I. Matching (Definitions): One (1) point each. Match the term in the right column to the phrase in the left column. Each has only one answer and some of the answers in the left column will not be used.
v1. Somites / a. Major groups of animals appear over a relatively short period of time at the beginning of the Proterozoicu2. Tagmosis / b. Sensory organs concentrated on one end of body
n3. Hydrostatic skeleton / c. Cells that create nematocysts
q4. Schizocoelom / d. Digestive structure of protists and sponges
s5. Enterocoelom / e. The ability of cell membranes to grow and fuse using a cytoskeleton of actin filaments and microtubules
r6. Pseudocoelom / f. Multicellular organisms that are absorptive heterotrophs and lack a blastula as part of their embryological development.
m7. Colonial hypothesis for origin of animals / g. Multicellular organisms that are ingesting heterotrophs and have a blastula as part of their embryological development.
b8. Cephalization / h. All life functions are confined within the boundaries of a single cell
j9. Radial Symmetry / i. Flattened organisms with two layers of cells. Once thought to be the most a primitive true animal, we now know they are related to Cnidarians.
d10. Food vacuole / j. Common in slow-moving or sessile organisms; the sense organs are distributed evenly around the body.
o11. Stephanopogon / k. A fluid-filled body cavity that allows organs to grow and can be used as a hydrostatic skeleton
e12. Cytosis / l. primitive nervous system in which nerve impulses travel in all directions rather than to and from a central nerve cord
t13. Calcichordates / m. Multicellularity arose when protist cells remained together after cell division, gradually developing a division of labor and dependence on one another.
c14. Cnidocytes / n. Muscles attach to a fluid filled sac
i15. Placozoans / o. A protist with cilia and multiple nuclei that was hypothesized to be the ancestor of the animals via syncitial subdividing. Cladistic analysis showed it was more closely related to Euglena than to the animals.
h16. Protoplasmic grade / p. Formed of separate ommatidia which lack focusing lenses but are extremely good at detecting movement.
a17. Cambrian Explosion / q. Body cavity forms by splits in the mesoderm.
g18. Animal / r. Body cavity is lined by mesoderm on one side only
l19. Nerve net / s. Body cavity forms by outpockets from the gut (digestive tract) into the mesoderm.
p20. Compound eye / t. Extinct echinoderms may have pharyngeal gill slits
u. Segments that make up the body become specialized for different functions
v. The mesoderm forms muscle segments that attach to the notochord
w. A gel-like layer between the ectoderm and endoderm
II. Multiple Choice: three (3) points each; Only one answer is correct.
1. Which of the following correctly describes the evolution of flight in insects:
a. wingless insects -> followed by insects with fixed, laterally held wings -> insects with folding wings -> beetles with a hardened exoskeleton covering that could be folded over the flying wings when they were folded.
b. wingless insects -> insects with folding wings -> followed by insects with fixed, laterally held wings ->beetles with a hardened exoskeleton covering that could be folded over the flying wings when they were folded.
c. beetles with a hardened exoskeleton covering that could be folded over the flying wings when they were folded -> followed by insects with fixed, laterally held wings -> insects with folding wings -> wingless insects.
d. wingless insects evolved independently into insects with fixed, laterally held wings and into insects with folding wings (these two kinds of insects appeared at the same time). Beetles with a hardened exoskeleton covering that could be folded over the flying wings when they were folded evolved later from insects with folding wings.
e. all of the above are possible; we have no clues about how flight evolved..
