Food enters a flatworm’s body cavity through a muscular tube called a flame cell. pharynx. ganglion. coelom. 1 2 3 4 5

Some flatworms have clusters of nerve cells that control the nervous system. Each cluster is called a(an) ganglion. brain. eyespot. flame cell. 1 2 3 4 5

Most free-living flatworms are hermaphrodites. parasites. members of the class Cestoda. flukes. 1 2 3 4 5

Many flatworms can detect changes in the amount of light in their environment using groups of cells called flame cells. nerve cords. ganglia. eyespots. 1 2 3 4 5

Why don’t most parasitic flatworms need a complex digestive system? They produce metabolic wastes such as ammonia and urea. They are carnivores. They obtain nutrients from food that has already been digested by their host. They excrete water through flame cells. 1 2 3 4 5

Free-living flatworms, most of which live in marine environments or fresh water, are flukes. turbellarians. tapeworms. roundworms. 1 2 3 4 5

An adult tapeworm uses its scolex to attach itself to the intestinal wall of its host. digest food. store sperm. store fertilized eggs. 1 2 3 4 5

In the tapeworm, both male and female reproductive organs are contained in each mature scolex. proglottid. cyst. egg. 1 2 3 4 5

An intermediate host is an organism in which a parasite reproduces asexually. reproduces sexually. causes tissue decay. clogs blood vessels. 1 2 3 4 5

Roundworms have a one-way digestive tract. true coelom. mantle. radula. 1 2 3 4 5

In a pseudocoelom, mesoderm partially lines the germ layer. body cavity. blood vessels. pharynx. 1 2 3 4 5

A pseudocoelom forms between the mesoderm and endoderm. ectoderm. true coelom. none of the above 1 2 3 4 5

Roundworms have a digestive system with two openings. with one opening. within a true coelom. none of the above 1 2 3 4 5

To move, roundworms use their proglottids. hydrostatic skeleton. tentacles. pharynx. 1 2 3 4 5

How do the body systems of parasitic roundworms generally compare to those of free-living roundworms? They are more complex. They are simpler. Parasitic roundworms lack a reproductive system. Free-living roundworms have an internal transport system. 1 2 3 4 5

The nervous system of a roundworm includes a simple brain. a complex brain. a single ganglion. several ganglia. 1 2 3 4 5

People can be infected with roundworms by drinking contaminated water. eating contaminated food. insects that bite. all of the above 1 2 3 4 5

What causes the disease called elephantiasis? flukes filarial worms hookworms ascarid worms 1 2 3 4 5

A person who has trichinosis likely contracted it from walking barefoot on soil infested with Trichinella worms. eating undercooked meat containing Trichinella cysts. mosquitoes. coming in contact with Trichinella-infested snails. 1 2 3 4 5

In earthworms, food is ground into small pieces in the crop. gizzard. pharynx. esophagus. 1 2 3 4 5

The body of an annelid has a backbone. an external shell. segments. stinging tentacles. 1 2 3 4 5

Which of these animals has a true coelom? filarial worm tapeworm planarian leech 1 2 3 4 5

In annelids, nitrogen-containing wastes are eliminated by clitella. parapodia. nephridia. gills. 1 2 3 4 5

In an earthworm, the dorsal blood vessel functions like a heart because it connects to sinuses. receives blood from gills. contracts and helps pump blood. connects to ring vessels. 1 2 3 4 5

In earthworms, inability to produce offspring might be associated with lack of a true coelom. the inability of a worm to fertilize its own eggs. a malfunction of the nephridia. a malfunction of the clitellum. 1 2 3 4 5

A type of worm that is an external parasite is the tapeworm. polychaete. leech. earthworm. 1 2 3 4 5

The muscular extension of a leech that penetrates the tissue of its host is the septum. radula. proboscis. ganglion. 1 2 3 4 5

The bristlelike structures on some annelids’ bodies are called setae. suckers. nephridia. ganglia. 1 2 3 4 5

Earthworms benefit gardeners because their tunnels provide passageways for leeches. polychaetes. plant roots and water. planarians. 1 2 3 4 5

The larvae of many marine annelids are ecologically important because they poison coral reefs. are eaten by fishes and other marine animals. feed on earthworms. none of the above 1 2 3 4 5

disturbed sediment abundance of bacteria abundance of algae What water conditions could be expected in an area where large numbers of mud-dwelling, filter-feeding, marine annelids are found? disturbed sediment abundance of bacteria abundance of algae all of the above 1 2 3 4 5

