BIO 182 EXAM 4 UPDATED WITH
DETAILED ANSWERS GRADED
A+ 2026 LATEST
Be familiar with the common characteristics of animals - answer-Multicellular
heterotrophs
Lack cell walls
Most have nerves, muscles, and capacity to move at some point in the life cycle
Able to reproduce sexually
Specialized sensory structures and nervous system
Cells exist in extensive extracellular matrix
Unique cell junctions
What type of life cycle do all animals show? - answer-gametic meiosis
What is the most likely ancestor of animals? - answer-choanoflagellates
What are the 3 major features that were traditionally used to classify animals? Know the
different variations on these 3 major features. - answer-Presence or absence of different
tissue types
Metazoa- all animals
Metazoa divided based on whether there are specialized tissues
Parazoa- without specialized tissues or organs
Porifera- sponges
Eumetazoa- more than one type of tissue and organ
Symmetry
Radial Symmetry- refers to animals that are identical all around a central axis (Radiata)
Bilateral Symmetry- exists where there is only one way to split the animal into equal
halves (Bilateria)
,Embryonic Development
Protostome
Spiral cleavage
Cleavage is determinate
Blastopore becomes mouth
Deuterostome
Radial cleavage
Cleavage is indeterminate- pluripotent stem cells
Blastopore becomes anus
What is the focused gene for molecular analysis used in animal diversity? - answer-
Small ribosomal subunit RNA
What are the 2 new invertebrate clades that resulted from molecular analysis of the
rRNA region of the genome? - answer-Ecdysozoa
Lophotrochozoa
For this chapter, you should know each of the phylum names (13 total phyla) that are
the end points of the phylogenetic tree of invertebrates. You should also be able to be
able to draw the tree and know the major traits that divide the clades on the tree. -
answer-MulticellularityNo tissues/parazoa (Porifera) Tissues Radial symmetry (Cnidaria
and Ctenophora) Bilateral symmetry Deuterostome development
(Echinodermata(invertebrates) and Chordata(vertebrates) Protostome development
Lophotrochozoa(Left to right: Platyhelminthes, Rotifera, Bryozoa, Brachipoda, Mollusca,
Annelida) Ecdysis (Nematoda, Arthropoda)
Parazoa/Porifera - answer-Sponges
Loosely organized and lack tissues
No apparent symmetry
Adults sessile, larvae free-swimming
Water drawn through pores into spongocoel
, Flows out through osculum
Reproduce sexually and asexually
Cnidaria - answer-Radial symmetry
Two body forms
Sessile polyp- tubular body with tentacles surrounding opening (mouth and anus)
Motile medusa- umbrella-shaped body with a mouth on the underside surrounded by
tentacles
Simple muscles and nerves
Not true muscles (not of mesoderm origin)
Ctenophora - answer-Radial symmetry
Comb jellies
First complete gut- mouth and anus
Eight rows of cilia on surface beat for propulsion
Largest animals to use cilia for locomotion
Two long tentacles without stinging cells
Complete digestive tract
Lophotrochozoa - answer-Members have either a lophophore
Bryozoans
Brachiopods
Rotifers
Or a trochophore larval stage
Mollusks
Annelids
Platyhelminthes
DETAILED ANSWERS GRADED
A+ 2026 LATEST
Be familiar with the common characteristics of animals - answer-Multicellular
heterotrophs
Lack cell walls
Most have nerves, muscles, and capacity to move at some point in the life cycle
Able to reproduce sexually
Specialized sensory structures and nervous system
Cells exist in extensive extracellular matrix
Unique cell junctions
What type of life cycle do all animals show? - answer-gametic meiosis
What is the most likely ancestor of animals? - answer-choanoflagellates
What are the 3 major features that were traditionally used to classify animals? Know the
different variations on these 3 major features. - answer-Presence or absence of different
tissue types
Metazoa- all animals
Metazoa divided based on whether there are specialized tissues
Parazoa- without specialized tissues or organs
Porifera- sponges
Eumetazoa- more than one type of tissue and organ
Symmetry
Radial Symmetry- refers to animals that are identical all around a central axis (Radiata)
Bilateral Symmetry- exists where there is only one way to split the animal into equal
halves (Bilateria)
,Embryonic Development
Protostome
Spiral cleavage
Cleavage is determinate
Blastopore becomes mouth
Deuterostome
Radial cleavage
Cleavage is indeterminate- pluripotent stem cells
Blastopore becomes anus
What is the focused gene for molecular analysis used in animal diversity? - answer-
Small ribosomal subunit RNA
What are the 2 new invertebrate clades that resulted from molecular analysis of the
rRNA region of the genome? - answer-Ecdysozoa
Lophotrochozoa
For this chapter, you should know each of the phylum names (13 total phyla) that are
the end points of the phylogenetic tree of invertebrates. You should also be able to be
able to draw the tree and know the major traits that divide the clades on the tree. -
answer-MulticellularityNo tissues/parazoa (Porifera) Tissues Radial symmetry (Cnidaria
and Ctenophora) Bilateral symmetry Deuterostome development
(Echinodermata(invertebrates) and Chordata(vertebrates) Protostome development
Lophotrochozoa(Left to right: Platyhelminthes, Rotifera, Bryozoa, Brachipoda, Mollusca,
Annelida) Ecdysis (Nematoda, Arthropoda)
Parazoa/Porifera - answer-Sponges
Loosely organized and lack tissues
No apparent symmetry
Adults sessile, larvae free-swimming
Water drawn through pores into spongocoel
, Flows out through osculum
Reproduce sexually and asexually
Cnidaria - answer-Radial symmetry
Two body forms
Sessile polyp- tubular body with tentacles surrounding opening (mouth and anus)
Motile medusa- umbrella-shaped body with a mouth on the underside surrounded by
tentacles
Simple muscles and nerves
Not true muscles (not of mesoderm origin)
Ctenophora - answer-Radial symmetry
Comb jellies
First complete gut- mouth and anus
Eight rows of cilia on surface beat for propulsion
Largest animals to use cilia for locomotion
Two long tentacles without stinging cells
Complete digestive tract
Lophotrochozoa - answer-Members have either a lophophore
Bryozoans
Brachiopods
Rotifers
Or a trochophore larval stage
Mollusks
Annelids
Platyhelminthes
