vocab Flashcards
abiotic factor
nonliving physical or chemical condition in an environment
acid rain
precipitation that contains nitric and/or sulfuric acids
adaptation
inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment
age structure
proportion of people in different age groups in a population
allele
alternative form of a gene
analogous structures
similarities among unrelated species that result from convergent evolution
antibiotic
medicine that kills or slows the growth of bacteria
artificial selection
selective breeding of domesticated plants and animals to produce offspring with desired genetic traits
binomial
two-part Latin name of a species
biodiversity
variety of life on Earth
biological magnification
process by which pollutants become more concentrated in successive trophic levels of a food web
biome
major type of terrestrial ecosystem that covers a large region of Earth
biosphere
all the parts of the planet that are inhabited by living things; sum of all Earth’s ecosystems
biotechnology
use of organisms to perform practical tasks
biotic factor
any living part of an environment
carrying capacity
number of organisms in a population that an environment can maintain
cellular differentiation
increasing specialization in structure and function of cells during development of a multicellular organism
chromosome theory of inheritance
generalization that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance pattern
cladogram
phylogenetic tree constructed from a series of two-way branch points, suggesting ancestral relationships among species
codominance
inheritance pattern in which a heterozygote expresses the distinct traits of both alleles
codon
in RNA, a three-base “word” that codes for one amino acid
commensalism
symbiotic relationship in which one organism benefits, while the other organism is neither harmed nor helped
community
all the organisms living in an area
conservation biology:
application of biology to counter the loss of biodiversity
continental drift
motion of continents about Earth’s surface on plates of crust floating on the hot mantle
convergent evolution:
process in which unrelated species from similar environments have adaptations that seem very similar
cross-fertilization
process by which sperm from one flower’s pollen fertilizes the eggs in a flower of a different plant
deforestation
clearing of forests for agriculture, lumber, or other uses
deletion
change to a chromosome in which a fragment of the chromosome is removed
density-dependent factor
factor that limits a population more as population density increases
density-independent factor
factor unrelated to population density that limits a population
derived character
homologous characteristic that unites organisms as a group
descent with modification
process by which descendants of ancestral organisms spread into various habitats and accumulate adaptations to diverse ways of life
dihybrid cross
mating of two organisms that differ in two characters
DNA fingerprint
an individual’s unique banding pattern on an electrophoresis gel, determined by restriction fragments of the person’s DNA
dominant
descriptive of an allele in a heterozygous individual that appears to be the only one affecting a trait
Down syndrome
general set of symptoms in people with trisomy 21
duplication
change to a chromosome in which part of the chromosome is repeated
ecology
scientific study of the interactions among organisms and between organisms and their environment
ecosystem
community of living things plus the nonliving features of the environment that support them
embryo
stage in human development from the first division of the zygote until about nine weeks after fertilization
endosymbiosis
process by which eukaryotic cells may have evolved from small symbiotic prokaryotes that lived within other, larger host cells
eutrophication
rapid growth of algae in bodies of water, due to high levels of nitrogen and often phosphate
evolution
generation-to-generation change in the proportion of different inherited genes in a population that account for all of the changes that have transformed life over an immense time
exponential growth
growth of a population that multiplies by a constant factor at constant time intervals
extinct
no longer existing as a living species on Earth
fitness
contribution that an individual makes to the gene pool of the next generation compared to the contributions of other individuals
fossil
preserved remains or marking left by an organism that lived in the past
fossil record
chronological collection of life’s remains in sedimentary rock layers
gel electrophoresis
technique for sorting molecules or fragments of molecules by length
gene flow
exchange of genes between populations
gene locus
specific location of a gene on a chromosome
gene pool
all of the alleles in all the individuals that make up a population
genetic counselor
person trained to collect, analyze, and explain data about human inheritance patterns
genetic drift
change in the gene pool of a population due to chance
genetic linkage
tendency for alleles of genes on the same chromosome to be inherited together
genetic marker
specific portion of DNA that varies among individuals
genetics
study of heredity
genome
complete set of an organism’s genetic material
