SB9 Flashcards
Ecosystems and material cycles
Define ecosystem
The living + non-living parts of a specific area
Define habitat
The non-living part of an ecosystem
Define community
All population of all organisms in an ecosystem
Define population
all members of one species in an ecosystem
Define niche
The role of one species within an ecosystem
Define interdependent
Species that rely on others in a community for resources
Define biomass
The total tissue mass that makes up an organism
Define the purpose of a food web
- Shows feeding relationships between organisms in a community
- Used to predict what will happen if change occur
Define abiotic factors + give examples
- Physical and chemical non-living factors that may have an effect on an ecosystem
- Light, temp, space, soil pH, wind, oxygen/carbon dioxide concentration
Define biotic factors + give examples
- Living components in an ecosystem that affect other living organisms
- Predators, Competition
Define indicator species
Organisms whose presence signifies the presence/absence of pollution
Define eutrophication
When a water body becomes overly enriched with nutrients, leading to the plentiful growth of simple plant life
Define parasitism
Relationship where one organism benefits by feeding off of a host - causes harm to the host
Define mutualism
Relationship where organisms live together and mutually benefit from it
Define biodiversity
Variety of plant and animal life in a habitat
Define reforestation
Planting a new forest where an old one has been cut down
Define the purpose of conservation programs
Made to protect rare/endangered species
Define captivity
Where endangered animals are bred in protected environments to increase their numbers
Define food security
Having sufficient access to safe and healthy food at all time
Define potable
Safe to drink
Define the role of nitrifying bacteria
Turns ammonia in decaying matter into nitrates and nitrites
Define the role of nitrogen-fixing bacteria
Turns nitrogen gas in the environment into ammonia in order to create ammonium ions
Define the role of denitrifying bacteria
Turns nitrites and nitrates back into nitrogen gas
Define the purpose food preservation + give examples
- Slow down the rate of growth of decomposers to keep food fresher for longer
- Adding salt/sugar, modified atmosphere packaging, canning, pickling, sealing, chilling, freezing
Define compost
Waste garden material that is well decayed
How do you measure population
- Take samples using quadrats that are placed randomly (using an RNG) in an area split into squares
- Number of individuals in each quadrat is counted
What is the calculation for population size
number of organisms in all quadrats * (total area/ combined area of all quadrats)
What are food chains also known as
Trophic levels
Place these in order and describe their trophic level:
Carnivore
Autotroph
Herbivore
Autotroph - producer
Herbivore - primary consumer
Carnivore - secondary
How to measure the effect of abiotic factors
- Use a belt transect
- Peg out a long tape measure (>20m) starting in an area with none - heavy shade
- Make measurements at regular intervals
- Place top left hand corner of quadrat at measurement point and measure + record the abiotic factors at that area
- Record abundance of selected plant
- Repeat at each measurement point
Why do we not randomly place quadrats when measuring the effect of abiotic factors
So we can observe a gradual change in effect
What is water pollution caused by
Poisonous substances released by factories e.g mercury, fertilisers, sewage
Advantages of indicator species
+ Easy to locate in appropriate places
+ Don’t require a lot of equipment to collect them
+ Abundance gives idea of long-term health of area
Disadvantages of indicator species
- Doesn’t give accurate information about level of pollution
- Doesn’t give idea of rapid changes in pollution levels
How does malaria work
- Mosquito sucks blood of previously infected person
- Mosquito bites another person inputting protists into their bloodstream
- Protists travel from blood - liver - liver cells
- Protists multiply in the liver and eventually burst out and into blood cells
- Protists multiply in blood and burst in a cycle
- Destruction of red blood cells = fatigue, fever, anamemia
Advantages of fish farming
+ Better fed fish
+ Produces more fish
Disadvantages of fish farming
- Kept in small spaces
- Parasites spread easier
How does eutrophication work
- Fertilisers are added to field, heavy rain washes fertilisers off
- Nitrates and phosphates dissolve in soil water and those not taken up are washed into a stream
- Increase nitrate and phosphate concentration in water leads to rapid surface algae growth
- Blocks sunlight from passing and reaching underwater plants so they die and less oxygen is produced
- Decompsers increase oxygen usage
- Fish die due to lack of oxygen to respire
What is food security reduced by
- Increased population
- Climate change
- New pests and pathogens
- Armed conflict
Describe the water cycle
- Evaporation = water in bodies of water turn to gas
- Condensation = water vapour cools and turns in clouds
- Transport = clouds pushed far away by strong winds
- Precipitation = rain/snow/sleet falls from the sky
- Surface runoff = excess water runs along the surface of wet ground
- Infiltration = water that has fallen and is absorbed into the ground and stored by aquifiers
- Transpiration = water is constantly pulled up to the leaves of plants and is once again evaporated
How is water made potable
- Filtration = remove debris
- Chlorination = to kill any pathogens
How is seawater made into freshwater
- Desalination (boiling/reverse osmosis)
- Distillation
What is decay caused by
Decomposers (microorganisms)
Why is nitrogen necessary
It is needed to create nitrogen containing compounds such as DNA and proteins
How to increase nitrogen concentration
- Artificial/natural fertilisers
- Crop rotation
Advantages and disadvantages of artificial fertilisers
+ Easy to use
+ No risk of pathogens
- Expensive
- Few types of nutrients
Advantages and disadvantages of natural fertilisers
+ Cheaper
+ Allows animal waste to be removed
- Less concentrated nutrients as they have complex chains of nitrogen
- High risk of pathogens
How does crop rotation help soil
- Increase fertility by adding nitrates from crop containing nitrogen-fixing bacteria
What types of crop contain nitrogen-fixing bacteria
- Legumes
- Fallow
- Green manure
Why is compost good for soil
- ## Increases soil fertility by increasing the number of nutrients
What is rate of decomposition affected by
- Number of organisms
- Oxygen level
- Water
- Soil pH
- Temperature
How do you calculate rate of decomposition
Mass lost/number of days
Why is interdependence important
It allows organisms to depend on each other to prevent damages to the ecosystem
