B7: Ecology Flashcards
State the levels of organisation in an ecosystem
- individual, population,community, ecosystem
what is an ecosystem?
- the interaction between the biotic components and abiotic components
State the 4 factors that plants may compete for:
- light
- space
- wate4
- mineral ions from soil
State 3 the factors that animals might compete for
- food
- mates
- territory
what is intraspecific competition?
- competition within a species
what is interspecific competition
- competition between different species
what is interdependence?
- different species in an ecosystem depend on each other for various resources ,
what is a stable community?
- A community in which all the biotic factors and all abiotic factors are balanced
- so that population sizes remain relatively constant
Define a ‘ community’
All of the populations of different species living together in a habitat
Define abiotic factors and give three examples
abiotic: the non-living aspects of an ecosystem
examples: temperature, light and wind intensity, soil pH, oxygen levels
Define biotic factors and give three examples
biotic: The living components of an ecosystem
examples: food availability, pathogens,
predators
why might light intensity affect plants in an ecosystem?
different species of plants may have different optimum light intensities for growth
why does temperature affect an ecosystem?
different species of plants and animals may have different optimum temperatures for growth and survival
how does soil pH affect an ecosystem?
- certain plants may grow better in either alkaline or acidic soil
- soil pH may affect the appearance of the plant
How does moisture level affect an ecosystem?
- many plants cannot survive in waterlogged soil as their roots cannot respire
- certain plants are adapted to high moisture levels
How does low wind intensity affect an ecosystem?
- plant seeds are more likely to germinate in locations with lower wind intensity
- which may also attract animals that depend on the plant to live nearby
How does soil mineral content affect an ecosystem?
- most plants require a high level of soil minerals to grow well
Give an example of a type of plants that have adapted to low soil mineral content
- carnivorous plants catch insects to compensate for the low level of soil mineral content
How does carbon dioxide concentration affect plants in an ecosystem?
- higher Co2 concentration leads to more plant growth
How does oxygen concentration affect an ecosystem? aquatic animals
- aquatic animals cannot survive in areas with low O2 concentration
Define ‘ adaptations’
- features that enable organisms to survive in their living environment
what are organisms living in extreme environments called?
- extremophiles
give three examples of extreme living environments
- high temperature
- high pressure
- high salt concentration
State an example of where extremophile bacteria can be found
in deep sea vents
Define population
a species that interbreed and occupy the same habitat
Define habitat
- the place in which an organism lives
What do food chains show?
- the feeding relationships of different organisms and the flow of energy between the organisms
Define biomass
- the total mass of living material
what are trophic levels
the stages in a food chain
what do arrows in a food chain represent?
- the direction of biomass transfer
- the flow of energy
describe a simple food chain
producer - primary consumer - secondary consumer - tertiary consumer
what is a producer and what types of organisms are primary producers?
- an organism that makes its own food
- photosynthetic organisms like green plants and algae that trap energy from the sun
what are primary, secondary, tertiary consumers?
primary: an organism that feeds on producers
secondary: an organism that feeds on primary consumers
tertiary: an organism that feeds on secondary consumers
what is a predator?
- a consumer that kills and eats other animals
what is prey?
- an animal that is killed and eaten by another animal
Describe the pattern of predators and prey in a stable community
- the numbers of predators and prey rise and fall in cycles
why are producers the first trophic level?
- producers provide all biomass for he food chain ( production of glucose via photosynthesis)
- the rest of the food chain involves the transfer of this biomass
what piece of apparatus is used to measure the abundance and distribution of organisms in an area?
- quadrat
what piece of apparatus is used to study the distribution of organisms across a gradient?
- belt transect
when considering the abundance of organisms, what is meant by the term ‘ mean ‘
- the average number of organisms
how is the arithmetic mean calculated?
- sum of each number of each organism / the total number of each type of organism
when considering the abundance of different organisms, what is meant by the term ‘’ mode ‘’
the most populous organism
when considering the abundance of organisms what is meant by the term ‘‘median’’
- organism that represents the middle value when the numbers of each organism are arranged from lowest to highest
Required practical: measuring the population size of a common species in a habitat
- choose a starting point on the school field in an area where the grass is often cut
- use random numbers to generate a set of coordinates to place your first quadrat
- count the number of different plant species within this quadrat (the species richness)
- return to your starting position and repeat steps two and three a further 14 times using different random numbers
- repeat steps one to four for a part of the school field which the grass is infrequently cut
- compare your results by calculating a mean for each location
Describe how materials cycle through the living and non-living components of an ecoystem
- organisms take in elements from their surroundings eg soil air
- these elements are converted to complex molecules which become biomass
- they are then transferred along food chains
- elements are then returned to environment during excretion and decomposition of dead organisms
Give three molecules which are cycled through ecosystems
- oxygen
- carbon dioxide
- water
Describe the carbon cycle
- plants fix carbon dioxide into organic molecules during photosynthesis
- the organic carbon-containing molecules are passed onto organisms that eat the plants
- carbon dioxide is released back into the atmosphere by respiration from animals and plants
- burning fossil fuels also releases carbon dioxide into the atmosphere
why is the carbon cycle important?
