Which of the following did NOT occur during the Cambrian Explosion?

1
Which of the following did NOT occur during the
Cambrian Explosion?

• 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
Paleontologists discover the fossil of an animal
that lived 570 million years ago. This animal
probably

• was flat and plate-shaped.
• had a hard shell.
• was organized into a front and a back end.
• lived on land.

3
One characteristic that made early animals
different from all animals of today was their

• habitat.
• body segmentation.
• body plan.
• bilateral symmetry.

4
The diversity of invertebrate phyla underwent its
greatest increase

• before the Cambrian Period.
• during the Cambrian Period.
• after the Cambrian Period.
• both before and after the Cambrian Period.

5
Animals of the Cambrian Period typically had all
of the following EXCEPT

• body symmetry.
• segmentation.
• some type of skeleton.
• a backbone.

6
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?

• an armored worm
• a jellyfish
• a snail
• a clam

7
Which of the following group of invertebrates are
deuterostomes?

• worms
• arthropods
• mollusks
• echinoderms

8
The classification of an animal as a deuterostome
or a protostome is based on

• its body symmetry.
• whether or not it has a coelom.
• what happens to the blastopore.
• the number of germ layers it has.

9
In a protostome, the blastopore becomes a(an)

• mouth.
• anus.
• zygote.
• blastula.

10
A body cavity that forms between the germ layers
is called a(an)

• coelom.
• blastopore.
• mesoderm.
• ectoderm.

11
An acoelomate is an animal that has

• 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.

12
Some type of body symmetry is found in all
invertebrates EXCEPT

• cnidarians.
• mollusks.
• sponges.
• flatworms.

13
Which invertebrates exhibit radial symmetry?

• cnidarians and echinoderms
• sponges and flatworms
• roundworms and annelids
• mollusks and arthropods

14
Cephalization refers to the

• 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.

15
Animal X has no coelom and no cephalization.
Animal X is either a

• mollusk or an arthropod.
• flatworm or a roundworm.
• mollusk or an echinoderm.
• sponge or a cnidarian.

16
Animal Y has three germ layers, bilateral
symmetry, and no coelom. Animal Y is a(an)

• sponge.
• arthropod.
• flatworm.
• mollusk.

17
In Figure 291, the space labeled X is called a

• protostome.
• deuterostome.
• coelom.
• pseudocoelom.

18
One animal that has a body construction like that
shown in Figure 291 is a

• flatworm.
• roundworm.
• sponge.
• jellyfish.

19
Which of the following characteristics is NOT
found in any radially symmetrical invertebrate?

• cephalization
• specialized cells
• specialized organs
• a coelom

20
One way to distinguish a roundworm from an
annelid is to

• count their germ layers.
• examine their body symmetry.
• compare the structure of their body cavities.
• determine whether they have cephalization.

21
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

22
Which of the following invertebrates has a closed
circulatory system, nephridia, and a hydrostatic
skeleton?

• an echinoderm
• an annelid
• a flatworm
• a sponge

23
If an animal has a digestive tract, an open
circulatory system, and an exoskeleton, it could
be a(an)

• arthropod.
• echinoderm.
• cnidarian.
• roundworm.

24
Invertebrates that break down their food through
intracellular digestion include

• annelids.
• mollusks.
• arthropods.
• sponges.

25
Which invertebrate has a gastrovascular cavity?

• arthropod
• mollusk
• cnidarian
• roundworm

26
A true digestive tract is found in

• annelids.
• sponges.
• cnidarians.
• flatworms.

27
One difference between a gastrovascular cavity
and a digestive tract is that

• 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.

28
Gases diffuse most efficiently across a
respiratory membrane if the membrane is

• thick and dry.
• thin and dry.
• thick and moist.
• thin and moist.

29
Which of these invertebrates exchange gases
through gills?

• insects
• spiders
• clams
• land snails

30
In insects, gas exchange takes place through a
network of

• tracheal tubes.
• mantle cavities.
• book lungs.
• blood vessels.

31
Most flatworms are small and very thin.
Therefore, they can supply their cells with
oxygen and remove metabolic wastes by means of

• 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.

32
The distinguishing feature of a closed
circulatory system is that

• 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.

33
In an open circulatory system, blood

• never leaves the heart.
• does not come in direct contact with the tissues.
• is always contained within a system of blood
  vessels.
• is pumped through a system of sinuses.

34
An example of an animal with an open circulatory
system is a(an)

• sponge.
• cnidarian.
• arthropod.
• annelid.

35
The giant squid is a large, very active
invertebrate. What type of circulatory system do
you think it has?

• open circulatory system
• closed circulatory system
• water vascular system
• no circulatory system

36
Which of the following is a function of an
excretory system?

• 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

37
Which structures are NOT part of an excretory
system?

• flame cells
• spiracles
• Malpighian tubules
• nephridia

38
What would happen to a flatworm if its flame
cells stopped functioning?

• It would be unable to pump blood.
• It would accumulate urea.
• It would swell.
• It would dry up.

39
Which of the following best describes uric acid?

• 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

40
Expelling uric acid from the body and having a
respiratory surface that is covered with mucus
are two ways that some invertebrates can

• process food more efficiently.
• reduce water loss.
• respond to their environment.
• supply oxygen to their cells.

41
The eyespots of flatworms can

• detect the presence of light.
• detect motion.
• detect color.
• form images.

