1. Which of the following is correct regarding the phylogenetic nature of kingdom Protista?
a. Scientists have placed all of the known protist species into at least one of the major monophyletic clades.
b. All members of the kingdom share characteristics that are unique to Protists.
c. The kingdom as a whole is paraphyletic.
d. All of the above are correct.
The correct answer is c—
A. Answer a is incorrect. The majority of protists have not yet been classified within single, monophyletic clades.
The correct answer is c—
B. Answer b is incorrect. The kingdom is an artificial construct, in reality the members are defined by a lack of common characteristics with other kingdoms rather than many shared characteristics.
The correct answer is c—The kingdom as a whole is paraphyletic.
C. Answer c is correct. See Figure 29.1.
The correct answer is c—
D. Answer d is incorrect. Answer c is correct.
2. Which of the following events is believed to have occurred first in eukaryotic evolution?
a. Secondary endosymbiosis of chloroplasts
b. Endosymbiosis of a cyanobacteria
c. Endosymbiosis of an energy-producing bacteria
d. Infolding of the plasma membrane
The correct answer is d—
A. Answer a is incorrect. Refer to Figure 29.4.
The correct answer is d—
B. Answer b is incorrect. Refer to Figure 29.4.
The correct answer is d—
C. Answer c is incorrect. Refer to Figure 29.4.
The correct answer is d—Infolding of the plasma membrane
D. Answer d is correct. Refer to Figure 29.4.
3. Which of the following would be a key identifying characteristic of an organelle that has undergone secondary endosymbiosis?
a. A single plasma membrane
b. A set of two plasma membranes
c. Four plasma membranes
d. None of the above
The correct answer is c—
A. Answer a is incorrect. Refer to Figure 29.5.
The correct answer is c—
B. Answer b is incorrect. Refer to Figure 29.5.
The correct answer is c—Four plasma membranes
C. Answer c is correct. Consider chloroplast endosymbiosis. In the primary endosymbiotic event, the single-membraned bacteria are engulfed by the eukaryotic membrane, resulting in two membranes. If this organism now enters another eukaryotic cell by endosymbiosis, there will be two membranes around the original chloroplast, plus the cell membrane of the eukaryote that engulfed it in the primary endosymbiotic event (three membranes). However, the membrane of the second engulfing endosymbiont envelops the entire cell with its own membrane. This leaves the secondary endosymbiont with four membranes around the chloroplast.
The correct answer is c—
D. Answer d is incorrect. Refer to Figure 29.5.
4. The evolution of which of the following provides for higher levels of genetic recombination and variation?
a. Schizogony
b. Sexual reproduction
c. Asexual reproduction
d. Budding
The correct answer is b—
A. Answer a is incorrect. Schizogony does not provide for high levels of variation.
The correct answer is b—Sexual reproduction
B. Answer b is correct. Combined with fertilization, sexual reproduction provides for a high level of genetic recombination.
The correct answer is b—
C. Answer c is incorrect. A sexual reproduction does not provide for high levels of variation.
The correct answer is b—
D. Answer d is incorrect. Budding does not provide for high levels of variation.
5. A protist that lacks mitochondria would most likely be classified with the ______.
a. Rhodophyta
b. Parabasalida
c. Euglenozoa
d. Stramenophila
The correct answer is b—
A. Answer a is incorrect. Rhodophyta possess mitochondria.
The correct answer is b—Parabasalids
B. Answer b is correct. The lack of mitochondria is a characteristic of the parabasalida and the diplomonads.
The correct answer is b—
C. Answer c is incorrect. The Euglenozoa possess mitochondria.
The correct answer is b—
D. Answer d is incorrect. The Stramenophila possess mitochondria.
6. Which of the following statements best describes the term kinetoplastid?
a. An organism with a single mitochondrion in each cell
b. A form of locomotion in the Alveolata
c. A form of asexual reproduction in the euglenoids
d. A Golgi-like organelle found in the Alveolata
The correct answer is a—An organism with a single mitochondrion in each cell
A. Answer a is correct. Typanosomes are a form of kinetoplastid.
The correct answer is a—
B. Answer b is incorrect. This term does not apply to the alveolates.
The correct answer is a—
C. Answer c is incorrect. The term is not associated with reproduction.
The correct answer is a—
D. Answer d is incorrect. The name of the Golgi-like organelles in the Alveolata is alveoli.
7. A species that is photosynthetic, with fine hairs on the flagella, would be classified with which of the following groups?
