Review: Variation

Organisms are classified according to shared characteristics. This process has led to the development of a classification system that has various levels of organization. Which of the following levels of classification is of the lowest hierarchy?

• kingdom

• class

• species

• domain

In the 1700s, Carolus Linnaeus tried to classify all living things. He developed a seven-level system of classification, which is still used today. Linnaeus grouped lower levels into successively higher levels, based on shared characteristics. What group is made up of different species?

• family

• class

• genus

• species

The illustration above shows that the number of types of organisms changes from one classification level to another.

Why are there fewer kinds of organisms at each lower level of classification?

• The higher the level of classification, the more closely related the organisms become.

• The lower the level of classification is, the more complex the organism becomes

• The higher the level of classification is, the smaller the size of the organism.

• The lower the level of classification, the more closely related the organisms become.

The earliest classification system was developed by Aristotle in the 4^th century B.C. This system classified all living things as either plants or animals. The two-kingdom system remained in place until 1866, when the kingdom Protista was created. What new information most likely led scientists to revise the existing classification system?

• the magnifying glass showed scientists that plants were made up of cells

• the microscope enabled scientists to discover single-celled organisms

• the microscope showed that cells of plants and animals have different structures

• the telescope enabled scientists to see objects they could not view before

The Linnaean system of classification groups organisms into levels based upon shared characteristics. Which statement about the hierarchy of classification is incorrect?

• The species level represents the smallest level of classification.

• Each kingdom can be divided into different phylum.

• A genus cannot contain members of a different species.

• Organisms can belong to the same class, but different orders

This illustration above shows a system that Shelby developed to classify different animals. Based on the information provided, which of the following best describes how Shelby placed the animals into each category?

• according to their structural features

• according to their genetic similarities

• according to their behavioral features

• according to the locations of their habitats

Rather than using common names, scientists use binomial nomenclature when classifying organisms. Which is the correct way to write the binomial nomenclature of dogs?

• Canis familiaris

• canis familiaris

• Canis Familiaris

• Canis familiaris

An organism is multicellular, cannot move about freely, lives on land, and decomposes other organisms for food. Into which kingdom would this organism be classified?

• Archaea

• Fungus

• Plant

• Protist

All plants are classified together in the plant kingdom. What is one way that plants are different from fungus?

• Plants are multi-cellular.

• Plants are prokaryotic.

• Plants cannot move freely.

• Plants produce their own food.

When Linnaeus created his taxonomy as scientists began studying single-celled organisms under the microscope, they generally classified them as either plants or animals. For example, bacteria are single-celled organisms, some of which make their own food. However, in 1866, biologist Ernst Haeckel created a third kingdom for all single-celled organisms. He called this kingdom Protista. Which statement best summarizes why single celled organisms are now classified in separate kingdoms?

• Advancements in technology showed that animals and plants are closely related.

• Plants and bacteria both contain cell walls and share more characteristics than separate them.

• The discovery of new evidence led to a reclassification of single celled organisms.

• The plant kingdom was getting two large, so scientists divided it into two kingdoms.