Deck 13: The Smaller Ecdysozoan Phyla

Question 1

Much of the success of nematodes is due to their

A)hydrostatic skeleton.
B)well-developed circular and longitudinal muscles.
C)outer, noncellular, collagenous cuticle.
D)ciliated covering.
E)parthenogenetic reproduction.

Answer 1

C

Question 2

Ecdysozoan animals

A)are all pseudocoelomates.
B)are all acoelomates.
C)are all coelomates.
D)molt their cuticle.
E)derive their nutrients from symbiotic relationships with algae.

Answer 2

D

Question 3

Structures that function in chemoreception and are found at the anterior and posterior ends of nematodes are the

A)spicules and lips.
B)bursa and the nucleus.
C)scalids and the placids.
D)zonites and the mastax.
E)amphids and the phasmids.

Answer 3

E

Question 4

Kinorhynchs are found exclusively in __________ environments.

A)terrestrial
B)freshwater
C)marine
D)stagnant pond
E)rapidly flowing stream

Question 5

The __________ are some of the most abundant animals on earth.

A)nematodes
B)rotifers
C)kinorhynchs
D)gastrotrichs
E)nematomorphans

Question 6

A pseudocoelom lacks

A)peritoneum and mesenteries.
B)muscles.
C)a digestive tract.
D)excretory organs.
E)reproductive organs.

Question 7

A filarial worm which infects dogs,particularly common in the United States,is

A)pinworms.
B)mange.
C)ringworm.
D)heartworm.
E)tapeworms.

Question 8

Nematodes are typically

A)dioecious and dimorphic.
B)monoecious and dimorphic.
C)dioecious and amorphic.
D)monoecious and monomorphic.
E)monoecious and amorphic.

Question 9

The nematodes are commonly known as

A)flatworms.
B)segmented worms.
C)roundworms.
D)beard worms.
E)tongue worms.

Question 10

Members of the phylum Nematomorpha are commonly called

A)pinworms.
B)hookworms.
C)horsehair worms.
D)heartworms.
E)spiny-headed worms.

Question 11

In the osmoregulatory/excretory system of aquatic nematodes,ventral gland cells called __________ are located posterior to the pharynx.

A)coxae
B)renettes
C)protonephridia
D)kidneys
E)amphids

Question 12

All of the following have a cuticle that is molted except one.

A)Loricifera
B)Priapulida
C)Nematoda
D)Rotifera
E)Kinorhyncha

Question 13

The neck of a kinorhynch has spines called

A)plastids.
B)phasmids.
C)placids.
D)scalids.
E)amphids.

Question 14

The pinworm,Enterobius vermicularis,commonly infects humans when

A)infective larvae bore through the soles of the feet.
B)metacercaria are taken in while eating raw fish.
C)poorly cooked pork containing infective larvae are consumed.
D)eggs containing infective larvae are consumed.
E)mosquitoes carry microfilaria from host to host.

Question 15

One method of avoiding infection by Trichinella spiralis is to

A)use insect repellents to prevent mosquito bites.
B)wash and peel raw vegetables before eating them.
C)wear shoes.
D)purify water before drinking it.
E)cook pork thoroughly before eating it.

Question 16

The osmoregulatory organs of nematodes are

A)malpighian tubules.
B)metanephridia.
C)renettes.
D)protonephridia.
E)kidneys.

Question 17

The process of shedding the outer body covering is called

A)autotomy.
B)ecdysis.
C)syncytialism.
D)metamorphosis.
E)lysis.

Question 18

The phylum name Kinorhyncha refers to

A)their bioluminescence.
B)their lack of spines.
C)their posterior spines.
D)their degenerate nervous system.
E)their method of burrowing.

Question 19

A human condition caused by filarial worms is called

A)elephantiasis.
B)trichinosis.
C)brucellosis.
D)sclerosis.
E)dermatitis.