2. In the evolution of insects, development by complete metamorphosis is:
a. an advantage because the young, which look like miniature versions of the adults, can be easily recognized by the parents and cared for.
b. an advantage because the larval stage helps the adult rear the next generation of offspring
c. an advantage because the larval stage, which may have a different biology from the adult, can live in a habitat the adult cannot survive. Therefore, the insect species as a whole can occupy and take advantage of more than one niche.
d. an advantage because it permits the evolution of wings
3. In the origin of multicellular organisms, cells become differentiated (take on different functions and morphologies) even though all cells have all the genes. For example, in skin cells, genes that code for liver enzymes are not used but they are still present. Which of the following is true about the evolution of differentiation:
a. Differentiation evolved from the gene regulation system that is present in bacteria and protists.
b. The HOX genes determine which of the other genes are activated and which are turned off. These genes have only been found in animals (but we have not finished looking in all other groups yet).
c. The HOX genes determine which of the other genes are activated and which are turned off. These genes finish the job earlier in protostomes than in deuterostomes.
d. Genes can remain turned off even following mitosis (this has been demonstrated in some protists as well as animals). All of the genes are re-activated only upon meiosis so that the egg and sprem create a zygote that begins completely undifferentiated.
e. All of the above.
f. a and b are true but c and d are false.
4. Some of the oldest fossils of multicellular organisms are found in the Edicarian Hills of Australia. Which of the following is true of the Ediacara organisms:
a. They have a unique body construction consisting of layers of cells that form chambers (analogous to the air chambers in an air mattress), leading some paleontologists to suggest that they are a unique form of multicellular life not related to animals and which is no longer alive today.
b. They are all Archaeocyaths and the represent some of the earliest sponge fossils.
c. They have a unique body construction consisting of a mesoderm lined body cavity but lacking a complete digestive tract, leading some paleontologists to suggest that they are actually lichens and not animals at all.
d. The fossils are the earliest land animals.
f. None of the above are true (Edicarians are plant fossils)
g. a and c are true, but not b or d.
5. In sponges (Phylum Porifera):
a. The cells at A are Pincocytes. They are the only true tissue layer in sponges.
b. The space at B is a pseudocoelom
c. The cells at C (the pink cells) are amoebocytes. They have pores in them that allow water into the sponge and are responsible for transporting nutrients around the body.
d. The cells at D are Choanocytes which are responsible for creating a water current from which food is strained. These cells are very similar to the cells of the single-celled Choanoflagellates.
e. All of the above are true.
6. In the evolution of cnidarians and platyhelminthes, which of the following is true:
a. cnidarians show greater efficiency in feeding over sponges because they have true muscles and sponges just have contractile muscle filaments inside of cells.
b. The platyhelminthes show greater efficiency at locomotion over the cnidarians because they have a nervous system and the cnidarians do not.
c. The platyhelminthes show greater efficiency at locomotion over the cnidarians because they have muscles and the cnidarians have no contractile system at all.
d. The platyhelminthes show greater efficiency at locomotion over the cnidarians because they use the mesoderm instead of the mesoglea as an attachment for its muscles to pull against.
e. All of the above are true.
7. Cnidarians have two body forms:
a. "A" is a medusa which has a complete digestive tract, "B" is a polyp which has a single opening for both food and expulsion of waste.
b. "A" is a blastula and it does not feed but instead just produces egg and sperm
c. "A" is a polyp which has mesoderm in addition to endoderm and ectoderm and "B" is a medusa which has only endoderm and ectoderm
d. "A" is a larvae, and "B" is an adult
e. None of the above are true
8. Body cavities (coeloms):
a. which are remnants of the blastocoel, are called pseudocoeloms
b. which form from new openings lined by mesoderm are called true coeloms
c. Are an advantageous feature because they give space for organs and the the digestive tract to grow, expand and change shape without crushing other parts of the body.
d. which form from splits in mesoderm, are called schizocoeloms.
e. all of the above.
f. a, c and d but not b
g. c and d but not a or b
9. Chaetognaths are to Arthropods as:
a. Brachiopods are to Bryozoans
b. Echinoderms are to Vertebrates
c. Pseudocoelom is to mesoglea
d. Trachae-spiracle system is to gills
e. Tardigrades are to Hemichoates
10. In the evolution of multicellular animals, which of the following is true.
a. Multicellularity allows animals to become larger in size than single celled protists. This is an advantage because larger organisms can be eaten by fewer predators.
