Metazoa

Question 1

Define metazoa

Answer 1

Multicellular, eukaryotic heterotrophs with an extracellular matrix (ECM). Organised tissue allows motility.

Question 2

What is an extracellular matrix (ECM)?

Answer 2

A connective tissue between cells, comprising of collagen, proteoglycans, and adhesive glycoproteins.

Question 3

What does the ECM allow?

Answer 3

The migration of metazoan cells through the mesenchyme (connective tissue), which is important in development.

Question 4

What is the differences between protozoans and metazoans?

Answer 4

Protozoans are usually unicellular and metazoans are multicellular.

Question 5

Define the Plant kingdom

Answer 5

Multicellular autotrophs with chloroplasts and cellulose cell walls

Question 6

Define the Fungi kingdom

Answer 6

Multicellular and unicellular autotrophs with chitin cell walls

Question 7

What are choanaflagellates the sister taxon to?

Answer 7

Metazoa

Question 8

Describe choanaflagellates

Answer 8

Can be free-living or flagellum propelled and can form colonies that can act together.

Question 9

What is the word for a colony that acts together?

Answer 9

Protomulticellularity

Question 10

What four groups are included in metazoa?

Answer 10

Porifera, ctenophora, cnidaria, bilatera

Question 11

When are porifera motile and when are they sessile?

Answer 11

Motile as larvae and sessile as adults

Question 12

Name four things that porifera don’t have

Answer 12

Organs, nerve, muscles, or symmetry

Question 13

Describe the tissue organisation of porifera

Answer 13

Incipient tissue organisation (external epithelium)

Question 14

Name a feature of porifera

Answer 14

Choanocytes

Question 15

What are choanocytes?

Answer 15

Flagellated cells creating internal water currents

Question 16

How are ctenophores motile?

Answer 16

From groups of cilia (ctenes)

Question 17

What type of symmetry do ctenophores have?

Answer 17

Radial

Question 18

What type of digestive system do ctenophores have?

Answer 18

Through gut (diploblastic)

Question 19

Name three characters of ctenophores

Answer 19

Muscles, nerves, and some sensory capabilities

Question 20

Describe placozoa

Answer 20

A phylum of small, flat ‘animals’. They are aggregates of cells with no organs.

Question 21

How many species are there is the placozoa phylum?

Answer 21

3

Question 22

How do placozoa reproduce?

Answer 22

Asexual budding

Question 23

Describe how placozoa are heterotrophic

Answer 23

They digest detritus on their ventral system

Question 24

How do placozoa move?

Answer 24

They have a ciliated epithelium

Question 25

Name two things that placozoa do not have

Answer 25

Tissues and symmetry

Question 26

What phylum was traditionally seen as the sister taxon to all other animals?

Answer 26

Porifera

Question 27

Why were porifera traditionally seed as a sister clade to all other animals?

Answer 27

Their morphology

Question 28

What phylum is now seen as the sister taxon to all other animals?

Answer 28

Ctenophora (using phylogenomics)

Question 29

What are the two models of molecular evolution?

Answer 29

Simple and complex

Question 30

Describe the simple model of molecular evolution

Answer 30

Changes between AGCT have equal probability and rate

Question 31

What can AGCT sites be?

Answer 31

Homogenous (equal rates of change) or heterogenous (vary in rates of change and evolution)

Question 32

Describe long branch attraction

Answer 32

When taxa appear to be more closely related because they have both undergone a large amount of change