Taxonomy And Cladistics

Question 1

What is taxonomy?

Answer 1

The science of classification

Question 2

What is cladistics?

Answer 2

A way of categorising organisms into clades

Question 3

What is a taxon?

Answer 3

A group of related organisms

Question 4

What is a clade?

Answer 4

A grouping which unites all taxa descended from a common ancestor

Question 5

What is a species?

Answer 5

Two organisms belong to the same species if they can breed and produce viable offspring.

Question 6

What is a morphospecies?

Answer 6

Classical species concept where two organisms belong to the same species if they conform to a fixed type (look the same).

Question 7

Biological species concept ( Mayr 1942)

Answer 7

Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.

Question 8

Phylogenetic species concept

Answer 8

An irreducible group whose members are descended from a common ancestors and who all possess a combination of derived traits.

Question 9

Plesiomorphy

Answer 9

Ancestral/ basal trait shared by two or more taxa.

Question 10

Apomorphy

Answer 10

Derived trait unique to a taxon.

Question 11

Agamospecies

Answer 11

Asexual species

Question 12

Biospecies

Answer 12

Reproductively isolated sexual species

Question 13

Ecospecies

Answer 13

Ecological niche occupiers

Question 14

Evolutionary species

Answer 14

Evolving lineages

Question 15

Genetic species

Answer 15

Common gene pool

Question 16

Taxonomic species

Answer 16

Defined by a taxonomist

Question 17

Taxonomic Hierarchy of Ranks

Answer 17

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 18

Phylogeny

Answer 18

The evolutionary relationships between taxa.

Question 19

What can phylogenies be based on?

Answer 19

Morphological characteristics and genetic characteristics.

Question 20

Why is reptilia not a clade?

Answer 20

Reptiles are non-avian non-mammalian amniotes as it contains everything but mammals and birds due to the furthest common ancestor. Thus is a paraphyletic group instead.

Question 21

Paraphyletic group

Answer 21

A group that consists of an ancestor and some but not all of its descendants.

Question 22

Polyphyletic group

Answer 22

A group that consists of of multiple distantly related organisms and does not contain the common ancestor if the group.

Question 23

Why isn’t amphibia a correct term to use?

Answer 23

Would also include mammals, reptiles and birds which are in the same clade. Use lissamphibia instead.

Question 24

What is embryology?

Answer 24

The study of the prenatal development of gametes, fertilisation and development of embryos and fetuses.

Question 25

Recapitulation theory (Haeckel 1870)

Answer 25

A historical theory that embryo development mirrors successive stages of evolution.

Question 26

Why is Haekel’s recapitulation theory defunct?

Answer 26

He over represented the biological significance of features in his embryo diagrams.

Question 27

Evo-devo

Answer 27

Changes in the timing and positioning of embryonic development affects the change of the shape of a descendent’s body compared to its ancestor.

Question 28

What are the stages of cell cleavage?

Answer 28

Fertilised egg or oocyte
Morsula
Blastula
Gastrula

Question 29

Describe morulation

Answer 29

A solid ball of cells is formed called a morula and cell cleavage occurs.

Question 30

Describe blastulation

Answer 30

A hollow ball of cells around a blastocoel. This is called a blastula.

Question 31

Describe gastrulation

Answer 31

A multi-layered ball of cells called a gastrula forms. Then the germ cell layers form. Then the mesoderm and the coelom form and the fate of the blastopore is determined.

Question 32

Mesoderm

Answer 32

The middle of the three embryonic germ layers first delineated during gastrulation. Gives rise to the skeleton, circulatory system, muscles, excretory system and most of the reproductive system.

Question 33

Coelom

Answer 33

The principal body cavity in most animals, located between the intestinal canal and the body wall.

Question 34

What is radial cleavage?

Answer 34

Embryonic development in which the planes of cell division are parallel and perpendicular to the animal-vegetal axis of the embryo.

Question 35

Animal-vegetal axis

Answer 35

The placement of the nucleus in the oocyte. The embryo is divided into two hemispheres; the animal pole and the vegetal pole within a blastula.

Question 36

The animal pole

Answer 36

Small cells that divide rapidly and is heavily pigmented.

Question 37

The vegetal pole

Answer 37

Large yolky cells that divide slowly and is unpigmented.

Question 38

What is spiral cleavage?

Answer 38

A form of complete cleavage in which the cleavage planes are at oblique angles to the animal-vegetal axis.

Question 39

What does the blastopore become?

Answer 39

The mouth, the anus, or both.

Question 40

Describe ‘‘coelenterates’’ in terms of embryogenesis

Answer 40

Have diploblastic germ layers
No cell cleavage
No coelom (acoelmate)
Blastopore is mouth and anus

Question 41

Describe protosomes in terms of embryogenesis

Answer 41

Have triploblastic germ layers
Spiral cell cleavage
Coelom formed by splitting mesodermal embryonic tissue (schizocoelomate)
Blastopore becomes mouth

Question 42

Describe deuterostomes in terms of embryogenesis

Answer 42

Have triploblastic germ layers
Radial cell cleavage
Coelom formed from outpocketing of the endoderm (enterocoelom)
Blastopore becomes the anus