42
An example of an invertebrate with a hydrostatic
skeleton is a(an)

• spider.
• sponge.
• sea star.
• earthworm.

43
An endoskeleton is a

• shell of a mollusk.
• fluid-filled body cavity that supports the
  muscles.
• structural support located inside the body.
• hard body covering made of chitin.

44
Which of the following invertebrates would be
most likely to reproduce by external
fertilization?

• an arachnid
• an insect
• a land snail
• a cnidarian

45
Which statement refers to sexual reproduction?

• 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 parents body wall.

46
Animals with skeletons were more numerous in the
Cambrian Period than in earlier periods.
_________________________

• True
• False

47
Mollusks are classified as pseudocoelomates.
_________________________

• True
• False

48
During early development, the zygote divides
repeatedly to form a hollow ball of cells called
a blastopore. _________________________

• True
• False

49
In deuterostomes, the blastopore forms a(an)
mouth. _________________________

• True
• False

50
Arthropods have bilateral symmetry.
_________________________

• True
• False

51
The only deuterostomes with radial symmetry are
cnidarians. _________________________

• True
• False

52
The difference between a coelomate and a
pseudocoelomate has to do with the lining of the
body cavity. _________________________

• True
• False

53
An animal that feeds on other animals by
swallowing them whole is most likely to use
intracellular digestion. _________________________

• True
• False

54
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. _____________________
____

• True
• False

55
Book lungs and tracheal tubes are used for
breathing in terrestrial invertebrates.
_________________________

• True
• False

56
If an animals blood never comes in direct
contact with its tissues, the animal has an open
circulatory system. _________________________

• True
• False

57
The excretory system of animal X functions to
conserve body water while removing nitrogenous
wastes. Animal X most likely lives on land.
_________________________

• True
• False

58
Muscles work by becoming longer.
_________________________

• True
• False

59
Arthropods have an endoskeleton.
_________________________

• True
• False

60
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. _________________________

• True
• False

61
Participant Scores
62
____________________ fossils are tracks and
burrows made by soft-bodied animals whose bodies
were not fossilized.
63
Over the course of evolution, ____________________
allowed animals to increase in body size with a
minimum of new genetic material.
64
The only invertebrates that lack both
cephalization and a coelom are cnidarians and
____________________.
65
A body cavity lined partially with mesoderm is
called a(an) _________________________.
66
The opening in the blastula is known as the
____________________.
67
Echinoderms differ from cnidarians in that
echinoderms develop from three ___________________
_ layers.
68
Most invertebrates that rely on rapid movement
for survival have ____________________ symmetry.
69
A digestive tract is a _________________________
that is open at both ends.
70
If an invertebrate has gills, it most likely
lives in a(an) ____________________ environment.
71
Figure 292
72
In Figure 292, the structure labeled X is called
a(an) ____________________.
73
The function of the structure labeled X in Figure
292 is to rid the body of excess
____________________.
74
The simplest nervous systems are called
____________________.
75
If an animal moves by contracting muscles that
surround a body cavity filled with fluid, the
animal has a(an) ____________________ skeleton.
76
In some invertebrates, eggs are fertilized
outside the females body. This type of
fertilization is known as ________________________
_ fertilization.
77
An individual that can produce both male and
female gametes is called a(an) ___________________
_.
78
Why are animal fossils more abundant from the
Cambrian Period than from earlier periods?
79
Name three invertebrate phyla with bilateral
symmetry.
80
Animal Z has three germ layers, a true coelom,
and cephalization. Which invertebrate phyla could
animal Z could be a member of?
81
What is a blastopore?
82
What characteristic related to development makes
echinoderms different from all other
invertebrates?
83
Explain the advantage of cephalization.
84
What is the definition of a coelomate?
85
What is intracellular digestion?
86
Why must the surfaces of respiratory systems be
moist?
87
Figure 293
88
Identify each circulatory system shown in Figure
293 as open or closed.
89
What do the arrows represent in Figure 293?
90
Why must all animals eliminate ammonia from their
bodies?
91
What can you infer about the habitat of an
invertebrate that eliminates nitrogenous wastes
in the form of uric acid?
92
Which of the three main kinds of skeletal systems
would be least likely to function properly in an
animal that is severely dehydrated?
93
Explain why budding does not maintain genetic
diversity in a population.
94
The animals that existed before the Cambrian
Period were probably very simple. Describe two
ways in which these animals may have obtained
nutrients.
95
Explain how studying the development of
invertebrates can provide information that is
useful in classifying invertebrates.
96
Describe the changes in internal specialization
that occurred during the evolution of animals.
97
Compare and contrast cnidarians, mollusks, and
echinoderms in terms of body symmetry, presence
of a body cavity, and cephalization.
98
Describe the structure of a book lung, and
explain why this structure is well suited for gas
exchange.
99
In some animals, blood can be distinguished from
extracellular fluid, which is the liquid solution
that surrounds the cells of an animals body.
Explain why such a distinction is possible for
animals with a closed circulatory system but not
for animals with an open circulatory system.
100
To remove nitrogenous wastes, some terrestrial
invertebrates convert ammonia to urea. Why is
that advantageous for these invertebrates?
101
Describe the organization of nervous systems in
cnidarians, flatworms, and cephalopod mollusks.
102
Contrast hydrostatic skeletons, exoskeletons, and
endoskeletons in terms of their structures.
103
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.