is this statement true or false? living things are classified by the characteristics they have in common.

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Classification of Living Things: Principles of Classification

Think about an elephant.  Develop a mental image of it.  How would you describe it to someone who has never seen one?  Take a moment to consider carefully . . .Click the button to see if

your mental image was accurate.

Very likely your mental image was a visual one like the picture.  Humans primarily emphasize traits that can be seen with their eyes since they mostly rely on their sense of vision.  However, there is no reason that an elephant or any other organism could not be described in terms of touch, smell, and/or sound as well.  Think about an elephant again but this time in terms of non-visual traits . . .

Not surprisingly, biologists also classify organisms into different categories mostly by judging degrees of apparent similarity and difference that they can see.  The assumption is that the greater the degree of physical similarity, the closer the biological relationship.

On discovering an unknown organism, researchers begin their classification by looking for anatomical features that appear to have the same function as those found on other species.  The next step is determining whether or not the similarities are due to an independent evolutionary development or to descent from a common ancestor.  If the latter is the case, then the two species are probably closely related and should be classified into the same or near biological categories.

Human arm bones

Homologies are anatomical features, of different organisms, that have a similar appearance or function because they were inherited from a common ancestor that also had them.  For instance, the forelimb of a bear, the wing of a bird, and your arm have the same functional types of bones as did our shared reptilian ancestor.  Therefore, these bones are homologous structures.  The more homologies two organisms possess, the more likely it is that they have a close genetic relationship.

There can also be nonhomologous structural similarities between species.  In these cases, the common ancestor did not have the same anatomical structures as its descendants.  Instead, the similarities are due to independent development in the now separate evolutionary lines.  Such misleading similarities are called homoplasies .  Homoplastic structures can be the result of parallelism, convergence, or mere chance.

Parallelism , or parallel evolution, is a similar evolutionary development in different species lines after divergence from a common ancestor that did not have the characteristic but did have an initial anatomical feature that led to it.  For instance, some South American and African monkeys evolved relatively large body sizes independently of each other.  Their common ancestor was a much smaller monkey but was otherwise reminiscent of the later descendant species.  Apparently, nature selected for larger monkey bodies on both continents during the last 30 million years.Convergence , or convergent evolution, is the development of a similar anatomical feature in distinct species lines after divergence from a common ancestor that did not have the initial trait that led to it.  The common ancestor is usually more distant in time than is the case with parallelism.  The similar appearance and predatory behavior of North American wolves and Tasmanian wolves (thylacines) is an example.  The former is a placental mammal like humans and the latter is an Australian marsupial like kangaroos.  Their common ancestor lived during the age of the dinosaurs 125 million years ago and was very different from these descendants today.  There are, in fact, a number of other Australian marsupials that are striking examples of convergent evolution with placental mammals elsewhere.

Australian Tasmanian wolf or tiger

(now extinct) North American wolf

Last Tasmanian Tiger, Thylacine, 1933 (silent film): To return here, you must click

the "back" button on your browser program.             (length = 43 secs)

Examples of Convergent Evolution--ant eating mammals from four continents       This link takes you to an external website.  To return here, you must click the "back"

button on your browser program.

Both parallelism and convergence are thought to be due primarily to separate species lines experiencing the same kinds of natural selection pressures over long periods of time.

Analogies are anatomical features that have the same form or function in different species that have no known common ancestor.  For instance, the wings of a bird and a butterfly are analogous structures because they are superficially similar in shape and function.  Both of these very distinct species lines solved the problem of getting off of the ground in essentially the same way.  However, their wings are quite different on the inside.  Bird wings have an internal framework consisting of bones, while butterfly wings do not have any bones at all and are kept rigid mostly through fluid pressure.  Analogies may be due to homologies or homoplasies, but the common ancestor, if any, is unknown.

Source : www2.palomar.edu

Classification of Living Things

CK-12 Life Science For Middle School covers: Cell Biology, Genetics, Evolution, Prokaryotes, Protists, Fungi, Plants, The Animal Kingdom, The Human Body, and Ecology.

2.3 Classification of Living Things

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Last Modified: Jun 28, 2017

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Characteristics, needs and classification of living things Flashcards

Memorize flashcards and build a practice test to quiz yourself before your exam. Start studying the Characteristics, needs and classification of living things flashcards containing study terms like 5 Characteristics of all living things, Organism, Cell and more.

