Biology Final Exam 2

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Evolution

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The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

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Species

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A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g., Homo sapiens

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Fossile

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The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.

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Catastrophism

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The theory that changes in the earth's crust during geological history have resulted chiefly from sudden violent and unusual events.

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Gradulism

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The hypothesis that evolution proceeds chiefly by the accumulation of gradual changes (in contrast to the punctuational model).

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uniformitarianism

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The theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes.

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Variation

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A change or difference in condition, amount, or level, typically with certain limits.

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Adaptation

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A change or the process of change by which an organism or species becomes better suited to its environment.

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population

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All the inhabitants of a particular town, area, or country

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Natural Selection

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The process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.

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Heritability

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Heritability is the proportion of observed differences on a trait among individuals of a population that are due to genetic differences. Factors including genetics, environment and random chance can all contribute to the variation between individuals in their observable characteristics (in their "phenotypes").

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Artificial Selection

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The breeding of plants and animals to produce desirable traits. Organisms with the desired traits, such as size or taste, are artificially mated or cross-pollinated with organisms with similar desired traits.

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Gene pool

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The stock of different genes in an interbreeding population.

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Allele frequency

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Allele frequency, or gene frequency, is the proportion of a particular allele (variant of a gene) among all allele copies being considered. It can be formally defined as the percentage of all alleles at a given locus in a population gene pool represented by a particular allele.

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Normal Distribution

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A function that represents the distribution of many random variables as a symmetrical bell-shaped graph.

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Microevolution

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Evolutionary change within a species or small group of organisms, especially over a short period.

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Directional Selection

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In population genetics, directional selection is a mode of natural selection in which an extreme phenotype is favored over other phenotype, causing the allele frequency to shift over time in the direction of that phenotype.

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Stabilizing Selection

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Stabilizing selection (not the same thing as negative selection) is a type of natural selection in which genetic diversity decreases and the population mean stabilizes on a particular trait value.

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disruptive Selection

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Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.

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Gene Flow

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In population genetics, gene flow (also known as gene migration) is the transfer of alleles or genes from one population to another. Migration into or out of a population may be responsible for a marked change in allele frequencies (the proportion of members carrying a particular variant of a gene).

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Genetic Drift

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Variation in the relative frequency of different genotype in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

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Bottleneck Effect

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Bottlenecks and Founder Effects. Genetic drift can cause big losses of genetic variation for small populations. Population bottlenecks occur when a population's size is reduced for at least one generation.

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Founder Effect

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The reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors.

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Sexual Selection

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Natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.

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Relative Dating

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Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age, (i.e. estimated age).

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Radiometric Dating

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A method of dating geological specimens by determining the relative proportions of particular radioactive isotopes present in a sample.

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Isotope

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Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

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Half-Life

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The time taken for the radioactivity of a specified isotope to fall to half its original value.

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Index Fossile

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A fossil that is useful for dating and correlating the strata in which it is found.

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Geologic time scale

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The geological time scale (GTS) is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history.

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Era

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A long and distinct period of history.

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Period

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A length or portion of time.

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Epoch

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A division of time that is a subdivision of a period and is itself subdivided into ages, corresponding to a series in chronostratigraphy.

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Ecology

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The branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

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Community

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A group of people living in the same place or having a particular characteristic in common.

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Ecosystem

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A biological community of interacting organisms and their physical environment.

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Biome

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A large naturally occurring community of flora and fauna occupying a major habitat, e.g. forest or tundra.

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Biotic

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Relating to or resulting from living organisms.

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Abiotic

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Physical rather than biological; not derived from living organisms.

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Biodiversity

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The variety of plant and animal life in the world or in a particular habitat, a high level of which is usually considered to be important and desirable.

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Keystone Species

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A keystone species is often a dominant predator whose removal allows a prey population to explode and often decreases overall diversity. Other kinds of keystone species are those, such as coral or beavers, that significantly alter the habitat around them and thus affect large numbers of other organisms.

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Producer

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Produces materials for other living things in the environment.

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Autroph

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An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

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Consumer

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A person or thing that eats or uses something.

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Heterotoph

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An organism deriving its nutritional requirements from complex organic substances.

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Chemosynthesis

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The synthesis of organic compounds by bacteria or other living organisms using energy derived from reactions involving inorganic chemicals, typically in the absence of sunlight.

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Food Chain

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A series of organisms each dependent on the next as a source of food.

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Herbivore

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An animal that feeds on plants.

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Carnivore

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An animal that feeds on other animals.

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Omnivore

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An animal or person that eats a variety of food of both plant and animal origin.

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Detritivore

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An animal which feeds on dead organic material, especially plant detritus.

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Decomposer

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Decomposers are organisms that break down dead or decaying organisms, and in doing so, carry out the natural process of decomposition. Like herbivores and predators, decomposers are heterotrophic, meaningthat they use organic substrates to get their energy, carbon and nutrients for growth and development.

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Specialist

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A living being who concentrates primarily on a particular subject or activity; a person highly skilled in a specific and restricted field.

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Generalist

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A person competent in several different fields or activities.

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Trophic level

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Each of several hierarchical levels in an ecosystem, consisting of organisms sharing the same function in the food chain and the same nutritional relationship to the primary sources of energy.

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Food Web

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A system of interlocking and interdependent food chains.

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Hydrologic Cycle

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The sequence of conditions through which water passes from vapor in the atmosphere through precipitation upon land or water surfaces and ultimately back into the atmosphere as a result of evaporation and transpiration —called also hydrological cycle.

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Biogeochemical Cycle

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In Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical substance moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth.

