Unit 4 Lesson 2: Classification of Living Things Flashcards
Since ancient times, people have worked to develop a system for classifying millions of different kinds of plants, animals, bacteria, and other living things on Earth. This classification, called
Taxonomy
Early civilizations organized living things into two groups:
those with blood and those without blood.
Taxonomy is a living science, meaning it is changing as new discoveries are made. How do Modern taxonomical systems classify animals?
Modern taxonomical systems are moving from classifying organisms by shared superficial characteristics, to grouping them by their genetic relationships. In the same way that Medieval naturalists used their increasing knowledge to better group and understand organisms, today’s scientists work with new technologies to deepen our understanding of the relationships between living things.
taxonomy
the branch of science concerned with naming, classifying, and describing the relationships between all living things on Earth
How did Aristotle classify animals
The Greek naturalist Aristotle used a system that separated plants from animals. Aristotle further organized animals into groups based on their physical characteristics (having live births, having four legs, laying eggs, etc.).
What does taxonomy allow people to do
This classification, called taxonomy, allows people to understand the relationships between living things and to study their similarities, differences, and needs.
botanist
plant scientist
What did Swedish botanist (plant scientist) named Carolus Linnaeus do
During the 1700s, a Swedish botanist (plant scientist) named Carolus Linnaeus developed a new system of classification which became the standard for the modern world. Linnaeus created a standardized system for identifying and naming plants and animals
How did Linnaeus group people
He organized living things into large kingdoms of plants and animals. Within each kingdom, he further classified living things into smaller and smaller groups.
Animals, for instance, can be classified as follows:
Phylum (with or without a backbone)
Class (mammal, bird, fish, insect, reptile, amphibian)
Order
Family
Genus
Species
Individual species are officially labeled with the name of their
genus and species.
For example, the scientific label for modern human beings is
Homo sapiens
A human’s full taxonomic classification is as follows:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens
While Linnaean classification is still the basis for taxonomy, new ideas and technologies have expanded and changed his system. For example: What did Darwin do
Darwin’s discoveries regarding evolution helped scientists to better understand the complex relationships among living things. In particular, scientists have learned that the appearance of a modern animal does not necessarily reflect its evolutionary path or its relationship to other animals.
What is an example of Darwins idea by Thomas Henry Huxley
An example of this is Thomas Henry Huxley’s use of fossils to argue that birds are directly descended from (and thus related to) dinosaurs.
While Linnaean classification is still the basis for taxonomy, new ideas and technologies have expanded and changed his system. For example: Discovery of the microscope:
The invention of the microscope led to the discovery of living organisms too small to be seen with the naked eye or a magnifying glass. Bacteria, viruses, and archaea (single celled organisms without nuclei) are all organisms that were unknown to Linnaeus. They were later classified into additional kingdoms. Currently, there are six kingdoms used by scientists.
While Linnaean classification is still the basis for taxonomy, new ideas and technologies have expanded and changed his system. For example: In the last twenty years, several new taxonomic systems have been suggested by researchers who are discovering new life forms and uncovering their relationships to one another. Describe the one suggested in 2015
One system, suggested in 2015, includes seven kingdoms. Separate kingdoms are recommended for specific forms of life such as fungi (spores such as mushrooms), protozoans (a particular type of single-celled organism), and archaea.
People who study taxonomy, called ….
People who study taxonomy, called systematists, are still engaged in the process of discovering new life forms and classifying them.
paleontologist
scientist who studies pre-human life
What do paleontologists do
Meanwhile, paleontologists are constantly discovering new fossil and DNA evidence that changes our views of exactly how specific life forms evolved.
What is the Linnaean classification system?
The Linnaean classification system, created by the Swedish botanist Linnaeus, is the system used to name and classify all living things on Earth.
As an organism is placed within each group of the Linnean levels, the traits that classify it become more and more specific. Where whold animal with a backbone be placed?
An animal with a backbone will be placed in the phylum Chordata (a word that simply means “having a spinal cord”).
Developing the rules of taxonomy is somewhat challenging. Elaborate
One of the original taxonomic systems classified all life as either plant or animal. That’s it. From there, things could become a bit more specific. Animals or plants could be classified as belonging to the air, or to the water. However, this system did not account for organisms like ducks. Where should they be classified? A duck is not clearly an air animal, or a water animal. Ducks fly. They walk on the ground and they live in the water. Obviously, this method of classification did not work well for all organisms.
