1. Invertebrates Chapter 33
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

2. Why do sponges (phyla Calcarea and Silicea) represent a separate lineage, distinct from all other animal phyla?
They are sedentary and resemble plants.
Most individuals are hermaphrodites.
They do not have specialized cell types.
They have only two layers of cells.
They lack true tissue layers.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

3. Cnidaria include groups with a variety of body forms, but all share which common feature?
All are filter feeders.
All are strong swimmers.
All have a gastrovascular cavity and tentacles.
All live in tropical oceans.
All reproduce mainly asexually.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

4. The group known as Lophotrochozoa includes about 18 animal phyla (all Bilateria except nematodes, arthropods, echinoderms, and chordates) and has a huge diversity of body forms. On what basis are all these animals thought to be in the same clade?
DNA sequences
embryo structure
body cavity
type of skeleton
arrangement of appendages
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

5. Among flatworms that are internal parasites, which of the following would be expected?
light-sensitive eyes
prolific asexual reproduction in a vertebrate host
limited to microscopic size
suckers or piercing mouthparts
defenses against host immune systems
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

6. The clam, snail, and octopus are all molluscs
The clam, snail, and octopus are all molluscs. The muscular foot of a snail is homologous to, i.e., derived from the same structure as, which one of these?
head of the octopus
shell of the clam
legs of the octopus
siphon tube of the clam
mantle of the clam
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

7. The evolutionary origin of extensive complexity in arthropod body plans is thought to be associated with which of these morphological changes?
the origin of a chitinous exoskeleton
the origin of numerous appendages
the specialization of diverse body segments
the addition of numerous identical body segments
the fusion of body segments and reduction of appendages
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

8. Which of these genetic changes is thought to have led to the increasing complexity of the arthropod body plan?
increased number of Hox genes for body segmentation
changes in regulation of Hox genes for body segmentation
increased number of Hox genes for appendages
changes in regulation of Hox genes for appendages
increased complexity in genes for exoskeleton arrangements
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

9. Flatworms, roundworms, and segmented worms share all of the following traits except which one?
bilateral symmetry
three embryonic tissue layers
presence of a digestive cavity
digestive tract with mouth and anus
muscle tissue and a hydrostatic skeleton
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

10. All of the following were important contributions to the large adaptive diversity of insects except which one?
diverse mouthparts for feeding on different substances
multiple origins of wings in different insect groups
expansion of flowering plant diversity
invasion of many terrestrial habitats by insects
diverse reproductive and social behaviors
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.

11. In addition to their molecular DNA similarities, the phyla Echinodermata (including sea stars) and Chordata (including the vertebrates) share which derived trait?
body symmetry of adult animals
type of skeleton
means of locomotion
development pattern of larvae
type of circulatory system
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings.