Sponges & Placozoans – Ch12 | Complete Test Bank

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CHECK ALL THE APPLY. Choose all options that best completes the statement or answers the question.
1) What would occur if choanocytes were no longer able to function within a sponge? Check all that apply.

A) Ova may not form.
B) Sperm may not form.
C) Water flow would cease.
D) Collagen would not be produced.

MULTIPLE CHOICE - Choose the one alternative that best completes the statement or answers the question.
2) Which one of the following statements regarding the origin of metazoans has the most support?

A) The choanoflagellates share features with the sponges, like having collars of microvilli surrounding a flagellum and being colonial. These shared features suggest a link to at least one metazoan lineage.
B) Metazoans are derived from many separate lineages of unicellular organisms.
C) Ancient metazoans, similar to members of the phylum Placozoa, have been ruled out as ancestral metazoans.
D) Modern sponges have a genetic makeup that reflects their ancestral status.

3) Which statement about adult sponges is false?

A) Their bodies are aggregations of one cell type.
B) They do not have a mouth.
C) Their bodies areusually asymmetrical.
D) Their apparently simple structure is deceptive.

4) The sponges date back to

A) the Devonian period or "age of fishes."
B) the early time of anaerobic prokaryotes.
C) the Cambrian period and probably earlier.
D) the time of the first prokaryotes but the sponges left no fossil evidence for lack of hard parts.

5) The order in which a drop of ink would pass by the structures in an asconoid sponge is

A) spongocoel-ostia-osculum.
B) osculum-spongocoel-ostia.
C) osculum-ostia-spongocoel.
D) ostia-spongocoel-osculum.
E) ostia-osculum-spongocoel.

6) The simplest canal system is found in the

A) asconoids.
B) leuconoids.
C) syconoids.

7) The most complex and the most common body form of sponges is found in the

A) asconoids.
B) leuconoids.
C) syconoids.

8) Flagellated canals of syconoid sponges form by evagination of the body wall. These sponges often develop through a simple vase-like stage. Which of the following is a logical hypothesis based on this evidence?

A) Asconoid sponges were derived from syconoid ancestors.
B) Leuconoid sponges were derived from syconoid ancestors.
C) Syconoid sponges were derived from leuconoid ancestors.
D) Syconoid sponges were derived from asconoid ancestors.
E) Leuconoid sponges were derived from asconoid ancestors.

9) The extracellular matrix found in sponges is

A) spongin.
B) collagen.
C) pinacoderm.
D) mesohyl or mesenchyme.

10) Calcareous or siliceous elements of the sponge body wall provide support. These elements are called

A) amoebocytes.
B) pinacocytes.
C) choanocytes.
D) spicules.
E) spongin.

11) The outer thin, flat, epithelial-like cells that cover the outside and some inside surfaces of sponges, are

A) amoebocytes.
B) pinacocytes.
C) choanocytes.
D) spicules.
E) spongin.

12) The modified cells of sponges that form circular bands and provide just a little constriction to control water flow are

A) amoebocytes.
B) choanocytes.
C) spicules.
D) myocytes.

13) A sponge feeds by

A) using a net to trap food particles.
B) squeezing the spongocoel cavity to suck debris in and out through the osculum.
C) beating the flagella of collar cells to form a current to bring food in, followed by absorption of the food by collar cells.
D) beating the flagella of collar cells to form a current that runs from from the osculum to the pores, followed by the ingestion of food by amoebocytes in the central cavity of the sponge.

14) Specialized archaeocytes that secrete spicules are

A) collencytes.
B) sclerocytes.
C) choanocytes.
D) spongocytes.
E) lophocytes.

15) Specialized archaeocytes that secrete spongin are

A) collencytes.
B) sclerocytes.
C) choanocytes.
D) spongocytes.
E) lophocytes.

16) Specialized archaeocytes that secrete large quantities of collagen are

A) collencytes.
B) sclerocytes.
C) choanocytes.
D) spongocytes.
E) lophocytes.

17) The structural protein found in all sponges is

A) elastin.
B) collagen.
C) gorgonin.
D) spiculin.
E) None of the choices is correct

18) Cells responsible for water flow and capture of some particles are the

A) myocytes.
B) archaeocytes.
C) choanocytes.
D) pinacocytes.
E) lophocytes.

19) Which is NOT a trait of sponges?

A) They are sessile filter feeders.
B) Their body wall has two incipient "cell layers".
C) Their flagellated collar cells move water.
D) Water enters through the osculum.
E) Amoeboid cells digest food and make skeletal fibers and gametes.

20) If a sponge is fragmented and cells are dissociated from one another, the cells will

A) reproduce sexually.
B) die from being separated.
C) form spicules in the pattern of the cloth.
D) reorganize their structure and function, and clumps of isolated cells will form a new sponge.

21) Which of the following statements about sponges is NOT correct?

A) Larvae are ciliated and swim to new locations.
B) Sponges are classified by spicule type and material.
C) Sponges comprise a sister group to all other animals.
D) Sponges share few characteristics with other animals.
E) Sponge cells can transform from one cell type to another, a trait not seen in other kinds of animals.

22) Which of the following is NOT found in at least some sponges?