Question 20

__________ is a condition in which cells,or the nuclei in syncytia,are constant in number for the entire animal,and for a given organ for all members of the species.

A)Neoteny
B)Eutely
C)Protandry
D)Autotomy
E)Protogyny

Question 21

The spiny head of a loriciferan is called the

A)introvert.
B)proboscis.
C)acanthor.
D)corona.
E)acanthocephala.

Question 22

Necator spp.includes a variety of hookworms.All of the following are characteristics of this genus WITH ONE EXCEPTION.

A)Adult worms attach to small intestine epithelia where they feed on blood and other tissues.
B)The definitive host acquires an infection when filariform larvae penetrate the host's skin.
C)Eggs are deposited onto soil with feces from an infected host.
D)Infections are common in northern climates, and eggs remain dormant over winter months.

Question 23

An important function of the cuticle of most ecdysozoans,with the exception of the arthropods,is that

A)it is a rigid supportive exoskeleton.
B)it interacts with the pseudocoelom to function as hydrostatic skeleton.
C)it is a surface for diffusion of excretory wastes and respiratory gases.
D)it is a surface for absorption of nutrients in parasitic species.

Question 24

The life cycle of Ascaris lumbricoides involves all of the following except one.

A)Eggs are deposited onto soil or in water with human feces.
B)There is no intermediate host.
C)Worms attain sexual maturity in the large intestine of a human host.
D)Larvae mature in the human lungs after embryonated eggs are ingested by a human.

Question 25

Adult nematomorphs are free living; the larvae are

A)found in benthic marine habitats.
B)parasitic in the respiratory systems of vertebrates.
C)found in the lymph system of humans.
D)parasitic in arthropods.
E)encysted in muscle tissue of mammals.

Question 26

The life cycle of Wuchereria includes the ___________ as an intermediate host and vector.The __________ of this parasite are picked up by this vector from the human host.These larvae mature before being carried back to the human.The parasites eventually mature to adults in the human ____________.

A)flea; hexacanths; small intestine
B)mosquito; microfilaria; heart
C)mosquito; microfilaria; lymphatic system
D)tsetse fly; sporozoites; circulatory system

Question 27

All of the following statements regarding nematode phylogeny are true except one.

A)All nematodes that are plant or animal parasites belong to a single clade.
B)The old classification based on two classes is incorrect.Molecular analysis suggests that there are three nematode clades.
C)Ancestral nematodes were probably marine organisms.
D)Freshwater nematodes are found in all three clades.Marine nematodes are found in two of the three clades.

Question 28

The pinworm,Enterobius vermicularis,is the most common nematode parasite in developed countries because the life cycle of this parasite is relatively easy to complete and reinfection and transmission between hosts readily occurs.All of the following,EXCEPT ONE,are attributes of the life cycle that help this parasite thrive.

A)There is no intermediate host.
B)Eggs are very small and easily contaminate bed clothes and linens.
C)Eggs are ingested after sewage contaminates drinking water.
D)Gravid females deposit eggs in the perianal area at night creating an itching sensation.

Question 29

Nematodes move with characteristic whiplike movements.They are incapable of localized contractions along the body wall,similar to those observed in earthworms.Which of the following elements of nematode structure explain their particular form of locomotion? Check all that apply.

A) Nematodes have a collagenous cuticle that is flexible but tough.
B)Nematodes have both circular and longitudinal muscles associated with their body wall.
C)Nematodes are pseudocoelomate.
D) Nematodes have longitudinal muscles associated with their body wall.

Question 30

The life cycle of Trichinella is unusual for other nematode parasites in that

A)there is no intermediate host.
B)female nematodes give birth to live larvae that encyst within the maternal host.
C)sexual dimorphism is present.
D)it is very host specific.

Question 31

The most recent ecdysozoan phylum to be described is the phylum

A)Lobatocercebrida.
B)Placozoa.
C)Ctenophora.
D)Loricifera.
E)Gnathostomulida.