Which of the following is evidence that mollusks and annelids may be closely related? Both groups have setae. Both groups have a trochophore larva. Neither group has lungs. Both groups include both marine and terrestrial animals. 1 2 3 4 5

Mollusks have a pseudocoelom. a true coelom. a body cavity between the ectoderm and mesoderm. no body cavity. 1 2 3 4 5

Why is an open circulatory system adequate for a bivalve, such as a clam, but not for a cephalopod, such as a squid? Bivalves are largely sedentary, whereas a squid is fast-moving. Bivalves have relatively low oxygen demands. Squids have relatively high oxygen demands. all of the above 1 2 3 4 5

The thin layer of tissue that covers a mollusk’s body is called the mantle. foot. visceral mass. shell. 1 2 3 4 5

The tubelike structure through which water enters and leaves a mollusk’s body is the sinus. siphon. coelom. mantle cavity. 1 2 3 4 5

In the open circulatory system of some mollusks, blood is found only in sinuses. only in blood vessels. in blood vessels and sinuses. only in gills. 1 2 3 4 5

The spade-shaped burrowing structure of one group of mollusks and the tentacles of another group are both modifications of the foot. mantle. shell. visceral mass. 1 2 3 4 5

A pond snail is an example of a(an) gastropod. flatworm. roundworm. annelid. 1 2 3 4 5

The most active mollusks are the gastropods. cephalopods. bivalves. nudibranchs. 1 2 3 4 5

Which characteristic would allow you to differentiate a nautilus from another type of mollusk? It has a shell. It has up to 90 tentacles. It has a single foot. all of the above 1 2 3 4 5

Cephalopoda/cuttlefish Gastropoda/land slug Bivalvia/clam Which pair of terms does NOT include a class of mollusks and an example of an animal in that class? Cephalopoda/cuttlefish Gastropoda/land slug Bivalvia/clam Cephalopoda/nudibranch 1 2 3 4 5

Bivalve communities that live near undersea volcanic vents obtain their food mostly from symbiotic bacteria. symbiotic algae. detritus. filter-feeding. 1 2 3 4 5

Filter-feeding bivalves can be used to monitor the environmental health of a habitat because the bivalves reproduce rapidly in polluted water. the bivalves concentrate pollutants and microorganisms in their tissues. the bivalves live near deep-sea vents. some bivalves never get cancer. 1 2 3 4 5

The feeding types that occur within the phylum Mollusca include herbivores. carnivores. detritivores. all of the above 1 2 3 4 5

Roundworms are the simplest animals to have three embryonic germ layers. _________________________ True False 1 2 3 4 5

Turbellaria is a class of parasitic flatworms True False 1 2 3 4 5

A flatworm’s eyespots can detect chemicals. _________________________ True False 1 2 3 4 5

An unidentified worm specimen that has a one-way digestive tract suspended in a pseudocoelom is likely to be a(an) annelid. _________________________ True False 1 2 3 4 5

Undigested material leaves a roundworm’s body through the anus True False 1 2 3 4 5

Filarial worms might quickly spread through populations of birds and mammals over a large area because they are spread by contact with contaminated soil. _________________________ True False 1 2 3 4 5

Annelids and mollusks, both of which possess a coelom, may be more closely related to each other than either is to flatworms or roundworms. _________________________ True False 1 2 3 4 5

Unlike most parasitic worms, polychaetes typically attach to their host externally. _________________________ True False 1 2 3 4 5

A worm found in a stream that is attached to a rock by a posterior sucker is a member of the class Oligochaeta. _________________________ True False 1 2 3 4 5

Polychaetes are annelids that help aerate and mix layers of soil, improving the soil’s quality. _________________________ True False 1 2 3 4 5

Mollusks are soft-bodied animals that usually have an internal or external shell. _________________________ True False 1 2 3 4 5

Annelids and mollusks may have shared a common ancestor more than 550 million years ago. _________________________ True False 1 2 3 4 5

The type of body cavity shared by all mollusks is a pseudocoelom True False 1 2 3 4 5

In clams and oysters, two shells are held together by powerful muscles—a trait common to all cephalopods. ____________________ True False 1 2 3 4 5

Around active deep-sea vents, symbiotic bacteria provide food for bivalve communities. _________________________ True False 1 2 3 4 5

Participant Scores Participant 1 Participant 2 Participant 3 Participant 1 Participant 2 Participant 3 Participant 4 Participant 5

