Question 1

How does a ribbon worm differ from a flatworm?
A)A flatworm has a complete digestive system.
B)A ribbon worm has a mouth and an anus.
C)Flatworms are deuterostomes.
D)Flatworms are radially symmetrical and ribbon worms are bilaterally symmetrical.

Accepted Answer

Ribbon worms have a complete digestive system with a mouth and an anus, whereas flatworms have a blind gut with only one opening for both ingestion and excretion.

Question 2

Chelicerae function as
A)eyes.
B)fangs or pincers.
C)jaws or mandibles.
D)teeth.
E)wings.

Accepted Answer

Chelicerae are modified mouthparts that function as fangs or pincers in arachnids, including spiders and scorpions.

Question 3

Which one of the following annelid structures or events is not correctly paired with its role in locomotion?
A)circular muscles contract-segment becomes thin and long
B)longitudinal muscles contract-segment becomes thick and short
C)fluid in coelom-provides a hydrostatic skeleton
D)septum-allows each segment to move independently
E)chaetae-provides gas exchange surface for body muscles

Accepted Answer

Chaetae are not involved in locomotion, but rather serve as bristles that help an annelid grip onto surfaces or burrow through substrate.

Question 4

Which one of the following incorrectly matches a molluscan group with a feature characterizing that group?
A)Gastropoda-torsion
B)Nudibranchs-extensive gills in mantle cavity
C)Bivalvia-reduced head and no radula
D)Polyplacophora-eight calcareous plates
E)Cephalopoda-closed circulatory system

Accepted Answer

Nudibranchs do not have extensive gills in their mantle cavity, they actually have exposed respiratory structures called cerata.

Question 5

Which one of the following incorrectly matches a molluscan structure with its typical function?
A)ctenidia-secretion of the shell (when present)
B)visceral mass-houses organs of digestion,excretion,reproduction
C)foot-locomotion
D)nephrostome-collection of nitrogenous wastes
E)radula-feeding organ

Accepted Answer

Ctenidia are the respiratory structures in mollusks, not involved in the secretion of the shell.

Question 6

The rigid chitinous exoskeleton of an arthropod has all of the following functions except it
A)provides a place for muscle attachment.
B)protects the animal from predators.
C)impedes water loss.
D)maintains a uniform size for all individuals of that species.
E)prevents injury to the animal.

Accepted Answer

The rigid chitinous exoskeleton provides a place for muscle attachment, protects the animal from predators, impedes water loss, and prevents injury to the animal. However, it does not maintain a uniform size for all individuals of that species. Arthropods undergo molting, where they shed their exoskeleton and grow a new one. The process of molting allows arthropods to increase in size, which means that they do not maintain a uniform size throughout their lifespan.

Question 7

Nauplius,a unique kind of larva,is characteristic of
A)mites.
B)crustaceans.
C)horseshoe crabs.
D)insects.
E)chelicerates.

Accepted Answer

Nauplius is a type of larva that is characteristic of crustaceans, such as crabs and shrimp. It is a small, planktonic stage in the development of crustaceans and is easily recognizable by the three pairs of appendages used for swimming and feeding. The other options (mites, horseshoe crabs, insects, and chelicerates) do not have this characteristic larval stage.

Question 8

Air passage into the trachea of most insects is controlled by the closing and opening of valves,which operate special openings called
A)spiracles.
B)ocelli.
C)ommatidia.
D)book lungs.
E)Malpighian tubules.

Accepted Answer

The air passage into the trachea of most insects is controlled by the opening and closing of spiracles. Spiracles are special openings that function as valves. Therefore, the correct choice is A) spiracles.

Question 9

Eyes with single lenses that respond to light and darkness are found in many arthropods; these are the
A)compound eyes.
B)ocelli.
C)apposition eyes.
D)ommatidia.
E)superposition segments.

Accepted Answer

Single lenses that respond to light and darkness are called ocelli. They are found in many arthropods.

Question 10

The excretory structures of terrestrial arthropods are slender projections from the digestive tract that are attached at the junction of the midgut and hindgut.These are called
A)flame cells.
B)kidneys and bladders.
C)Malpighian tubules.
D)nephridia.
E)ocelli.

Accepted Answer

The slender projections from the digestive tract of terrestrial arthropods are the Malpighian tubules, which are responsible for excretion.

Question 11

A marine biologist makes a presentation about crustaceans to your biology class.He explains that he has recently received an NSF grant to study sessile crustaceans.You are only aware of one group of sessile crustaceans.This crustacean must be
A)a lobster.
B)a crayfish.
C)a shrimp.
D)a barnacle.
E)the nauplius.

Accepted Answer

Barnacles are the only group of sessile crustaceans commonly studied in biology. They are filter feeders that attach themselves to hard surfaces such as rocks or the hulls of ships. The NSF grant in question likely focuses on some aspect of barnacle behavior, physiology, or ecology.