geographic isolation
separation of populations as a result of geographic change or migration to geographically isolated places
geologic time scale
Earth’s history organized into four eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic
global warming
rise in Earth’s average temperature
genetically modified organism (GMO)
organism that has acquired genetic material by artificial means
greenhouse effect
process by which atmospheric gases trap heat close to Earth’s surface and prevent it from escaping into space
habitat
an organism’s specific environment, with characteristic abiotic and biotic factors
half-life
time it takes for 50 percent of a radioactive isotope sample to decay
heterozygous
having different alleles for a gene
homozygous
having identical alleles for a gene
hybrid
offspring of two different true-breeding varieties
intermediate inheritance
inheritance in which heterozygotes have a phenotype intermediate between the phenotypes of the two homozygotes
interspecific competition
competition between species that depend on the same limited resource
introduced species
species moved by humans to new geographic areas, either intentionally or accidentally
inversion
change to a chromosome in which a fragment of the original chromosome is reversed
limiting factor
condition that restricts a population’s growth, such as space, disease, and food availability
macroevolution
major biological changes evident in the fossil record
mass extinction
episode of great species loss
microclimate
climate in a specific area that varies from the surrounding climate region
microevolution
evolution on the smallest scale—a generation-to-generation change in the frequencies of alleles within a population
monohybrid cross
mating of two organisms that differ in only one character
messenger RNA (mRNA)
RNA molecule transcribed from a DNA template
mutagen
physical or chemical agent that causes mutations
mutation
any change in the nucleotide sequence of DNA
mutualism
type of symbiotic relationship in which both organisms involved benefit
natural selection
process by which individuals with inherited characteristics well-suited to the environment leave more offspring than do other individuals
niche
unique living arrangement of an organism defined by its habitat, food sources, time of day it is most active, and other factors
nondisjunction
event during meiosis in which homologous chromosomes or sister chromatids fail to separate
ozone
atmospheric gas (O3) that absorbs ultraviolet radiation, shielding organisms from its damaging effects
parasitism
relationship in which a parasitic organism obtains its food at the expense of a host organism
polymerase chain reaction (PCR)
technique that makes many copies of a certain segment of DNA without using living cells
pedigree
family tree that records and traces the occurrence of a trait in a family
phenotype
observable traits of an organism
phylogenetic tree
branching diagram, suggesting evolutionary relationships, that classifies species into groups within groups
population
group of individuals of the same species living in a particular area at the same time
population density
number of individuals of a particular species per unit area or volume
predation
interaction in which one organism consumes another
primary succession
rocess by which a community arises in a virtually lifeless area with no soil
Punnett square
diagram showing the probabilities of the possible outcomes of a genetic cross
recessive
descriptive of an allele in a heterozygous individual that does not appear to affect a trait
recombinant DNA technology
technology that combines genes from different sources into a single DNA molecule
reproductive isolation
condition in which a reproductive barrier keeps two species from interbreeding
secondary succession:
change following a disturbance that damages an existing community but leaves the soil intact
sex-linked gene
gene located on a sex chromosome
speciation
Formation of new species
stem cell
cell with the potential to develop into one of several types of differentiated cells
sustainable development
use of natural resources in a way that allows them to renew themselves and be available for the future
symbiotic relationship
close interaction between species in which one species lives in or on the other
taxonomy
identification, naming, and classification of species
testcross
mating of an individual of unknown genotype but dominant phenotype with a homozygous recessive individual
trait
variation of a particular inherited character
transcription
process by which a DNA template is used to produce a single-stranded RNA molecule
transgenic
genetically modified organism whose source of new genetic material is a different species
translation
process by which a sequence of nucleic acids in RNA is used to direct the production of a chain of specific amino acids
translocation
change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome
transposon
genetic element that moves from one location to another in a genome
tropics
regions between 23.5° N latitude and 23.5° S latitude; warmest temperature zones on Earth
variation
difference among members of a species
vestigial structure
remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species
