Unit 3 - Chapters 3-5: Living World

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

Eukaryotic cell

cell that has a nucleus and other membrane-bound organelles

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.


A group of similar organisms that can breed and produce fertile offspring.


Scientific study of interactions among organisms and between organisms and their environment


A group of individuals that belong to the same species and live in the same area


the natural home or environment of an animal, plant, or other organism.


All the different populations that live together in an area


A biological community of interacting organisms and their physical environment.


a broad, regional type of ecosystem characterized by distinctive climate and soil conditions and a distinctive kind of biological community adapted to those conditions.

natural greenhouse effect

Heat buildup in the atmosphere due to the presence of 'greenhouse' gases like carbon dioxide, methane, and water vapor.





range of tolerance

the limits to the abiotic conditions that a species can tolerate

limiting factor principle

the distribution of an organism or the structure of an ecosystem can be explained by the control exerted by the single factor (such as temperature, light, water) that is most deficient, that is, that falls below the levels required


Organisms that make their own food (photosynthesis or chemosynthesis)


obtain energy by consuming other organisms


An animal that eats both plants and animals


decomposers decompose dead material by chemically breaking it down. detritivores feed directly on the meat of dead animals

aerobic respiration

Respiration that requires oxygen

anaerobic respiration

Respiration in the absence of oxygen. This produces lactic acid.


Process by which cells release energy in the absence of oxygen

food chain

A series of steps in which organisms transfer energy by eating and being eaten

food web

A community of organisms where there are several interrelated food chains


total amount of living tissue within a given trophic level

ecological effieciency

the proportion of consumed energy that can be passed from one trophic level to another

gross primary productivity

the amount of sugar that the plants produce in photosynthesis

Net Primary Productivity (NPP)

The energy captured by producers in an ecosystem minus the energy producers respire


the variety of life in the world or in a particular habitat or ecosystem.

species diversity

The number and relative abundance of species in a biological community.

ecosystem diversity

variety of habitats, living communities, and ecological processes in the living world

functional diversity

Biological and chemical processes or functions such as energy flow and matter cycling needed for the survival of species and biological communities


Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.


Changes in physical structure, function, or behavior that allow an organism or species to survive and reproduce in a given environment.


a random error in gene replication that leads to a change

differential reproduction

Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits.


Formation of new species

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring

background extinction

gradual process of a species becoming extinct

mass extinction

event in which many types of living things become extinct at the same time

species richness

the number of different species in a community

generalist species

Species that does not rely on a single source of prey

specialist species

consumer that eats only one type of organism

native species

Species that normally live and thrive in a particular ecosystem

invasive species

species that enter new ecosystems and multiply, harming native species and their habitats

indicator species

Species that serve as early warnings that a community or ecosystem is being degraded.

keystone species

A species that influences the survival of many other species in an ecosystem

foundation species

species that plays a major role in shaping a community by creating and enhancing a habitat that benefits other species

interspecific competition

competition between members of different species

competitive exclusion principle

Ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time


An interaction in which one organism kills another for food.


Process by which two species evolve in response to changes in each other


A relationship between two organisms of different species where one benefits and the other is harmed


A relationship between two species in which both species benefit


A relationship between two organisms in which one organism benefits and the other is unaffected

resource partitioning

The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species

population dynamics

The study of how complex interactions between biotic and abiotic factors influence variations in population size.

intrinsic rate of increase

rate at which the population of a species would grow if it had unlimited resources

biotic potential

The maximum rate at which a population could increase under ideal conditions

environmental resistance

All the limiting factors that act together to limit the growth of a population.

carrying capacity

Largest number of individuals of a population that a environment can support

reproductive time lag

the period needed for the birth rate to fall and the death rate to rise in response to resource overconsumption

r vs k selected species

-Cane toads, mosquitoes: small body size, early maturity, short life span, large broods, little or no parental care
-Humans or mammals: do not produce large numbers of offspring, long life spans, slow development, late reproduction, large body size, paren

founder effect

genetic drift that occurs after a small number of individuals colonize a new area

demographic bottleneck

A population founded when just a few members of a species survive a catastrophic event or colonize new habitat geographically isolated from other members of the same species.

genetic drift

random change in allele frequencies that occurs in small populations


Continued breeding of individuals with similar characteristics

minimum viable population size

The number of individuals needed for long-term survival of rare and endangered species

density dependent factors

limiting factor that depends on population size

independent population control

affected by factors that affect birth and death rates such as abiotic factors and environmental factors


A species whose population size fluctuates slightly above
and below its carrying capacity


population growth may occasionally surge, or irrupt, to a high peak and then crash to a more stable lower level or, in some cases, to a very low, unstable level.


populations fluctuate and regular cyclic or boom-and-bust cycles


population fluctuates randomly with no recurring pattern

primary succession

An ecological succession that begins in an area where no biotic community previously existed

secondary succession

Succession following a disturbance that destroys a community without destroying the soil

early successional species/pioneer species

usually characterized by high growth rates, smaller size, high degree of dispersal, and high rates of per capita population growth (ex. lichen, algae, fungi)

midsuccessional plant species

Grasses and low shrubs that are less hardy than early successional plant species. (ex. red-osier dogwood, salmonberry, Pacific nine-bark, trailing blackberry, and willows)

late successional plant species

Mostly trees that can tolerate shade and form a fairly stable complex forest community. (ex. white spruce, Canadian hemlock, Pacific silver fir, coast redwood)