According to the endosymbiotic theory, why was it adaptive for the larger (host) cell to keep the engulfed cell alive, rather than digesting it as food?
A) The engulfed cell provided the host cell with adenosine triphosphate (ATP).
B) The engulfed cell provided the host cell with carbon dioxide.
C) The engulfed cell allowed the host cell to metabolize glucose.
D) The host cell was able to survive anaerobic conditions with the engulfed cell alive.
A)
The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?
A) cyanobacteria → green algae → land plants
B) cyanobacteria → green algae → fungi → land plants
C) red algae → brown algae → green algae → land plants
D) cyanobacteria → red algae → green algae → land plants
A)
A particular species of protist has obtained a chloroplast via secondary endosymbiosis. You know this because the chloroplasts ________.
A) have nuclear and cyanobacterial genes
B) are exceptionally small
C) have three or four membranes
D) have only a single pigment
C)
All protists are ________.
A) unicellular
B) eukaryotic
C) symbionts
D) mixotrophic
B)
An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?
A) It relies on photosystems that float freely in its cytosol.
B) It must have gained extra mitochondria when it lost its plastids.
C) It engulfs organic material by phagocytosis or by absorption.
D) It has an endospore.
C0
Which of the following have chloroplasts (or structures since evolved from chloroplasts) thought to be derived from ancestral green algae?
A) stramenopiles
B) apicomplexans
C) dinoflagellates
D) chlorarachniophytes
D)
Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "chromatophores." The chromatophores are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants.
The closest living relative of P. chromatophora is the heterotroph P. ovalis. P. ovalis uses threadlike pseudopods to capture its prey, which it digests internally. Which of the following, if observed, would be the best reason for relabeling P. chromatophora as a mixotroph instead of an autotroph?
A) a pigmented central vacuole, surrounded by a nucleomorph
B) a vacuole with food inside
C) a secretory vesicle
D) a contractile vacuole
B)
Use the following information to answer the question.
Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "chromatophores." The chromatophores are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants.
Which process could have allowed the nucleomorphs of chlorarachniophytes to be reduced, without the net loss of any genetic information?
A) conjugation
B) horizontal gene transfer
C) phagocytosis
D) meiosis
B)
When a mosquito infected with Plasmodium first bites a human, the Plasmodium ________.
A) gametes fuse, forming an oocyst
B) cells infect the human liver cells
C) cells cause lysing of the human red blood cells
D) oocyst undergoes meiosis
B
Which two genera have members that can evade the human immune system by frequently changing their surface proteins?
A) Plasmodium and Trypanosoma
B) Trichomonas and Paramecium
C) Trichomonas and Trypanosoma
D) Trypanosoma and Entamoeba
A)
Which of the following pairs of protists and their ecological roles are correctly matched?
A) apicomplexans—parasites of animals
B) euglenozoans—primarily mixotrophic
C) dinoflagellates—parasites of plants
D) entamoebas—free-living soil organisms
A)
Dinoflagellates ________.
A) possess two flagella
B) are all autotrophic
C) lack mitochondria
D) include species that cause malaria
A)
You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile, using many short extensions of the cytoplasm, each featuring the 9 + 2 filament pattern. It has well-developed organelles and two nuclei, one large and one small. This organism is most likely to be a ________.
A) foraminiferan
B) radiolarian
C) ciliate
D) kinetoplastid
C)
Which of the following is characteristic of ciliates?
A) They use pseudopods as feeding structures.
B) They are often multinucleate.
C) They can exchange genetic material with other ciliates by the process of mitosis.
D) Most live as solitary autotrophs in fresh water.
B
Diatoms are mostly asexual members of the phytoplankton. Diatoms lack any organelles that might have the 9 + 2 pattern. They obtain their nutrition from functional chloroplasts, and each diatom is encased within two porous, glasslike valves. Which question would be most important for one interested in the day-to-day survival of individual diatoms?
A) How do diatoms get transported from one location on the water's surface layers to another location on the surface?
B) How do diatoms with their glasslike valves keep from sinking into poorly lit waters?
C) How do diatoms with their glasslike valves avoid being shattered by the action of waves?
D) How do diatom sperm cells locate diatom egg cells?
B
A large seaweed that floats freely on the surface of deep bodies of water would be expected to have which of the following?
A) rigid stems
B) bladders
C) true roots
D) gel-forming proteins
B)
Reinforced, threadlike pseudopods that can perform phagocytosis are generally characteristic of ________.
A) foramifera
B) water molds
C) dinoflagellates
D) oomycetes
A
A porous test (shell) of calcium carbonate, through which pseudopodia protrude, is characteristic of ________.
A) diatoms
B) foraminiferans
C) ciliates
D) water molds
B
A gelatinous seaweed that grows in shallow, cold water and undergoes heteromorphic alternation of generations is most probably what type of alga?
A) red
B) green
C) brown
D) yellow
C
You are given four test tubes, each containing an unknown protist, and your task is to read the following description and match these four protists to the correct test tube.
When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tubes 1, 3, and 4 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals the presence of one large nucleus and one small nucleus in each organism.
Test tube 3 contains ________.
A) Paramecium
B) Pfiesteria (dinoflagellate)
C) Entamoeba
D) Plasmodium
D
You are given four test tubes, each containing an unknown protist, and your task is to read the following description and match these four protists to the correct test tube.
When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tubes 1, 3, and 4 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals the presence of one large nucleus and one small nucleus in each organism.
Test tube 4 contains ________.
A) Paramecium
B) Pfiesteria (dinoflagellate)
C) Entamoeba
D) Plasmodium
A
32) You are given four test tubes, each containing an unknown protist, and your task is to read the following description and match these four protists to the correct test tube.