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Nitrogen Fixation

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The chemical processes by which atmospheric nitrogen is assimilated into organic compounds, especially by certain microorganisms as part of the nitrogen cycle.

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Biomass

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The total mass of organisms in a given area or volume.

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Energy pyramid

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An energy pyramid is a graphical model of energy flow in a community. The different levels represent different groups of organisms that might compose a food chain. From the bottom-up, they are as follows: Producers — bring energy from nonliving sources into the community.

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Habitat

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

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Ecological Niche

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The place or function of a given organism within its ecosystem. Note : Different organisms may compete for the same niche. For example, in a forest there may be a niche for an organism that can fly and eat nectar from blossoms.

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Competitive Exclusion

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The inevitable elimination from a habitat of one of two different species with identical needs for resources.

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Ecological Equivalent

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Species that use similar niches in different habitats or locations are called ecological equivalents. The evolution of life has resulted in general types of habitats and certain successful ways of exploiting the resources in those habitats.

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Competition

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The activity or condition of competing.

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predation

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The preying of one animal on others.

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Symbiosis

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Interaction between two different organisms living in close physical association, typically to the advantage of both

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Mutualism

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Symbiosis that is beneficial to both organisms involved.

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Commensalism

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An association between two organisms in which one benefits and the other derives neither benefit nor harm.

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parasitism

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Parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred primarily to organisms visible to the naked eye, or macroparasites (such as helminths).

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population density

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Is a measurement of population per unit area or unit volume; it is a quantity of type number density.

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population dispersion

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Species distribution is the manner in which a biological taxon is spatially arranged. Species distribution is not to be confused with dispersal, which is the movement of individuals away from their area of origin or from centers of high population density.

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Survivorship curve

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A survivorship curve is a graph showing the number or proportion of individuals surviving to each age for a given species or group (e.g. males or females). Survivorship curves can be constructed for a given cohort (a group of individuals of roughly the same age) based on a life table.

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Immigration

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The action of coming to live permanently in a foreign area.

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Emigration

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Emigrate means to leave one's country to live in another. Immigrate is to come into another country to live permanently. Migrate is to move, like bird in the winter. The choice between emigrate,immigrate, and migrate depends on the sentence's point of view.

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Exponential Growth

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Growth whose rate becomes ever more rapid in proportion to the growing total number or size.

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Logistic Growth

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When resources are limited, populations exhibit logistic growth. In logistic growth, population expansion decreases as resources become scarce, leveling off when the carrying capacity of the environment is reached, resulting in an S-shaped curve.

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Carrying Capacity

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The number of people, other living organisms, or crops that a region can support without environmental degradation.

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population crash

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Sudden decline in the number of organisms that belong to a certain species.

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Limiting Factor

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The factor that limits the reaction rate in any physiological process governed by many variables. 2 : the environmental factor that is of predominant importance in restricting the size of a population

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Density Dependent Limiting Factor

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Any factor limiting the size of a population whose effect is dependent on the number of individuals in the population. For example, disease will have a greater effect in limiting the growth of a large population, since overcrowding facilitates its spread.

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Density Independent Limiting Factor

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Any factor limiting the size of a population whose effect is not dependent on the number of individuals in the population. An example of such a factor is an earthquake, which will kill all members of the population regardless of whether the population is small or large.

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Succession

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A number of people or things sharing a specified characteristic and following one after the other.

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primary succession

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Is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited.

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pioneer species

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Pioneer species are hardy species which are the first to colonize previously disrupted or damaged ecosystems, beginning a chain of ecological succession that ultimately leads to a more biodiverse steady-state ecosystem.

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Secondary Succession

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Is the series of community changes which take place on a previously colonized, but disturbed or damaged habitat. Examples include areas which have been cleared of existing vegetation (such as after tree-felling in a woodland) and destructive events such as fires.

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Non Renewable resources

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A resource of economic value that cannot be readily replaced by naturalmeans on a level equal to its consumption. Most fossil fuels, such as oil, natural gas and coal are considered nonrenewable resources in that their use is not sustainable because their formation takes billions of years.

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Renewable resources

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Any resource, such as wood or solar energy, that can or will be replenished naturally in the course of time.

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Ecological Footprints

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The impact of a person or community on the environment, expressed as the amount of land required to sustain their use of natural resources.

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pollution

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The presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects.

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Smog

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Fog or haze combined with smoke and other atmospheric pollutants.

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particulate

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of, relating to, or in the form of minute separate particles.

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Acid Rain

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Rainfall made sufficiently acidic by atmospheric pollution that it causes environmental harm, typically to forests and lakes. The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulfur and nitrogen oxides, which combine with atmospheric water to form acids.

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Greenhouse Effect

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The trapping of the sun's warmth in a planet's lower atmosphere due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.

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Global Warming

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A gradual increase in the overall temperature of the earth's atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, chlorofluorocarbons, and other pollutants.

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Indicator Species

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A thing, especially a trend or fact, that indicates the state or level of something.

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Biomagnification

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The concentration of toxins in an organism as a result of its ingesting other plants or animals in which the toxins are more widely disbursed.

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Habitat Fragmentation

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Habitat fragmentation is the process by which habitat loss results in the division of large, continuous habitats into smaller, more isolated remnants.

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Introduced species

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An introduced, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its native distributional range, which has arrived there by human activity, either deliberate or accidental.

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Umbrella Species

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Umbrella species are species selected for making conservation-related decisions, typically because protecting these species indirectly protects the many other species that make up the ecological community of its habitat. Species conservation can be subjective because it is hard to determine the status of many species.

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Sustainable Development

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Economic development that is conducted without depletion of natural resources.