G6 fiffGlossary
F
F 1 generation The first generation of offspring in a series of
genetic crosses. Compare F 2 generation and P generation.F 2 generation The second generation of offspring in a series of
genetic crosses. Compare F 1 generation and P generation.facilitated diffusion Diffusion that requires transport proteins.
Compare simple diffusion.fact A direct and repeatable observation of any aspect of the natural
world. Compare theory.falsifiable Able to be refuted.
family The unit of classification in the Linnaean hierarchy above
genus and below order.fermentation A metabolic pathway by which most anaerobic
organisms extract energy from organic molecules. It begins with
glycolysis and is followed by a special set of rea ctions whose only
role is to help perpetuate glycolysis. Fermentation enables organ-
isms to generate ATP anaerobically.ferns A group of vascular, nonflowering plants that reproduce via
spores.fertilization The fusion of two gametes, resulting in a zygote.
flagellum (pl. flagella) A long, whiplike structure that assists
bacteria in locomotion.flower A structure in angiosperms that enhances sexual repro-
duction by bringing male gametes (sperm cells) to the female
gametes (egg cells) in highly efficient ways, by attracting animal
pollinators through scent, shape, and color.food chain A single direct line of who eats whom among species in
a community. Compare food web.food web The way in which various and often overlapping food
chains of a community are connected.fossil The mineralized remains or impression of a formerly living
organism.founder effect A form of genetic drift that occurs when a small
group of individuals establishes a new population isolated from
its original, larger population.freshwater biome An aquatic biome whose character is defined
by the terrestrial biomes that it borders or through which its
water flows. Lakes, rivers, and wetlands are all part of the fresh-
water biome.fruiting body In fungi, the structure resulting from mating that
releases offspring as sexual spores.Fungi The fungi. One of the six kingdoms of life, in the domain
Eukarya, distinguished by their modes of reproduction. Fungi
are absorptive heterotrophs.G
G 0 phase A nondividing state of the cell.
G 1 phase “Gap 1,” the first phase in the life of a newborn cell.
G 2 phase “Gap 2,” the phase of the cell cycle between the S phase
and cell division.gamete A sex cell. Male gametes are sperm; female gametes are
eggs. Compare somatic cell.gene The basic unit of information, consisting of a stretch of DNA,
that codes for a distinct genetic characteristic.gene expression The process by which genes are transcribed into
RNA and then translated to make proteins.gene flow The exchange of alleles between populations.
gene regulation The changing of the genes that are expressed in
response to internal signals or external cues that allows organ-
isms to adapt to their surroundings by producing different
proteins as needed.gene therapy A genetic engineering technique for correcting
defective genes responsible for disease development.genetic bottleneck A form of genetic drift that occurs when a
drop in the size of a population causes a loss of genetic variation.genetic carrier An individual who has only one copy of a recessive
allele for a particular disease and therefore can pass on the disor-
der allele but does not have the disease.genetic code The information specified by each of the 64 possible
codons.genetic cross A controlled mating experiment performed to
examine how a particular trait may be inherited.genetic disorder A disease caused by an inherited mutation,
passed down from a parent to a child.genetic divergence The presence of differences in the DNA
sequences of genes.genetic drift A change in allele frequencies produced by random
differences in survival and reproduction among the individuals
in a population.genetic engineering The permanent introduction of one or more
genes into a cell, tissue, or organism.genetic modification (GM) Altering the genes of an organism
for a specific purpose.genetic recombination The exchange of DNA between homolo-
gous chromosomes brought about by crossing-over, contributing
to variation in gametes.genetic trait Any inherited characteristic of an organism that can
be observed or detected in some manner.genome The complete set of genes of an organism.
genotype The allelic makeup of a specific individual with respect
to a specific genetic trait. Compare phenotype.genus (pl. genera) The unit of classification in the Linnaean hier-
archy above species and below family.geographic isolation The condition in which populations are
separated by physical barriers. Compare ecological isolation and
reproductive isolation.global warming A significant increase in the average surface
temp erature of Earth over decades or more. Compare climate
change.