Deck 30: An Introduction to Animals

Question 1

If you think of the earthworm body plan as a drinking straw within a pipe, where would you expect to find most of the tissues that developed from endoderm?

A) lining the straw
B) lining the space between the pipe and the straw
C) forming the outside of the pipe
D) forming the outside of the straw

Answer 1

A

Question 2

Which of the following is a feature of the tube-within-a-tube body plan in most animal phyla?

A) The outer tube consists of a hard exoskeleton.
B) The outer tube consists of digestive organs.
C) The mouth and anus form the ends of the inner tube.
D) The two "tubes" are separated by tissue that comes from embryonic endoderm.

Answer 2

C

Question 3

As you are on the way to Tahiti for a vacation, your plane crash-lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms, and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select three organisms and observe them in detail, making the notations found in the accompanying table. Which organism would you classify as an animal?

A) organism A
B) organism B
C) organism C

Answer 3

C

Question 4

Which of the following statements concerning animal taxonomy is (are) TRUE?
1) Animals are more closely related to plants than to fungi.
2) All animal clades based on body plan have been found to be incorrect.
3) Kingdom Animalia is monophyletic.
4) Animals only reproduce sexually.
5) Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.

A) 5 only
B) 1 and 2
C) 3 and 5
D) 3, 4, and 5
E) 2 and 4

Question 5

Use the following information to answer the question below.
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
Which of the following Tp traits is different from those of most other animals?

A) Tp is multicellular.
B) Tp lacks muscle and nerve cells.
C) Tp has cilia.
D) Tp lacks cell walls.

Question 6

You find a new species of worm and want to classify it. Which of the following lines of evidence would allow you to classify the worm as a nematode and not an annelid?

A) It undergoes protostome development.
B) It is segmented.
C) It is triploblastic.
D) It has a coelom.
E) It sheds its external cuticle to grow.

Question 7

At which developmental stage should one be able to first distinguish a diploblastic embryo from a triploblastic embryo?

A) fertilization
B) cleavage
C) gastrulation
D) coelom formation
E) metamorphosis

Question 8

Which of the following is (are) unique to animals?

A) cells that have mitochondria
B) the structural carbohydrate, chitin
C) nervous system signal conduction and muscular movement
D) heterotrophy
E) flagellated gametes

Question 9

The digestive system of most animals is lined with cells through which nutrients are absorbed. What is the embryonic origin of these cells?

A) endoderm
B) ectoderm
C) mesoderm

Question 10

The last common ancestor of all animals was probably a ________.

A) unicellular chytrid
B) unicellular yeast
C) multicellular algae
D) multicellular fungus
E) flagellated protist

Question 11

In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at is a protostome and not a deuterostome?

A) There is evidence of cephalization.
B) There is a well-developed coelom.
C) The animal is triploblastic.
D) The animal is clearly bilaterally symmetrical.
E) The mouth develops first, and the anus develops later.

Question 12

Which morphological trait evolved more than once in animals, according to the phylogeny based on DNA sequence data found in the accompanying figure?

A) coelom
B) bilateral symmetry
C) segmentation
D) tissue
E) protostome development

Question 13

According to the evidence collected so far, the animal kingdom is ________.

A) monophyletic
B) paraphyletic
C) polyphyletic
D) euphyletic
E) multiphyletic

Question 14

The central nervous system is lacking in animals that have ________.

A) a complete gut
B) bilateral symmetry
C) radial symmetry
D) a closed circulatory system
E) excitable membranes

Question 15

What unique characteristic do all deuterostomes have in common?

A) Adults are bilaterally symmetrical.
B) Embryos have pharyngeal pouches that may or may not form gill slits.
C) All have a spinal column.
D) All have specialized head and tail regions.
E) The pore (blastopore) formed during gastrulation becomes the anus.

Question 16

Which tissue type, or organ, is NOT correctly matched with its germ layer tissue?

A) nervous-mesoderm
B) muscular-mesoderm
C) stomach-endoderm
D) skin-ectoderm
E) skeletal-mesoderm

Question 17

If in the future the current molecular evidence regarding animal origins is further substantiated, what will be TRUE of any contrary evidence regarding the origin of animals derived from the fossil record?

A) The contrary fossil evidence will be seen as a hoax.
B) The fossil evidence will be understood to have been interpreted incorrectly because it is incomplete.
C) The fossil record will henceforth be ignored.
D) Phylogenies involving even the smallest bit of fossil evidence will need to be discarded.
E) Only phylogenies based solely on fossil evidence will need to be discarded.

Question 18

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

A) type of symmetry (bilateral vs. radial vs. none)
B) type of body cavity (coelom vs. pseudocoelom vs. no coelom)
C) number of embryonic tissue types (diploblasty vs. triploblasty)
D) type of development (mouth first vs. anus first)

Question 19

Which of the following would you classify as something other than an animal?