Question 12

Which one of the following statements about the phylum Brachiopoda is false?
A)Brachiopods are often misidentified as bivalves.
B)Brachiopods were much more diverse in the past.
C)As in bivalves,the valves in brachiopods are lateral (left and right)to the body axis.
D)Most brachiopods are sessile (attached).
E)The lophophore resides within the brachiopod's shells.

Accepted Answer

Brachiopods have dorsal and ventral valves rather than the lateral (left and right) valves found in bivalves. This is a key difference between the two groups.

Question 13

Decapod crustaceans (shrimps,lobsters,and crabs)all lack
A)a carapace,a dorsal cephalothorax shield.
B)a ventral line of appendages,swimmerets.
C)a tail spine,telson.
D)chelicerae.

Accepted Answer

Decapod crustaceans do not have chelicerae, which are the mouthparts found in arachnids such as spiders and scorpions. Decapod crustaceans have a pair of mandibles instead. Option A is incorrect as decapod crustaceans do have a carapace, which is a dorsal cephalothorax shield. Option B is incorrect as decapod crustaceans have a ventral line of appendages called swimmerets. Option C is incorrect as decapod crustaceans have a tail spine called a telson.

Question 14

In arthropods,locomotion is accomplished by muscles that work against
A)each other.
B)the exoskeleton.
C)a hydrostatic skeleton.
D)mineralized bones.
E)the pseudocoel.

Accepted Answer

Arthropods have an external exoskeleton that provides support and protection. Muscles in the arthropod's body work against this exoskeleton to provide locomotion.

Question 15

Compound eyes are composed of independent visual units called
A)apposition segments.
B)ocelli.
C)ommatidia.
D)retinas.
E)simple eyes.

Accepted Answer

Compound eyes are made up of many repeating units called ommatidia, each with its own lens and photoreceptor cells. These units work together to create a mosaic image that is then processed by the brain to form a larger image.

Question 16

The side to side thrashing of a nematode is accomplished by contraction of its circular muscles.

Accepted Answer

Nematodes lack circular muscles and instead use longitudinal muscles for their side-to-side thrashing movement.

Question 17

An invertebrate biologist is conducting research with crabs.Her interest is ecdysis.This implies that she studies
A)tagmatization processes in crustaceans.
B)how ommatidia function individually in a compound eye.
C)how the HOX gene controls the fusion of the head and thorax into the cephalothorax.
D)how ocelli evolved from mere photoreceptors to imaging lens.
E)the molting process.

Accepted Answer

Ecdysis refers to the molting process, which is the shedding of the outer exoskeleton in order for the organism to grow bigger. Therefore, the invertebrate biologist studying ecdysis is likely focused on the process of molting in crabs.

Question 18

Spiders and certain other arthropods which lack jaws or mandibles are placed in a subphylum called
A)Agnathae.
B)Amandibulata.
C)blood suckers.
D)chelicerates.
E)mandibulates.

Accepted Answer

Spiders and certain other arthropods which lack jaws or mandibles belong to the subphylum Chelicerata. This subphylum is characterized by the presence of chelicerae, which are specialized appendages used for feeding and defense.

Question 19

Which one of the following insect organ systems has placed the greatest limitation on their body size?
A)nervous system
B)digestive system
C)respiratory system
D)reproductive system
E)excretory system

Accepted Answer

The respiratory system is the limiting factor for insect size because oxygen and carbon dioxide transport is limited by simple diffusion through a system of tracheae, which are small tubes that penetrate the insect body. As the size of the insect increases, the distance between the tracheae and the internal organs becomes too great for simple diffusion to supply sufficient oxygen or remove carbon dioxide. This limits the maximum size of insects, preventing them from growing larger than a few inches.

Quiz 33: Protostomes

How does a ribbon worm differ from a flatworm?

Chelicerae function as

Which one of the following annelid structures or events is not correctly paired with its role in locomotion?

Which one of the following incorrectly matches a molluscan group with a feature characterizing that group?

Which one of the following incorrectly matches a molluscan structure with its typical function?

The rigid chitinous exoskeleton of an arthropod has all of the following functions except it

Nauplius,a unique kind of larva,is characteristic of

Air passage into the trachea of most insects is controlled by the closing and opening of valves,which operate special openings called

Eyes with single lenses that respond to light and darkness are found in many arthropods; these are the

The excretory structures of terrestrial arthropods are slender projections from the digestive tract that are attached at the junction of the midgut and hindgut.These are called

A marine biologist makes a presentation about crustaceans to your biology class.He explains that he has recently received an NSF grant to study sessile crustaceans.You are only aware of one group of sessile crustaceans.This crustacean must be

Which one of the following statements about the phylum Brachiopoda is false?

Decapod crustaceans (shrimps,lobsters,and crabs) all lack

In arthropods,locomotion is accomplished by muscles that work against

Compound eyes are composed of independent visual units called

The side to side thrashing of a nematode is accomplished by contraction of its circular muscles.

An invertebrate biologist is conducting research with crabs.Her interest is ecdysis.This implies that she studies

Spiders and certain other arthropods which lack jaws or mandibles are placed in a subphylum called

Which one of the following insect organ systems has placed the greatest limitation on their body size?