- carbon-containing molecules such as glucose are important for living organisms
- to grow and provide energy for vital functions within cells
Describe the water cycle
- water from lakes and oceans evaporates
- the evaporated water condenses into clouds and returns to earth as precipitation
- the water from precipitation is useful for life on land
- the water then returns to rivers and oceans through surface runoff
why is the water cycle important?
- living organisms require water
- the water cycle provides organisms on land with a continuous supply of water
why are microorganism important for the cycling of materials through an ecosystem
- microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter
- the decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use
define decomposition
- the breakdown of dead materials into simpler organic matter
how do decomposers break down dead matter?
- decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules
what are the two types of decomposition?
- aerobic decomposition ( with oxygen)
- anaerobic decomposition (without oxygenn)
give three factors which affect the rate of decomposition
- oxygen availability
- temperature
- water content
why is oxygen required for decomposition?
- most decomposers require oxygen for aerobic respiration
how does the availability of oxygen affect the rate of decomposition
- as oxygen levels increase, the rate of decomposition increases
- the converse
why can decomposition still occur in the absence of oxygen
some decomposers respire anaerobically
- although the rate of decomposition is slower as anaerobic respiration produces less energy
how does soil water content affect the rate of decomposition?
- decomposers require water to survive
- in moist conditions the rate of decomposition is high
- in waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases
why does decomposition require water?
- required for the secretion of enzymes and absorption of dissolved molecules
how does temperature affect the rate of decomposition ?
decomposers release enzymes:
- rate highest at 50 degrees
- lower temperatures , enzymes work too slowly rate decreases
- high temperatures, enzymes denature, decomposition stops
how is the rate of change calculated when considering the decay of biological material.
rate of change= change in value/ change in time
what is compost?
- the nutrient-rich product of the rapid decay of wate biological material
- dead plants and animal waste
how is compost used?
- used as natural fertiliser to promote growth of crops or garden plants
describe how biogas generators work?
- Anaerobic decay in animal waste produces methane gas.
- Biogas generators can be used to produce methane gas as a fuel
give 3 examples of environmental conditions and describe how they affect communities
- temperature
- availability of water
- composition of atmospheric gases
- they affect the abundance and distribution of organism within communities
how can differing temperatures be bad for certain communities?
- if the temperature is too low, growth will be slower as organisms will use more energy to stay warm
- if the temperature is too high, organisms can die and water will become limited as evaporation increases
how can changes in water levels affect ecosystems?
- low : animals may have to migrate to find water
- high: melting ice caps may destroy the habitats of some animals
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how can atmospheric gases affect ecosystems?
- some organisms cannot survive when certain gases are present
- polluted water can cause illness to animals that drink it
how is sulfuric acid formed and what detrimental impacts can sulfur dioxide have on the environment?
- formed when fossil fuels containing impurities are burnt
- sulfur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources
how is carbon monoxide formed and what detrimental impacts can carbon monoxide have on the environment?
- carbon monoxide is formed from the incomplete combustion of fossil fuels
- it binds irreversibly to haemoglobin which prevents it from carrying oxygen
- too much exposure can cause unconsciousness and death
name 5 greenhouse gases
- water vapour
- carbon dioxide
- nitrous dioxide
- methane
- CFCs
give 3 human activities that contribute to greenhouse gases
- burning fossil fuels
- deforestation
- large scale livestock farming
how do greenhouse gases lead to global warming?
- greenhouse gases allow heat from the sun to enter the atmosphere
- the gases act as a ‘ blanket’ and trap the heat in the atmosphere
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what is biodiversity?
- the variety of the different species on earth or within an ecosystem
what is the importance of biodiversity?
- to maintain the stability of an ecosystem
how does biodiversity ensure the stability of an ecosystem?
- it reduces the dependence on particular species for resources eg. food and shelter, - so that even if one species is removed other species can still survive
give two reasons why human consumption of resources and waste production increased?
- rapid rise in human population
- increase in standard of living
where does pollution occur and state examples of each
- air ( smoke, acidic gases)
- land ( landfill waste, chemicals)
- water ( sewage, fertiliser, chemicals)
how does eutrophication occur?
- fertiliser from farms pollute the water, causing excessive algae growth
- this depletes the oxygen in the water, causing other plants and animals to die
- dead plants are decomposed by bacteria and the oxygen level decreases further
give 4 human activities which reduce the land available for animals and plants
- buildings
- farming
- quarrying
- disposing of waste
why have peat bpgs been destroyed?
- to produce compost to increase food production
why does the destruction of peat bogs greatly contribute to the greenhouse effect?