A) sponges
B) coral
C) jellyfish
D) choanoflagellates

Question 20

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________.

A) preying on animals
B) ingesting prey
C) consuming living, rather than dead, prey
D) using enzymes to digest their food

Question 21

The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following is most directly involved in the evolution of these variations in metamorphosis?

A) artificial selection of sexually immature forms of insects
B) changes in the homeobox genes governing early development
C) the evolution of meiosis
D) the development of an oxidizing atmosphere on Earth
E) the origin of a brain

Question 22

To reproduce, many plants produce seeds-structures containing embryonic offspring along with nutrients inside a tough case. These offspring develop after being released by the parent plant. To which animal reproductive strategy is seed production most comparable?

A) oviparous reproduction
B) ovoviviparous reproduction
C) viviparous reproduction

Question 23

Use the following information to answer the question below.
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
Tp's body symmetry seems to be most like that of ________.

A) most sponges
B) cnidarians
C) worms
D) tetrapods

Question 24

You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?

A) It is triploblastic.
B) It has bilateral symmetry.
C) It possesses sensory structures at its anterior end.
D) Muscular activity of its digestive system distorts the body wall.

Question 25

What was an early selective advantage of a coelom in animals? A coelom ________.

A) contributed to a hydrostatic skeleton, allowing greater range of motion
B) was a more efficient digestive system
C) allowed cephalization and the formation of a cerebral ganglion
D) allowed asexual and sexual reproduction

Question 26

Choanoflagellates ________.

A) are usually parasitic
B) are motile as adults
C) are a sister group to animals
D) are animals

Question 27

Following the fusion of gametes in Obelia, the resulting cell divides via mitosis to become a ________.

A) larva
B) polyp
C) nymph
D) medusa

Question 28

An organism that exhibits cephalization probably also ________.

A) is bilaterally symmetrical
B) has a hydrostatic skeleton
C) has a coelom
D) is segmented
E) is diploblastic

Question 29

An adult animal that possesses bilateral symmetry would most likely be ________.

A) triploblastic
B) a deuterostome
C) coelomates
D) diploblastic

Question 30

Due to its unusual habitat (inside the digestive tracts of other animals), the tapeworm lacks a ________.

A) reproductive system
B) mouth
C) digestive tract
D) mouth and a digestive tract
E) reproductive and digestive system

Question 31

Suppose a researcher for a pest-control company developed a chemical that inhibited the development of an embryonic mosquito's endodermal cells. Which of the following would be a likely mechanism by which this pesticide works?

A) The mosquito would develop a weakened exoskeleton that would make it vulnerable to trauma.
B) The mosquito would have trouble digesting food, due to impaired gut function.
C) The mosquito would have trouble with respiration and circulation, due to impaired muscle function.
D) The mosquito wouldn't be affected at all.

Question 32

Which of the following is most likely to be aquatic?

A) suspension feeder
B) mass feeder
C) deposit feeder
D) fluid feeder

Question 33

A radula is a specialized feeding organ used to scrape material off of a substrate for ingestion, much like a cheese grater scrapes shreds off of a block of cheese. Snails, which have this structure, are thus which kind of feeder?

A) suspension feeder
B) fluid feeder
C) deposit feeder
D) mass feeder

Question 34

Comb jellies may not be the most familiar animal to you, but they are critical in the food chain because they make up a significant portion of the planktonic biomass. Their feeding strategy is predatory and involves adhesives or mucus on their tentacles or other body parts. What feeding tactic do these animals use?

A) suspension feeder
B) fluid feeder
C) deposit feeder
D) food-mass feeder

Question 35

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

A) spongin concentration (gm/unit volume)
B) rate of cribrostatin synthesis (molecules/unit time)
C) number of pores per sponge
D) number of spicules per sponge
E) number of choanocytes per sponge

Question 36

A: Morphological phylogeny. B: Molecular phylogeny.
In the traditional morphological phylogeny (A), the phylum Platyhelminthes is depicted as a sister taxon to the rest of the protostome phyla and as having diverged earlier from the lineage that led to the rest of the protostomes. In the molecular phylogeny (B), Platyhelminthes is depicted as a lophotrochozoan phylum. What probably led to this change?

A) Platyhelminthes ceased to be recognized as true protostomes.
B) Similarity of genetic information has led to realization that some morphological features are evolutionarily flexible (e.g., coelom formation) and so cannot be used as a diagnostic character.
C) All Platyhelminthes must have a well-developed lophophore as their feeding apparatus.
D) Platyhelminthes' close genetic ties to the arthropods became clear as their Hox gene sequences were studied.

