematodes, microbes
19
Q
converts trophic levels
A
- each stage in the food chain
- producer = an organism that converts light energy into chemical energy through photosynthesis
- consumers = organisms that obtain their energy by feeding on other organisms
- food chains rarely have more trophic levels after a quaternary consumer as there is not sufficient biomass and stored energy left to support any further organisms
20
Q
calculating net biomass production
A
gross production - respiratory losses
21
Q
calculating ecological efficiency
A
biomass transferred to next trophic level / biomass available at previous trophic level X100
22
Q
efficiency at producer level
A
- only convert 1-3% of sunlight they receive into chemical energy and therefore biomass
- not all solar energy is available for photosynthesis, a lot of it is reflected, transmitted through the leaf or a unusable wavelength
- other factors may be a limiting factor to photosynthesis such as water availability
- a proportion of energy is ‘lost’ as it is used for photosynthetic reactions
23
Q
efficiency at consumer levels
A
- convert at most 10% of biomass in food to organic tissue
- not all biomass of an organism is eaten
- some energy is transferred to the environment as metabolic heat from movement or respiration
- some parts of an organism are eaten but indigestible, so energy content is egested as faeces
- some energy lost in excretory materials
24
Q
how can human activities manipulate biomass through ecosystems
A
Agriculture
- provided with required abiotic factors
- competition and predators removed
- creates very simple food chains, so fewer trophic levels so as much energy as possible is transferred to humans
25
Fencing
- use of structures to separate and contain animals and crops
- reduces loss to predators and pests, increasing yield and therefore biomass available to humans
26
greenhouses
- artificial environment for growing plant crops
- abiotic needs of plants are met, increasing biomass production
27
pesticides and herbicides
- use of chemicals to kill insect herbivores and weeds
- biomass losses to insect consumers and competition are reduced, increasing yield and available biomass
28
stabling
- animals are sheltered indoors and provided with food
- reduces energy movement through maintenance of temperature and restricted movement, reduced biomass lost through respiration
29
food chain management
- agricultural food chains restricted typically to 2or 3 trophic levels
- minimises energy/biomass lost at each trophic level, so more available to human consumers
30
decomposers
- an organism that feeds on and breaks down dead plant or animal matter
- turns organic compounds into inorganic ones (nutrients) available to photosynthetic producers in the ecosystem
- primarily microscopic fungi and bacteria, but also larger fungi such as toadstools
- saprotrophs because they obtain their energy from dead or waster organic material
- digest food externally by releasing enzymes which break down complex organic molecules into simpler soluble molecules
31
detritivores
- help to speed up the decay process by feeding on detritus (dead and decaying material)
- break detritus down into smaller pieces of organic material which increases the surface area for decomposers to work on
- perform internal digestion
- e.g. woodlice, earthworms, maggots
32
Recycling nitrogen
- essential element for making amino acids and nucleic acids in plants and animals
- animals obtain nitrogen from the food they eat, but plants need to take in nitrogen from their environment
- nitrogen is abundant in the atmosphere, but plants cannot take up nitrogen gas
- bacteria play a very important role in converting nitrogen into a form useable to plants
33
nitrogen fixation
- nitrogen fixing bacteria (e.g. azobacter and rhizobium)
- contain nitrogenase
- combines atmospheric nitrogen with hydrogen to produce ammonia (NH3)
- other bacteria convert the ammonia into other organic compounds that can be absorbed and used by plants
- some are free living soil bacteria (Azobacter)
- come live inside root nodules (Rhizobium) of leguminous plants (plants gain amino acids, bacteria gains carbohydrates)
34
nitrification
- ammonium compounds in the soil are converted into nitrogen containing molecules that can be used by plants
- oxidation reaction, so only occurs in well aerated soil
- nitrifying bacteria (e.g. nitrosomonas) oxidise ammonium compounds into nitrites (NO2-)
- nitrobacter oxidise nitrites into nitrates (NO3-)
- nitrate ions are highly soluble so is how most nitrogen enters a plant
35
denitrification
- in the absence of water( (waterlogged soils) denitrifying bacteria convert nitrates in the soil back into nitrogen gas
- under anaerobic conditions
- bacteria use nitrates as a source of energy for respiration and nitrogen gas is released
36
ammonification
- decomposers convert nitrogen containing molecules in dead organisms and waste products into ammonium compounds
37
nitrogen cycle
- nitrogen gas in atmosphere into ammonia in soil through nitrogen fixation by bacteria and ammonification by decomposers
- nitrification of ammonia into nitrites then nitrates by nitrifying bacteria
(denitrification by anaerobic bacteria)
- uptake and assimilation by plants
- plant protein eaten by animals and converted into animal proteins
- death, decay
- nitrogen fixation by non-living processes
38
processes involved in the carbon cycle
- photosynthesis
- respiration
- combustion
- feeding
- death
- decomposition
39
Main processes in the carbon cycle
- carbon stored in producers in the form of macromolecules (e.g. proteins, lipids) converted through photosynthesis
- passes up food chain when eaten
- carbon compounds in dead organisms released by decomposers
- carbon released as CO2 into the atmosphere through respiration and combustion of fossil fuels
- if decomposition is prevent (e.g. in peat bogs or ocean floors) carbon is 'trapped' and remains form fossil fuels
40
succession
the progressive replacement of one dominant type of species or community by another in an ecosystem until a stable climax community is formed
41
primary succession
occurs on an area of land that has been newly formed or exposed such as bare rock. There is no soil or organic material present to begin with
42
secondary succession
occurs on areas of land where soil is present, but contains no plant or animal species e.g. bare earth remaining after a forest fire
43
deflected succession
- human activities can halt natural flow of succession and prevent the ecosystem from reaching a climax community
