SB9 Ecosystems and Material Cycles Flashcards
List abiotic factors
temperature, amount of water, light intensity, levels of pollutants
List biotic factors
competition, predation
Define mutualism
a relationship between two organisms from which both benefit
Define interdependence
organisms depending on each other for food and shelter in order to survive and reproduce
Describe the use of quadrats
A quadrat is a square frame enclosing a known area
What are the energy transfers that occur between trophic levels?
The sun is the source of energy - plants convert light energy into glucose - a primary consumer eats the plant - a secondary consumer eats the animal
Less energy is transferred for each trophic level and the mass of organisms goes down as you go up levels
Why are food chains only so long?
Each time you go up a level, the mass an therefore biomass decreases, so you would have to consume a lot to make it efficient
Formula for efficiency between trophic levels
energy transferred to next level / energy available at previous level X 100
Explain how communities are affected by abiotic factors
Population sizes will increase and decrease depending on the factors affecting their habitat conditions
How do you use belt transects to study distribution along a gradient?
Mark a line and place quadrats on this line at regular intervals. Collect the data and find the percentage coverage in the quadrats and compare results across thegradient
Define the biotic factor : predation
the more predators there are, the less prey there will be
Define the biotic factor : competition
organisms compete against each other for the same resources
Define the abiotic factor : temperature
eg. distribution of bird species in Germany is changing due to rise of avg. temperature
Define the abiotic factor : amount of water
eg. daisies grow best in slightly damp soils. If soil becomes too dry or waterlogged, the population will decrease
Define the abiotic factor : light intensity
eg. as trees grow and provide more shade, grasses may be replaced by fungi which are better to cope in low light intensity
Define the abiotic factor : levels of pollutants
eg. lichen are able to survive if the concentration of sulfur dioxide is too high
Define parasitism
a relationship between two species where only one benefits
Give examples of parasites and mutualists
Parasites - fleas
Mutualists - bees visiting flowers and pollinating them
Define eutrophication
An excess of nutrients in water due to too much nitrates and fertilisers added, which can lead to the death of many species
Disadvantages to non-indigenous species
- Can compete with indigenous species over resources
- Brings new diseases that indigenous species may not be immune to
Disadvantages of fish farming
- huge amounts of waste
- breeding ground for parasites
- predators (eg. sea lions) are attracted to nets and become trapped in them and die
- farmed fish can escape into the wild, and harm indigenous species
Define conservation and give examples
Conservation schemes can protect biodiversity by preventing species from dying out eg. protecting a species’ natural habitats, using seed banks to store seeds, introducing captive breeding programmes
Define reforestation
When land where forest previously stood is replanted to form a new forest
Benefits to maintaining biodiversity
- protecting the human food supply
- ensuring minimal damage to food chains
- providing future medicines
- cultural aspects
- ecotourism
- providing new jobs
Define food security
Access to enough food that is safe for us to eat with the right balance of nutrition
How is increasing consumption of meat and fish, and increasing animal farming affecting food security?
As people become wealthier, people eat meats and fish that are higher up in the food chain. These have less biomass, and therefore more of it is needed to produce the same amount of food as crops. You risk over-fishing
How is sustainability affecting food security?
Sustainability means meeting the needs of today’s population without affecting the ability of future generations to meet their needs
How is environmental changed affecting food security?
Burning fossil fuels releases lots of CO2, causing global warming. Climate change affects the growth of crops, which could reduce yields
How are new pests and pathogens affecting food security?
Pests and pathogens can cause damage to crops and livestock
How is food preserved?
- Storing foods in a fridge or freezer lowers temp. of food, and slows down decomposition
- Airtight cans stops microorganisms getting in
- Drying food removes water needed for bacteria to grow and survive on the food
How is compost made?
by decomposed organic matter that is then used as a fertiliser for crops and garden plants
How does temperature affect the rate of decay?
A warm temp. speeds up the rate of enzyme-controlled reactions in microbes, so decay happens faster
How does water content affect the rate of decay?
Decay takes place faster in moist environments as the organisms involved in decay need water to survive
How does oxygen availability affect the rate of decay?
Decomposition is faster where there is plenty of O2 available as there is O2 for the microorganisms to respire with
Name some indicator species
- Stonefly larvae = clean water
- Blood worms / sludge worms = polluted water
- Lichen = clean air
- Blackspot fungus = clean air
Disadvantages to indicator species
Don’t give accurate figures for how much pollution is present, and there may be other factors impacting absence/presence of species
Indicator species for water pollution
- Stonefly larvae / freshwater shrimps are sensitive to concentration of dissolved oxygen in the water
- Blood worms / sludge worms indicate a very high level of water pollutant as they only live in polluted conditions
Indicator species for air pollution
- Lichen are sensitive to concentration of sulfur dioxide
- Blackspot fungus is found on rose leaves in clean air
