Biology [CHAPTER 28] (Protists) – Flashcards

Why have protists been "mixed in" with plants, animals, and fungi under the hypothesis that groups eukaryotes into five supergroups? A) Many protists are more closely related to plants, animals, or fungi than they are to each other. B) The discovery of very small protists, similar in size to prokaryotes, has made the former classification scheme obsolete. C) Recent evidence makes it clear that the former kingdom Protista was paraphyletic. D) The discovery that protists had organelles made it clear that they should be grouped with other eukaryotes. E) Both the first and third answers are correct.

The placement of all protists in one kingdom caused dissatisfaction among taxonomists mainly because _____. A) various pieces of evidence indicate that the kingdom Protista cannot be monophyletic B) some protists are autotrophic and others are heterotrophic C) protist cells are more similar to prokaryotic cells than to eukaryotic cells D) various pieces of evidence indicate that the Protista are not polyphyletic E) All of the listed responses are correct.

Which of the following is one of the main weaknesses of the proposed classification scheme in which all eukaryotes are divided into five supergroups? A) It does not take into account the importance of endosymbiosis. B) It does not explain the extra membranes found in some plastids. C) It postulates that photosynthetic protists arose by way of endosymbiosis. D) It does not account for "amitochondriate" protists. E) It shows all five supergroups diverging simultaneously from a common ancestor.

Organisms are classified as Excavata based on _____. A) their origin by secondary endosymbiosis of a red alga B) morphological studies of the cytoskeleton C) the presence of pseudopodia D) their lack of true mitochondria E) their mode of obtaining energy

Which example below is a characteristic shared by diplomonads and parabasalids? A) Both lack mitochondria. B) Both lack plastids. C) Both have a single flagellum. D) Both have two nuclei. E) Both are adapted to aerobic environments.

How do trypanosomes withstand the attack of a host's immune system? A) They specifically poison helper T cells. B) The molecular composition of their surface changes continually. C) They live only in the cerebrospinal fluid, where the immune system can't reach them. D) They reproduce so fast that they can compensate for the death rate caused by the immune system. E) All of the listed responses are correct.

Which of these groups includes photosynthetic unicellular organisms with flagella and contractile vacuoles? A) apicomplexans B) diatoms C) euglenids D) dinoflagellates E) ciliates

Although controversial, chromalveolates are proposed as a clade whose common ancestor _____. A) was a multinucleate mass B) engulfed an alpha proteobacterium in a primary endosymbiosis event C) engulfed a photosynthetic red alga in a secondary endosymbiosis event D) was the first mixotroph E) lost its mitochondria

Apicomplexans are currently assigned to the chromalveolates because _____. A) they have life cycles with both sexual and asexual stages B) they have true roots, stems, and leaves C) they are parasites D) the apicoplast, a modified plastid, appears to be of red algal origin E) Both the first and third responses are correct.

In many types of protist life cycles, the union of two gametes that results in a diploid zygote is called _____. A) mixotrophy B) blooming C) syngamy D) endosymbiosis E) alternation of generations

What do a carnivorous dinoflagellate, a parasitic apicomplexan, and a ciliate have in common? A) All three are parasitic on other species of organisms. B) All three form colonies of cells. C) All three are photosynthetic. D) All three are heterotrophic and autotrophic. E) All three have sacs known as alveoli just beneath their plasma membranes.

Which organisms are capable of producing a "red tide"? A) euglenids B) chrysophytes (diatoms) C) sporozoans D) dinoflagellates E) None of the listed responses is correct.

Which of these groups includes species that produce a substance that is toxic to humans? A) ciliates B) euglenids C) dinoflagellates D) apicomplexans E) diatoms

Which of these groups includes parasitic unicellular organisms with a complex of organelles specialized for penetrating host cells and tissues? A) dinoflagellates B) ciliates C) apicomplexans D) euglenoids E) diatoms

Which of these groups is characterized by cells that have more than one nucleus? A) dinoflagellates B) diatoms C) euglenids D) ciliates E) apicomplexans

How do ciliates generate genetic variation? A) asexual reproduction B) binary fission C) conjugation D) alternation of generations E) None of the listed responses is correct.

