Chapter 2- Classification and Relationships

Question 1

The arrangement of organisms into groups based on shared characteristics, often to understand evolutionary relationships.

Answer 1

Classification

Question 2

Organisms that consist of more than one cell, often organized into tissues and organs.

Answer 2

Multicellular

Question 3

Multicellular animals that develop from a blastula, typically differentiated into various cell types.

Answer 3

Metazoans

Question 4

The term used to describe a group of ancient, multicellular organisms that lived during the Ediacaran period, before the Cambrian explosion.

Answer 4

Ediacaran fauna

Question 5

The rapid diversification of life that occurred during the Cambrian period, approximately 541 million years ago, resulting in the emergence of many modern animal phyla.

Answer 5

Cambrian explosion

Question 6

Relating to the form or structure of organisms.

Answer 6

Morphological

Question 7

Pertaining to the evolutionary history and relationships among or within groups of organisms.

Answer 7

Phylogenetic

Question 8

Related to the structure of organisms, particularly regarding the organization of their physical parts.

Answer 8

Anatomical

Question 9

Observable characteristics related to the form and structure of organisms.

Answer 9

Morphological traits

Question 10

Shared, derived characteristics that can be used to infer evolutionary relationships among taxa.

Answer 10

Synapomorphies

Question 11

Referring to a group of organisms that includes an ancestor but not all of its descendants.

Answer 11

Paraphyletic

Question 12

Describing a group of organisms that includes a single ancestor and all of its descendants.

Answer 12

Monophyletic

Question 13

A diagram that illustrates the arrangement of the different taxonomic groups based on their evolutionary relationships.

Answer 13

Dendrogram

Question 14

A classification approach that considers both the evolutionary history and the degree of similarity among different organisms.

Answer 14

Evolutionary systematics

Question 15

A method of classification based on the common ancestry and shared characteristics of species, using synapomorphies to define groups.

Answer 15

Cladistics

Question 16

Features that originate from a common ancestor and can be used to determine evolutionary relationships.

Answer 16

Homologous characters

Question 17

Traits that have similar functions but do not arise from a common evolutionary origin.

Answer 17

Analogous characteristics

Question 18

The direction of change in evolutionary traits, distinguishing between ancestral and derived states.

Answer 18

Polarity

Question 19

A statistical technique used to assess the reliability of a phylogenetic tree by resampling the data.

Answer 19

Bootstrapping

Question 20

Diagrams that represent the evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics.

Answer 20

Phylogenic trees

Question 21

A branching point on a phylogenetic tree where a common ancestor is represented.

Answer 21

Node

Question 22

Two lineages that share an immediate common ancestor.

Answer 22

Sister groups

Question 23

A species or group that is used to root a phylogenetic tree, helping to infer the direction of evolution.

Answer 23

Outgroup

Question 24

Multicellular animals that develop from a blastula, typically differentiated into various cell types.

Answer 24

Metazoans

Question 25

Organisms that consist of a single cell.

Answer 25

Unicellular

Question 26

Referring to organisms that do not have a cellular structure.

Answer 26

Acellular

Question 27

Organisms that can be divided into two mirror-image halves along a single plane.

Answer 27

Bilaterally symmetrical

Question 28

The concentration of sensory and nervous tissues at one end of an organism, leading to the formation of a head.

Answer 28

Cephalization

Question 29

Organisms that can be divided into similar halves by multiple planes passing through the central axis.

Answer 29

Radially symmetrical

Question 30

Layers of cells that develop during embryonic development and give rise to different tissue types in the organism.

Answer 30

Germ layers

Question 31

Organisms that have two germ layers: ectoderm and endoderm.

Answer 31

Diploblastic

Question 32

The outermost germ layer that develops into the outer covering of the body and the nervous system.

Answer 32

Ectoderm

Question 33

The innermost germ layer that develops into the innermost lining of the digestive tract and associated organs.

Answer 33

Endoderm

Question 34

Organisms that have three germ layers: ectoderm, endoderm, and mesoderm.

Answer 34

Triploblastic

Question 35

The middle germ layer that develops into muscles, the circulatory system, and other internal structures.

Answer 35

Mesoderm

Question 36

Organisms that possess a coelom, a fluid-filled body cavity lined with mesoderm.

Answer 36

Coelomates

Question 37

Animals with a true coelom fully lined with mesodermal cells.

Answer 37

Eucoelomates

Question 38

A group of coelomate animals in which the mouth develops from the blastopore during early embryonic development.

Answer 38

Protostomes

Question 39

The process of coelom formation in protostomes, whereby the coelom forms through a split in the mesoderm.

Answer 39

Schizocoely

Question 40

A group of coelomates in which the anus develops from the blastopore, with the mouth forming later.

Answer 40

Deuterostomes

Question 41

The process of coelom formation in deuterostomes, in which the coelom arises from pouches of the archenteron.

Answer 41

Enterocoely

Question 42

The region of an egg where the embryo develops and is typically associated with the formation of future embryonic tissues.

