Chapter 15: Biological Classification
The Importance of Scientific Names

Each kind of organism on Earth is assigned a unique _____________________
_______________________________________
o ___________________________________________

All biologists, regardless of their native language, use scientific names when
speaking or writing about organisms

Most organisms also have __________________________________

Using scientific names enables scientists to exchange information about an
organism and to be certain that they are referring to the same living thing
What’s in a Scientific Name?

First word describes the organism in a __________________________

The second word identifies the ___________________________ of living thing

The first word of a scientific name is the name of the _________________ to
which the organism belongs
o Group of animals that share major characteristics

The second word in a scientific name identifies one particular kind of
organism within the genus

Scientists call each different kind of organism a ______________________

The correct name for an organism must include ________________ parts of its
scientific name
Scientific Names Must Conform to a Set of Rules

All scientific names must consist of ___________________ words

Two different organisms cannot be assigned the same name

Organisms in different genera cannot have the same _____________________
________________

When choosing a name for a species, biologists often pick a name that
describes the _______________________________________________ of an
organism
Why are Scientific Names in Latin?

In the Middle Ages, when scientists began to name organisms, Latin was used
in academic circles

Scientists and other scholars found it easier to communicate with each other
in Latin

Latin was the language of the scholar and was used for all spoken and written
communication

Easier to still use Latin than to rename all ___________________________
known organisms

Latin is a _________________________________________
Linnaeus Devised the Two-Name System

The modern system of naming organisms was developed by Swedish botanist
___________________________________

In Linnaeus’s day, organisms were given very long Latin names (sometimes
more than 15 words), which were often changed according to the whims of
particular scientists

Linnaeus assigned a standard, two-word Latin name to each organism known
in his time
Writing a Scientific Name is Simple

When you write a scientific name, always ______________________ the
genus name

Begin the second word with a ______________________________________

Both part of a scientific name are underlined or written in italics
o Homo sapiens
o Homo sapiens

After the first use of the full scientific name, the genus name can be
abbreviated as a single letter if the meaning is clear
o H. sapiens
Classification of Living Things

The Greek philosopher ______________________ grouped animals by their
physical similarities

Today biologists classify organisms based on their physical, genetic,
biochemical, and behavioral similarities

The classification of organisms is based on decisions made by many scientists
using available information

The science of classifying living things is called _________________________

Taxonomists are scientists who examine, classify, and argue about where
organisms fit in a group

In a hierarchical system of classification, species are assigned to genera,
genera are assigned to families, and families are assigned to groups of
________________________________
Organisms are Classified by Similarity

In biological classification, organisms are assigned to a group because they
____________________________________________________________ with
other members of that group

The biological hierarchy of classification has seven different levels
o Kingdom, phylum, class, order, family, genus, and species

The smallest group in biological classification is the __________________

Similar species are collected into a _________________

Similar genera are united into a ______________________

Families that are alike are combined into an _________________

Similar orders are collected into a ________________

Classes are united into a ____________________

Finally, similar phyla are collected into a ______________________

The more classification categories two species share, _____________________
___________________________________________________
Biological Classification

Kristy

_____________________

Poured

_____________________

Coffee

_____________________

On

_____________________

Fred’s

_____________________

Green

_____________________

Shirt

_____________________
Classification and Evolution

The biological hierarchy of classification is based on the fact that different
degrees of similarity exist among organisms

For Darwin, classification provided strong evidence supporting
__________________________

Organisms are similar because they descended from a common ancestor

The more similarities two organisms share, the _________________________
they shared a common ancestor

Thus, the more classification categories two organisms share, the more closely
related they are
Similarity Does not Guarantee Close Relationship

Compare the two ocean-dwelling animals seen here

Both have ________________________________, _______________________
_____________, and ________________________________

Would you say these organisms are closely related?