- agriculture is one of the main reasons deflected succession occurs
- trampling and grazing by domesticated animals means large areas of land remains grassland
- removing existing vegetation to plant crops means crops become final community
- burning as a means of forest clearing increases biodiversity as it provides space and nutrient-rich ash for other species such as shrubs to grow
44
plagioclimax
the final stage formed when succession is stopped artificially
45
characteristics of a pioneer community
- colonisers e.g. lichen
- hostile conditions
- low species diversity
- instability
46
characteristics of a climax community
- dominant species e.g. woodland
- less hostile conditions
- high species diversity
- stability
47
long term and short term fluctuations in atmospheric carbon dioxide
Short term:
- fluctuate through the day as photosynthesis only occurs during the day, removing CO2 from the atmosphere, so CO" levels are higher at night
- CO2 levels are lower in summer than winter as photosynthesis rates are higher
Long term:
Increased significantly due to:
- combustion of fossil fuels
- deforestation
48
when does primary succession occur
- after volcanic eruptions, when deposited lava cools and solidifies, creating igneous rock
- sand is blown by the wind or deposited by the sea to create new sand dunes
- silt and mud are deposited at river estuaries
- glaciers retreat, depositing rubble and exposing rock
49
main seral stages
- pioneer community
- intermediate community
- climax community
50
the process of succession
(pioneer community)
- bare rock/ barren land
- colonisers like lichen carried by wind or in animal droppings start to break down bare rock
(intermediate community)
- weathering of bare rock provides particles that form the basis of soil
- contains nutrients and retains water so supports secondary colonisers e.g. mosses
- may provide food for animal species
- decay creates a layer of humus
- followed by tertiary colonisers e.g. ferns
- abiotic conditions increasingly favour grasses, shrubs and then small trees
(climax community)
- a few dominant plant and animal species e.g. woodland
- stable state
- climate determines dominant species
- biodiversity decreases as dominant species outcompetes others
-
51
adaptations of organisms in the pioneer community
- the ability to produce large numbers of seeds or spores which are blown by the wind and deposited on new land
- seeds that germinate rapidly
- ability to photosynthesise
- tolerance of extreme environments
- ability to fix nitrogen from the atmosphere, adding to soil minerals
52
adaptations of organisms in the intermediate community
- tolerance of low water and mineral environments
- waxy cuticle to prevent water loss
- at each stage, species are better adapted, outcompeting others
53
adaptations of organisms in the climax community
Temperate climates
- trees dominant as mild temperatures and abundant water
Subarctic conditions:
- herbs or shrubs dominant as temperature and water availability is low
54
Animal succession
- similar to plant succession but lower as they have to move in from neighbouring areas and new land is often geographicallty isolated
- primary colonisers such as insects and worms consume and shelter in mosses and lichens present
- secondary colonisers such as ammals and reptiles will arrive when conditions are suitable e.g. suitable food source and sufficient plant cover
55
distribution
- where individual organisms are found within an ecosystem
- usually even throughout an ecosystem as organisms are generally found where abiotic and biotic factors favour them
- usually measured using a belt or line transect
56
abundance
- the number of individuals of a species present in an area at any given time
- may fluctuate daily
- immigration and births will increase the number, emigration and death will decrease the number
- usually estimated through sampling techniques
57
measuring pant abundance
- quadrats are placed randomly in an area
estimated number in population (per m²) = number of individuals in a sample / area of sample (m²)
58
measuring animal abundance
- capture-mark-release-recapture method used to estimate population sizes of animals that are mobile
- capture as many individuals as possible in a sample area
- mark or tag each individual
- release marked animals back into the sample area and allow time for them to redistribute themselves throughout the habitat
- recapture as many individuals as possible in the original sample area
- record the numbers of marked and unmarked individuals present in the sample
- release all individuals back into their habitat
- use the Lincoln index to estimate population size
Estimated population size = (number of individuals in first sample * number of individuals in second sample) / number of recaptured marked individuals
59
Lincoln index
Estimated population size = (number of individuals in first sample * number of individuals in second sample) / number of recaptured marked individuals
60
Simpson's index of diversity
always results in a value between 0 and where 0 represents no diversity and 1 represents infinite diversity. the higher the value the more diverse the habitat
61
Quadrats
Used to measure how common organisms are in a sample area or to compare how common organisms are in different sample areas
- area to be sampled divided into a grid
- random number generator used to pick coordinates of sample area
- quadrat (frame enclosing known area) placed in coordinate
- organisms in quadrat counted
- repeat procedure and calculate mean
- can sample additional areas to compare effect or factors such as sunny vs shaded
62
transect
used to study how distribution of organisms change across an area
- line marked out in the sample area
- either count organisms that touch the line or place quadrats across the line at set intervals and count the organisms
- repeat procedure and calculate mean
63
pitfall trap
Sample insects etc. living on the ground
- hole or container dug into ground with steep sides
- covered to keep out rain and predators
- insects fall and cannot escape
64
pooter
Sample and identify individual insects
- container with two tubes, one covered with mesh
- covered tube is sucked which draws air and insects into the container
65
beating net/tray
Sample insects living in trees/bushes
- net/tray held underneath tree/bush
- foliage is shaken, insects fall onto net/tray
66
sweep net
Sample insects living in long grass, rivers etc.
- fine net with long handle to be used in a sweeping motion to capture insects
