Which of the following did NOT occur
during the Cambrian Explosion?
1.
Animals acquired specialized cells,
tissues, and organs.
There was an extraordinary growth in
animal diversity.
Animals evolved simpler body plans.
Animal appendages became specialized
for a variety of functions.
2.
3.
4.
1
2
3
4
5
25% 25% 25% 25%
1
2
3
4
Paleontologists discover the fossil of an
animal that lived 570 million years ago. This
animal probably
1. was flat and plate- 25% 25% 25% 25%
shaped.
2. had a hard shell.
3. was organized
into a front and a
back end.
4. lived on land.
1
2
3
4
5
1
2
3
4
One characteristic that made early animals
different from all animals of today was their
1. habitat.
2. body
segmentation.
3. body plan.
4. bilateral
symmetry.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
The diversity of invertebrate phyla
underwent its greatest increase
1.
before the Cambrian
Period.
during the Cambrian
Period.
after the Cambrian
Period.
both before and after
the Cambrian Period.
2.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Animals of the Cambrian Period typically
had all of the following EXCEPT
1. body symmetry.
2. segmentation.
3. some type of
skeleton.
4. a backbone.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Biologists trace the evolution of invertebrate groups by
studying their appearance in the fossil record. For which
invertebrate would this type of study be most difficult?
1.
2.
3.
4.
1
an armored worm
a jellyfish
a snail
a clam
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of the following group of
invertebrates are deuterostomes?
1.
2.
3.
4.
1
worms
arthropods
mollusks
echinoderms
2
3
4
5
25%
1
25%
25%
2
3
25%
4
The classification of an animal as a
deuterostome or a protostome is based on
1. its body symmetry.
2. whether or not it has
a coelom.
3. what happens to the
blastopore.
4. the number of germ
layers it has.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
In a protostome, the blastopore
becomes a(an)
1.
2.
3.
4.
1
mouth.
anus.
zygote.
blastula.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
A body cavity that forms between
the germ layers is called a(an)
1.
2.
3.
4.
1
coelom.
blastopore.
mesoderm.
ectoderm.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
An acoelomate is an animal that
has
1.
a body cavity lined with endoderm
and ectoderm.
a body cavity partially lined with
mesoderm.
a body cavity completely lined with
mesoderm.
no body cavity between the germ
layers.
2.
3.
4.
25%
1
1
2
3
4
5
25%
25%
2
3
25%
4
Some type of body symmetry is
found in all invertebrates EXCEPT
1.
2.
3.
4.
1
cnidarians.
mollusks.
sponges.
flatworms.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which invertebrates exhibit
radial symmetry?
1. cnidarians and
echinoderms
2. sponges and
flatworms
3. roundworms and
annelids
4. mollusks and
arthropods
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Cephalization refers to the
1.
division of the body into upper and
lower sides.
concentration of sense organs and
nerve cells in the front of the body.
joining together of specialized cells to
form tissues.
formation of a body cavity between
the germ layers.
2.
3.
4.
1
2
3
4
5
25% 25% 25% 25%
1
2
3
4
Animal X has no coelom and no
cephalization. Animal X is either a
1. mollusk or an
arthropod.
2. flatworm or a
roundworm.
3. mollusk or an
echinoderm.
4. sponge or a
cnidarian.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Animal Y has three germ layers, bilateral
symmetry, and no coelom. Animal Y is a(an)
1.
2.
3.
4.
1
sponge.
arthropod.
flatworm.
mollusk.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
In Figure 29–1, the space labeled X is called a
25%
25%
25%
25%
1
1.
2.
3.
4.
2
3
protostome.
deuterostome.
coelom.
pseudocoelom.
4
5
One animal that has a body construction like
that shown in Figure 29–1 is a
1.
2.
3.
4.
1
flatworm.
roundworm.
sponge.
jellyfish.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of the following characteristics is NOT
found in any radially symmetrical
invertebrate?
25% 25%
25%
25%
1. cephalization
2. specialized cells
3. specialized
organs
4. a coelom
1
2
3
4
5
1
2
3
4
One way to distinguish a
roundworm from an annelid is to
1.
