A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A postdoctoral student thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus?

Look for cell walls under a microscope.
See if it reproduces sexually.
Determine whether it is unicellular or multicellular.
See if it is a eukaryote or prokaryote.
Figure out whether it is autotrophic or heterotrophic.

Look for cell walls under a microscope.

Fungal cells have cell walls, and animal cells do not.

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that only animals derive their nutrition by

using enzymes to digest their food.
consuming living, rather than dead, prey.
ingesting it.
preying on animals.

ingesting it.
Which of the following is (are) unique to animals?

heterotrophy
flagellated gametes
cells that have mitochondria
the structural carbohydrate, chitin
nervous conduction and muscular movement

nervous conduction and muscular movement
The last common ancestor of all animals was probably a

multicellular algae.
unicellular yeast.
flagellated protist.
unicellular chytrid.
multicellular fungus.

flagellated protist.
What is the probable sequence in which the following clades of animals originated, from earliest to most recent?
1. tetrapods
2. vertebrates
3. deuterostomes
4. amniotes
5. bilaterians

5 > 3 > 2 > 4 > 1
3 > 5 > 2 > 1 > 4
5 > 3 > 2 > 1 > 4
3 > 5 > 4 > 2 > 1
5 > 3 > 4 > 2 > 1

5 > 3 > 2 > 1 > 4
An adult animal that possesses bilateral symmetry is most certainly also

triploblastic.
eucoelomate.
a deuterostome.
highly cephalized.

triploblastic.
Gastrulation is the process that directly forms the _____.

blastula
organs
muscles
primary germ layers
central nervous system

primary germ layers
Which of the following is NOT a characteristic of all animals?

They are all multicellular.
They ingest their food.
They are eukaryotes.
They are heterotrophic.
They have tissues, organs, and organ systems.

They have tissues, organs, and organ systems.

Sponges are considered animals, and they lack these levels of organization.

An important trend in animal evolution was cephalization. An animal is said to show cephalization when it _____.

has bilateral symmetry
is large
has tissue specialization
has an aggregation of sensory neurons at the anterior end
has a hard, outer covering

has an aggregation of sensory neurons at the anterior end

Cephalization is an evolutionary trend toward the concentration of sensory equipment at the anterior end. It is associated with bilateral symmetry.

Which of the following animals does NOT have a body cavity?

nematode
clam
earthworm
mouse
flatworm

flatworm

Flatworms are acoelomates, even those that are not classified as acoels.

During embryological development, the anus forms before the mouth in _____.

slugs
humans
arthropods
earthworms
flatworms

humans

During gastrulation, the developing digestive tube of the embryo initially has a single opening, the blastopore. After the archenteron develops, a second opening forms at the opposite end of the gastrula. The mouth of many protostomes develops from the first opening, whereas in deuterostomes the mouth is derived from the second opening.

At which developmental stage should one be able to first distinguish a protostome embryo from a deuterostome embryo?

gastrulation
metamorphosis
coelom formation
fertilization
cleavage

cleavage
What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates

have a complete digestive system with mouth and anus, whereas pseudocoelomates have a digestive tract with only one opening.
have a body cavity, whereas pseudocoelomates have a solid body.
have a gut that lacks suspension within the body cavity, whereas pseudocoelomates have mesenteries that hold the digestive system in place.
contain tissues derived from mesoderm, whereas pseudocoelomates have no such tissue.
have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.

have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.
You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?

Muscular activity of its digestive system distorts the body wall.
It possesses sensory structures at its anterior end.
It is triploblastic.
It has bilateral symmetry.

Muscular activity of its digestive system distorts the body wall.
Which of the following is descriptive of protostomes?

radial and determinate cleavage, blastopore becomes mouth
spiral and determinate cleavage, blastopore becomes mouth
spiral and indeterminate cleavage, blastopore becomes mouth
radial and determinate cleavage, blastopore becomes anus
spiral and determinate cleavage, blastopore becomes anus

spiral and determinate cleavage, blastopore becomes mouth
The most ancient branch point in animal phylogeny is that between having

radial or bilateral symmetry.
true tissues or no tissues.
a well-defined head or no head.
a body cavity or no body cavity.
diploblastic or triploblastic embryos.

true tissues or no tissues.
A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45 degrees and to lie in the grooves between larger, underlying cells (i.e., spiral cleavage).

This embryo may potentially develop into a(n)

earthworm.
fish.
sea urchin.
turtle.
sea star.

earthworm.
Which of the following statements is correct?

Eumetazoans have three embryonic tissue layers.
Sponges are diploblastic animals.
The origin of all extant animal phyla can be traced to the Cambrian explosion.
All animals share a common ancestor.
Most animal phyla belong to the clade Radiata.

All animals share a common ancestor.

It is thought to have been a protist similar to a choanoflagellate.

With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive.
1. ecdysozoan
2. protostome
3. eumetazoan
4. triploblastic

3, 4, 1, 2
4, 2, 3, 1
3, 4, 2, 1
4, 3, 2, 1
4, 3, 1, 2

3, 4, 2, 1
If a multicellular animal lacks true tissues, then it can properly be included among the

eumetazoans.
choanoflagellates.
lophotrochozoans.
metazoans.
bilateria.

metazoans.
Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If true, this finding would

strengthen sponges’ evolutionary ties to the Eumetazoa.
mean that sponges must no longer be classified as animals.
confirm the identity of sponges as “basal animals.”
mean that extinct sponges must have been the last common ancestor of animals and fungi.
require sponges to be reclassified as choanoflagellates.

confirm the identity of sponges as “basal animals.”
What is true of the deuterostomes in the molecular phylogeny (B) that is not true in the traditional phylogeny (A)?

Deuterostomia now includes the Acoela.
It diverged from the rest of the Bilateria earlier than did the Acoela.
Deuterostomia is paraphyletic.
To maintain Deuterostomia as a clade, some phyla had to be removed from it.
It is actually a grade, rather than a clade.

To maintain Deuterostomia as a clade, some phyla had to be removed from it.
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