chapter 18 classification
______ and ______ are the two smallest categories.
Genus & species
Linnaeus's seven levels of classification are—from largest to smallest—
Kingdom Phylum Class Order Family Genus Species
Because 18th century scientists understood ____ ____ _____, they used those languages for scientific names.
Latin and Greek
_______ ___________ is a rapidly changing science.
Modern classification
Scientists realized there were enough differences among organisms to make 5 kingdoms:
Monera Protista Fungi Plantae Animalia
_________ ________ accumulate in different species at about the same rate.
Neutral mutations
The kingdom_______ is composed of eukaryotic organisms that cannot be classified as animals, plants, or fungi (Catch All Kingdom").
Protista
They can be unicellular or multicellular; photosynthetic or heterotrophic; and can share characteristics with plants, fungi, or animals.
Protista
This domain is organized into four kingdoms:
Protista Fungi Plantae Animalia
Characteristics that appear in recent parts of a lineage but not in its older members are called
derived characters.
Systems of classification adapt to new
discoveries.
Natural selection and other processes have led to a staggering
diversity of organisms.
The______ is a more inclusive category than any other—larger than a kingdom.
domain
There is great diversity within the animal kingdom, and many species exist in nearly ______ ______ of the planet.
every part
Cladograms help scientists understand how one lineage branched from another in the course of
evolution.
The strategy of grouping organisms is based on evolutionary history and is called
evolutionary classification.
Comparisons of DNA are used to mark the passage of
evolutionary time.
They live in
extreme environments.
Genera that share many characteristics are grouped in a larger category, the_____.
family
Most_______ can move about.
animals
Linnaeus classified organisms into two kingdoms—
animals and plants.
However,_________ ____ _____ share an evolutionary ancestor that is more recent than the ancestor that barnacles and limpets share.
barnacles and crabs
Superficial similarities once led _________ _____ __________ to be grouped together.
barnacles and limpets
In _________ ________, each species is assigned a two-part scientific name.
binomial nomenclature
When taxonomists classify organisms, they organize them into groups that have
biological significance.
Linnaeus not only named species, he also grouped them into
categories.
Their cells have thick, rigid cell walls that surround a
cell membrane.
The cells of animals do not have
cell walls.
Plants have cell walls that contain
cellulose.
These names were not standardized because different scientists described different
characteristics.
Many biologists now use a method called
cladistic analysis.
Derived characters can be used to construct a________ (also known as a branching diagram), a diagram that shows the evolutionary relationships among a group of organisms.
cladogram
The next larger category, the_____, is composed of similar orders.
class
Similarities in DNA can be used to help determine
classification and evolutionary relationships.
To study the diversity of life, biologists use a _________ _________ to name organisms and group them in a logical manner.
classification system
The higher the level of the taxon, the further back in time is the _______ ________ of all the organisms in the taxon.
common ancestor
Comparing sequences in two species shows how dissimilar the genes are, and shows when they shared a
common ancestor.
Organisms that appear very similar may not share a recent
common ancestor.
A cladogram shows the evolutionary relationships between
crabs, barnacles, and limpets.
Barnacles and crabs are classified as_________, and limpets are_______.
crustaceans & mollusks
Most fungi feed on _____ __ _______ ______ matter by secreting digestive enzymes into it and absorbing small food molecules into their bodies.
dead or decaying organic
A molecular clock relies on mutations to
mark time.
The more similar the DNA of two species, the more recently they shared a common ancestor, and the more closely they are
related in evolutionary terms.
Linnaeus grouped species into larger taxa mainly according to visible
similarities and differences.
The second part of the name is unique to each ______ within the genus. This part of the name often describes an important trait or where the organism lives. The______ name is lowercased.
species
Biologists have identified and named about __ _______ species so far.
1.5 million
They estimate that _________ additional species have yet to be discovered.
2-100 million
As new information is gained about organisms in the domains _______ ____ ________, they may be subdivided into additional kingdoms.
Bacteria and Archaea
The domain Archaea corresponds to the kingdom
Archaebacteria.
developed a naming system called binomial nomenclature.
Carolus Linneaus
____ evidence shows evolutionary relationships of species.
DNA
The more two species have diverged from each other, the less similar their
DNA will be.
The six-kingdom system of classification includes:
Eubacteria Archaebacteria Protista Fungi Plantae Animalia
Recently, biologists recognized that Monera were composed of two distinct groups:
Eubacteria and Archaebacteria.
The domain Bacteria corresponds to the kingdom
Eubacteria.
The three domains are: _______, which is composed of protists, fungi, plants, and animals. _______, which corresponds to the kingdom Eubacteria. _______, which corresponds to the kingdom Archaebacteria.
Eukarya Bacteria Archaea
_______ is the study of evolutionary relationships among organisms.
Phylogeny
The only known differences among living things were the__________ _____ that separated animals from plants.
fundamental traits
The first part of the name is the _____ to which the organism belongs. A_____ is a group of closely related species. The _____ name is capitalized.
genus
Members of the kingdom Fungi are
heterotrophs.
The scientific name is
italicized.
The______ is the largest and most inclusive of Linnaeus's taxonomic categories.
kingdom
Cladistic analysis identifies and considers only new characteristics that arise as
lineages evolve.
Its________ display the greatest variety.
members
A ________ ______ uses DNA comparisons to estimate the length of time that two species have been evolving independently.
molecular clock
The genes of many organisms show important similarities at the
molecular level.
The plant kingdom includes cone-bearing and flowering plants as well as
mosses and ferns.
They can be either ________ (mushrooms) or________ (yeasts).
multicellular & unicellular
Members of the kingdom Animalia are
multicellular and heterotrophic.
Members of the kingdom Plantae are
multicellular, photosynthetic autotrophs.
Simple _______ in DNA structure occur often.
mutations
This practice is still followed in naming
new species.
Plants are_______—they cannot move from place to place.
nonmotile
The domain Eukarya consists of organisms that have a
nucleus.
Common names of organisms vary, so scientists assign___ scientific name for each species.
one
An____ is a broad category composed of similar families.
order
Their cell walls lack __________, and their cell membranes contain unusual lipids not found in any other organism.
peptidoglycan
Their cell walls contain
peptidoglycan.
Several different classes make up a______.
phylum
The first attempts at standard scientific names described the _________ ____________ of a species in great detail.
physical characteristics
Biologists currently group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just
physical similarities.
Each level is called a____, or taxonomic category.
taxon
Molecular analyses have given rise to a new __________ _________ that is now recognized by many scientists.
taxonomic category
In the discipline of_________, scientists classify organisms and assign each organism a universally accepted name.
taxonomy
Members of the domain Archaea are
unicellular prokaryotes.
Members of the domain Bacteria are
unicellular prokaryotes.
