Chapter 18 Organisms and Their Environment, Chapter 19 Human Influences On Ecosystems Flashcards
Define ecology:
the study of organisms and their environment
Define habitat:
the place where an organism lives
Define community:
All of the populations of all the different species in an ecosystem
Define ecosystem:
a unit containing all of the organisms in a community and their environment, interacting together
Define niche:
the role of an organism
in its natural environment;
the way in which it interacts with other organisms
and with the non-living parts of the environment
Define food chain:
A diagram showing
the flow of energy
from one organism
to the next,
beginning w a producer
Define food web:
a network
of interconnected
food chains
Define producer:
An organism
that makes its own organic nutrients,
generally using energy from sunlight,
through photosynthesis
Define herbivore:
An animal that
gets its energy by
eating plants
Define consumer:
An organism that
gets its energy by
feeding on other organisms
Define carnivore:
An animal that
gets its energy from
eating other animals
Define decomposer:
An organism that
gets its energy from
dead/waste organic material
Define pyramid of numbers:
A diagram
in which the area of the bar
at each trophic level
shows the relative nr of organisms
at that level in the food chain
Define trophic level:
The position of
an organism
in a food chain, food web/pyramid of biomass/numbers
Define pyramid of biomass:
A graph showing
the relative quantity of biomass
at each trophic level
Define Pyramid of Energy:
A graph showing
the relative quantity of energy
at each trophic level
Define nitrogen fixation:
Converting inert nitrogen gas
into a more reactive form,
such as nitrate ions/ammonia
Define nitrification:
Converting ammonium ions to nitrate ions
Define denitrification:
Converting nitrate ions to nitrogen gas
*nitrate is 1 part nitrogen, 3 parts oxygen
Define lag phase:
The stage at the start
of a population growth curve
where the population remains small
and grows only very slowly
Define log/exponential phase:
The stage in
a population growth curve
where the population grows
at its maximum rate;
birth rate exceeds death rate
Define stationary phase:
The stage in
a population growth curve
where the population remains ** roughly constant**;
birth rate equals death rate
Define death phase:
The final stage in
a population growth curve
where the population falls;
death rate exceeds birth rate
Define sigmoid growth curve:
an S-shaped curve showing the
change in the size of a population
through all the phases in population growth
Define limiting factor:
A factor that is in short supply,
which stops an activity (such as photosynthesis)
happening at a faster rate
Define age period:
A diagram showing
the relative numbers
of individuals of different ages
in a population
Define monoculture:
An area of ground covered by a single crop, with almost no other species present
Define biodiversity:
The number of different species that live in an area
Define extinction:
The complete loss of a species from earth
Define greenhouse gasses:
Gases such as carbon dioxide and methane that trap heat within the atmosphere
Define greenhouse effect:
The heating effect on the Earth of the trapping of heat by greenhouse gas’s was;
Note that this is a natural and useful effect as without it the Earth would be much too cold to support life
Define enhanced greenhouse effect:
The increased heating effect
caused by an increase of greenhouse gases
in the atmosphere
Define eutrophication:
A chain of events
caused by addition of extra plant nutrients to water,
resulting in a decrease in
the concentration of dissolved oxygen available for organisms that require it for aerobic respiration
Define non-biodigradible:
Not able to be broken down by decomposers
Fine sustainable resource:
One that is produced as rapidly as it is removed from the environment; so that it does not run out.
Define endangered:
At serious risk of becoming extinct
Define captive breeding:
Keeping animals in captivity (eg. in a zoo) and allowing them to breed, in order to increase the numbers in the population
Define seed banks:
Facilities in which seeds of different plant species/crop varieties, are stored for long periods of time, in order to conserve as many different species and varieties as possible
Define insemination (AI):
Introducing semen, containing sperm, to the reproductive organs of a female, fertilization occurs in her body in the normal way
Define in vitro fertilization (IVF):
Adding semen, containing sperm, to eggs in a container in a laboratory, fertilization occurs in the container, and the embryos can later be inserted into the body of a female
Define population:
A group of organisms, of the same species, living in the same area, at the same time
