Quiz#6-metazoa. sponges, cnidiria, bilateroa. mollusca, annelida

Question 1

what evidence supports the hypothesis that animals are a monophyletic group?

Answer 1

phylogenetic analysis of gene sequences(of genomes) give evidence of this.Also it is said that all animals descended from ancestor containing unique cell junctions and proteoglycans in extracellular matrix

Question 2

radial cleavage

Answer 2

the first few divisions of the fertilized egg(zygote) where there is an even pattern and complete distribution of yolk(celll nutritive material nourishing embryo) w/in the egg…this radial cleavage is an ancestral condition for animals except sponges.

Question 3

spiral cleavage

Answer 3

a complicated permutation of radial cleavage

Question 4

cleavage

Answer 4

the first few divisions of the zygote cell…causing the number of cells in the embryo to double after each cleavage.

Question 5

hox genes

Answer 5

specify body pattern and axis formation , leading to the developmental similarities across animals

Question 6

Proteoglycan

Answer 6

extracellular matrix molecules that consititute on synapomorphy of animals

Question 7

collagen

Answer 7

extracellular matrix molecules also found in ancestor of animals.

Question 8

diplobasty

Answer 8

as animals conitnued to develop… cell layers differentiated and animals with diplobasty contained embryos with two cell layers…the ectoderm and endoderm…this exhibits the ancestral condition

Question 9

triplobasty

Answer 9

animals with embryos that contain 3 layers ..the ectoderm, mesoderm, and endoderm…this is a synapomorphy of triploblastic animals(placozoans, ctenophhores, cnidarians)…

Question 10

gastrulation

Answer 10

early development in animals in which a hollow ball(one cell thick) forms and indentation that then forms a cup shaped called blastopore

Question 11

prostostomes

Answer 11

one of the two main groups that are contained within the triplobastic orgnamisnsm that undergoes gastru;ation.. In the prostostomes..the mouth arises frm the blastopore and the anus forms later

Question 12

deuterostome

Answer 12

second main gropup within the triploblastic. This group in which the anus forms first and the mouth will form later,

Question 13

body plan

Answer 13

animal general structure and arrangement of organs and functions of the various parts…animals share body plans but can vary tremendously on four features, symmetry, body cavity(any fluidfilled space within multicellular organism), body segmentation, external appendages

Question 14

coelom

Answer 14

body cavity(fluidfilled space) Enclosed on the inside and outside by mesoderm allowing for better control over the animals movement of fluids.

Question 15

segmentation

Answer 15

division into different parts of body allowing for specialization of different regions and also allows body to alter shape, to increase body movement.

Question 16

sponges

Answer 16

are the simplest of animals, with no symmetry, no true organs and no distinct embryonic cell layers,only , a few specialized cells…they have a body plan built from an aggregation of cells built around a water canal system…..where water and food is absorbed by the sponge.//..can be filter feeders or carnivores…both asexual and sexual reproduction….

Question 17

spicules

Answer 17

hard sponge skeletal structures that may be simple and small or large and complex…some may be very flexible

Question 18

choanocytes

Answer 18

are cells in sponges that capture food particles

Question 19

cnidarians

Answer 19

organisms such as sea anemonie, jellyfish, that have a mouth connected to a blind sac called gastrovascular cavity that aids in gas exchange, circulation, digestion, and hydrostatic skeleton…the cnidarians have both sessile and motile life stages…they are specialized carnivores that use toxin in their nematocysts to capture prey

Question 20

gastrovascular cavity

Answer 20

that aids in gas exchange, circulation, digestion, and hydrostatic skeleton..the opening serves as both anus and mouth

Question 21

ployp stage

Answer 21

sessile stage in the cnidarians where stalk(stem) is attached to a substratum…mature polyps will develop into medusae through asexual budding

Question 22

medusa

Answer 22

the motile stage of the cnidarians …that is free swimming and shaped like an umbrella(jellyfish)

Question 23

planula larvae

Answer 23

the fertilized egg that develps into freeswimming cilliated larvae that will go on to become a polypse and then a medusa

Question 24

Trochophore larvae

Answer 24

The larvae form of the lophotrochozoan clade that uses ciliia for locomotion bringing plankton closer to larva that can then ingest the plankton…these are among the major groups of the clade along with annelids ,mollusks,ribbon worms,and bryozoans

Question 24

osculum

Answer 24

mouth opening in sponge, used to expel water.

Question 25

Exoskeletons

Answer 25

Cuticles(external covering) of mostly arthropods thst finction as external skeletons..thickened by layers of protein and strong waterproof pokysaccaride called chitin…those with these skeletons cant move in wormlike manner nor use cilia for locomotion…it can also impede passage of oxygen and nutrients…thats why these orgnsms evolved new mechanusms..

Question 26

Foot,visceral mass, mantle

Answer 26

3shared parts of the mollusks….

1) foot is a large muscular irgan that originally was the organ of licomotion and support..but has now been modufied to arms ir tentacles…it can also be reduced in some groups
2) the ventral