___________________________________ does not guarantee ______________
________________________

Because the number of differences between sharks and dolphins far exceeds
the number of similarities, it is easy to reject the hypothesis that these animals
are close relatives
Methods of Taxonomy

The example of the shark and dolphin illustrates the difficulty in determining
which similarities will be useful when classifying an organism

There are two alternative methods of choosing which similarities are
important

The first method is __________________________
Taxonomy and Technology

Biologists have traditionally compared the appearances of organisms in order
to discover the relationships among them

Biologists also consider the ________________________________________,
_____________________________________________, __________________
_____________________, and ____________________________ from
fertilization to adulthood

Technological advances have enabled biologists to study the genes that
produce the traits used to classify organisms

Taxonomists use techniques of molecular biology to compare the DNA
nucleotide sequences of different organisms

Comparisons of _____________________________________ are especially
important for the taxonomist because mutations are random events

As time passes, more mutations tend to occur in the DNA of a particular
species

Thus, DNA acts as a ______________________________________
What Is a Species?

A species is just a level in the classification system to which scientists assign
very similar organisms

Over time, species change and give rise to new species in a process known as
_________________________

Biologists have traditionally defined a species as organisms that are able to
_______________________ with each other to produce fertile offspring and
that usually do not reproduce with members of other groups

This definition works well for most animals

For example, the horse and the zebra belong to different species

Although they can mate, the resulting offspring, the “zebroid”, is
__________________

________________________________________ between species are not
always perfect

____________________ are offspring that result from interbreeding by
individuals of different species
o ______________________________________________
A Species is a Unique Kind of Organism

A species is basically a unique kind of organism

Members of a species share at least ____________________________________
_____________________________ not found in other similar organisms

In sexually reproducing species, this distinctive characteristic is maintained
from generation to generation because members of different species do not
interbreed
Six – Kingdom System

Biologists used to classify every living thing into either kingdom
____________________ or kingdom ______________________

However, numerous living things do not quite fit either description

For example, where would a mushroom fit?

Since Linnaeus’s time, biologists have learned a great deal about the
_____________________________________________________ of living
things

This information has enabled them to make increasingly precise distinctions
among the major groups of organisms

Most biologists now use a ___________________________ system of
classification
o ________________________________
o ________________________________
o _________________________________
o _________________________________
o _________________________________
o _________________________________
Bacteria

All prokaryotes, also called _________________________, are in the
kingdoms Archaebacteria or Eubacteria

The bacteria represent the _______________________________________
groups on earth

They have adapted to almost every environment

All bacteria ________________________________________________
Kingdom Archaebacteria

The archaebacteria evolved before ___________________________ filled our
atmosphere and now are found in extreme environments

Fewer than _____________________________ have been recognized so far

Archaebacteria are believed to be the ancestors of the ____________________
Kingdom Eubacteria

Contains most of the __________________________________________ that
share our world

They are an extremely diverse group, containing both autotrophic and
heterotrophic forms

Approximately __________________________________ have been
characterized so far, but many more exist

Eubacteria are believed to be the ancestors of __________________________
______________________________________________, organelles within
eukaryotic cells
Kingdom Protista

All the multicellular eukaryotes not classified as plants, animals, or fungi are
assigned to this kingdom

Protists include ______________________________, such as Amoeba and
Paramecium, and algae, such as seaweeds and kelps

Slime molds and water molds also belong to this kingdom
Kingdom Fungi

______________________________________________________ are members
of this kingdom

Instead of roots, stems, and leaves, fungi are made of ____________________
___________________________ that penetrate the soil or decaying organisms,
absorbing nutrients from them

Fungi do not contain __________________________________ and cannot
make their own food by photosynthesis
Kingdom Plantae

This kingdom includes only terrestrial multicellular organisms that use
photosynthesis to obtain their nutrients

Nearly all plants occur on ______________________________, but a few grow
submerged in fresh water, and a very few grow at the edges of the sea

Plants cells have ____________________________

Because some green algae are so similar to plants they have been identified as
the ancestral groups for this kingdom
Kingdom Animalia

The first members of this kingdom evolved in the _______________________

The largest number of animal phyla are still found only in the _____________

Organisms in kingdom Animalia are ________________________________

Animals do not photosynthesize

Their cells do not have cell walls

Nearly all animals have some sort of __________________________________