THOUGHT QUESTIONS (Second Exam).docx

THOUGHT QUESTIONS (Second Exam) The Protozoa Differentiate the functions of the macro- and micronuclei of ciliates. What is the advantage of having dimorphic nuclei as compared to the monomorphic nucleus of other protozoans?

Apicomplexans are widespread and common parasites of worms, echinoderms, insects, and vertebrates (including humans). What characteristics do these protozoans have that makes them highly infctiv (efficient as parasites)?

How can foram fossils provide clues about past cold and warm periods, and global temperature change?

What characteristics separate Euglenozoans from Chlorophytes (i.e. Volvox, green algae)?

The Porifera and Diploblastic Animals Why are sponges considered metazoans instead of a colony of unicellular organisms if they are only composed of similar cells (choanocytes)?

Some species of sponge do not have spicules (i.e. Spongia). What are the advantages and disadvantages of having only spongin as a skeletal component?

Why is the most recent cnidarian evolutionary sequence (Anthozoa --> Scyphozoa --> Hydrozoa) strongly contested or deemed unlikely?

Explain the effect of global warming on the corals.

Several species of hard corals can have multiple forms per species. These forms are massive (boulder-like), tabulate (table-like), foliose (leaf-like), digitate, branching, encrusting, and fungilid (dome-shaped). What factors or conditions dictate which coral form these anthozoans adapt? Explain your answer.

THE LOPHOTROCHOZOA Why is Schistosomiasis prevalent in some regions in the Philippines (such as Leyte)? Relate this to the life cycle of Schistoma.

Can a proglottid survive when detached from the scolex of a tapeworm? Explain.

Explain the developmental processes that give rise to a pseudocoelom.

Why are endoparasites such as trematodes and nematodes localized or restricted to specific organss or parts of the host. What mechanisms explain such localization?

THE ECDYSOZOA What is the evolutionary significance of segmentation and how did it come about?

About three quarters of the known leech species are blood-suckers, while the rest are predators. What is the explanation behind this adaptation from predatory to blood-sucking mode of feeding?

Among the mollusks, only cephalopods have eyes similar to those of vertebrates. what is the significance of this adaptation to this group?

Why are shellfish commonly used for bio-indication and bioremediation of polluted bodies of water?

Why are gastropods common vectors of parasites such as nematodes?

How have insects become the most successful group, from an evolutionary perspective?

Among the malacostracans, hermit crabs do not have hardened exoskeletons in their abdomen. Thus, it is necessary for them to live in empty shells to protect their soft parts. How does a hermit crab choose its shell?

How do colonial insects, such as bees and ants, navigate to and from their nests?

How is web form and orientation related to the lifestyle or habit of a spider?

THE DEUTEROSTOMIA What are the mechanisms behind the ability of some echinoderms to lose and regenerate body parts?

Why are echinoderms unsuccessful in colonizing terrestrial and freshwater habitats?

How do echinoderms defend themselves from predators and competitors?

Discuss the similarities and differences between the feeding mechanisms of tunicates from bivalves and sponges.

What are the characteristics that unite the birds and reptiles into a single clade?

Marine mammals, such as dolphins and whales, do not have gills. How do these organisms go about living in the marine habitat in the absence of gills for respiration?