2.
count their germ layers.
examine their body
symmetry.
compare the structure of
their body cavities.
determine whether they
have cephalization.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which sequence correctly expresses the
order in which major invertebrate features
evolved?
three germ layers  tissues 
multicellularity  coelom
coelom  tissues  three germ
layers  multicellularity
multicellularity  tissues 
three germ layers  coelom
multicellularity  three germ
layers  coelom  tissues
1.
2.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of the following invertebrates has a
closed circulatory system, nephridia, and a
hydrostatic skeleton?
25% 25%
25%
25%
1. an echinoderm
2. an annelid
3. a flatworm
4. a sponge
1
2
3
4
5
1
2
3
4
If an animal has a digestive tract, an open
circulatory system, and an exoskeleton, it
could be a(an)
25% 25%
25%
25%
1. arthropod.
2. echinoderm.
3. cnidarian.
4. roundworm.
1
2
3
4
5
1
2
3
4
Invertebrates that break down their food
through intracellular digestion include
1.
2.
3.
4.
1
annelids.
mollusks.
arthropods.
sponges.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which invertebrate has a
gastrovascular cavity?
1.
2.
3.
4.
1
arthropod
mollusk
cnidarian
roundworm
2
3
4
5
25%
1
25%
25%
2
3
25%
4
A true digestive tract is found in
1.
2.
3.
4.
1
annelids.
sponges.
cnidarians.
flatworms.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
One difference between a gastrovascular
cavity and a digestive tract is that
1.
25%
a gastrovascular cavity has specialized regions, but
a digestive tract does not.
a gastrovascular cavity has one opening, and a
digestive tract has two.
digestion is extracellular in a gastrovascular cavity
and intracellular in a digestive tract.
food can be processed more efficiently in a
gastrovascular cavity than in a digestive tract.
2.
25%
3.
25%
4.
25%
1
2
3
4
5
Gases diffuse most efficiently across a
respiratory membrane if the membrane is
1.
2.
3.
4.
1
thick and dry.
thin and dry.
thick and moist.
thin and moist.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of these invertebrates
exchange gases through gills?
1.
2.
3.
4.
1
insects
spiders
clams
land snails
2
3
4
5
25%
1
25%
25%
2
3
25%
4
In insects, gas exchange takes
place through a network of
1.
2.
3.
4.
1
tracheal tubes.
mantle cavities.
book lungs.
blood vessels.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Most flatworms are small and very thin. Therefore,
they can supply their cells with oxygen and remove
metabolic wastes by means of
1.
simple diffusion
between body surface
and the environment.
an open circulatory
system without a heart.
an open circulatory
system with one heart.
a closed circulatory
system with one heart.
2.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
The distinguishing feature of a
closed circulatory system is that
1.
2.
it does not include a heart.
blood is contained within vessels that
extend throughout the body.
blood is kept at low pressure.
blood is circulated less efficiently than
in an open circulatory system.
3.
4.
25% 25%
1
1
2
3
4
5
2
25%
3
25%
4
In an open circulatory system,
blood
1. never leaves the heart.
2. does not come in direct contact
with the tissues.
3. is always contained within a
system of blood vessels.
4. is pumped through a system of
sinuses.
25%
1
1
2
3
4
5
25%
25%
2
3
25%
4
An example of an animal with an
open circulatory system is a(an)
1.
2.
3.
4.
1
sponge.
cnidarian.
arthropod.
annelid.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
The giant squid is a large, very active
invertebrate. What type of circulatory system
do you think it has?
1. open circulatory
system
2. closed circulatory
system
3. water vascular
system
4. no circulatory
system
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of the following is a function
of an excretory system?
1.
eliminating nitrogenous wastes from
the body
exchanging oxygen and carbon
dioxide with the environment
gathering and processing information
from the environment
obtaining and digesting food
2.
3.
4.
25%
1
1
2
3
4
5
25%
2
25%
3
25%
4
Which structures are NOT part
of an excretory system?
1. flame cells
2. spiracles
3. Malpighian
tubules
4. nephridia
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
What would happen to a flatworm if
its flame cells stopped functioning?
1. It would be unable
to pump blood.
2. It would
accumulate urea.
3. It would swell.
4. It would dry up.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of the following best
describes uric acid?
