Chapter 18 - Classification

Question 1

What is systematics?

Answer 1

Systematics is the science of grouping and naming organisms. The goal of systematics is to organize living things into groups that have biological meaning.

Question 2

What is bionomial nomenclature and who developed it?

Answer 2

Bionomial nomenclature is a two word naming system developed by Carolus Linnaeus.

Question 3

How is an organism’s scientific name written?

Answer 3

The name is written in italics and typically in Latin. (sometimes Greek) The first word, the genus, is always capital and the second word, the species, is always lowercase.

Question 4

What are taxa?

Answer 4

Taxa (singular: taxon) are larger groups that have a biological meaning.

Question 5

What 7 groups make up Linnaeus’s system of classification?

Answer 5

The 7 groups are kingdom, phylum, class, order, family, genus, and species.

Question 6

What is the goal of phylogenetic systematics? (evolutionary classification)

Answer 6

The goal is to group species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences.

Question 7

What is phylogeny?

Answer 7

Phylogeny is the study of how living and extinct organisms are related to one another.

Question 8

What is a clade?

Answer 8

A clade is a group of species that include a single common ancestor and all descendants of that ancestor— living and extinct. A clade must be a monophyletic group. A monophyletic group must include all species that are descended from a common ancestor and cannot include any species that are not descended from that common ancestor.

Question 9

What is a cladogram?

Answer 9

A cladogram links groups of organisms by showing how evolutionary lines branched off from common ancestors.

Question 10

What is a derived character?

Answer 10

It is a trait that arose in the most recent common ancestor of a particular image and was passed along to its descendants.

Question 11

What does the tree of life show?

Answer 11

It shows current hypotheses regarding evolutionary relationships among the taxa.

Question 12

What are the 6 kingdoms?

Answer 12

The 6 kingdoms are Eubacteria, Archaebacteria, Protista, Fungi, Plantae, and Anamalia.

Question 13

How have the number of kingdoms evolved?

Answer 13

Initially, in the 1700s, Plantae and Animalia were the only kingdoms. However, in the late 1800s, a new subgroup of Plantae known as Protista was introduced. In the 1950s, Plantae was divided yet again and Fungi joined the other kingdoms. Protista was also split, generating Monera. Finally, Monera was divided into Eubacteria and Archaebacteria.

Question 14

What is a domain?

Answer 14

A domain is a larger, more inclusive taxonomic category than a kingdom.

Question 15

Why are common names not useful to biologists?

Answer 15

Common names aren’t useful because the same animal can be called many names.

Question 16

What is cladistics?

Answer 16

Cladistics is a method of hypothesizing relationships among organisms — in other words, a method of reconstructing evolutionary trees. The basis of a cladistic analysis is data on the characters, or traits, of the organisms in which we are interested.

Question 17

Identify the two parts of a scientific name and explain what information can sometimes be inferred from the scientific name of an organisms

Answer 17

An example is Acer rubrum. The genus, Acer, tells us that the organism that we are classifying is a maple tree. The species, rubrum, tells us that the organism is red. Thus, we know that we are classifying and observing a red maple tree.

Question 18

What does each node on a cladogram represent?

Answer 18

Each node represents the last point at which the new lineages shared a common ancestor.

Question 19

What do protists, plants, fungi, and animals always have in common?

Answer 19

They are all eukaryotic.

Question 20

What are the 3 domains?

Answer 20

Bacteria corresponds to the Kingdom Eubacteria. They are all unicellular and prokaryotic. Their cells have thick, rigid walls that surround a cell membrane and contain a substance known as peptidoglycan. Next, Archaea are also unicellular and prokaryotic. They live in extreme environments and also have cell walls. However, their cell walls lack peptidoglycan. Finally, Eukarya consists of all organisms that have a nucleus.