lec 5

Question 1

animals belong in a clade called______, what else does it include

Answer 1

Opisthokonta, includes fungi and some protists

Question 2

why is opisthikonta named that

Answer 2

prosteriorly placed flagellum

Question 3

5 not unique features to kingdom animalia

Answer 3

1. multicellularity
   2.lack cell walls
2. are chemoheterotrophic
3. mostly sexual
4. are animate- can move

Question 4

unique characteristics of metazoans
(5)

Answer 4

1. gastrulation and embryonic tissue layering
2. unique types of intercellular junctions
3. type IV collagen
4. striated myofibrils and actin-myosin contractile elements
5. HOX GENES)

Question 5

anisogamy

Answer 5

small motile sperm, large nonmotile eggs

Question 6

do animals share similar patterns of fertilization and early embryonic development? describe it

Answer 6

most of them do share similar patterns.
1. diploid zygote initially undergoes a number of mitotic
cell divisions without growth of cells between divisions
2. eventually a ball of cells is formed
3. blastula invaginates at one end in many taxa, forms gastrula
4.gastrula has two clear layers of cells

Question 7

direct development

Answer 7

embryo
gradually develops towards adult form
without sudden changes in morphology

Question 8

indirect development

Answer 8

involves one or
more intermediate stages whose morphology and behaviour
differs greatly from sexually mature adult
stage

Question 9

what are intermediate stages in indirect development called?

Answer 9

each called a
larva

Question 10

intercellular junctions

Answer 10

specialized areas of contact
between plasma membranes of adjacent epithelial cells

Question 11

Epithelia

Answer 11

tissues in which the component cells have an
aligned polarity, and are joined by intercellular juncltions, associate w extracellular matrix. to BASAL LAMINA

Question 12

three main functions of intercellular
junctions in metazoans

Answer 12

1. BARRIER- concentration gradients
2. ADHESIONcell-cell or cell-substrate adhesion
3. COMMUNICATIONallowing intercellular communication

Question 13

collagen IV

Answer 13

-rope-like molecules
called collagen, glue b/w cells and let them collaborate.
-synapomorphy of metazoa (some sponges lost it tho)

Question 14

basal lamina

Answer 14

thin layer of extracellular matrix that is
secreted by the epithelial cells and on which the living cells
of the epithelium

Question 15

striated myofibrils
and actin-myosin
contractile elements

Answer 15

-allow for movement in some parts of body.
-some myosin types
appear to be ancestral to the Metazoa

Question 16

homeobox

Answer 16

regulatory genes that produce proteins
that can turn other genes on and off

Question 17

homeobox genes that control anterior
to posterior developmental sequence
of embryo

Answer 17

Hox genes

Question 18

where are hox genes absent

Answer 18

absent in sponges, placozoans and ctenophores

Question 19

the Metazoa groupis

Answer 19

monophyletic

Question 20

when did animals arise

Answer 20

prior to Cambrian Explosion

Question 21

where do hypotheses w metazoan evolution and lineage come from

Answer 21

on early embryo morphology and
hypothetical ancestral forms

Question 22

Haeckel’s
gastraea
hypothesis

Answer 22

-a version of colonial theory
-the transition to
a multicellular condition occurred by invagination, a developmental process that
resulted in a hollow “gastraea.”

Question 23

the two colonial theories branched from the theory of the

Answer 23

hypothetical colonial flagellate
ancestor

Question 24

Metschnikoff’s “planuloid”
hypothesis

Answer 24

-the first metazoan was solid and developed by ingression of cells
- similar to cnidarian planula larvae

Question 25

Bütschli’s “plakula

Answer 25

metazoans that arose after sponges had flattened disc-shaped
bodies with 2 layers of flagellated cells
Placozoans support this

Question 26

what supports butschlis theory

Answer 26

discovery of placozoans

Question 27

what supports phylum placozoa

Answer 27

cross striated cilary rootlets

Question 28

Trichoplax adhaerens

Answer 28

-was the only species in placozoa until recently
-resembles Butschlis plankula hypothesis

Question 29

placozoa features

Answer 29

1. lack basal lamina
2. shiny spheres of possibly repellant chemicals present in flattened and monociliate upper layer

Question 30

how do placozoa move

Answer 30

cilary gliding along flat surfaces or swimming for v small mfs

Question 31

reproduction in placozoa

Answer 31

fission
budding off small flagellated swarmers

Question 32

diet of placozoa and digestion

Answer 32

-likely includes algae
-external digestion

Question 33

what is placozoa+ proifera called?
what about remaining amimals?

Answer 33

parazoa
eumetazoa

Question 34

Hox genes

Answer 34

homeobox genes control anterior
to posterior developmental sequence
of embryo

Question 35

main constituent of the basal lamina

Answer 35

Collagen

Question 36

main constituent of the basal lamina

Answer 36

Collagen