RNA contains the base _____ rather than thymine.

plasma (cell) membran,  nucleus, cytoplasm

No growth in population size.

survivorship

Probability of newborn individuals of a cohort surviving to particular ages.

semelparity

Condition of having a single reproductive effort in a lifetime.

r-selection

Favorable life history strategy under certain environmental conditions; characterized by a high reproductive rate with little or no attention given to offspring survival.

replacement reproduction

Population in which each person is replaced by only one child.

rate of natural increase (r)

Growth rate dependent on the number of individuals that are born each year and the number of individuals that die each year.

population distribution

The pattern of dispersal of individuals living within a certain area.

population

group of organisms of the same species occupying a certain area and sharing a common gene pool.

limiting factor

less-developed country (LDC)

Country that is becoming industrialized; typically, population growth is expanding rapidly, and the majority of people live in poverty.

K-selection

Favorable life-history strategy under stable environmental conditions characterized by the production of a few offspring with much attention given to offspring survival.

habitat

Place where an organism lives and is able to survive and reproduce.

Growth, particularly of a population, in which the increase occurs in the same manner as compound interest.

ecosystem

Biological community together with the associated abiotic environment; characterized by a flow of energy and a cycling of inorganic nutrients.

ecology

doubling time

Abiotic factor, such as fire or flood, that affects population size independent of the population's density.

density-dependent factor

demography

community

cohort

Group of individuals having a statistical factor in common, such as year of birth, in a population study.

Largest number of organisms of a particular species that can be maintained indefinitely by a given environment.

biosphere

Zone of air, land, and water at the surface of the Earth in which living organisms are found.

In demographics, a display of the age groups of a population; a growing population has a pyramid-shaped diagram.

The return to Earth in rain or snow of sulfate or nitrate salts of acids produced by commercial and industrial activities.

autotroph

Organism that can capture energy and synthesize organic molecules from inorganic nutrients.

biogeochemical cycle

Circulating pathway of elements such as carbon and nitrogen involving exchange pools, storage areas, and biotic communities.

biomass

The number of organisms multiplied by their weight.

camouflage

Process of hiding from predators in which the organism's behavior, form, and pattern of coloration allow it to blend into the background and prevent detection.

carnivore

character displacement

Tendency for characteristics to be more divergent when similar species belong to the same community than when they are isolated from one another.

Organic compounds containing carbon, chlorine, and fluorine atoms. CFCs such as Freon can deplete the ozone shield by releasing chlorine atoms in the upper atmosphere.

In ecology, community that results when succession has come to an end.

coevolution

Mutual evolution in which two species exert selective pressures on the other species.

commensalism

Symbiotic relationship in which one species is benefited, and the other is neither harmed nor benefited.

Theory that no two species can occupy the same niche in the same place and at the same time.

consumer

Organism that feeds on another organism in a food chain generally; primary consumers eat plants, and secondary consumers eat animals.

decomposer

Organism, usually a bacterium or fungus, that breaks down organic matter into inorganic nutrients that can be recycled in the environment.

denitrification

Conversion of nitrate or nitrite to nitrogen gas by bacteria in soil.

detritivore

Any organism that obtains most of its nutrients from the detritus in an ecosystem.

Role an organism plays in its community, including its habitat and its interactions with other organisms.

Visual depiction of the biomass, number of organisms, or energy content of various trophic levels in a food web—from the producer to the final consumer populations.

The gradual replacement of communities in an area following a disturbance (secondary succession) or the creation of new soil (primary succession).

ecosystem

Biological community together with the associated abiotic environment; characterized by a flow of energy and a cycling of inorganic nutrients.

eutrophication

Enrichment of water by inorganic nutrients used by phytoplankton. Often, overenrichment caused by human activities leads to excessive bacterial growth and oxygen depletion.

The order in which one population feeds on another in an ecosystem, thereby showing the flow of energy from a detrivore (detrital food chain) or a producer (grazing food chain) to the final consumer.

In ecosystems, a complex pattern of interlocking and crisscrossing food chains.

Predicted increase in the Earth's temperature due to human activities that promote the greenhouse effect.

Reradiation of solar heat toward the Earth, caused by an atmosphere that allows the sun's rays to pass through but traps the heat in the same manner as the glass of a greenhouse.

Gases in the atmosphere such as carbon dioxide, methane, water vapor, ozone, and nitrous oxide that are involved in the greenhouse effect.

habitat

Place where an organism lives and is able to survive and reproduce.

herbivore

heterotroph

Organism that cannot synthesize organic compounds from inorganic substances and therefore must take in organic food.

host

Organism that provides nourishment and/or shelter for a parasite.

mimicry

Model to explain the biodiversity of an island based on distance from the mainland and the island's size.

mutualism

Symbiotic relationship in which both species benefit in terms of growth and reproduction.

Process whereby free atmospheric nitrogen is converted into compounds, such as ammonium and nitrates, usually by bacteria.

nitrification

Process by which nitrogen in ammonia and organic compounds is oxidized to nitrites and nitrates by soil bacteria.

omnivore

Organism in a food chain that feeds on both plants and animals.

Accumulation of O3, formed from oxygen in the upper atmosphere; a filtering layer that protects the Earth from ultraviolet radiation.

parasite

Species that is dependent on a host species for survival, usually to the detriment of the host species.

parasitism

Symbiotic relationship in which one species (the parasite) benefits in terms of growth and reproduction to the detriment of the other species (the host).

Early colonizer of barren or disturbed habitats that usually has rapid growth and a high dispersal rate.

predation

Interaction in which one organism (the predator) uses another (the prey) as a food source.

producer

Photosynthetic organism at the start of a grazing food chain that makes its own food—e.g., green plants on land and algae in water.

Mechanism that increases the number of niches by apportioning the supply of a resource such as food or living space between species.

symbiosis

Amount of a substance that moves from one component of the environment to another within a specified period of time.

Interdependent and continuous circulation of water from the ocean, to the atmosphere, to the land, and back to the ocean.