Exam 33: An Introduction to Invertebrates

In the figure, which two main clades branch from the most recent common ancestor of the eumetazoans?

A farm dam, usually dry during winter, has plenty of water and aquatic pond life during the summer. One summer, Sarah returns to the family farm from university. Observing the pond, she is fascinated by some six-legged organisms that can crawl about on submerged surfaces or, when disturbed, seemingly "jet" through the water. Watching further, she is able to conclude that the "mystery organisms" are ambush predators, and their prey includes everything from insects to small fish and tadpoles. -If the pond organisms are larvae, rather than adults, Sarah should expect them to have all of the following structures, except ________.

A farm dam, usually dry during winter, has plenty of water and aquatic pond life during the summer. One summer, Sarah returns to the family farm from university. Observing the pond, she is fascinated by some six-legged organisms that can crawl about on submerged surfaces or, when disturbed, seemingly "jet" through the water. Watching further, she is able to conclude that the "mystery organisms" are ambush predators, and their prey includes everything from insects to small fish and tadpoles. -Sarah observed that the mystery pond organisms never come up to the pond's surface. If she catches one of these organisms and observes closely, perhaps dissecting the organism, she should find ________.

Which of the following statements about bryozoans (ectoprocts) is correct?

All insects ________.

While sampling marine plankton in a lab, a student encounters large numbers of fertilised eggs. The student rears some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth. The embryo develops into a trochophore larva and eventually has a true coelom. These eggs probably belonged to a(n) ________.

Which of the following changes would lead to an increase in surface-area-to-volume ratios?

Nudibranchs, a type of predatory sea slug, can have various protuberances (that is, extensions) on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear many chemoreceptors. Dorsal plumules, usually located posteriorly, perform respiratory gas exchange. Cerata usually cover much of the dorsal surface and contain nematocysts at their tips. -The stingers of honeybees have a function most similar to that of ________.

Which of the following can be found in the mesohyl of a sponge?

As you are walking along a beach, you find an animal and believe that it belongs to the class Asteroidea. Which of the following characteristics would support your hypothesis that the animal is a sea star and not another type of echinoderm?

Which of the following combinations of phylum and description is incorrect?

Planarians lack dedicated respiratory and circulatory systems. This deficiency does not cause a problem because ________.

Many terrestrial arthropods exchange gases with their environments by using tracheae, tubes that lead from openings (called spiracles) in the animal's exoskeleton or cuticle directly to the animal's tissues. Some arthropods can control whether their spiracles are opened or closed; opening the spiracles allows the carbon dioxide produced in the tissues to travel down the tracheae and be released outside the animal. Klok et al. measured the carbon dioxide emitted over time (represented by VCO₂) by several species of centipedes. The figures present graphs of their results for two species, Cormocephalus morsitans and Scutigerina weberi. (C. J. Klok, R. D. Mercer, and S. L. Chown. 2002. Discontinuous gas-exchange in centipedes and its convergent evolution in tracheated arthropods. Journal of Experimental Biology 205:1019-29.) Copyright 2002 The Company of Biologists and the Journal of Experimental Biology. Look at the graph for Scutigerina weberi (note the scale of the y-axis) in the figure. - What is the best interpretation of these results?

Many terrestrial arthropods exchange gases with their environments by using tracheae, tubes that lead from openings (called spiracles) in the animal's exoskeleton or cuticle directly to the animal's tissues. Some arthropods can control whether their spiracles are opened or closed; opening the spiracles allows the carbon dioxide produced in the tissues to travel down the tracheae and be released outside the animal. Klok et al. measured the carbon dioxide emitted over time (represented by VCO₂) by several species of centipedes. The figures present graphs of their results for two species, Cormocephalus morsitans and Scutigerina weberi. (C. J. Klok, R. D. Mercer, and S. L. Chown. 2002. Discontinuous gas-exchange in centipedes and its convergent evolution in tracheated arthropods. Journal of Experimental Biology 205:1019-29.) Copyright 2002 The Company of Biologists and the Journal of Experimental Biology. Look at the graph for Cormocephalus morsitans in the figure. What is the best interpretation of these results?

Nudibranchs, a type of predatory sea slug, can have various protuberances (that is, extensions) on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear many chemoreceptors. Dorsal plumules, usually located posteriorly, perform respiratory gas exchange. Cerata usually cover much of the dorsal surface and contain nematocysts at their tips. -The spiracles and tracheae of insects have a function most similar to that of ________.

Molecular studies have changed many of the phylogenetic relationships previously identified by morphological studies. An example of such a change is ________.

The increase in plant species diversity allowed which of the following events?

The presence of a lophophore in a newly discovered species would suggest that the species ________.

The phylum Cycliophora was discovered in 1995. They are tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is saclike and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are coelomates, do not moult (though their host does), and their embryos undergo spiral cleavage. -Basing your inferences on information in the paragraph, to which clades should cycliophorans belong?

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