a. Chlorophyta
b. Euglenozoa
c. Alveolata
d. Stramenophila
The correct answer is d—
A. Answer a is incorrect. Although photosynthetic, the Chlorophyta lack the fine hairs.
The correct answer is d—
B. Answer b is incorrect. Although some Euglenazoa are photosynthetic, they lack the fine hairs.
The correct answer is d—
C. Answer c is incorrect. Although some Alveolata are photosynthetic, they lack the fine hairs.
The correct answer is d—Stramenophila
D. Answer d is correct. Although fine hairs are not present in all members of this group, it is one of the defining characteristics.
8. The organism that causes red tide is a(n) ______and belongs to the clade ______.
a. apicomplexan; Alveolata
b. kinetoplastid; Euglenozoa
c. dinoflagellate; Alveolata
d. brown algae; Stramenopila
The correct answer is c—
A. Answer a is incorrect. Apicomplexans are animal parasites.
The correct answer is c—
B. Answer b is incorrect. Red tide is not caused by a member of the Euglenozoa.
The correct answer is c—dinoflagellate; Alveolata
C. Answer c is correct. Red tide is caused by toxins from a dinoflagellate.
The correct answer is c—
D. Answer d is incorrect. Red tide is not caused by a member of the Stramenophila.
9. What characteristic separates the Rhodophyta and the Chlorophyta?
a. Method of locomotion
b. Lack of mitochondria
c. Method of reproduction
d. Form of photosynthetic pigments
The correct answers are a and d—
A. Rhodophyta have lost their flagella while some Chlorophyta (e.g. Chlamydomonas) retain flagella.
The correct answers are a and d—
B. Both Rhodophyta and Chlorophyta have mitochondria
The correct answers are a and d—
C. Both multicellular Chlorophyta and Rhodophyta have alternation of generations.
The correct answers are a and d—
D. Rhodophyta have photosynthetic pigments not found in Chlorophyta. They include phycoerythrin, phycocyanin, and allophycocyanin.
10. Which of the following lines represents a monophyletic group?
a. Euglenoids
b. Amoebas
c. Forams
d. Slime molds
The correct answer is a—Euglenoids
A. Answer a is correct. Euglenoids are the only monophyletic group on the list.
The correct answer is a—
B. Answer b is incorrect. Amoeba have a paraphyletic origin.
The correct answer is a—
C. Answer c is incorrect. The forams are paraphyletic.
The correct answer is a—
D. Answer d is incorrect. The slime molds are a paraphyletic group.
11. The disease malaria is caused by a species of the genus______, which belongs to the ______.
a. Giardia; diplomonads
b. Plasmodium; apicomplexans
c. Paramecium; ciliates
d. Trypanosoma; kinetoplastids
The correct answer is b—
A. Answer a is incorrect. Malaria is not caused by a member of this genus or clade.
The correct answer is b—Plasmodium; apicomplexans
B. Answer b is correct.
The correct answer is b—
C. Answer c is incorrect. Malaria is not caused by a member of this genus or clade.
The correct answer is b—
D. Answer d is incorrect. Malaria is not caused by a member of this genus or clade.
12. In the following below, which multicellular eukaryotic kingdom is NOT linked to its correct protistan ancestor?
a. Viridiplantae—Chlorophyta
b. Fungi—Oomycetes
c. Animals—Choanoflagellates
d. All of the above are linked correctly.
The correct answer is b—
A. Answer a is incorrect. The origin or the plants is rooted in the Chlorophyta.
The correct answer is b—Fungi—Oomycetes
B. Answer b is correct. At one time scientists believed that this was true. Recent evidence has suggested that this is not the origin of the fungi.
