27. Protists

Which of the following is one of the main weaknesses of the proposed classification scheme in which all eukaryotes are divided into four supergroups?

Which of the listed examples is a characteristic shared by diplomonads and parabasalids?

Apicomplexans are currently assigned to the SAR clade because __________.

Which of these groups includes photosynthetic unicellular organisms with flagella and contractile vacuoles?

How do trypanosomes withstand the attack of a host's immune system?

What do a carnivorous dinoflagellate, a parasitic apicomplexan, and a ciliate have in common?

Which organisms are capable of producing a "red tide"?

Which of these groups includes parasitic unicellular organisms with a complex of organelles specialized for penetrating host cells and tissues?

Which of these groups is characterized by cells that have more than one nucleus?

What is the purpose of the "floats" in some brown algae?

__________ is a protist that causes late blight of potatoes and was responsible for the Irish potato famine of the 19th century.

In lab class, a plasmodial slime mold is used as a demonstration organism. One of the students does not understand why this organism is not considered multicellular. How would you explain it to her?

Which of the following organisms is commercially harvested to extract algin from their cell walls?

Which of these groups includes unicellular organisms that, due to the structure of their cell walls, can withstand pressures equal to the pressure under each leg of a table supporting an elephant?

What role do diatoms play in the global carbon balance affecting global warming?

Which of the following groups of algae is/are most closely related to land plants?

On some areas of the seafloor, one could observe an "ooze" that is hundreds of meters thick. What creates this ooze?

Many species of red algae are adapted to deeper water due to the fact that __________.

How can dinoflagellates be harmful to humans? a. They are transmitted by mosquitoes and cause malaria. b. They produce toxins that can be absorbed by clams and other shellfish which, when eaten by people, can lead to paralytic shellfish poisoning. c. They cause amoebic dysentery which leads to severe diarrhea and dehydration. d. They are transmitted by tsetse flies and cause 'sleeping sickness.'

Which pair of protists has support structures composed of silica? a. dinoflagellates and diatoms b. diatoms and radiolarians c. radiolarians and forams d. forams and amoebozoans

Which of the following members of the SAR supergroup is incorrectly paired with its clade? a. stramenopiles—brown algae b. alveolates—parasites such as Plasmodium c. alveolates—dinoflagellates d. Rhizaria—diatoms

Chlamydomonas is a unicellular green alga. How does it differ from a photosynthetic bacterium, which is also single-celled? How does it differ from a protozoan, such as an amoeba? How does it differ from larger green algae, such as sea lettuce (Ulva)?

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. 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.

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Researchers have proposed that slime molds could be used to help to plan the paths of future roadways and railways. Justify this statement.

The buildup of CO2 in the atmosphere resulting from the burning of fossil fuels is regarded as a major contributor to global warming. Diatoms and other microscopic algae in the oceans counter this buildup by using large quantities of atmospheric CO2 in photosynthesis, which requires small quantities of iron. Experts suspect that a shortage of iron may limit algal growth in the oceans. Some scientists have suggested that one way to reduce CO2 buildup might be to fertilize the oceans with iron. The iron would stimulate algal growth and thus the removal of more CO2 from the air. A single supertanker of iron dust, spread over a wide enough area, might reduce the atmospheric CO2 level significantly. Do you think this approach would be worth a try? Why or why not?