- peat bogs are stores of carbon ( carbon sinks) and burning them releases a large volume if carbon dioxide into the atmosphere
why have large-scale deforestation activities occurred?
- to provide land for cattle or rice fields
- to grow crops to produce biofuels
what is the greenhouse effect?
- greenhouse gases trap energy from the sun as heat in the atmosphere , keeping the temperature on earth suitable for life
what is causing global warming
- the increase in levels of greenhouse gases in the atmosphere
- causing the temperature on earth to increase
what are the 2 harmful effects of deforestation?
- destruction of many animals habitats
- releases large amounts of greenhouse gases
state 6 consequences of global warming
- rising sea levels
- melting polar ice caps
- changing weather pattern
- migration of animals to find suitable habitats
- tropical diseases becoming more common
- extinction of species
describe 6 the steps taken to maintain biodiversity
- breeding programmes for endangered species
- protection and rebuilding habitats
- replanting field margins and hedgerows
- reduce deforestation
- reduce carbon dioxide emissionns
- recycling rather than disposing in landfills
what is the purpose of replanting hedgerows and field margins?
- there is higher biodiversity in the margins than the fields that they surround
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what are trophic levels? how are they represented
- the stages in a food chain
- represented by umbers, starting from 1
what is trophic levels 1-2
1: plants and algae which make their own food ( through photosynthesis called producers )
2: herbivores which eat producers- called primary consumers
what is trophic levels 3-4
3: carnivores that eat herbivores called secondary consumers
4: carnivores that eat other carnivores called tertiary consumers
what is an apex predator?
- a carnivore with no predators
how do decomposers break down dead matter?
- decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules
- soluble small food molecules then diffuse into the microorganism
what is biomass?
- the dry mass of all of the living organisms in an area
why is dry mass used for measuring biomass
the wet mass varies as the volume of water in the organism varies
how do u calculate the efficiency of biomass transfer?
efficiency=( energy transferred/total energy available) x 100
what percentage of the incident energy from light or photosynthesis do producers transfer?
1%
what percentage of the biomass rom one trophic level is transferred to the level above it in feeding
- approx 10%
why are biomass transfers not 100% efficient ? (4)
- egestion ( removal of faeces)
- excretion ( removal of waste products e.g urine containing urea and water)
- respiration ( loss of carbon dioxide and water) in which large amounts of glucose are used
- the production of inedible bones and shells
how does the efficiency of biomass transfers affect the number of trophic levels in a biomass pyramid?
- the less efficient the transfers, the fewer trophic levels and the fewer organisms in higher trophic levels
what is a biomass pyramid?
- a pyramid that shows the total dry mass of organisms at each trophic level
- trophic level 1 is at the bottom of the pyramid
what is food security?
- having enough food to be able to feed a population
state the 6 biological factors threatening food security
- rising birth rates
- changing diets in developed countries - food is transported around the world
- new pests and pathogens
- environmental changes affecting food production
- increased cost of agriculture
- armed conflicts
give five ways to improve the efficiency of food production
- feed animals high protein foods to increase growth
- reduce their energy loss to the environment:
- limiting movement
- regulating their surrounding temperature
- feed animals antibiotics to prevent diseases
give three advantages of intensive farming ?
- higher yield of food
- more efficient
- allows easier quality control
give 4 disadvantages of intensive farming?
- may lead to antibiotic resistance
- cost is high
- ethical objections e.g limiting movement of animals may cause them harm
- biodiversity may be reduced
give two ways fish stocks can be conserved
- control the size of gas in fishing nets to prevent juvenile fish from being killed
- introduce fishing quotas
what is a transgenic organism?
- an organism that has been genetically modified to contain genetic material from another source
state an example of genetically modified foods
- golden rice
give three reasons why crops are genetically modified?
- to improve nutritional value
- to be pest resistant
- to be pesticide resistant
what are advantages of golden rice?
- it contains additional beta-carotene which can be converted too vitamin A in the body
- this supplements people who do not obtain enough Vitamin A in their diet to prevent night blindness from forming
what is mycoprotein?
- a protein-rich substance used to make meat substitute food for vegetarians and vegans
how is mycoprotein produced
- Fusarium, a fungus is grown on glucose syrup in aerobic conditions
- the biomass is harvested and purified to get the mycoprotein
explain how making dog food from insects could improve human food
security in the future (3)
- less land required so there are more space for crops for humans
- less methane (from animals) therefore less global warming
- (therefore) less harmful effects of global warming on (human) food production
Explain why the fermenter is sterilised before use (2)
- kills microorganisms microbes
- which compete for food / oxygen
Explain why Fusarium needs glucose and oxygen.
for (aerobic) respiration
(which) releases energy (for growth
suggest why it is useful for bubbles of air and materials to move around
inside the fermenter
so Fusarium can
* grow faster / better
* get sufficient food / glucose / mineral
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