Chapter 33

1) Use the following information to answer the question. The phylum Cycliophora was discovered in 1995. They are tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is saclike and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. Which of these features is least useful in assigning the phylum Cycliophora to a clade of animals?

Which of these, if discovered among cycliophorans, would cause the most confusion concerning our current understanding of cycliophoran taxonomy?

The feeding stage of cycliophorans ________.

Basing your inferences on information in the paragraph, to which clades should cycliophorans belong?

5) One should expect to find cilia associated with the feeding apparatus of ________.

6) Sponges ________.

7) Which of the following is most likely to be aquatic?

8) Which of the following can be found in the mesohyl of a sponge?

Which of the following factors, when used to label the horizontal axis of the graph, would account most directly for the shape of the plot?

10) Healthy corals are brightly colored because they ________.

11) In terms of food capture, which sponge cell is most similar to the cnidocyte of a cnidarian?

12) The crown-of-thorns sea star, Acanthaster planci, preys on the flesh of live coral. If coral animals are attacked by these sea stars, then what actually provides nutrition to the sea star, and which chemical (besides the toxin within their nematocysts) do the corals rely on for protection?

One day, Tommy, a student in an undersupervised class of 40 fifth graders, got the urge to pet Nemo (the clown fish), who was swimming among the waving petals of a pretty underwater "flower" that had a big hole in the midst of the petals. Tommy giggled upon finding that these petals felt sticky. A few hours later, Tommy was in the nurse's office with nausea and cramps. Microscopic examination of his fingers would probably have revealed the presence of ________.

The teacher and class were especially saddened when the colonial hydrozoan died. They had watched it carefully, and the unfortunate creature never even got to produce offspring by budding. Yet, everyone was elated when one of the students noticed a small colonial hydrozoan growing in a part of the tank far from the location of the original colony. The teacher was apparently unaware that these hydrozoans exhibit ________.

15) The sharp, inch-long thorns of the crown-of-thorns sea star are its spines. These spines, unlike those of most other sea stars, contain a potent toxin. If it were discovered that crown-of-thorns sea stars do not make this toxin themselves, then the most likely alternative would be that this toxin is ________.

Normally, the clown fish readily swims among the tentacles of the sea anemones; the parrot fish avoids them. One hypothesis for the clown fish's apparent immunity is that they slowly build a tolerance to the sea anemone's toxin. A second hypothesis is that a chemical in the mucus that coats the clown fish prevents the nematocysts from being triggered. Which of the following graphs supports the second, but not the first, of these hypotheses?

Normally, the clown fish readily swims among the tentacles of the sea anemones; the parrot fish avoids them. One hypothesis for the clown fish's apparent immunity is that they slowly build a tolerance to the sea anemone's toxin. A second hypothesis is that a chemical in the mucus that coats the clown fish prevents the nematocysts from being triggered. Which of the following graphs supports the first, but not the second, of these hypotheses?

18) The presence of a lophophore in a newly discovered species would suggest that the species ________.

19) You find what you believe is a new species of animal. Which of the following characteristics would enable you to argue that it is more closely related to a flatworm than it is to a roundworm?

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

21) Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.

22) Against which hard structure do the circular and longitudinal muscles of annelids work?

23) While sampling marine plankton in a lab, a student encounters large numbers of fertilized eggs. The student rears some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth. The embryo develops into a trochophore larva and eventually has a true coelom. These eggs probably belonged to a(n) ________.

Which structure do sea slugs use to feed on their prey?

The nematocysts most likely reach the skin of sea slugs through branches of the ________.

The nematocysts of sea slugs should be most effective at protecting individual sea slugs from predation if the predators ________.

If the dinoflagellate-containing sea slug P. ianthina preys on coral animals, then it would be most surprising to find that ________.

In the graph, the percent of the oxygen demand contributed by the dinoflagellates is greater than 100% during much of the year. What is the fate of this "excess" energy?

If the teacher wanted to show the students what a lophophore is and how it works, the teacher would point out a feeding ________.

29) The sea slug Elysia chorotica has no nematocysts or dinoflagellates but, rather, has "naked" chloroplasts in its skin. The chloroplasts are all that remain of the seaweed (Vaucheria sp.) that Elysia feeds upon. The chloroplasts are transferred to the skin; consequently, this slug is green. It spends most of its time basking in shallow water on the surface of seaweeds. How should we expect its chloroplasts to benefit the Elysia sea slug?

31) What would be the most effective method of reducing the incidence of blood flukes in a human population?

According to the graph, during which season(s) of the year is the relationship between the sea slug and its dinoflagellates closest to being commensal?

33) Planarians lack dedicated respiratory and circulatory systems. This deficiency does not cause a problem because ________.

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

35) Which characteristic is shared by cnidarians and flatworms?

36) If a lung were to be found in a mollusc, where would it be located?

37) Parasitism is one of the most widespread lifestyles ever to evolve. Which of the following is consistent with this finding?

