Chapter 27

Why are protists considered paraphyletic? a. They include many extinct forms, including lineages that no longer have any living representatives. b. They include some but not all descendants of their most recent common ancestor. c. They represent all of the descendants of a single common ancestor. d. Not all protists have all of the synapomorphies that define the Eukarya, such as a nucleus.

What does amoeboid motion result from? a. interactions among actin, myosin, and ATP b. coordinated beats of cilia c. the whiplike action of flagella d. action by the mitotic spindle, similar to what happens during mitosis and meiosis

According to the endosymbiosis theory, what type of organism is the original ancestor of the chloroplast? a. a photosynthetic archaean b. a cyanobacterium c. an algal-like, primitive photosynthetic eukaryote d. a modified mitochondrion

Explain the logic behind the claim that the nuclear envelope is a synapomorphy that defines eukaryotes as a monophyletic group.

Consider the endosymbiosis theory for the origin of the mitochondrion. How did each endosymbiotic partner benefit from the relationship?

Why was finding a close relationship between mitochondrial DNA and bacterial DNA considered particularly strong evidence in favor of the endosymbiosis theory?

The text claims that the evolutionary history of protists can be understood as a series of morphological innovations that established seven distinct lineages, each of which subsequently diversified based on innovative ways of feeding, moving, and reproducing. Explain how the Alveolata support this claim.

Which of the following best describes movement in Physarum? a. Cilia propel the slime mold. b. Flagella propel the slime mold. c. The slime mold moves by amoeboid motion. d. The slime mold moves by gliding motility.

Physarum is a plasmodial slime mold, whereas Dictyostelum is a cellular slime mold (see Bioskills 11 ). Compare and contrast movement by the migrating slug stage of Dictyostelium to the plasmodial stage of Physarum.

Propose an experiment that would test whether the coating of extracellular slime changed the speed at which the slime mold moved across the substrate.

Develop simple experiments to test whether Physarum prefers (1) brightly lit or dark environments; (2) dry or moist conditions; (3) oats or sugar as a food source.

Develop simple experiments to test whether Physarum prefers (1) brightly lit or dark environments; (2) dry or moist conditions; (3) oats or sugar as a food source.