The correct answer is b—
C. Answer c is incorrect. The origin of the animals is rooted in the Choanoflagellates.
The correct answer is b—
D. Answer d is incorrect. One of the above is linked incorrectly.
13. One of the earliest examples of multicellularity occurs in the ______.
a. euglenoids
b. amoebas
c. red algae
d. cellular slime molds
The correct answer is d—
A. Answer a is incorrect. Euglenoids are not multicellular.
The correct answer is d—
B. Answer b is incorrect. Amoebas are not multicellular.
The correct answer is d—
C. Answer c is incorrect. Although multicellular, the red algae are not the earliest example.
The correct answer is d—cellular slime molds
D. Answer d is correct.
14. The origin of which of the following does NOT represent an endosymbiotic event?
a. Mitochondria
b. Chloroplasts
c. Nucleus
d. All of the above are endosymbiotic events
The correct answer is c—
A. Answer a is incorrect. The origin of mitochondria is due to endosymbiosis with an aerobic bacterium.
The correct answer is c—
B. Answer b is incorrect. The origin of chloroplasts is due to endosymbiosis with a photosynthetic bacterium.
The correct answer is c—Nucleus
C. Answer c is correct. The nucleus originated due to an infolding of the plasma membrane, not endosymbiosis.
The correct answer is c—
D. Answer d is incorrect. One of the above did not originate by endosymbiosis.
15. In Paramecium, removal of which of the following organelles would inhibit sexual reproduction?
a. The alveoli
b. The micronucleus
c. The macronucleus
d. The cytoproct
The correct answer is b—
A. Answer a is incorrect. This organelle is not associated with reproduction.
The correct answer is b—The micronucleus
B. Answer b is correct. Micronuclei are involved in conjugation and sexual reproduction.
The correct answer is b—
C. Answer c is incorrect. The macronucleus is formed as a result of sexual reproduction, not as a necessary structure for it.
The correct answer is b—
D. Answer d is incorrect. The cytoproct is an exocytoic vesicle and is not involved in reproduction.
Challenge Questions
1. Many species of diplomonads and parabasilida lack mitochondria, yet remain aerobic. In chapter 9 you were introduced to the mitochondria as the site of aerobic respiration. If these species retained their aerobic capabilities, what must have happened to the metabolic pathways?
Answer—Remember that many species of bacteria are aerobic, although they do not have mitochondria. Therefore, possessing mitochondria is not a necessity. For the aerobic diplomonads and parabasilida that lack mitochondria, the metabolic pathways must have been moved into the cytoplasm or onto other internal membranes of the cell.
2. Review the diversity of photosynthetic pigments in the Protista. Can photosynthesis be used as a basis of classification? Explain your answer.
Answer—Photosynthesis as a metabolic process represents a clear case of convergent evolution, with many different species trying out a variety of photosynthetic pigments (see the brown and red algae as an example). Therefore, being photosynthetic is not a good characteristic for classification because photosynthetic pathways have diverged since the original cyanobacteria were endosymbiosed. However, the use of specific photosynthetic pigments is often used as a characteristic for classification since similar pigments are usually encoded by similar genes, which suggests an evolutionary link.
3. Most scientists will agree that the protist kingdom is a mess. Some scientists believe that these organisms should be placed within the multicellular eukaryotic kingdoms (plants, fungi, and animals). Do you think that this approach is practical? Support your answer.
Answer—Answers may vary. The biggest obstacle occurs with the Protista that are neither animal-like, plantlike, or funguslike. An example is the euglenoids, which can obviously be placed in both the plants and animals. Supporters of moving the protistans into the other kingdoms will state that the origins of the three multicellular kingdoms are obviously rooted in the protists. Many evolutionary biologists believe that the concept of kingdoms is no longer useful in constructing evolutionary hypotheses and that it is best to focus on cladistic approaches unconstrained by traditional kingdom names.
4. You are viewing a previously unidentified alga under a high-powered microscope. The chloroplast appears to have four membranes surrounding it. Which group of algae would you predict is most closely related to your new species? Why?
Answer—The most likely group is the brown algae where secondary endosymbiosis resulted in the four membranes around the chloroplast. Refer to figure 29.5 for a more detailed explanation.
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