Characteristics, needs and classification of living things

5 Characteristics of all living things

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(1) Have a cellular organization

(2) contain similar chemicals

(3) use energy

(4) respond to their surroundings

(5) grow and develop

(6) reproduce

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Organism

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A living thing

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Terms in this set (56)

5 Characteristics of all living things

(1) Have a cellular organization

(2) contain similar chemicals

(3) use energy

(4) respond to their surroundings

(5) grow and develop

(6) reproduce Organism A living thing Cell

Building block of structures in an organism

Unicellular organism

Made of only one cell

Multicellular organism

Made of many cells

TRUE OR FALSE: Living things react to what happens around them?

TRUE Stimulus

A change in an organism's surroundings. For example, light is a stimulus.

Response

An action or behavior an organism takes when it reacts to a stimulus. For example, a plant bending toward light is a response

What happens when a living organism grows?

It gets larger.

What happens when an organism develops?

It produces a more complex organism

What happens to an organism's cells when an organism grows and develops?

The organism's cells use energy to make new cells.

TRUE OR FALSE: When an organism reproduces it produces offspring that look nothing like the organism.

FALSE. The offspring are like its parents.

TRUE OR FALSE: Living things come from non-living things.

FALSE: Living things arise through reproduction.

Francesco Redi

Set up an experiment to show that rotting meat does not produce flies

Louis Pasteur

Carried out experiment that showed bacteria could only be produced only from bacteria

4 Basic needs of all living organisms

(1) Water (2) Food (3) Living space

(4) Staple internal conditions

Why do living things need water?

Water dissolves body chemicals and carries the chemicals through the body

Autotrophs

Living things that make their own food. Plants are autotrophs.

Heterotrophs

Get energy by feeding on other living things. Animals are heterotrophs

TRUE OR FALSE: Living things must get food, water, and shelter from where they live.

TRUE

Stable internal conditions

Keeping the conditions inside an organism's body stable even when conditions around it changes. For example, your body temperature stays the same even as air temperature changes

Homeostasis

Stable living conditions

Why do biologists use classification?

To organize living things into groups so that organisms are easier to study.

What is classification?

Grouping things based on their similarities

Taxonomy

The scientific study of how living things are classified

Carolus Linnaeus

Devised a system of naming organisms in which each organism has a unique, two-part scientific name

Under Linnaeus' system, what were the two parts of the scientific name?

The first part is the genus, the second part is a distinctive feature of the organism

Genus

A group of similar organisms. Example, all cats belong to the genus Felis

The two words in a scientific name make up a _________.

Species Species

A group of similar organisms that can mate and produce offspring that can also mate and reproduce.

TRUE OR FALSE: Scientific names make it easier for scientists to talk about animals.

TRUE. For example, woodchucks are also called "groundhogs" and "whistlepigs"; but when using the scientific name scientists know they're talking about animal.

The more classifications levels that two organisms share_____

the more characteristics they have in common.

Eight levels of classifying organisms:

(1) domain (2) kingdom (3) phylum (4) class (5) order (6) family (7) genus (8) species

Which classification has the largest number of organisms?

Domain. It is the highest level of classification.

Lowest level in classification system.

Species. Characteristics of a species are very specific. Only one kind of organism is in the species level.

Organism are placed into domains and kingdoms base on what 3 factors?

(1) cell type

(2) ability to make food

(3) number of cells in their bodies

What are the 3 domains?

(1) Bacteria (2) Archaea (3) Eukarya Bacteria

Single-celled living things.

TRUE OR FALSE: Bacteria are Prokaryotes

TRUE Prokaryotes

Living things that do not have a nucleus

Nucleus

A dense area in a cell that holds genetic material

TRUE OR FALSE: All bacteria are autotrophic.

FALSE: Some are autotrophic, some cannot make their own food (they are heterotrophic)

Where can you find members of the domain Archaea?

In harsh environments like hot springs

Archaea

Single-celled organisms that DO NOT have a nucleus. Some Archaea make their own food (autotrophic) other cannot (heterotrophic)

TRUE OR FALSE: Archaea have similar chemical makeup to bacteria

Source : quizlet.com