The most recently discovered phylum in the animal kingdom (1995) is the phylum Cycliophora. It includes three species of 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 sac-like and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are eucoelomate, 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?
A) having a true coelom as a body cavityB) having a body symmetry that permits a U-shaped intestine
C) having embryos with spiral cleavage
D) lacking ecdysis (molting)
Answer: A
Basing your inferences on information in the previous paragraph, to which clade(s) should cycliophorans belong?
1. Eumetazoa2. Deuterostomia
3. Bilateria
4. Ecdysozoa
5. Lophotrochozoa
A) 1 only
B) 1 and 3
C) 1, 3, and 5
D) 2, 3, and 4
E) 2, 3, and 5
Answer: C
If harboring large populations of cycliophorans neither helps nor harms their lobster hosts, then cycliophorans can be properly considered to be
1. parasites.
2. mutualists.
3. commensals.
4. symbionts.
5. endosymbionts.
A) 1 and 4
B) 2 and 4
C) 3 and 4
D) 2 and 5
E) 3 and 5
Answer: C
On the basis of the cleavage pattern of cycliophoran embryos, which of these should be true?
A) It has determinate development.
B) The blastopore becomes the anus.C) They are deuterostomes.
D) A cell separated from a four-cell embryo should develop into a complete organism.
Answer: A
Using similarities in embryonic development, body symmetry, and other anatomical features to assign an organism to a clade involves
1. cladistics based on body plan.2. molecular-based phylogeny.
3. morphology-based phylogeny.
A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1 and 3
Answer: E
Which of these, if discovered among cycliophorans, would cause the most confusion concerning our current understanding of cycliophoran taxonomy?
A) if the ciliated feeding ring is a lophophoreB) if embryos are diploblastic
C) if the body cavity is actually a pseudocoelom
D) if the organisms show little apparent cephalization
Answer: B
What is true of the feeding stage of cycliophorans?
1. It is chemoheterotrophic.
2. It is sessile.
3. It captures food in a manner similar to that of animals with lophophores.
4. It has radial symmetry.
A) 1 and 2
B) 1 and 3
C) 2 and 4
D) 1, 2, and 3
E) 2, 3, and 4
Answer: D
Cycliophorans have two types of larvae. One type of larva is produced when the digestive system of a female is impregnated by a male. The digestive system then collapses and develops into a larva, which swims away in search of a new host after the surrounding female dies. Which is the embryonic tissue that is apparently most important in forming this type of larva?
A) mesohylB) mesoderm
C) ectoderm
D) endoderm
E) mesoglea
Answer: D
Learn More :
Biology
- A student observes a wormlike organism crawling about on dead organic matter. Later, the organism sheds its outer covering. One possibility is that the organism is a larval insect (like a maggot). However, it might be a member of the phylum ________, and one way to distinguish between the two possibilities is by looking for ________.
- Nematode worms and annelid worms share which of the following features?
- How many of the following can be used to distinguish a nematode worm from an annelid worm? 1. type of body cavity 2. number of muscle layers in the body wall 3. presence of segmentation 4. number of embryonic tissue layers 5. shape of worm in cross-sectional view
- Humans most frequently acquire trichinosis by
- Which of the following is a characteristic of nematodes?
- Which of the following is found only among annelids?
- A radula is present in members of which clade(s)?
- A terrestrial mollusc without a shell belongs to which clade?
- Which mollusc clade includes members that undergo embryonic torsion?
- If a lung were to be found in a mollusc, where would it be located?
- A brachiopod can be distinguished from a bivalve by the presence of
- 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)
- The larvae of many common tapeworm species that infect humans are usually found
- What would be the most effective method of reducing the incidence of blood flukes in a human population?
- Planarians lack dedicated respiratory and circulatory systems because
- The excretory organs of annelids are
- Against which hard structure do the circular and longitudinal muscles of annelids work?
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- Which characteristic(s) is (are) shared by both cnidarians and flatworms?
- Corals are most closely related to which group?
- Which clade in the phylum Cnidaria includes "jellies" with rounded (as opposed to boxlike) medusae?
- The members of which clade in the phylum Cnidaria occur only as polyps?
- Which of the following is true of members of the phylum Cnidaria?
- How many of the following are characteristics of at least some members of the phylum Cnidaria? 1. a gastrovascular cavity 2. a polyp stage 3. a medusa stage 4. cnidocytes 5. a pseudocoelom
- Sponges are most accurately described as
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