1.
more toxic than ammonia,
leaves the body through
excretory pores
more toxic than ammonia,
leaves the body through the
rectum
less toxic than ammonia, leaves
the body through excretory
pores
less toxic than ammonia, leaves
the body through the rectum
2.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Expelling uric acid from the body and having a
respiratory surface that is covered with mucus are
two ways that some invertebrates can
1. process food
more efficiently.
2. reduce water loss.
3. respond to their
environment.
4. supply oxygen to
their cells.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
The eyespots of flatworms can
1. detect the
presence of light.
2. detect motion.
3. detect color.
4. form images.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
An example of an invertebrate with
a hydrostatic skeleton is a(an)
1.
2.
3.
4.
1
spider.
sponge.
sea star.
earthworm.
2
3
4
5
25%
1
25%
25%
2
3
25%
4
An endoskeleton is a
1.
2.
shell of a mollusk.
fluid-filled body cavity
that supports the
muscles.
structural support
located inside the body.
hard body covering
made of chitin.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Which of the following invertebrates would
be most likely to reproduce by external
fertilization?
25% 25%
25%
25%
1. an arachnid
2. an insect
3. a land snail
4. a cnidarian
1
2
3
4
5
1
2
3
4
Which statement refers to
sexual reproduction?
1.
All offspring are genetically
identical to the parent.
Offspring are produced from
the fusion of male and
female gametes.
An organism breaks into
pieces that grow into new
individuals.
New individuals are
produced from outgrowths of
the parent’s body wall.
2.
3.
4.
1
2
3
4
5
25%
1
25%
25%
2
3
25%
4
Animals with skeletons were more numerous in the
Cambrian Period than in earlier periods.
_________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
Mollusks are classified as
pseudocoelomates.
_________________________
1. True
50%
50%
2. False
1
2
3
4
5
1
2
During early development, the zygote divides
repeatedly to form a hollow ball of cells called a
blastopore. _________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
In deuterostomes, the blastopore forms
a(an) mouth.
_________________________
1. True
50%
50%
2. False
1
2
3
4
5
1
2
Arthropods have bilateral symmetry.
_________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
The only deuterostomes with radial
symmetry are cnidarians.
_________________________
1. True
50%
50%
2. False
1
2
3
4
5
1
2
The difference between a coelomate and a
pseudocoelomate has to do with the lining of the
body cavity. _________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
An animal that feeds on other animals by swallowing them
whole is most likely to use intracellular digestion.
_________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
Animal A has a respiratory surface area of 50 mm2, and animal B has a
respiratory surface area of 25 mm2. If other features of their respiratory
surfaces are the same, the rate of gas exchange will be greater in
animal A. _________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
Book lungs and tracheal tubes are used for
breathing in terrestrial invertebrates.
_________________________
1. True
50%
50%
2. False
1
2
3
4
5
1
2
If an animal’s blood never comes in direct contact
with its tissues, the animal has an open circulatory
system. _________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
The excretory system of animal X functions to conserve
body water while removing nitrogenous wastes. Animal X
most likely lives on land. _________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
Muscles work by becoming longer.
_________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
Arthropods have an endoskeleton.
_________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
The eruption of a volcano creates a new island in the
ocean. Animals that settle on the island can increase in
number most rapidly if they reproduce asexually.
_________________________
1. True
2. False
1
2
3
4
50%
5
1
50%
2
Participant Scores
0
0
Participant 1
Participant 2
0
0
0
Participant 3
Participant 4
Participant 5
____________________ fossils are tracks
and burrows made by soft-bodied animals
whose bodies were not fossilized.
1
2
3
4
5
0 of 5
Over the course of evolution, ____________________
allowed animals to increase in body size with a minimum of
new genetic material.
1
2
3
4
5
0 of 5
The only invertebrates that lack both
cephalization and a coelom are cnidarians
and ____________________.
1
2
3
4
5
0 of 5
A body cavity lined partially with mesoderm
is called a(an)
_________________________.
1
2
3
4
5
0 of 5
The opening in the blastula is known as
the ____________________.
1
2
3
4
5
0 of 5
Echinoderms differ from cnidarians in that
echinoderms develop from three
____________________ layers.
1
2
3
4
5
0 of 5
Most invertebrates that rely on rapid
movement for survival have
____________________ symmetry.
1
2
3
4
5
0 of 5
A digestive tract is a
_________________________ that is open
at both ends.