A) Spicules of calcium carbonate
B) Spicules of silica
C) Spicules of fibrous protein
D) Spongin, a fibrous protein

23) Which of the following statements about sponges is NOT correct?

A) Sponges lack nerve fibers.
B) Sponges lack fully developed muscle fibers.
C) Ameboid cells capture food particles from the water.
D) Sponges reproduce asexually by budding or by regeneration from a small piece.
E) If a sponge is fragmented and cells dissociate, cells undergo somatic embryogenesis and clumps of cells can form a new organism.

24) In most sponges, the free-swimming larva produced by sexual reproduction is called a(n)

A) bud.
B) gemmule.
C) apopyle.
D) parenchymula.
E) plasmodium.

25) Reproduction in at least some sponges is

A) asexual by budding.
B) asexual by gemmules.
C) sexual with both male and female sex cells in one individual.
D) asexual by fragmentation.
E) All of the choices are correct

26) The unique feature of sponge development in members of the class Calcarea is the amphiblastula which

A) produces new buds.
B) generates gemmules.
C) determines the types of spicules produced.
D) turns inside out during its development.
E) controls the process of regeneration.

27) In glass sponges, archaeocytes fuse their pseudopodia to form a

A) bud.
B) spongin network.
C) micropyle.
D) leuconoid framework.
E) trabecular reticulum.

28) The demosponges

A) constitute only a small number of species.
B) are mostly marine but include the freshwater sponges.
C) have the asconoid-type canal system.
D) are referred to as calcium or chalk sponges.
E) form the most beautiful glass spicule patterns.

29) The largest impact that the loss of sponges would have on the environment would be

A) collapse of most food chains.
B) extinctions of other species that are symbionts of sponges.
C) alteration of ocean currents.
D) alteration of gases in water and the atmosphere.
E) loss of filtration.

30) Why are bath sponges so soft?

A) Silica is washed away, but the calcium carbonate remains in the sponge.
B) Spongin spicules are washed away, but the silky silica remains in the sponge.
C) The choanocytes and amoebocytes are soft, so the body of the sponge is soft.
D) Bath sponge support is provided primarily by spongin proteins, which are soft.
E) All of the choices are correct.

31) Placozoans

A) are flat, plate-like animals with no symmetry.
B) are probably advanced mesozoans.
C) have calcareous spicules.
D) have three germ layers.

32) Placozoans feed by

A) sharing food produced by symbiotic algae in their diffuse tissues.
B) gliding over their food, secreting enzymes, and absorbing products.
C) filtering food that moves through them in tiny pores.
D) taking food in through a ventral tube, digesting it, and expelling wastes back out the tube.
E) taking food in through a central tube, digesting it, and moving wastes out the anus.

33) As a manager of the specimen collection at a natural history museum, you are charged with identifying new specimens that are donated. You are presented with a sponge of unknown origin. When you examine it, you find siliceous spicules. To which class or classes might this sponge belong?

A) Calcispongiae
B) Demospongiae
C) Hexactinellida
D) The only class that could be ruled out is class Calcarea.

34) If you observe an unknown sponge and find that its spongocoel is lined with choanocytes, it must belong to the class __________.

A) Calcispongiae
B) Demospongiae
C) Hexactinellida
D) Homoscleromorpha

35) What would be the effect if the archaeocytes of a sponge were no longer able to function?

A) Digestion would cease.
B) Reproduction would cease.
C) Skeletal support would weaken over time.
D) Water flow into the sponge would not occur.

FILL IN THE BLANK. Write the word or phrase that best completes each statement or answers the question.
36) Out of all metazoans, members of the phylum __________________ have the smallest nuclear genome but the largest mitochondrial genome.

37) The tough protein fibers sometimes found in sponge skeletons are of a substance called _____________.

38) The water outlet in sponges is known as a/an __________________.

39) The flagellated cells embedded in the mesohyl of a sponge are called ___________________.

40) Thin, epithelial-type cells covering the outer surface of sponges are the ________________.

41) About 80% of particulate organic carbon in the marine environment is in the form of the smallest particles that sponges can consume, and phagocytosis of these particles is carried out by the ____________.

42) All digestion in sponges is intracellular and is carried out by the ____________________.

43) Internal buds of freshwater sponges that can withstand adverse conditions are ____________________.

44) Deep-sea sponges with six-rayed siliceous spicules and a trabecular reticulum belong to the ______________.

45) About 95% of the sponges belong to the class __________.

ESSAY. Write your answer in the space provided or on a separate sheet of paper.
46) There are a few marine sponges that are large enough that a small person could crawl inside. Would you have to worry about your tissues being digested?

47) Sponge beds have been heavily "fished" for bath sponges and in other cases pollution or an imbalance in organisms has devastated other sponge beds. What is the likely overall consequence of this in the ocean environment?

48) Explain the concept of monophyly as it applies to the animals. How do the relationships of placozoans and poriferans contribute to our understanding of the base of the animal tree?

49) Describe the characteristics of the Phylum Porifera. Which of those characteristics support the contention that the sponges are the basal group of the Animal kingdom?

50) Explain the unique attributes of hexactinellids as compared to other sponges.

51) New evidence suggests that the calcarea belong to a clade separate from other sponges. Discuss the evidence upon which this idea is based.