Deck 33: Protostome Animals

Question 1

Figure 33.1
Refer to Figure 33.1.Suppose new molecular analyses indicated that the phylum Annelida had diverged from the arthropod lineage after Onychophora and Tardigrada.What would this imply about protostome evolution?

A)Segmentation evolved only once within protostomes.
B)The annelid lineage gained and then lost the ability to molt.
C)The annelid lineage gained and then lost jointed limbs.
D)A and B
E)A and C

Answer 1

D

Question 2

The presence of a lophophore in a newly discovered species would suggest which of the following?

A)This species grows by shedding its exoskeleton.
B)This species grows by shedding its cuticle.
C)This species is probably an arthropod.
D)This species is a suspension feeder.

Answer 2

D

Question 3

The protostome developmental sequence arose just once in evolutionary history,resulting in two main subgroups-Lophotrochozoa and Ecdysozoa.What does this finding suggest?

A)These two subgroups have a common ancestor that was a protostome.
B)The protostomes are a monophyletic group.
C)Division of these two groups occurred after the protostome developmental sequence appeared.
D)All of the above apply.

Answer 3

D

Question 4

The major evolutionary split of protostome animals was into

A)coelomates and acoelomates.
B)segmented and nonsegmented animals.
C)arthropods and molluscs.
D)diploblasts and triploblasts.
E)lophotrochozoans and ecdysozoans.

Question 5

To which of the following terrestrial habitats would it be easiest for an aquatic animal to adapt?

A)tundra (very low temperature,very low precipitation,low plant biomass)
B)temperate forest (moderate temperature,moderate precipitation,moderate plant biomass)
C)rain forest (high temperature,high precipitation,high plant biomass)
D)boreal forest (low temperature,low precipitation,high plant biomass)
E)subtropical desert (high temperature,very low precipitation,low plant biomass)

Question 6

Suppose you were a researcher choosing a model organism with which to study animal genetics.Which of the following characteristics would be least desirable for this organism?

A)small size
B)long life span
C)frequent reproduction
D)simple diet
E)quick maturation

Question 7

The common ancestor of the protostomes had a coelom.What does this suggest?

A)All lophotrochozoans have a coelom.
B)There are no pseudocoelomates within the protostomes.
C)There are no acoelomates within the protostomes.
D)None of the above answers apply.

Question 8

Which mollusc group can be described as having several calcium carbonate plates along their dorsal side?

A)bivalves
B)gastropods
C)chitons
D)cephalopods

Question 9

Drosophila and Caenorhabditis are two widely used model organisms for biological research.Which of the following advantages do they not have in common?

A)They can be kept in large numbers due to their small size.
B)Their entire genomes have been sequenced.
C)They develop relatively quickly.
D)Their embryonic cells all follow a predetermined developmental path.

Question 10

Which of these mollusc features substitutes for the coelom by providing a space for organ development and circulation of bodily fluids?

A)visceral mass
B)foot
C)mantle
D)none of the above

Question 11

Whiteflies are common pest insects found on cotton,tomato,poinsettia,and many other plants.Nymphs are translucent and mostly sessile,feeding on their host plants' phloem (sap)from the undersides of leaves.They undergo incomplete metamorphosis into winged adults.Because whitefly nymphs cannot escape predation by moving,you hypothesize that their translucent bodies make them hard to spot by predators.How could you directly test this hypothesis?

A)Compare rates of predation on whitefly nymphs on plant leaves of different colors (e.g.,red vs.green poinsettia leaves).
B)Compare rates of predation on whitefly nymphs coated with a nontoxic dye vs.undyed whitefly nymphs.
C)Compare rates of predation on whitefly nymphs vs.whitefly adults.
D)Compare rates of predation on whitefly nymphs by predators that are translucent vs.predators that are not translucent.
E)Compare rates of predation on whitefly nymphs feeding on poisonous plants vs.those feeding on nonpoisonous plants.

Question 12

Which of the following do Nematoda and Arthropoda not have in common?

A)The initial pore formed in the gastrula stage becomes the mouth.
B)They are suspension feeders.
C)They grow by shedding their outer covering.
D)They are both ecdysozoans.

Question 13

Among protostomes,which morphological trait has shown the most diversity?

A)type of symmetry (bilateral vs.radial vs.none)
B)type of body cavity (coelom vs.pseudocoelom vs.acoelom)
C)number of embryonic tissue types (diploblasty vs.triploblasty)
D)direction of gastrulation (protostome vs.deuterostome)

Question 14

Which of the following attributes is not true for both arthropod exoskeletons and mollusc shells?