Which protists were once categorized as fungi due to their multinucleate filaments that resemble hyphae? A) golden algae B) dinoflagellates C) oomycetes D) parabasalids E) stramenopiles

_____ is a protist that causes late blight of potatoes and was responsible for the Irish potato famine of the 19th century. A) Dictyostelium discoideum B) Laminaria C) Entamoeba D) Dinobryon E) Phytophthora infestans

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? A) diatoms B) ciliates C) dinoflagellates D) euglenids E) apicomplexans

Which characteristic is shared by most diatoms, golden algae, and brown algae at least at some stage of their life cycles? A) They all have flagella with numerous fine, hairlike projections. B) All are autotrophs. C) All are stramenopiles. D) All of the listed responses are correct. E) None of the listed responses is correct.

The general term given to a plantlike body that lacks true stems, leaves, and roots and that shows little tissue differentiation is _____. A) rhizoid B) gametophyte C) stipe D) thallus E) holdfast

What is the purpose of the "floats" in some brown algae? A) anchoring the seaweed B) absorbing iodine and carbon dioxide from seawater C) protecting the seaweed from drying out D) facilitating photosynthesis E) protecting seaweed from crashing waves

Which of the following organisms is commercially harvested to extract algin from their cell walls? A) golden algae B) brown algae C) marine green algae, such as Ulva D) dinoflagellates E) diatoms

What role do diatoms play in the global carbon balance affecting global warming? A) Diatoms release large amounts of carbon dioxide, a greenhouse gas, into the atmosphere. B) During a bloom, diatom populations increase rapidly, providing many more photosynthetic organisms to the plankton population. C) During a bloom, diatom populations may increase rapidly. If many diatoms die and sink to the bottom without being eaten, they effectively pump carbon dioxide out of the atmosphere. D) Diatomaceous earth can be used to filter carbon dioxide from the atmosphere. E) Diatoms release large amounts of methane, a greenhouse gas, into the atmosphere.

On some areas of the seafloor, one could observe an "ooze" that is hundreds of meters thick. What creates this ooze? A) the decaying porous shells of forams B) the tests of dead radiolarians C) the tests of dead diatoms D) the gel-forming polysaccharides secreted by brown and red algae E) colonies of plasmodial slime molds

Many species of red algae are adapted to deeper water due to the fact that _____. A) their photosynthetic pigments efficiently absorb blue and green light B) their red pigments readily absorb red light C) their cell walls are adapted to withstand bright light D) they grow long stalks with floats on the ends to hold the blades near the surface E) All of the listed responses are correct.

The red algae are characterized by _____. A) population explosions known as "red tides" B) a red coloration in all their species C) flagellated gametes that do not require water for fertilization to occur D) multinucleated portions E) especially diverse life cycles

Which of the following groups of algae is/are most closely related to land plants? A) blue-green algae B) red algae C) brown algae D) green algae E) All of the listed responses are correct.

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? A) Plasmodial slime molds are not able to reproduce sexually, so therefore they are not truly multicellular. B) Multicellular organisms are seen only in the kingdoms Animalia and Plantae. C) The plasmodium is undivided by membranes and contains many diploid nuclei; therefore, it is not technically multicellular. D) The distinct cells that make up the plasmodium do not cooperate, so they do not represent a truly multicellular organism. E) The nuclei found in the plasmodium of a plasmodial slime mold are diploid.

To which supergroup do amoebas belong? A) Chromalveolates B) Rhizaria C) Unikonta D) Apicomplexans E) None of the listed responses is correct.

It is estimated that protists perform up to what percentage of the world's photosynthesis? A) 5% B) 10% C) 50% D) 40% E) 30%

Hypermastigotes are important endosymbionts that live in the guts of _____. A) cattle B) humans C) rabbits D) ants E) termites