Ecosystem Flashcards
What is a habitat
The place where an organism lives
Definition of population
All organisms of one species in a habitat
What is a producer
An organism that produces organic molecules using sunlight energy
What is a consumer
An organism that eats other organisms
What is a decomposer
An organism that breaks down dead or undigested organic material
What is a trophic level
A stage in a food chain occupied by a particular group of organisms
What is an ecosystem
All organisms living in a certain area and all the non-living conditions found there
What are biotic factors
The living features of an ecosystem
Examples of biotic factors
Presence of predators or food
What are abiotic factors
The non living features of an ecosystem
Examples of abiotic factors
Temperature, rainfall, soil nutrients availability
What is the main route by which energy enters an ecosystem
Photosynthesis
What is the main route by which energy enters an ecosystem
Photosynthesis
How do plants store energy
As biomass
What is biomass
Biomass is the mass of living material
How much energy is lost
90%
What is ecology
This is the study of the relationship between organisms and their environment
Why is soil important for plants
It provides the minerals needed for growth
Water (for photosynthesis)
Anchorage for the roots
What does sandy soil contain
0-10% clay, 0-10% silt, 80-100% sand
What does clay contain
50-100% clay, 0-45% silt, 0-45% sand
What does loam contain
10-30% clay, 30-50% silt, 25-50% sand
How does particle size affects the air content and permeability of soils
Few air spaces retain water and flood easily
Lots of large air spaces does not retain water
Describe clay
Clay has fine particle, is easily waterlogged, and forms clumps when wet. The particles are small. They have a permeability to water as water is retained in soil.
Describe loam
Particles are small and large. They have a medium permeability to water as their retention is good. It retains water but doesn’t become waterlogged
Describe sandy soil
They have many and large air spaces. They have poor permeability, little water is retained in soil. Has coarse and well separated particles. Sandy soil does not retain water and easily eroded.
What is a producer
An organism that converts light energy into chemical energy by the process of photosynthesis
What is a carnivore
Eats only other animals
What is a herbivore
Eats only plants
What is an omnivore
Eats both animals and plants
What is a primary consumers
Eats a producers. Usually, a herbivore
What is a secondary consumer
Eats a primary consumer, usually a carnivore but also be a herbivore
How is biomass lost
Biomass is lost in urine, faeces,and used to provide energy for movement, growth etc
How to calculate biomass at each trophic level
Multiply the biomass present in each organism by the total number of organisms in that trophic level
How is biomass measured for areas of land and areas of water
Areas of land- gm^-2
Areas of water- gm^-3
What is ecological efficiency
The efficiency with which biomass or energy is transferred from one trophic level to the next
What is net production
Gross production - respiratory losses
What is gross production
Total solar energy that plants convert to organic matter
Why is the concentration of CO2 greater at night than during the day
No light so no photosynthesis occurs
Lower temperature means that respiration happens at a slower rate
Why have the levels of CO2 increased over the past few hundred years
Combustion of fossil fuels CO2 which was locked up million of years ago below the Earth’s surface
Deforestation- removes photosynthesising biomass. Reduces volume of CO2 that can be removed from the atmosphere from the atmosphere
How is methane produced
Methane is produced when decomposers break down dead remains of organisms
Why has methane levels have more than doubled in the last 150 years
More extraction of fossil fuels
More decaying waste
More cattle
Natural stores such as frozen ground thawed
What is succession
The process of ecosystem change over time
State features of a pioneer species
Produces large quantities of easily dispersible seeds/spores
Withstand extreme conditions
Ability to fix nitrogen. Even if there is soil, it has few/no nutrients
Ability to photosynthesise
Rapid germination of seeds
Adaptations that enable marram grass to be a pioneer species
Deep roots
Tolerates salty environment
Describe primary successions
Begins by the colonisation of an inhospitable environment. This is the first serial stage. There is no soil. Pioneer species colonises the rock/bare ground and release minerals which enable other species to survive. As plants die and decompose the soil deepens and larger plants can now survive- stability increases. Diversity increases
What is climax community
Soil now rich and deep enough to support large trees
What is deflection succession
A community that remains stable only because human activity prevents succession from running its course
How does random sampling take place
Mark out a grid at right angles
Use a random number generator to pick the x coordinate the. The y coordinate
Take a sample from that place
Stage an advantage of random sampling
Data is not biased by selective sampling
State disadvantages of random sampling
May not cover all areas equally
Species with low presence may be missed
What is systematic sampling
It is a type of non-random sampling. Samples taken from fixed intervals across the habitat
State an advantage of systematic sampling
Useful when habitat shows a clear gradient in environmental factors
State an advantage for systematic sampling
Only species on the line/belt are recorded leading to an underestimate
What is stratified sampling
A type of non-random sampling that divides habitat into areas which appear to be different and sample each section separately
State an advantage of stratified sampling
Ensures all areas of habitat are sampled. Species are under represented
State disadvantages of stratified sampling
May lead to over representation
Could have a disproportionate number of samples taken in smaller areas that look different
What is opportunistic sampling
A type of non random sampling in which researchers takes samples based out on prior knowledge or during the process of collecting data. May sample on area that they know contains a particular species.
State an advantage of opportunistic sampling
Easier and faster than random sampling
State disadvantages of opportunistic sampling
Data may be biased
Overestimate of biodiversity
What is species richness
The number of different species living in a habitat
What is species evenness
A comparison of the number of individuals of each species living in a community
What is secondary succession
This occurs on areas of land where soil is present, but it contains no plants or animal species
What is the organic component of soil know as
Humus
When the soil becomes able to support the growth of new species of plants what is it known as
Secondary colonisers
What are dominant species
The most abundant species (by mass) present in the ecosystem at a given time
How do plants develop strategies to cope with different light intensities
In areas of low light they may have larger leaves. They may also develop photosynthesis pigments that require less light, or reproductive systems that operate only when light availability is at an optimum
What happens to a plant if they don’t have water
They will wilt as water is needed to keep cells turgid and so keep the plant upright. It is also required for photosynthesis
Why is fast flowing cold water a necessity in aquatic ecosystems
It contains high concentrations of oxygen
What happens if water in aquatic systems is too warm
The flow rate becomes too slow resulting in a drop in oxygen concentration that can lead to the suffocation of aquatic organisms
How is oxygen availability for plants reduced in waterlogged soil
The air spaces between the soil particles are filled with water
Shat do decomposers do
They break down dead organisms releasing nutrients back into the ecosystem
What percentage of the total energy originally present in the incident sunlight is ginally embodies as biomass in s tertiary consumer
Around 0.001%
How do you calculate biomass consumed
Mass (per metre squared per year) x area of land
What is decomposition
A chemical process in which a compound is broken down into smaller molecules or its constituent elements
What is a decomposer
This is an organism that feeds on and breaks down dead plant or animal matter, thus turning organic compounds into inorganic compounds. Decomposers are saprotrophs because they obtain their energy from dead organisms or organic material. This is saprobiotic nutrition.
What are detritivores
They help speed up the decay process by feeding on detritus. They break it down into smaller pieces of organic material, which increases the surface area for the decomposers to work on
What are detritus
Dead and decaying material
How is nitrogen used by living organisms
Nitrogen needs to be combined with other elements such as oxygen and hydrogen. Without bacteria, nitrogen would quickly become a limiting factor in ecosystems
Describe nitrogen-fixing bacteria
E.g. azotobacter and rhizobium, contain the enzyme nitrogenase, which combines atmospheric nitrogen with hydrogen to produce ammonia
What is ammonia
A form if nitrogen that can be absorbed and used by plants.
What is nitrogen fixation
When nitrogen is absorbed and used by plants.
State an example of free-living soil bacterium
Azotobacter
Describe rhizobium
Rhizobium live inside root nodules.
What are root nodules
These are growths on the roots of leguminous
What is nitrification
The process by which ammonium compounds in the soil are converted into nitrogen-containing molecules that can be used by plant
State the two steps in which nitrification takes placed
Nitrifying bacteria- oxidise ammonium compounds into nitrites (NO2-)
Nitrobacter- this is another genus of nitrifying bacteria. Oxidise nitrites into nitrates (No3)
What is denitrification
In the absence of oxygen e.g. in waterlogged soils,denitrifying bacteria convert nitrates in the soil back to nitrogen gas. It happens under anaerobic conditions
What is ammonification
The process by which decomposers convert nitrogen- containing molecules in dead organisms, faeces, and urine into ammonium compounds
Why are atmospheric carbon dioxide levels higher at night than during the day
Respiration is carried out by all living organisms throughout the day and night, releasing carbon dioxide at a relatively constant rate into the atmosphere.
Why is CO2 called a greenhouse gas
Increased levels of CO2 traps more thermal energy in the atmosphere
What is the final stage called when succession is artificially stopped
Plagioclimax
Which provides more information a line transect or belt transect and why
A belt transect as two parallel lines are marked and samples are taken of the area between these specific points
What is a population
A population is a group of similar organisms living in a given area at a given time
How do you calculate the estimated number in population
Number of individuals in sample / area of sample
How do you measure animal abundance
Use the capture-mark-release-recapture technique
State the formula for estimated population size
Number of individuals in 1st sample x number of individuals in 2nd sample / number of recaptured marked individuals
Index of diversity formula
D=N(N-1) / sum of(n-1)
D= diversity index
N= total number of organisms in an ecosystem
n= number of individuals in each species
