Biology Unit 1 Terms Flashcards
Biodiversity
the number and variety of
species and ecosystems on Earth
Species
all organisms capable of
breeding freely with each other under
natural conditions
Hybridization
the cross-breeding of two
different species
Morphology
the physical appearance
and characteristics of an organism; also
the science of the study of these physical
characteristics
Genetic diversity
the genetic variability
among organisms; usually referring to
individuals of the same species
Heterotroph
an organism that obtains
energy-rich nutrients by consuming living
or dead organisms
Autotroph
an organism that uses sources
of energy to produce nutrients from water,
gases, and/or minerals
Species diversity
a measure of diversity
that takes into account the quantity of
each species present, as well as the
variety of different species present
Structural diversity
the range of physical
shapes and sizes within a habitat or
ecosystem
Biological classification
the systematic
grouping of organisms into biological
categories based on physical and
evolutionary relationships
Taxonomy
the science of classifying all
organisms; taxonomists classify both living
and fossil species
Genus
a taxonomic level consisting of a
group of similar species
Binomial nomenclature
the formal system of naming species whereby each species is assigned a genus name followed by a specific name; the two words taken together form the species name
Taxon
a category used to classify
organisms
Kingdom
the highest taxonomic level
of the traditional Linnaean system of
classification
Dichotomous key
a series of branching,
two-part statements used to identify
organisms (or objects)
Phylogeny
the study of the evolutionary
relatedness between, and among, species
Phylogenetic tree
a diagram depicting
the evolutionary relationships between
different species or groups
Clade
a taxonomic group that includes
a single common ancestor and all its
descendants
Prokaryote
a single-celled organism
that does not contain membrane-bound
organelles
Eukaryote
any organism whose cells
contain organelles; some eukaryotic
organisms are single-celled, while others
are multicellular
Domain
the highest taxonomic level;
there are three domains of life
Pathogen
a disease-causing agent, often
a virus or micro-organism
Mutualism
m a relationship between two
species that live in very close association
with each other, whereby each benefi ts
from the association
Antibiotic
a substance that can kill or
weaken micro-organisms; natural antibiotics
are produced by bacteria or fungi, whereas
synthetic antibiotics are manufactured
Plasmid
a small loop of DNA often found
in prokaryotic cells; usually contains a
small number of genes
Capsule
an outer layer on some bacteria;
provides some protection for the cell
Coccus
a round bacterial cell
Bacillus
a rod-shaped bacterial cell
Spirillum
a spiral or corkscrew-shaped
bacterial cell
Obligate aerobe
an organism that cannot
survive without oxygen
Facultative aerobe
an organism that can
live with or without oxygen
Fermentation
an anaerobic process that
releases chemical energy from food
Obligate anaerobe
an organism that
cannot survive in the presence of oxygen
Binary fission
n the division of one parent
cell into two genetically identical daughter
cells; a form of asexual reproduction
Conjugation
a form of sexual
reproduction in which two cells join to
exchange genetic information
Endospore
a dormant structure that
forms inside certain bacteria in response
to stress; protects the cell’s chromosome
from damage
Virus
a small infectious particle
containing genetic material in the form
of DNA or RNA within a protein capsule
Capsid
a protein coat that surrounds
the DNA or RNA of a virus
RNA (ribonucleic acid)
a nucleic acid
found in all cells and some viruses; usually
carries genetic information that provides
instructions for synthesizing protein
Bacteriophage
a virus that infects
bacteria
Lysis
the rupturing of a cell; can occur
when newly made viruses are released
from a host cell
Lysogeny
a state of dormancy in which
viral DNA may remain within a host cell’s
chromosome for many cell cycle generations
Endosymbiosis
a relationship in which
a single-celled organism lives within the
cell(s) of another organism; recent fi ndings
suggest this may be very common
Haploid
a cell containing half the usual
complement of chromosomes
Zygote
a cell produced by the fusion of
two gametes
Diploid
a cell containing two copies of
each chromosome
Sporophyte
a diploid organism that
produces haploid spores in an alternation
of generations life cycle
Spore
a haploid reproductive structure;
usually a single cell; capable of growing
into a new individual
Gametophyte
a haploid organism
that produces haploid sex cells in an
alternation of generations life cycle
Alternation of generation
a life cycle in
which diploid individuals produce spores
that create haploid individuals; the haploid
individuals reproduce sexually, producing
sporophyte individuals and completing the
cycle
Mycellium
a branched mass of hyphae
Hypha
a thin fi lament that makes up the
body of a fungus
Chitin
a complex chemical found in the
cell walls of fungi and in the external
coverings of insects and crustaceans such
as lobsters and crabs
Dikaryotic
containing two separate nuclei
Mycorrhiza
a symbiotic relationship
between a fungus and a plant root
Bryophyte
a small seedless plant that
lacks vascular tissue
Pterophyte
a seedless vascular plant;
ferns are examples of pterophytes
Gymnosperm
a vascular plant that
produces seeds in special structures
called cones; gymnosperms are a major
plant group
Angiosperm
a plant that produces
flowers; angiosperms form the largest
group of living plants
Radial symmetry
symmetry around a central axis
Bilateral symmetry
symmetry around a midline
Vertebrate
an animal with a backbone or
a notochord
Notochord
a flexible rod found in some
chordates; in most modern chordates it is
replaced by vertebrae during embryonic
development
Invertebrate
an animal that does not
have a backbone; the great majority of
animal species are invertebrates
Germ layer
one of three layers that form
during early embryonic development in
most animals
Coelom
a body cavity present in some
animals; contains the animal’s internal
organs