Question 37

Use the following information and figure to answer the question below.
In a review paper published in 2000, Adoutte et al. examined some animal phylogenies generated by comparing the ribosomal RNA (rRNA) of animals from many different phyla. They then integrated these independently created phylogenies into one phylogeny that best fit all the data.
The figure below compares a traditional phylogeny based on morphological characteristics (A) to the new molecular-based phylogeny described by Adoutte et al. (B).
Note that platyhelminthes, nemerteans, and entoprocts, which do not have coeloms and are classified as acoelomates in the morphological phylogeny, are reclassified as lophotrochozoans in the molecular phylogeny. Similarly, groups classified as pseudocoelomates in the morphological phylogeny are reclassified as either lophotrochozoans or ecdysozoans in the molecular phylogeny; other lophotrochozoans and ecdysozoans have coeloms. Copyright 2000 National Academy of Sciences, U.S.A. (A. Adoutte, G. Balavoine, N. Lartillot, O. Lespinet, B. Prud'homme, and R. de Rosa. 2000. The new animal phylogeny. Proceedings of the National Academy of Sciences USA 97(9):4453-56.)

What does this reclassification based on molecular data imply about the evolution of acoelomates, pseudocoelomates, and coelomates?

A) Pseudocoelomates can be seen as an intermediate stage between acoelomate and coelomate development.
B) Although acoelomates and pseudocoelomates evolved only once, coelomates evolved multiple times in different lineages.
C) Only the animals that evolved earliest are acoelomates.
D) Some pseudocoelomates and acoelomates have evolved from coelomates.

Question 38

Most fish deposit fertilized eggs, but some sharks keep the fertilized egg inside the female until she gives birth to a relatively well-developed pup. These sharks would thus be characterized as ________.

A) live-bearing
B) ovoviviparous
C) oviparous
D) viviparous

Question 39

In the experiment outlined in the accompanying table, what would you expect to happen if researchers supplied an enzyme that blocked the expression of the Dll gene?

A) The embryo would have appendages in abnormal locations.
B) The origins of the embryo's appendages would fluoresce.
C) The developing embryo would have no appendages.
D) The embryo's appendages would be shorter than usual.

Question 40

From the information provided in the accompanying table, how would you classify the feeding strategy of organism C?

A) suspension feeding
B) predation
C) parasitism
D) suspension feeding and predation
E) predation and parasitism

Question 41

Dll is a gene known to direct limb development in the fruit fly. Researchers studying this gene have found that it is also expressed in developing appendages in animals from many other phyla, supporting the hypothesis that all animal appendages may be homologous. However, suppose researchers looking at Dll activity had instead found the results shown in the preceding table. These results suggest instead that ________.

A) Dll is not actually involved in appendage development
B) appendages evolved separately in protostomes and deuterostomes
C) appendages coevolved with segmentation
D) all animal appendages are homologous

Question 42

Suppose you came across a novel organism you suspected belonged to one of the following animal phyla: Porifera, Cnidaria, Ctenophora, or Acoela. Which of the following characteristics would NOT be helpful in placing the organism into the correct phylum?

A) the organism's feeding strategy
B) the organism's symmetry
C) whether the organism has a gut
D) whether the organism has muscles
E) whether adults are sessile or motile

Question 43

All sponges ________.

A) have three germ layers
B) are free swimming as adults
C) reproduce only asexually
D) are parasitic
E) are sessile and benthic as adults

Question 44

Most cnidarians are known to produce toxins. In fact, it has been claimed that one particular species produces the most deadly of all toxins on the planet. What feature of this group most likely evolved simultaneously with the evolution of these toxins?

A) the medusa body form
B) asexual reproduction
C) a slow-moving or sessile lifestyle in the adult
D) diploblastic design
E) bilateral symmetry in the mobile larval forms

Question 45

Sponges ________.

A) have larvae which are motile and move via the motion of cilia
B) are the simplest diploblastic animals
C) exhibit bilateral symmetry
D) have a nerve net but not a central nervous system
E) have feeding cells called spicules

Question 46

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

A) 1
B) 2 and 3
C) 3, 4, and 5
D) 1, 2, 3, and 4
E) 1 and 2

Question 47

Use the following information to answer the question below.
An elementary school science teacher decided to liven up the classroom with a saltwater aquarium. Knowing that saltwater aquaria can be quite a hassle, the teacher proceeded stepwise. First, the teacher conditioned the water. Next, the teacher decided to stock the tank with various marine invertebrates, including a polychaete, a siliceous sponge, several bivalves, a shrimp, several sea anemones of different types, a colonial hydra, a few coral species, an ectoproct, a sea star, and several herbivorous gastropod varieties. Lastly, she added some vertebrates-a parrotfish and a clownfish. She arranged for daily feedings of copepods and feeder fish.
The clownfish readily swims among the tentacles of the sea anemones; the parrotfish avoids them. One hypothesis for the clownfish'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 clownfish prevents the nematocysts from being triggered. Which of the following graphs supports the second, but not the first, of these hypotheses?

A)

B)

C)

D)

Question 48

Sponges are most accurately described as ________.

A) marine predators
B) chemoautrophs
C) freshwater scavengers
D) suspension feeders
E) aquatic predators