1
2
3
4
5
0 of 5
If an invertebrate has gills, it most likely lives
in a(an) ____________________
environment.
1
2
3
4
5
0 of 5
Figure 29–2
In Figure 29–2, the structure labeled X is
called a(an) ____________________.
1
2
3
4
5
0 of 5
The function of the structure labeled X in
Figure 29–2 is to rid the body of excess
____________________.
1
2
3
4
5
0 of 5
The simplest nervous systems are
called ____________________.
1
2
3
4
5
0 of 5
If an animal moves by contracting muscles that
surround a body cavity filled with fluid, the animal
has a(an) ____________________ skeleton.
1
2
3
4
5
0 of 5
In some invertebrates, eggs are fertilized outside the
female’s body. This type of fertilization is known as
_________________________ fertilization.
1
2
3
4
5
0 of 5
An individual that can produce both male
and female gametes is called a(an)
____________________.
1
2
3
4
5
0 of 5
Why are animal fossils more abundant from
the Cambrian Period than from earlier
periods?
1
2
3
4
5
0 of 5
Name three invertebrate phyla
with bilateral symmetry.
1
2
3
4
5
0 of 5
Animal Z has three germ layers, a true coelom,
and cephalization. Which invertebrate phyla could
animal Z could be a member of?
1
2
3
4
5
0 of 5
What is a blastopore?
1
2
3
4
5
0 of 5
What characteristic related to development
makes echinoderms different from all other
invertebrates?
1
2
3
4
5
0 of 5
Explain the advantage of
cephalization.
1
2
3
4
5
0 of 5
What is the definition of a
coelomate?
1
2
3
4
5
0 of 5
What is intracellular digestion?
1
2
3
4
5
0 of 5
Why must the surfaces of
respiratory systems be moist?
1
2
3
4
5
0 of 5
Figure 29–3
Identify each circulatory system shown
in Figure 29–3 as open or closed.
1
2
3
4
5
0 of 5
What do the arrows represent in
Figure 29–3?
1
2
3
4
5
0 of 5
Why must all animals eliminate
ammonia from their bodies?
1
2
3
4
5
0 of 5
What can you infer about the habitat of an
invertebrate that eliminates nitrogenous
wastes in the form of uric acid?
1
2
3
4
5
0 of 5
Which of the three main kinds of skeletal systems
would be least likely to function properly in an
animal that is severely dehydrated?
1
2
3
4
5
0 of 5
Explain why budding does not maintain
genetic diversity in a population.
1
2
3
4
5
0 of 5
The animals that existed before the Cambrian Period were
probably very simple. Describe two ways in which these
animals may have obtained nutrients.
1
2
3
4
5
0 of 5
Explain how studying the development of
invertebrates can provide information that is
useful in classifying invertebrates.
1
2
3
4
5
0 of 5
Describe the changes in internal
specialization that occurred during the
evolution of animals.
1
2
3
4
5
0 of 5
Compare and contrast cnidarians, mollusks, and
echinoderms in terms of body symmetry, presence
of a body cavity, and cephalization.
1
2
3
4
5
0 of 5
Describe the structure of a book lung, and
explain why this structure is well suited for
gas exchange.
1
2
3
4
5
0 of 5
In some animals, blood can be distinguished from extracellular fluid,
which is the liquid solution that surrounds the cells of an animal’s body.
Explain why such a distinction is possible for animals with a closed
circulatory system but not for animals with an open circulatory system.
1
2
3
4
5
0 of 5
To remove nitrogenous wastes, some terrestrial
invertebrates convert ammonia to urea. Why is
that advantageous for these invertebrates?
1
2
3
4
5
0 of 5
Describe the organization of nervous
systems in cnidarians, flatworms, and
cephalopod mollusks.
1
2
3
4
5
0 of 5
Contrast hydrostatic skeletons,
exoskeletons, and endoskeletons in terms of
their structures.
1
2
3
4
5
0 of 5
When individuals in a population are few and widely
scattered, hermaphrodites might have a better chance of
reproducing sexually than animals that have separate
sexes. Explain why.
1
2
3
4
5
0 of 5