Answer 42

Animal pole

Question 43

The region of the egg opposite the animal pole, associated with the formation of the yolk and supportive tissues.

Answer 43

Vegetal pole

Question 44

A type of cleavage in embryonic development where the cells divide symmetrically and align vertically.

Answer 44

Radial pattern

Question 45

A type of embryonic development where cells divide at an oblique angle, creating a spiral arrangement.

Answer 45

Spiral cleavage

Question 46

The smaller cells resulting from cleavage during early development.

Answer 46

Micromeres

Question 47

The larger cells resulting from cleavage during early development.

Answer 47

Macromeres

Question 48

A type of development in deuterostomes where the potential of embryonic cells remains flexible, allowing them to develop into complete organisms if separated.

Answer 48

Indeterminate or regulative

Question 49

A type of development in protostomes where the fate of embryonic cells is fixed very early in development.

Answer 49

Determinate or mosaic

Question 50

A small bulge that forms at one end of certain embryos, playing a role in determining cell fate.

Answer 50

Polar lobe

Question 51

The fluid-filled cavity that forms within the blastula, playing a role in embryo development.

Answer 51

Blastocoel

Question 52

A body cavity that is not lined with mesoderm-derived tissue.

Answer 52

Pseudocoel

Question 53

An organism possessing a pseudocoel, which provides a fluid-filled body cavity.

Answer 53

Pseudocoelomate

Question 54

Animals that lack a body cavity between the digestive tract and the outer body wall.

Answer 54

Acoelomate

Question 55

Any named group of organisms, such as a species or group of species.

Answer 55

Taxon

Question 56

A group of organisms that includes an ancestor and all its descendants.

Answer 56

Monophyletic

Question 57

A group that includes an ancestor but not all of its descendants.

Answer 57

Paraphyletic

Question 58

A group of organisms that can interbreed and produce fertile offspring.

Answer 58

Species

Question 59

The first part of a species' scientific name, indicating the genus to which the species belongs.

Answer 59

Generic name

Question 60

The second part of a species' scientific name, identifying the particular species within the genus.

Answer 60

Specific name

Question 61

The combination of the genus and specific name, used to identify a species uniquely.

Answer 61

Species name

Question 62

A proposed system of nomenclature for classifying organisms based on phylogenetic relationships rather than traditional taxonomic ranks.

Answer 62

The PhyloCode

Question 63

The process where unrelated or distantly related organisms evolve similar traits due to similar environmental pressures.

Answer 63

Convergence

Question 64

The existence of shared ancestry between a pair of structures, or genes, in different taxa.

Answer 64

Homology

Question 65

Referring to structures derived from a common ancestor.

Answer 65

Homologous

Question 66

The direction of evolutionary change in traits or characteristics.

Answer 66

Polarity

Question 67

Relating to land; organisms that live on land.

Answer 67

Terrestrial

Question 68

Relating to the ocean; organisms that live in saltwater environments.

Answer 68

Marine

Question 69

The area between the high tide and low tide marks, where organisms are exposed to air at low tide and submerged at high tide.

Answer 69

Intertidal

Question 70

The region of the ocean just below the intertidal zone, usually permanently underwater.

Answer 70

Subtidal

Question 71

The vast area of the sea that is not near the coast; also known as pelagic zones.

Answer 71

Open ocean

Question 72

Organisms that can move freely and actively.

Answer 72

Mobile

Question 73

Organisms that are inactive or fixed in one place and do not move around (e.g., attached to surfaces).

Answer 73

Sedentary

Question 74

Referring to organisms that drift or float in water, unable to swim against currents.

Answer 74

Planktonic

Question 75

Animals that primarily eat plants.

Answer 75

Herbivores

Question 76

Animals that primarily eat other animals

Answer 76

Carnivores

Question 77

Organisms that filter small particles from the water as it flows past them.

Answer 77

Suspension feeders

Question 78

Organisms that ingest sediment and extract organic matter as it moves through their digestive systems.

Answer 78

Deposit feeders

Question 79

Interactions between two different organisms living in close physical proximity, often with benefits to one or both.

Answer 79

Symbiotic associations

Question 80

The various types of interactions in a symbiotic relationship, which can include mutualism, commensalism, and parasitism.

Answer 80

Symbioses

Question 81

Organisms that live on the surface of another organism, often benefiting from the relationship.

Answer 81

Ectosymbionts

Question 82

Organisms that live within the body or cells of another organism, often having a mutualistic relationship.

Answer 82

Endosymbionts

Question 83

A symbiotic relationship in which both partners benefit.

Answer 83

Mutualism

Question 84

A symbiotic relationship in which one organism benefits while the other is neither helped nor harmed.

Answer 84

Commensalism

Question 85

Organisms that live on or in a host and benefit at the host's expense, often causing harm.

Answer 85

Parasites

Question 86

The organism that provides a living environment and resources to a parasite or symbiont.

Answer 86

Host