Metazoa

Question 1

Define Opisthokonts

Answer 1

they sahre two conpicuous features that are uncommon in other eukaryotes:
1. almost all cells in this group have flat mitochondrial cristae
2. flagellated cells typically have a single emergent flagellum that inserts at the posterior end of the cell that propels cell (think swimming sperm)

Question 2

Metazoa have 5 features, what are they?

Answer 2

1. collagen / Extracellular matrix (ECM)
   2.spermatozoid structure
2. centriole (at base of cilia)
3. meiosis directly produces gametes
4. desmosomes = cells can be joined by strong membranous junctions between cells

Question 3

Features of a spermatozoid structure?

Answer 3

1. conical head containing nucleus and acrosome
2. middle section containing mitochondria and two centrioles
3. flagellum

Question 4

define acrosome

Answer 4

an anterior prolongation of a spermatozoon that releases egg-penetrating enzymes.

Question 5

define desmosome

Answer 5

a structure where two adjacent cells are attached, formed from protein plaques in the cell membranes linked by filaments.

Question 6

when did the first Metazoa appear in the fossil record?

Answer 6

Precambrian period

Question 7

What is a phylum?

Answer 7

usually defined by having a set of distinct morphological features. The defining characteristic.

Question 8

What is the Ectoderm?

Answer 8

Outer layer in the germ layers of Eumetazoa

Question 9

Endoderm?

Answer 9

Inner layer in the germ layer of the germ layers of Eumetazoa

Question 10

define Diploblastic

Question 11

Define Triploblastic

Question 12

3 germ layers?

Answer 12

1. Ectoderm = surface of the embryo
2. Endoderm = inner-most germlayer (forms gut)
3. Mesoderm = between the ectoderm and endoderm in triploblastic animals

Question 13

Define Gastrulation

Answer 13

formation of the germ layers

Question 14

define Pseudocoelom

Answer 14

cavity not completely lined with mesoderm

Question 15

define True Coelom

Answer 15

cavity fully enclosed within thin sheets of mesodermally derived tissues

Question 16

define Acoelomates

Answer 16

no cavity between gut and body wall seen in flatworms

Question 17

define pseudocoelomates

Answer 17

“tube within tube” cavity not completely derived from mesoderm seen in nematodes

Question 18

define Coelomates

Answer 18

cavity completelyderived from mesoderm seen in annelids

Question 19

Define Protostome

Answer 19

blastopore forms the mouth first

Question 20

define deuterostome

Answer 20

blasopore forms the anus first

Question 21

Spiral cleavage is

Answer 21

planes of division are diagonal to vertical axis of embryo

Question 22

Radial cleavage is

Answer 22

planes of division are parallel or perpendicular to vertical axis of embryo

Question 23

determinate development is

Answer 23

early cleavage cells with rigid developmental fate (mosaic embryo)

Question 24

Indeterminate development is

Answer 24

early cleavage cells retain capacity to develop into completes embryo (regulative embryo)

Question 25

Define tripartite arrangement

Answer 25

three groups within the coelom in deuterosomes 1. prtocoel 2. mesocoel 3. metacoel

Question 26

Define Lophotrochzoans

Answer 26

clade uniting lophophore - bearing animals with those with a trochophore larvae

Question 27

Define Ecdysozoans

Answer 27

share the presence of a moulting cuticle

Question 28

what are Mesozoa?

Answer 28

minute wormlike animals, no tissues and no organs, composed of maybe 20-30 cells arranged in two layers are all parasites of marine invertebrates