Critical Thinking Questions

Describe how organisms are classified in the taxonomic classification system.
  1. The taxonomic classification system uses a hierarchical model to organize living organisms. At each sublevel, the organisms are more similar.
  2. The taxonomic classification system uses a hierarchical model to organize living organisms. At each sublevel, the number of organisms increases.
  3. The categories in the taxonomic classification system are organized from smaller, more specific categories to larger categories.
  4. In the hierarchal model for the taxonomic classification system, from the point of origin, the groups become less specific.
What is the correct way to format a two-word scientific name?
  1. Italicize both words. Both words are lower case.
  2. Italicize both words. The first word should be capitalized. The second word should be lower case.
  3. Italicize both words. Capitalize both words.
  4. Underline both words. Capitalize both words.
Some organisms that appear very closely related may not actually be closely related. Why is this?
  1. There are cases where organisms used to be closely related but diverged from each other and no longer look closely related.
  2. There are cases where organisms can interbreed making them look like a single species, when in fact they are not closely related at all.
  3. There are cases where organisms evolved through convergence and appear closely related but are not.
  4. There are cases when extremely distant taxa can recombine into a single group.
How does a phylogenetic tree relate to the passing of time?
  1. A phylogenetic tree relates to the passing of time because species branch off from each other at regular time intervals.
  2. A phylogenetic tree is not related to the passing of time because speciation is based on geographic changes.
  3. The phylogenetic tree only shows the order in which things took place.
  4. A phylogenetic tree relates to the passing of time when the diagram also shows how long ago the divergence from the common ancestor occurred.

Ancient Mayans believed that deities out of yellow and white maize created humans. Why is this not a good hypothesis?

Scientists use the cladistics system to organize what?
  1. homologous traits
  2. homoplasies
  3. analogous traits
  4. monophyletic groups
Describe how a clade relates to monophyletic group.
  1. Clades vary in size depending on the number of branches.
  2. All the organisms within a clade stem from a single point on the phylogenetic tree.
  3. A clade shows branches that do not share a single point.
  4. A clade shows groups that diverge at a different branch point.
Scientists apply the concept of maximum parsimony to do what?
  1. describe phylogenies accurately
  2. eliminate analogous traits
  3. identify mutations to DNA codes
  4. locate homoplasies

Look at the phylogenetic tree in Figure 20.11. You discover a new species of unicellular organisms in a pond. What kind of experiment would you need to perform in order to classify the organism as a ciliate, flagellate, trichomonad, microsporidia, or diplomonad?


Based on the phylogenetic tree below, is the domestic cat closer to a tiger or a cougar? Why?

This cladogram shows the evolutionary relationship of animals in the order Carnivora. The first branch of this tree leads to Canidae and Felidae. Felidae branches into Panthera and Leopardis. Panthera branches into Tiger, and into a branch containing Leopard, Lion, and Jaguar. Leopardis branches into Ocelot and Lynx. Lynx branches the Bobcat, and into another branch that includes Felis and Puma. Puma branches into Cougar and Cheetah. Felis branches into Jungle cat, and into a branch including African wild
Figure 20.19

Two cultures of bacteria are separated by a filter that blocks the movement of cells but allows free exchange of anything smaller than a bacterial cell. On one side of the filter, a sample of penicillin-resistant cells in culture broth is added, on the second side of the tube, a culture of penicillin-sensitive cells in culture is added. After 24 hours, resistant cells appear on the side with the cells sensitive to penicillin. Which three genetic mechanisms can account for appearance of the penicillin-resistant cells?

  1. a. transformation, transduction, and conjugation
  2. b. transformation, transduction, and mutation
  3. c. transformation, conjugation, and mutation
  4. d. transduction, conjugation, and mutation