The simplest animals to have three embryonic germ layers, bilateral symmetry, and cephalization are the soft, flattened worms called ____________________. 1 2 3 4 5 0 of 5

The primary host of Schistosoma mansoni is a(an) _________________________. 1 2 3 4 5 0 of 5

Roundworms have a tube-within-a-tube digestive tract with two openings—a mouth and a(an) ____________________. 1 2 3 4 5 0 of 5

Many free-living roundworms are ____________________, which are animals that eat other animals. 1 2 3 4 5 0 of 5

The larvae of the roundworm species named ____________________ form cysts in the host’s muscle tissue. 1 2 3 4 5 0 of 5

A filter-feeding annelid fans water through tubelike burrows and catches food particles in a ____________________ bag. 1 2 3 4 5 0 of 5

Annelids have a(an) ____________________ circulatory system, in which blood is contained in a network of blood vessels. 1 2 3 4 5 0 of 5

The type of embryonic tissue that lines a true coelom is called ____________________. 1 2 3 4 5 0 of 5

Sandworms and bloodworms are members of the class of marine annelids called ____________________. 1 2 3 4 5 0 of 5

Bottom-dwelling annelids from the class ____________________ are important in marine ecosystems and form part of the diets of fishes and crustaceans. 1 2 3 4 5 0 of 5

A marine animal that has a(an) ____________________ larva and a true coelom could be either an annelid or a mollusk—it is impossible to classify it without further information. 1 2 3 4 5 0 of 5

Many aquatic mollusks have a free-swimming larval stage, called a(an) ____________________ larva. 1 2 3 4 5 0 of 5

The shell of most mollusks is composed of ________________________, which is secreted by glands in the mantle. 1 2 3 4 5 0 of 5

The foot of most cephalopods is divided into eight or more arms called ____________________. 1 2 3 4 5 0 of 5

Some snails and other mollusks never seem to develop any form of ____________________. 1 2 3 4 5 0 of 5

What are the characteristics of flatworms? 1 2 3 4 5 0 of 5

What role do freshwater snails play in the life cycle of the blood fluke Schistosoma? 1 2 3 4 5 0 of 5

Describe the tube-within-a-tube body plan of roundworms. 1 2 3 4 5 0 of 5

What role does diffusion play in the lives of roundworms and flatworms? 1 2 3 4 5 0 of 5

How can washing vegetables before you eat them help prevent the severe malnutrition associated with ascarid worms? 1 2 3 4 5 0 of 5

How do hookworms infect humans? 1 2 3 4 5 0 of 5

How do the sense organs of free-living marine annelids differ from those of other annelids? 1 2 3 4 5 0 of 5

What structures enable leeches to cling to their hosts? 1 2 3 4 5 0 of 5

In what ways do earthworms improve soil quality? 1 2 3 4 5 0 of 5

What is the meaning of the Latin word molluscus What is the meaning of the Latin word molluscus? Why is this meaning appropriate for mollusks? 1 2 3 4 5 0 of 5

What are the four parts of the body plan of most mollusks? 1 2 3 4 5 0 of 5

How do most aquatic mollusks breathe? 1 2 3 4 5 0 of 5

What is a feature of land slugs and nudibranchs that sets them apart from other gastropods? 1 2 3 4 5 0 of 5

What has happened to the internal shell of squids over evolutionary time? 1 2 3 4 5 0 of 5

How can checks of bivalves warn public health officials of health problems related to water purity? 1 2 3 4 5 0 of 5

Describe the nervous system of a typical free-living flatworm. 1 2 3 4 5 0 of 5

How are tapeworms well adapted to living and reproducing inside the body of a host? 1 2 3 4 5 0 of 5

Describe the nervous system of a roundworm. 1 2 3 4 5 0 of 5

Describe the life cycle of the roundworm Ascarislumbricoides when pigs are the host organism. 1 2 3 4 5 0 of 5

Describe two modifications of the pharynx that allow different types of annelids to feed. 1 2 3 4 5 0 of 5

How are leeches used in the practice of medicine? 1 2 3 4 5 0 of 5

What might happen to the soil in an area where earthworms were killed by a pesticide, and why? 1 2 3 4 5 0 of 5

What is a trochophore? Why is it important in inferring evolutionary relationships? 1 2 3 4 5 0 of 5

How do filter-feeding bivalves obtain their food? 1 2 3 4 5 0 of 5

How do bivalves near active deep-sea vents obtain food? 1 2 3 4 5 0 of 5