Transcript Notes 2.1 - TeacherWeb

Notes 2.1
Scientists develop systems for
classifying living things.
Scientists classify millions of species.
• Until the 1600s, scientists classified organisms
according to their appearance.
• The invention of the microscope allowed
scientists to see structures and organisms that
were not visible before.
Classification and Taxonomy
• Classification: the process of arranging
organisms into groups based on similarities
• Taxonomy: the science of naming and
classifying organisms
• The purpose of classification and taxonomy is
to make information easier to find and
understand.
Classification and Taxonomy
• Until 1700s scientists could not agree on a
system
• Both overly long Latin scientific names and
common names can be confusing.
Using Classification
• Scientists use similarities and differences
among species, including appearance,
biology, and genetics.
• The more characteristics 2 organisms share,
the more similar their scientific names should
be in the classification system.
• See examples on page 45B.
Taxonomists study biological
relationships.
• Taxonomists: the scientists who classify and
name organisms based on their similarities
and differences.
• Taxon: a group of organisms that share certain
traits
• Taxons can be broad (animal) or more specific
(cat).
• A single species found in a fossil record can be
the ancestor of many species on Earth today.
Taxonomists study biological
relationships (continued)
• In order to classify organisms, scientists
compare a variety of traits.
• Trait: a characteristic or behavior
• If 2 organisms share a trait, taxonomists try to
determine if they share that trait because they
share an ancestor.
Continued
• Page 47B—the seahorse shares more traits
with a leafy sea dragon than the sargassum
seaweed or sargassum fish.
• Taxonomists take evidence and try to
reconstruct the evolution of a species.
• Then they place the species in the
classification system.
Physical Evidence
• Primary devices used—eyes and measuring
devices
• Collect samples and note characteristics—size,
color, weight, how obtain energy, internal
structures, outward appearance
• Individuals of a species have many similarites
and some differences.
Physical Evidence
• Skeletons, shells, and other hard parts of
organisms fossilize more easily.
• Scientists observe and measure this evidence.
• They also compare bones.
• All this physical evidence helps scientists see
that all living organisms are related by
evolution.
• Those most closely related share a more
recent ancestor.
Genetic Evidence
• Scientists can compare the components of a
gene from one organism with the components
of the same gene from another organism.
• Genetic evidence usually supports physical
evidence.
• See p. 49B—Red pandas are more closely
related to raccoons than Giant Pandas
Review Questions 49B
• 1. Classification allows taxonomists
to organize a great deal of data so
that it is easier to find and
understand.
Number 2
• Taxonomists study biological
relationships to discover how one
species evolved as compared
with another species.
Number 3
• Scientists look at DNA and
compare genes of organisms.
Number 4
• Having a universal naming system
allows people speaking different
languages to refer to all organisms
the same way. It’s easier to
understand.
Number 5
A marbled godwit would have marbled
feathers, wings, feet, and a beak.
Number 6
• Compare physical traits, such as color, size,
weight and how they get energy. Analyze
bones; compare to fossils; compare DNA.
Quiz Fill-in Terms
Classification
Evolution
physical
System
taxons
Taxonomy
Traits
genetic
Extended Response
• Explain how scientists may use
physical and genetic evidence to
determine how closely related two
species of birds are.
• Quiz Wednesday!