If that animal has fur and milk glands, it belongs to the order
Mammalia, the mammals.
The smallest groups in the Linnaean system are
genus and specie
An organism’s genus and species make up its
scientific name
What is the scientifc names for humans
Humans, for instance, belong to the genus Homo and the species sapiens, so their scientific name is Homo sapiens.
Because a species’ name comes from those smallest two categories, Linnaeus called his system
binomial nomenclature
binomial nomenclature
Binomial is a Latin word that means “two”, and nomenclature is a word that means “name”.
The hierarchies Linnaeus developed look like this:
Kingdom
Phylum
Class
Order
Family
Genus
Species
Finally, in 1990, a microbiologist called Carl Woese proposed a big change to taxonomy. What did he propose?
Building off the Linnaean system, Woese proposed that a higher category than kingdoms be added. He called that category “domains”.
There are three domains into which all living things can be classified.
These are Bacteria, Archaea, and Eukarya.
domain Bacteria
The members of the domain Bacteria are common prokaryotic organisms found just about everywhere. While some of them do cause disease, the main function of a lot of bacteria is decomposition. They break down dead organisms to release nutrients back into the ecosystem. No nucleus. examples include: *E.coli, Streptococcus *
Members of the domain Archaea are believed to be remnants of species alive during
Earth’s early years when conditions were much less hospitable than they are today. During that time, there was no oxygen in the atmosphere, and it was extremely hot.
the domain Archaea
Today, Archaea live in extreme environments where other life cannot survive. Like Bacteria, Archaea are prokaryotic, lacking a true nucleus in their cells.
An example of an Archaea is a species called a methanogen.
These organisms live in areas where methane gas is common (like it used to be billions of years ago). Methanogens can be found inside cow’s stomachs. The domain Archaea is not currently classified into kingdoms.
The third domain into which organisms are classified is called the Eukarya.
These organisms are eukaryotic, meaning they have a membrane-bound nucleus. Members of this domain include animals, plants, fungi, and protists – basically everything other than the prokaryotic organisms.
Every organism falls into one of the three domains. However, only the eukaryotic organisms can be classified into kingdoms. The four kingdoms of Eukaryotes are
he four kingdoms of Eukaryotes are the Animalia (animals), Plantae (plants), Fungi (fungus), and Protista (protozoans and algae). The kingdoms are classified using a hierarchy similar to that of the Linnaean system.
What is a species
A species is defined as a group of individuals that can reproduce.
What does it mean if two organisms are in the same genus
If two organisms are in the same genus, they also share the same domain, kingdom, phylum, class, order, and family.
Who should scietifc names be written
It is also common protocol that, whenever one is typing a scientific name, it should be italicized, with the first letter of the genus capitalized. The species name is lowercase. A scientific name should be underlined when written by hand.
When scientists find an organism they do not know, they use a tool called a ? to help them narrow down the options of what it could be. This is especially useful when examining species that look very much alike.
dichotomous key
How to use a dichotomous key
The key is based on physical characteristics of an organism. It presents two options (the prefix “di” means “two”) of having or not having the characteristic. To use the key, a scientist makes choices based on the organism’s observed traits. Once enough traits have been narrowed down the scientist reaches a point where she cannot go any further and must select a species name.
What is the relationship between Order and Family?
Organisms that are in the same Order are not necessarily in the same Family. However, organisms in the same Family are in the same Order.
Linnaean classification is the basis for taxonomy. However, new ideas and technologies have improved the original system. Among the most important of these are:
- The theories of natural selection and evolution. These theories suggest that animals and plants which look similar might not share a common ancestor. Scientists used these new ideas to begin basing their classifications on more than superficial resemblances.
- The discovery of genetics and DNA. This discovery allows scientists to better trace relationships among different species.
- The invention of the microscope. Carolus Linnaeus did not know single-celled life forms exist. Microscopes make it possible for scientists to observe and describe organisms which can’t be seen by the naked eye.
Why is taxonomy important?
It allows us to identify species, make important decisions about conservation, and discover new resources.
Taxonomy is an important tool in helping to choose which habitats and species to conserve.
Is the statement true or false?
This is true. Taxonomy is the process of identifying species and their place in the ecosystem. Thus, taxonomy is an important tool for conservation.