b. Multicellularity allows a division of labor among cells (cells differentiate into different types and specialize in function) and this makes them more efficient than protists.
c. Phylogenetic analysis indicates that multicellularity arose when a ciliated, multinucleate protist subdivided into multiple cells.
d. Phylogenetic analysis indicates that multicellularity arose when the cells of a colonial protist became specialized for different functions and gradually became so interdependent on each other that they could no longer function independently as individual cells.
e. None of the above are true.
f. a, b and c are true but d is false.
g. a, b, and d are true but c is false.
h. a, b, c, and d are all true.
11. In mollusks, there is a variety of body types. Two of the most different are the bivalves (Clams, etc) and the cephalopods (octopus, ammonites, and squid):
Which of the following is the most likely reason why these two look so different:
a. The bivalves evolved from a radial flatworm ancestor, while the cephalopods evolved from a bilateral annelid ancestor.
b. The bivalves are adapted for a sessile lifestyle, and so do not have a well-defined head end.
c. The cephalopods are adapted for rapid locomotion and so have bilateral symmetry.
d. The cephalopods are adapted for rapid locomotion and so have a well-defined head end.
e. None of the above are true.
f. d, b and c are true but a is false.
12. A consequence of the indeterminate cleavage/development seen in deuterostomes is:
a. formation of the complete digestive tract
b. ability of cells isolated from the early embryo to develop into viable identical individuals
c. arrangement of cleavage planes perpendicular to the egg’s vertical axis
d. unpredictable formation of the coelom due to either schizocoely or enterocoely
e. a mouth that forms from the blastopore
13. Annelids have body segmentation such that each segment has its own hydrostatic skeleton and muscle system. This system:
a. Allows fine control of locomotion because individual segments can be moved independently
b. Allows the forms to move forward with more thrust - they can anchor posterior segments down, push anterior segments forward, anchor the anterior segments, then pull the posterior segments forward. In this way the annelids became the first animals to burrow and live underground.
c. Is made even more efficient by the presence of striated muscle in the segments that attach to the rigid segmented cuticle.
d. All of the above are true.
e. a and b are true but c is false.
14. Despite their diversity and obvious evolutionary success, insects do not have as large a body size as vertebrates. This is probably due to:
a. the exoskeleton is not as strong as an endoskeleton and can not support the larger body size.
b. the fact that, following molting, the insect must swell before it secretes a new exoskeleton. Maintaining this puffed-up body form while the exoskeleton hardened would be impossible for very large arthropods (especially in the terrestrial environment).
c. the trachea-spiracle system of respiration depends largely on the passive movement of gases in and out of the body. This would not be possible in a large organism.
d. all of the above
e. b and c but not a
f. a and b but not c
15. Echinoderms all have 5-sided (pentamerous) symmetry rather than bilateral symmetry. The evolution of this symmetry is not surprising because echinoderms move very slowly and slow moving animals need to have their sense organs spread out around the body rather than concentrated at a head end (in other words no cephalization). The reason for 5-sides, rather than the radial symmetry seen in other slow moving animals is that this symmetry
a. Is necessary to accomodate the pharyngeal gill slits used by the echinoderms for filter feeding
b. allows the skeleton (which is calcium carbonate secreted by the mesoderm) to be cracked open less easily (no fracture lines can run straight across).
c. allows the skeleton (which is calcium phosphate secreted by the ectoderm) to more easily provide a lever system for the tube feed to pull against.
d. All of the above are true
III. Discussion
Arthropods were the first animals on land. What features evolved in arthropods that allowed them to colonize land?
IV. Matching to Phylogenetic Tree - Match the point on the evolutionary tree where the features described below evolved by placing the letter for the branch in the blank on the answer sheet that corresponds to each feature. Some letters are used more than once, others not at all, but each blank has only one answer.