A)They completely replace the hydrostatic skeleton.
B)They provide protection from predators.
C)They help retain moisture in terrestrial habitats.
D)None of the above answers apply.

Question 15

The body cavity type for arthropods and molluscs can best be described as

A)coelom.
B)pseudocoelom.
C)reduced coelom.
D)no coelom.

Question 16

In arthropods,the hemocoel performs which of the following functions?

A)provides space for the internal organs to grow and function
B)allows for the circulation of bodily fluids
C)acts as a hydrostatic skeleton-for mobility-in larval stages
D)all of the above

Question 17

When considering the wormlike phyla within the protostomes,which feature is most useful in distinguishing groups?

A)the type of body cavity
B)the presence or absence of a hemocoel
C)feeding structures or mouthparts
D)hydrostatic skeleton

Question 18

Which one of these mollusc groups can be classified as suspension feeders?

A)bivalves
B)gastropods
C)chitons
D)cephalopods

Question 19

As stated in the text,"DNA sequence data indicated that two major subgroups existed within the protostomes." This finding contradicts the long-held hypothesis that the protostomes are a monophyletic group.

Question 20

Here is a statement from the text: "The ability to live in terrestrial environments evolved independently in arthropods (at least twice),molluscs,roundworms,and annelids." What logical conclusion would you make from this statement?

A)All these groups have a coelom.
B)The common ancestor of all these groups was probably aquatic.
C)All these groups have the same type of body plan.
D)All these groups lost their coelom after moving to land.

Question 21

What do all the Lophotrochozoa phyla discussed in the text have in common?

A)They feed using lophophores,specialized ciliated structures.
B)They have trochophore larvae,which swim with the aid of a ring of cilia.
C)They have members that reproduce sexually and members that reproduce asexually.
D)They expand their bodies continuously during growth.
E)None of the above answers is correct.

Question 22

On which body segment are arthropod wings attached?

A)head
B)abdomen
C)thorax
D)evenly split between the abdomen and thorax

Question 23

A cephalopod's tentacles are modified from its

A)mantle.
B)visceral mass.
C)foot.
D)shell.
E)radula.

Question 24

What would be the best anatomical feature to look for to distinguish a gastropod from a chiton?

A)presence of a muscular foot
B)presence of a rasp-like feeding structure
C)production of eggs
D)number of shell plates

Question 25

Of what advantage is a large surface-area-to-volume ratio to the Platyhelminthes?

A)It enables them to live in dry habitats.
B)It enables them to survive on very little oxygen.
C)It enables the efficient transport of gases and nutrients without specialized structures.
D)It enables their blood vessels to transport oxygen and carbon dioxide more efficiently.
E)None of the above are advantages.

Question 26

Whiteflies are common pest insects found on cotton,tomato,poinsettia,and many other plants.Nymphs are translucent and mostly sessile,feeding on their host plants' phloem (sap)from the undersides of leaves.They undergo incomplete metamorphosis into winged adults.In many species that undergo metamorphosis,adults and juveniles consume different food sources.However,because adult and nymph whiteflies feed in the same manner from the same host plants,why might whiteflies undergo metamorphosis?

A)Adults are winged so they can escape predators more easily.
B)Adults are winged so they can feed more efficiently.
C)Adults are winged so they can retain moisture better in dry habitats.
D)Adults are winged so they can find mates more easily.
E)All of the above answers are correct.

Question 27

Many terrestrial arthropods exchange gases with their environments by using tracheae, tubes that lead from openings (called spiracles)in the animal's exoskeleton or cuticle directly to the animal's tissues. Some arthropods can control whether their spiracles are opened or closed; opening the spiracles allows the carbon dioxide produced in the tissues to travel down the tracheae and be released outside the animal. Klok et al. measured the carbon dioxide emitted over time (represented by VCO₂)by several species of centipedes. Figure 33.2 presents graphs of their results for two species, Cormocephalus morsitans and Scutigerina weberi. (C. J. Klok, R. D. Mercer, and S. L. Chown. 2002. Discontinuous gas-exchange in centipedes and its convergent evolution in tracheated arthropods. Journal of Experimental Biology 205:1019-29.)Copyright (c)2002, The Company of Biologists and the Journal of Experimental Biology.

Figure 33.2
Look at the graph for Scutigerina weberi (note the scale of the y-axis)in Figure 33.2.What is the best interpretation of these results?

A)The centipede had its spiracles open the entire time.
B)The centipede had its spiracles closed the entire time.
C)The centipede had its spiracles open when CO₂ emission peaked and closed when CO₂ emission was low.
D)The centipede had its spiracles closed when CO₂ emission peaked and open when CO₂ emission was low.

Question 28

Compare the graphs in Figure 33.2 of CO₂ emission for Cormocephalus morsitans and Scutigerina weberi.What hypothesis can you make about each centipede's habitat?

A)C)morsitans lives in a habitat that provides more carbon dioxide than S.weberi.
B)C)morsitans lives in a habitat with more predators than S.weberi.
C)C)morsitans lives in a colder habitat than S.weberi.
D)C)morsitans lives in a dryer habitat than S.weberi.

Question 29

Upon close inspection of movement in annelids and nematodes,you would notice an obvious difference.Nematodes tend to wriggle back and forth,while annelids tend to contract along their length as their girth swells and then thins out as they stretch.What anatomical feature explains this type of movement?

A)The annelids possess longitudinal muscle fibers that the nematodes lack.
B)The nematodes lack circular muscle fibers.
C)Nematodes lack a coelom.
D)Annelids have a highly specialized nervous system capable of more complex movements.

Question 30

What is not true of all arthropods?

A)They metamorphose during development.
B)They have jointed limbs.
C)They grow by molting.
D)They have segmented bodies.
E)They have an exoskeleton or cuticle.

Question 31

Which adaptation is unique to insects among all protostomes?

A)the ability to move via jointed limbs
B)the ability to move by flying
C)the ability to consume terrestrial plants
D)the ability to parasitize other organisms
E)the ability to metamorphose

Question 32

What is the only group of Mollusca that does not have a radula?

A)Bivalves
B)Gastropods
C)Chitons
D)Cephalopods
E)All molluscs have a radula.

Question 33

If you wanted to identify an unfamiliar protostome with a limbless,wormlike body,which characteristic would not be helpful in differentiating one species from another?

A)what kind of mouthparts the organism had
B)whether the organism metamorphosed into a different form
C)whether the organism moved using a hydrostatic skeleton
D)whether the organism's body was divided into segments

Question 34

What would be the most direct effect of removing or damaging an insect's antennae?

A)It would have trouble hearing.
B)It would have trouble mating.
C)It would have trouble eating.
D)It would have trouble seeing.
E)It would have trouble smelling.

Question 35

How would a terrestrial centipede most likely benefit from the ability to close its spiracles?

A)Closing spiracles would allow the centipede to move more quickly.
B)Closing spiracles would allow the centipede to retain more moisture in its tissues.
C)Closing spiracles would allow the centipede to stay warmer.
D)Closing spiracles would allow more oxygen from the environment to reach the centipede's tissues.
E)The centipede would not benefit at all.

Question 36

How could you tell a millipede apart from a centipede?

A)Millipedes have 1000 legs each,while centipedes have 100 legs each.
B)Millipedes have two pairs of legs per body segment,while centipedes have one.
C)Millipedes catch prey using poison,while centipedes are detritivores.
D)Millipedes bear live young,while centipedes lay eggs.
E)None of the above answers is correct.

Question 37

Which one of these groups does not molt?

A)Crustaceans
B)Arthropods
C)Molluscs
D)Chelicerata
E)Nematoda

Question 38

Many terrestrial arthropods exchange gases with their environments by using tracheae, tubes that lead from openings (called spiracles)in the animal's exoskeleton or cuticle directly to the animal's tissues. Some arthropods can control whether their spiracles are opened or closed; opening the spiracles allows the carbon dioxide produced in the tissues to travel down the tracheae and be released outside the animal. Klok et al. measured the carbon dioxide emitted over time (represented by VCO₂)by several species of centipedes. Figure 33.2 presents graphs of their results for two species, Cormocephalus morsitans and Scutigerina weberi. (C. J. Klok, R. D. Mercer, and S. L. Chown. 2002. Discontinuous gas-exchange in centipedes and its convergent evolution in tracheated arthropods. Journal of Experimental Biology 205:1019-29.)Copyright (c)2002, The Company of Biologists and the Journal of Experimental Biology.

Figure 33.2
Look at the graph for Cormocephalus morsitans.What is the best interpretation of these results?

A)The centipede had its spiracles open the entire time.
B)The centipede had its spiracles closed the entire time.
C)The centipede had its spiracles open when CO₂ emission peaked and closed when CO₂ emission was low.
D)The centipede had its spiracles closed when CO₂ emission peaked and open when CO₂ emission was low.