6.5 Ecosystems Flashcards
Ecosystem
a community of animals, plants and bacteria interrelated with the physical and chemical environment/ group of living and non living things and their interrelationships
Components of ecosystem
Habitat, population, community, niche
Habitat
Where an organism lives
Population
all of the organisms of one species who live in the same place at the same time and can breed together
Community
all the population of different species who live in the same place at the same time and can interact with each other
Niche
role of a specie/organism in an ecosystem = so specific that more than 2 species niche can’t overlap = one would outcompete the other if they came close to occupying the same niche
2 important factors in an ecosystem
Abiotic and biotic
Biotic is the…
Living factors
Biotic factors
- Competition
- Diseases
- Predation
- Consumers
- Decomposers
Abiotic is the…
Non living factors
Abiotic factors
- pH
- Temperature
- Humidity
- Weather
What should biotic and abiotic factors be like
Survival happens when there’s a good mixture of biotic and abiotic factors
What word would you use to describe ecosystems and why
Dynamic = constantly changing
2 main types of changes in ecosystems
Cyclic changes and unpredictable changes
Cyclic changes
change that repeats itself e.g. seasons and predator prey relationship = organisms can adapt to these changes e.g. hibernating in winter
Unpredictable changes
E.g. natural disasters
Biomass
Talking about energy
What is biomass transferred between
Trophic levels (energy levels)
Energy transfer diagram
Trophic levels
Producer
Primary consumer
Secondary consumer
Tertiary consumer
Producer
organism that can photosynthesise and produce organic molecules from water, co2, sunlight
Primary consumer
Consumes producer
Secondary consumer
Consumes primary consumer
Tertiary consumer
Usually ends w this because there’s no energy to transfer beyond this
What happens to heat energy through the ecosystem
released (lost as you go through energy levels through processes like respiration
Energy lost through the ecosystem through:
- heat energy
- Dead organisms and waste materials = further decomposed by bacteria and fungi which also release heat
Pyramid of numbers
The higher you go up the pyramid, the lower the number of organisms due to the energy loss
Why do we not rlly use pyramid of numbers
isn’t true reflection of the biomass, so pyramid of biomass is created (each bar is proportionate to the dry mass of the organism at each trophic level)
Which is better to look at: dry mass or wet mass and why
Dry mass is better than wet mass because it’s a true reflection of the organisms biomass as the wet mass can vary and be a reflection of water intake rather than biomass
Ecological efficiency equation
How to increase efficiency
By manipulating the transfer of biomass because productivity = rate of production of new biomass by producers
Two types of productivity
Gross primary productivity, net primary productivity
Gross primary productivity
rate at which plants convert light energy to chemical energy - rate of photosynthesis
Net primary productivity
how much of the chemical energy is transferred in the biomass - proportion of energy from the sun that has entered the food chain
How do you increase primary productivity
By manipulating the system to increase transfer
Ways to manipulate the system to increase transfer
- adjust the limiting factors from a reaction:
- Light levels (if limiting rate of photosynthesis - plant the crops early to allow a longer growing season or use light banks where the light are turned on 24/7)
- Water levels (have drought resistant strains)
- Temperature (grow the plants in greenhouses or plant crops early to allow a longer growing season = can miss winter/certain weather periods)
- Nutrients (crop rotation = soil would keep on being fertile)
- Pests (use pesticides or pest resistant breeds)
- Fungal diseases (use fungicides)
- Competition from weeds for light and nutrients (use herbicides)
Hiw to increase secondary productivity
for primary consumers to consume as much of the plants as possible
Manipulate system to increase transfer
Why is transfer not good in the first place
- Some plants die
- Some parts of the plants can’t be digested so Egestion through their faeces occurs
- Even when food is consumed, lots is respired and only a little amount is left for the transfer
How to manipulate the system to increase transfer (increase secondary productivity)
- harvest the animal before adulthood because lots of energy is used to grow into adults, so harvest right before that to reduce energy loss
- Use selective breeding to produce improved growth rate e.g. egg production and growth production
- Antibiotics to animals to avoid loss of energy to pathogens
- Use zero grazing policy = put animals in containers = more energy allocated to growth and muscle rather than finding food
- Transfer energy from producers to consumers is inefficient, therefore grains can be used to feed humans directly and there’s locations in the world where grains can’t be grown, but animals can survive
Issue w some factors used to increase transfer
Some of these factors aren’t ethical, so there must be a balance between the welfare of the animals and efficient food production.
