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 four organisms and observe them in detail, making the notations found in the figure.

In which of the organisms listed would you search for photosynthetic genes? A) organism A
B) organism B
C) organism C

D) organism D

B) organism B

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 four organisms and observe them in detail, making the notations found in the figure.

In which of the organisms listed would you search for collagen? A) organism A
B) organism B
C) organism C

D) organism D

C) organism C

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 materials

C) consuming living, rather than dead, prey
D) using enzymes to digest their food

B) ingesting materials

Trichoplax adhaerens 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 2,000 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. Individual animals move using cilia, and any "edge" can lead. T. adhaerens 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. T. adhaerens sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.

Which of the following T. adhaerens traits is different from all other known animals? A) T. adhaerens is multicellular.
C
C) T. adhaerens has cilia.

D) T. adhaerens lacks cell walls.

B) T. adhaerens lacks muscle and nerve cells.

What do animals ranging from corals to monkeys have in common? A) a mouth and an anus
B) number of embryonic tissue layers
C) some type of body symmetry

D) presence of Hox genes

D) presence of Hox genes

10) In individual insects of some species, whole chromosomes that carry larval genes are eliminated from the genomes of somatic cells at the time of metamorphosis. A consequence of this occurrence is that ________.
A) we could not clone a larva from the somatic cells of such an adult insect
B) such species must reproduce only asexually
C) the descendants of these adults do not include a larval stage
D) metamorphosis can no longer occur among the descendants of such adults

A) we could not clone a larva from the somatic cells of such an adult insect

Which tissue type or organ is not correctly matched with its germ layer tissue? CC
B) muscular—mesoderm
C) stomach—endoderm

D) skin—ectoderm

A) nervous—mesoderm

While looking at some seawater through your microscope, you spot the egg of an unknown animal. Which of the following tests could you use to determine whether the developing organism is a protostome or a deuterostome? See whether the embryo ________.
A) develops germ layers

B) exhibits spiral cleavage or radial cleavage C) develops a blastopore
D) develops an archenteron

B) exhibits spiral cleavage or radial cleavage C) develops a blastopore

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) The animal is triploblastic.

C) The animal is clearly bilaterally symmetrical. D) You see a mouth, but not an anus.

D) You see a mouth, but not an anus.

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.

C) The mouth and anus form the ends of the inner tube.

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

A) lining the straw

Among protostomes, which morphological trait has shown the most variation? A) type of symmetry (bilateral versus radial versus none)
B) type of body cavity (coelom versus pseudocoelom versus no coelom)
C) number of embryonic tissue types (diploblasty versus triploblasty)

D) type of development (protostome versus deuterostome)

B) type of body cavity (coelom versus pseudocoelom versus no coelom)

What 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) The pore (blastopore) formed during gastrulation becomes the anus.

D) The pore (blastopore) formed during gastrulation becomes the anus.

29) Soon after the coelom begins to form, a researcher injects a dye into the coelom of a deuterostome embryo. Initially, the dye should be able to flow directly into the ________. A) blastopore
B) blastocoel

C) archenteron
D) pseudocoelom

C) archenteron

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.

D) Muscular activity of its digestive system distorts the body wall.

One small animal phylum (Placozoa) contains only two species, Trichoplax adhaerens (T. adhaerens) and T. reptans. T. adhaerens is the only species seen in over a century. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2,000 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. Individual animals move using cilia, and any "edge" can lead. T. adhaerens 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. T. adhaerens sperm cells have never been observed. Embryos up to, but not past, the 64-cell (blastula) stage have been observed.

On the basis of information in the paragraph, which of these should be able to be observed in T. adhaerens?
A) a coelom
B) the process of gastrulation

C) eggs
D) a radially symmetric larval form

C) eggs

A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise 1 hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. This embryo may potentially develop into a(n) ________.
A) turtle

B) earthworm
C) sea star
D) sea urchin

B) earthworm

A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise 1 hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. If we were to separate these eight cells and attempt to culture them individually, then what is most likely to happen?

A) All eight cells will die immediately.
B) Each cell may continue development, but only into a nonviable embryo that lacks many parts. C) Each cell may develop into a full-sized, normal embryo.
D) Each cell may develop into a smaller-than-average, but otherwise normal, embryo.

B) Each cell may continue development, but only into a nonviable embryo that lacks many parts.

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

A) contributed to a hydrostatic skeleton, allowing greater range of motion

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 deuterostome.
B) The protostomes are a polyphyletic group.

C) Division of these two groups occurred after the protostome developmental sequence appeared.
D) The lophotrochozoans are monophyletic.

C) Division of these two groups occurred after the protostome developmental sequence appeared.

36) Which of these statements, if accurate, would support the claim that the ancestral cnidarians had bilateral symmetry?
A) Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.
B) Cnidarians have fewer Hox genes than bilaterians.

C) All cnidarians are acoelomate.
D) The presence of collar cells.

Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.

An organism that exhibits a head with sensory equipment and a brain probably also ________.
A) is bilaterally symmetrical
B) has a coelom

C) is segmented
D) is diploblastic
Answer: A

A) is bilaterally symmetrical