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.