Biology | Answers to Review Questions

Author Dr. George B. Johnson, Washington University
Author Dr. Peter H. Raven, Missouri Botanical Gardens & Washington University
Contributor Dr. Susan Singer, Carleton College
Contributor Dr. Jonathan Losos, Washington University

Answers to Review Questions

Chapter 32 (p. 664)

1. The polynomial system employed a string of several names to identify single organisms. It could vary from individual to individual, and so was both a cumbersome and nonsystematic technique for identification.

2. The current hierarchical taxonomic system names are as follows: species, genus, family, order, class, phylum, and kingdom. Genus and species are either underlined or italicized, and the species name is not capitalized.

3. Features reflecting evolutionary relatedness are used in cladistics. The resulting cladogram shows the historical order in which evolutionary branches arose during the history of the group.

4. Statistically-determined significant characters are given more weight or emphasis in phenetic analysis.

5. There is a greater fundamental difference between prokaryotes and eukaryotes than between plants and animals. All plants and animals have a true nucleus and several membrane-bound organelles. Prokaryotes have none of these structures. There are other differences between prokaryotes and eukaryotes, just as there are differences between plants and animals. However, the differences between prokaryotes and eukaryotes mentioned above are most basic.

6. The Fungi, Plantae, and Animalia have evolved from Protista.

7. Organelles such as chloroplasts and mitochondria and perhaps locomotor mechanisms such as basal bodies, cilia, and flagella were acquired through endosymbiotic bacteria.

8. Multicellular organisms possess a significant degree of coordination and integration among the individual cells of the group. Multicellularity arose many times in the evolutionary process. Its advantages are the ability to carry out activities, including self-protection, movement, and search for food and mates, with a complexity not possible by unicellular organisms.

9. Stress prompts sexual reproduction in many unicellular protists. The three major life cycles in eukaryotes are (1) zygotic meiosis, in which the zygote is the only diploid cell; on forming it, the cell immediately undergoes meiosis; (2) gametic meiosis, in which the gametes are the only haploid cells, and two fuse and form the diploid zygote that grows to adulthood; and (3) sporic meiosis, in which there is a regular alternation of generations between a multicellular haploid phase and a multicellular diploid phase. The diploid phase produces spores that grow into a haploid phase, which then produces gametes, two of which then fuse to form the diploid zygote, the first cell of the multicellular diploid phase.