38) Molecular studies have changed many of the phylogenetic relationships previously identified by morphological studies. An example of such a change is ________.

39) Molecular studies have changed many of the phylogenetic relationships previously identified by morphological studies. These changes indicate that ________.

40) Large animals need specialized organs for gas exchange because ________.

41) Toilets are a modern convenience that people often take for granted. In fact, they are helpful in preventing spread of disease because ________.

42) Imagine that you are a graduate student seeking an idea for a research project that will help us understand the evolution of a parasitic lifestyle from a free-living lifestyle. Which of the following outcomes would you expect if you compare the genes of parasitic species to relatives that are free living?

43) Imagine that you are a research chemist who wishes to develop a chemical adhesive that will work under water. Which of the following organisms might give you a clue about where to start?

44) Which of the following changes would lead to an increase in surface-area-to-volume ratios?

45) Without genetic variation, evolution cannot occur. Sexual reproduction leads to increased genetic variation, but male bdelloid rotifers have never been observed. Which of the following are correct statements with regard to evolution in bdelloid rotifers?

46) Which of the following statements about bryozoans (ectoprocts) is correct?

47) Nematodes and arthropods both ________.

48) Arthropod exoskeletons and mollusc shells both ________.

49) You find a multi-legged animal in your garden and want to determine if it is a centipede or a millipede. You take the animal to a university where a myriapodologist quickly tells you that you have found a centipede. Which of the following traits may have allowed her to make this distinction?

50) Whiteflies are common pest insects found on cotton, tomato, poinsettia, and many other plants. Nymphs are translucent and mostly sessile, feeding on their host plant's 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?

51) All insects ________.

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

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

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

Compare the graphs in the figure of carbon dioxide (CO2) emission for Cormocephalus morsitans and Scutigerina weberi. What hypothesis can you make about each centipede's habitat?

56) What would be the most direct effect of removing or damaging an insect's antennae? The insect would have trouble ________.

57) The heartworms that can accumulate within the hearts of dogs and other mammals have a pseudocoelom, an alimentary canal, and an outer covering that is occasionally shed. To which phylum does the heartworm belong?

58) A terrestrial animal species is discovered with the following larval characteristics: exoskeleton, system of tubes for gas exchange, and modified segmentation. A knowledgeable zoologist should predict that the adults of this species would also feature ________.

59) In a tide pool, a student encounters an organism with a hard outer covering that contains much calcium carbonate, an open circulatory system, and gills. The organism could potentially be a crab, a shrimp, a barnacle, or a bivalve. The presence of which of the following structures would allow for the most certain identification of the organism?

The claws on the foremost trunk segment of centipedes have a function most similar to that of ________.

The stingers of honeybees have a function most similar to that of ________.

The spiracles and tracheae of insects have a function most similar to that of ________.

The antennae of insects have a function most similar to that of ________.

If the pond organisms are larvae, rather than adults, Sarah should expect them to have all of the following structures, except ________.

Sarah observed that the mystery pond organisms never come up to the pond's surface. If she catches one of these organisms and observes closely, perhaps dissecting the organism, she should find ________.

Which of the following conclusions is most likely correct? A) Ants derive nourishment from the aphids. B) Ants protect the aphids from predators. C) Ants parasitize the aphids. D) Ants feed the aphids.

Imagine that you wished to discover if the ants protect the aphids from flying predators. You would exclude ants from the plants and count aphid population size under two conditions. Which of the following experiments would best help answer this question?

68) Soft-shell crab is a prized dish in many ocean-side resorts. Why are the crabs' shells soft?

69) Compared to insects with incomplete metamorphosis, insects with complete metamorphosis ________.

70) The increase in plant species diversity allowed which of the following events?

71) As you are walking along a beach, you find an animal and believe that it belongs to the class Asteroidea. Which of the following characteristics would support your hypothesis that the animal is a sea star and not another type of echinoderm?

72) The water vascular system of echinoderms ________.

73) Which of the following combinations correctly matches a phylum to its description?

74) Which of the following animal groups is entirely aquatic?

The bivalves started to die one by one; only the undamaged shells remained. To keep the remaining bivalves alive, the teacher would most likely need to remove the ________.

77) Echinoderms show enormous diversity in which of the following traits?

76) Which of the following statements is correct with respect to the evolutionary relationship between chordates and invertebrates?

1) A land snail, a clam, and an octopus all share

2) Which phylum is characterized by animals that have a segmented body?

3) The water vascular system of echinoderms

4) Which of the following combinations of phylum and description is incorrect?

In Figure 33.2, which two main clades branch from the most recent common ancestor of the eumetazoans?

In Figure 33.8, assume that the two medusae shown at step 4 were produced by one polyp colony. Review Concept 12.1 and Concept 13.3, and then use your understanding of mitosis and meiosis to evaluate whether the following sentence is true or false; if false, select the answer that provides the correct reason. Although the two medusae are genetically identical, a sperm produced by one will differ genetically from an egg produced by the other.