UNIT 1: Ecology Flashcards
ecology
the study of the interactions between organisms and between organisms and their environment
ecosystem
a group of clearly distinguished organisms that interact with their environment as a unit
biosphere
that part of the planet in which living organisms can be found
habitat
the place where a plant or animal lives
population
all the members of the same species living in the habitat
community
all the different populations of species living in the habitat
environmental factors (terrestrial): abiotic factors
non-living factors e.g. aspect, north facing slopes are cooler and darker than south facing (northern hemisphere only)
environmental factors (terrestrial): biotic factors
living factors e.g. available food, more food will enable more organisms to survive.
environmental factors (terrestrial): climatic factors
effects of weather over a long period of time e.g. rainfall
environmental factors (terrestrial): edaphic factors
effects of soil e.g. soil pH. ph affects growth of particular plants as pH effects enzyme action
energy flow
sun: ultimate source of energy
feeding allows energy flow from organism to organism
producers
photosynthetic organisms that make their own food
consumer
organisms that obtain their food from other organisms
primary consumers
feed on producers (herbivores, decomposers, detritus feeders, omnivores)
secondary consumers
feed on primary consumers (carnivores, scavengers, omnivores)
tertiary consumers
feed on secondary consumers (carnivores, scavengers, omnivores)
grazing food chain
a sequence of organisms in which each one is eaten by the next member in the chain
examples of food chains
leaf -> caterpillar -> thrush -> falcon.
grass -> rabbit -> fox.
algae -> limpet -> starfish -> gull.
plankton -> barnacle -> whelk -> crab.
food web
consists of two or more interlinked food chains
pyramid of numbers
represents the number or organisms at each stage in a food chain.
a way of comparing different communities of an ecosystem in order of different trophic levels
upright pyramids of numbers
the number of organisms at each trophic level decreases.
partially upright pyramid of numbers
the number of organisms at the beginning of the chain is very small when compared to the trophic levels that follow
inverted pyramid of numbers
the numbers of organisms at each trophic level increases
niche
the functional role an organism plays in a particular habitat e.g. fox’s role is to keep number of rabbits and hares down
nutrient recycling
the way in which elements ( such as carbon and nitrogen) are exchanged between living and non-living components of an ecosystem
pollution
any harmful addition to the environment
- domestic: household waste
- agricultural: pesticides, insecticides, fertilizers, slurry
- industrial: chimney smoke, chemicals
conservation
the wise management of our existing natural resources
agricultural conservation
- storing slurry in leak-proof pits
- only spread slurry on land in summer
- do not spread fertilisers or spray insecticides in wet conditions
- growing of organic crops and livestock
problems associated with waste disposal
- disease causing micro-organisms (pathogens)
- toxic / harmful chemicals
- nutrient elements: phosphorus and nitrogen can cause eutrophication of rivers and lakes.
- landfill sites are unsightly and attract vermin / scavengers.
- dumping waste at sea leads to pollution
- incineration can release toxic chemicals such as dioxins (which are known carcinogens)
agricultural waste minimisation
slurry is stored in leak-proof pits and only spread on land when it is dry.
Reduce, reuse, recycle
- do not buy foods that use excess packaging
- household objects can be reused
- many materials used can be recycled, such as glass bottles, paper, plastics, metals, and organic waste
role of microorganisms in waste management and pollution control
landfill sites: bacteria break down the organic waste.
sewage; small amounts of sewage are treated naturally by bacteria in water, large amounts of sewage have to be treated by sewage treatment plans (also involves bacteria)
inferences of a pyramid of numbers
- number of organisms declines as you go up the pyramid
- organisms body usually (but not always) increases as you go up the pyramid
limitations of a pyramid of numbers
- pyramid of numbers does not take into account the actual number of organisms involves.
- pyramid of numbers cannot be drawn to scale
- some are not technically pyramids - they are inverted
competition
occurs when organisms actively struggle for a resource that is in short supply - limits population growth
contest competition
active physical confrontation between two organisms with one organism obtaining all of the resource
scramble competition
struggle between a number of organisms with all the organisms obtaining a small amount of the resource
adaptation
occurs to reduce competition e.g. caterpillar eats cabbage, butterfly eats nectar
predation
the catching, killing and eating of another organism e.g. snake is a predator and a mouse is its prey
parasitism
occurs when two organisms of different species live in close association and one organism (parasite) obtains its food from, and to the disadvantage of, the second organism (host) e.g. athletes food, ringworm
symbiosis
occurs when two organisms of different species live in close association and atleast one of them benefits e.g. bacteria in human digestive system produce vitamin K and get food and a safe environment in return
factors in predator-prey relationships
- availability of food
- concealment
- movement
contemporary issues in population dynamics
disease
famine
war
contraception
Decomposers
Organisms that feed on dead organic matter
Detritus feeders
Organisms that feed on small pieces of dead organic matter
Nitrogen fixation
The conversion of nitrogen gas into ammonia, ammonium or nitrate
Nitrification
The conversion of ammonia and ammonium compounds to nitrite and then to nitrate
Denitfrication
The conversion of nitrates to nitrogen gas
Intra-specific competition
Takes place between members of the same species
Inter-specific competition
Occurs between members of different species
Predator
An organism that catches, kills and eats another organism
Prey
The organism that is eaten by the predator
