Acoelomorpha, Platyzoa, and Mesozoa

Question 1

While most of the platyhelminthes are free living or endoparasites, which one of the following taxa has an ectoparasitic life cycle?

Answer 1

Monogenea

Question 2

Members of phylum Platyhelminthes are called flatworms because their bodies are flattened

Answer 2

dorsoventrally.

Question 3

Cells that secrete mucus in the epidermis of the Turbellaria are called

Answer 3

rhabdites

Question 4

The body of the parasitic flatworms is covered in a syncytial layer called

Answer 4

tegument

Question 5

While the previous phyla have used intracellular digestion, within these three phyla extracellular digestion is the norm. Extracellular digestion means that

Answer 5

proteolytic enzymes are secreted into the gut.

Question 6

Another name for a protonephridium is a

Answer 6

flame cell.

Question 7

The cells that form a meshwork filling the spaces between muscles and organs that develops from mesoderm is called

Answer 7

parenchyma

Question 8

Protonephridia function in

Answer 8

osmoregulation.

Question 9

The nervous system of the flatworms has sensory, motor, and association nerves, and it is organized into a ________ pattern.

Answer 9

ladderlike

Question 10

Light-sensitive sense organs in the flatworms are called

Answer 10

ocelli

Question 11

Sense organs that respond to changes in water current directions are the

Answer 11

rheoreceptors

Question 12

Which of the following groups includes ectoparasites of fish and amphibians?

Answer 12

Monogenea

Question 13

The animals that are leaf-shaped endoparasites, have a tegument, and have complex life cycles are members of the class

Answer 13

Trematoda

Question 14

Cestodes are monoecious and lack a digestive tract. The reproductive units of the cestodes are called

Answer 14

proglottids

Question 15

The chain of proglottids is collectively called the ________, and the holdfast or attachment organ is called the

Answer 15

strobila, scolex.

Question 16

Which of the following organisms is a blood fluke?

Answer 16

Worms of the genus Schistosoma.

Question 17

The rhynchocoel is a cavity that contains the

Answer 17

heart

Question 18

In the digenetic trematodes, the first or invertebrate host is called the _________ and the second or final host, which is usually a vertebrate, is called the _________ host.

Answer 18

intermediate, definitive

Question 19

The members of phylum Rotifera are cosmopolitan, which means they are found in many different habitats, and the body is made of three parts. These three parts are the

Answer 19

head, trunk, and foot.

Question 20

The members of phylum Rotifera feed by the circular motion of the

Answer 20

corona

Question 21

The rotifers reproduce sexually by ________ eggs and asexually by ________ eggs.

Answer 21

mictic, amictic

Question 22

Which of the pseudocoelomate phyla has a two-part head, dorsal plates, and a ventral ciliary

Answer 22

Kinorhyncha

Question 23

Recent evidence suggests that Rotifera and Acanothocephala are closely related to the ____.

Answer 23

Gnathostomulida

Question 24

Several pseudocoelomate phyla are characterized by having a constant number of cells or nuclei, a condition referred to as ____.

Answer 24

eutely

Question 25

Most of the species of phylum Gnathostomulida have been found living between grains of sand or silt.

Answer 25

true

Question 26

The members of the phylum Gnathostomulida share a characteristic with rotifers because they both have grinding jaws.

Answer 26

true

Question 27

The jaw and pharynx of the Gnathostomulida are quite similar to those of the ____.

Answer 27

rotifera

Question 28

The pork tapeworm is Fasciolopsis hepatica.

Answer 28

false

Question 29

The human liver fluke, Clonorchis sinensis, is common in China, and can cause cirrhosis of the liver and death.

Answer 29

true

Question 30

The fact that some parasites have a first or intermediate host, and a final or definitive host, is reflected in the class name Digenea.

Answer 30

true

Question 31

The best-known turbellarian is the planarian, which is often used in the laboratory. The generic name of this organism is Clonorchis.

Answer 31

false

Question 32

The sense organs of the flatworm that help the organism maintain its equilibrium are called rheoreceptors.

Answer 32

false

Question 33

Of the phyla discussed in this chapter, all are primarily bilaterally symmetrical.

Answer 33

true

Question 34

Of the phyla discussed in this chapter, only the gnathostomulids have a circulatory system.

Answer 34

false

Question 35

The term proglottid is only used when referring to the cestodes.

Answer 35

true

Question 36

The parenchyma is different from mesoglea, as it is cellular, and is mesodermal in origin. But, because there is no cavity in this area around the gut, these worms are considered to be acoelomate.

Answer 36

true

Question 37

Neodermata is a taxonomic name proposed for the trematodes, monogeneans, and cestodes, as they have a unique tegument.

Answer 37

true

Question 38

In some turbellarians, the yolk that provides nutrition for the developing embryo is contained within the egg cell, a condition known as ectolecithal.

Answer 38

false

Question 39

Turbellarians are the only flatworms that may be both terrestrial and free-living.

Answer 39

true

Question 40

Cladistic analysis indicates that the class _____ is paraphyletic and will therefore probably be further divided into many more taxa.

Answer 40

Turbellaria