DQ9.1 Compare how Dictyostelium, Volvox, and choanoflagellates illustrate the importance of environmental inputs into the evolution of multicellularity.

DQ9.2 Why could it be argued that transcription the key to the complexity of multicellular eukaryotes?

DQ9.3 What evidence suggests that differentiated cells have retained pluripotency?

DQ9.4 Explain how genomic rearrangements are required to form a functional immunoglobulin-encoding gene (Fig. 9.10).

DQ9.5 Embryonic versus adult hemoglobin differs; explain the gene regulatory mechanism.

DQ9.6 Contrast the examples of posttranscriptional regulation involving the genes CyIIIa and CGRP.

DQ9.7 How are microRNAs involved in gene regulation? Challenge: How are they useful in studies of gene expression (p. 247) and in gene therapy?

DQ9.8 In 20 words or less, characterize cancer as one manifestation of the loss of a differentiated state.

DQ9.9 What synapomorphy is shared by flies (dipterans), moths and butterflies (lepidopterans), wasps, bees, and ants (hymenopterans -- not shown in Fig. 9.17), and beetles (coleopterans), compared with other winged insects? Challenge: Because these four insect orders account for two thirds of all described animal species, can you suggest any reason why this synapomorphy might be related to increased tendencies for speciation?

DQ9.10 Ecdysozoa, Lophotrochozoa, Deuterostomia. Assign each of the following to one of these three subclades of bilaterian (or triploblastic) metazoans: a) sea urchin; b) chiton; c) Christmas tree worm; d) C. elegans; e) shark; f) Drosophila; g) polyclad flatworm.

DQ9.11 Explain the strategy of a reverse genetic approach for unraveling developmental mechanisms.