Steps of the nitrogen cycle
Nitrification
Ammonification
Denitrification
Nitrogen fixation
Nitrification
Ammonification
Denitrification
Nitrogen fixation
Nitrogen cycle diagram
Saprotrophs
decomposing bacteria and fungi
What do the bacteria produce
enzymes which digest molecules into smaller molecules which are then reabsorbed by the organism and can be stored and respired.
How else can nitrogen fixation occur
by the haber process or lightning = only accounts for 10% of all nitrogen fixation
What’s nitrogen needed for
Protein synthesis
Azobacter
Free living in the soil
Rhizobium
lives in root nodules of legumes plants e.g. peas, beans
What’s rhizobium’s relationship w plants like
mutualistic relationship with the plant so the bacteria provides the plant with nitrogen and receives carbon in return
How has rhizobium developed this relationship w plants
- adapted this function because it contains a protein called leghaemoglobin = absorbs oxygen and keeps the conditions anaerobic = when the conditions are anaerobic, bacteria uses the enzyme nitrogen reductase to convert nitrogen into ammonium ions
Ammonification done by nitrosomonas bacteria
Chemoautotrophic
Nitrobacter
goes from nitrites to nitrates = nitrification = done through oxidation = needs to have aerobic conditions
Decomposers
feed on dead organic matters and turn them into inorganic matter. Saprophytic (feed on dead organic matter). Secrete enzymes out of their body to digest food = external digestion. Absorb digested food into their body by diffusion
Detritivores
feed on dead organic matters and turn them into inorganic matter. Internal digestion. Eat food and increase surface area of food they’re digesting to speed up the process of decomposition
Carbon cycle diagram
Succession
progressive change in a community overtime
What do you need for succession to begin
need pioneer species to reach the land
Examples of pioneer species
Algae and lichens
Why can pioneer species survive in these conditions
adapted to work in poor conditions and tolerate extreme conditions e.g. salty water, lack of fresh water
What do pioneer species do
start producing dead organic materials + other processes occur e.g. erosion of rocks, end up producing soil which allows larger plants e.g. mosses to grow = replace the pioneer species
Larger plants are replaced by smaller plants
What does succession end in
A climax community
Overview of succession
- Pioneer species colonise area
- Natural events e.g. rock erosion or wind blowing which creates more fertile soil + accumulation of nutrients = replaces pioneer species with new sets of species = add nutrients + those species are replaced as the nutrient levels build up
Primary succession
initial progressive change that occurs in a community of organisms overtime = directional, gradual change
Pioneer community
species that initially come in and colonise the area = adapted to live in harsher conditions
Climax community
final, stable community that exists after succession has finished
Deflected succession
succession is stopped/interfered w due to human interventions = results in a sub-climax community
Deflected succession is caused by:
- cutting grass
- Cutting down trees
- Building dams
- Burning land
- Use of fertilisers and herbicides
Distribution
Presence or absence
Abundance
Number of each specie
Quadrats
same as module 4 = systematic or random sampling can be used = to know how many samples to take, make a cumulative frequency table, look at species distribution and take a sample = measure how many new species are being found through every quadrat. Eventually you’ll find that you aren’t finding new species when you lay the quadrat down, so you stop taking samples.
Transects
good to look for gradients = line (just tape) and belt (use tape w quadrat) transects
Best way to check for distribution across a distance
Kite diagram