When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tubes 1, 3, and 4 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals the presence of one large nucleus and one small nucleus in each organism.
Test tube 1 contains ________.
A) Paramecium
B) Pfiesteria (dinoflagellate)
C) Entamoeba
D) Plasmodium
B
You are given four test tubes, each containing an unknown protist, and your task is to read the following description and match these four protists to the correct test tube.
When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tubes 1, 3, and 4 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals the presence of one large nucleus and one small nucleus in each organism.
Test tube 2 contains ________.
A) Paramecium
B) Pfiesteria (dinoflagellate)
C) Entamoeba
D) Triceratium (diatom)
D
Water's density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration, and using data from the table above, at which time of year should one expect diatoms to be storing excess calories mostly as oil?
A) mid-winter
B) early spring
C) late summer
D) late fall
C
Water's density and, consequently, its buoyancy decrease at warmer temperatures. Considering the impact of temperature, and the table above, in which environment should diatoms sinking be slowest?
A) cold fresh water
B) warm fresh water
C) cold seawater
D) warm seawater
C
Which term best describes the symbiotic relationship of well-fed P. bursaria to their zoochlorellae?
A) mutualistic
B) parasitic
C) predatory
D) pathogenic
A
The motility that permits P. bursaria to move toward a light source is provided by ________.
A) pseudopods
B) a single flagellum featuring the 9 + 2 pattern
C) many cilia
D) contractile vacuoles
C
A P. bursaria cell that has lost its zoochlorellae is said to be aposymbiotic. It might be able to replenish its contingent of zoochlorellae by ingesting them without subsequently digesting them. Which of the following situations would be most favorable to the reestablishment of resident zoochlorellae, assuming compatible Chlorella are present in P. bursaria's habitat?
A) abundant light, no bacterial prey
B) abundant light, abundant bacterial prey
C) no light, no bacterial prey
D) no light, abundant bacterial prey
B
A P. bursaria cell that has lost its zoochlorellae is aposymbiotic. If aposymbiotic cells have population growth rates the same as those of healthy, zoochlorella-containing P. bursaria in well-lit environments with plenty of prey items, then such an observation would be consistent with which type of relationship?
A) parasitic
B) competitive
C) toxic
D) mutualistic
B
Theoretically, P. bursaria can obtain zoochlorellae either vertically (via the asexual reproduction of its mother cell) or horizontally (by ingesting free-living Chlorella from its habitat). Consider a P. bursaria cell containing zoochlorellae but whose habitat lacks free-living Chlorella. If this cell subsequently undergoes many generations of asexual reproduction, if all of its daughter cells contain roughly the same number of zoochlorellae as it had originally contained, and if the zoochlorellae are all haploid and identical in appearance, then which statement is accurate? The zoochlorellae ________.
A) also reproduced asexually, at an increasing rate over time
B) also reproduced asexually, at a decreasing rate over time
C) also reproduced asexually, at a fairly constant rate over time
D) reproduced sexually, undergoing heteromorphic alternation of generations
C
Which process in Paramecium results in genetic recombination but no increase in population size?
A) budding
B) meiotic division
C) conjugation
D) binary fission
C
Refer to the study by Poulsen et al. and the figure above. Latrunculin A is a reversible toxin that disrupts the formation of actin fibers. A culture of a particular species of diatom was treated with this toxin diluted in a buffer, while another culture was treated only with the buffer (no toxin; control). The motility of cells in each culture was assessed by counting the number of cells that were moving during a defined period of time. Which of the following conclusions is reasonable based on the above figure?
A) Formation of actin fibers is not necessary for the movement in this species of diatom.
B) The buffer alone largely inhibited movement in this species of diatom.
C) In this species of diatom, fully formed actin fibers are necessary for movement.
D) In this species of diatom, fully formed myosin proteins are necessary for movement.
C
Refer to the study by Poulsen et al. and the figure above. The data graphed in the figure could be an artifact if latrunculin A kills this species of diatoms (that is, that may be why the cells are not moving). Which of the following would be the best evidence that latrunculin A is not killing the cells?
A) When the toxin was washed off the culture, the cells began to move again.
B) There was still a small percentage of motile cells in the culture treated with the toxin.
C) Most of the cells in the control were moving, indicating that they were alive.
D) When the toxin was applied to another species of diatom, 25% of them continued to move.
A
Refer to the study by Poulsen et al. and the figure above. Cultures of a species of diatom were treated with BDM, a reversible inhibitor of myosin function. Which of the following predictions is consistent with the hypothesis that an actin-myosin interaction is necessary for motility?
A) BDM will significantly decrease motility of the cells in culture.
B) BDM will not significantly alter motility of the cells in culture.
C) BDM will significantly increase motility of the cells in culture.
D) BDM will significantly increase motility of the cells in their natural habitats.
A
Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "chromatophores." The chromatophores are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants.
P. chromatophora secretes around itself a test, or case, of plates made of silica. Which of the following is another rhizarian that would be in competition with P. chromatophora for the silica needed to make these plates, assuming limited quantities of silica in the environment?
A) radiolarians
B) foraminiferans
C) dinoflagellates
D) diatoms
A
Including the membrane of the surrounding vesicle, how many phospholipid (notlipopolysaccharide) bilayers should be found around each P. chromatophora's chromatophore, and which one of these bilayers should have photosystems embedded in it?
A) two; innermost
B) two; outermost
C) three; innermost
D) three; outermost
A
Which of the following results would be most important in determining whether P. chromatophora's chromatophore is still an endosymbiont, or is an organelle, as the term chromatophore implies?
A) if P. chromatophora is less fit without its chromatophore than with it
B) if the chromatophore is less fit without the host cercozoan than with it
C) if there is ongoing metabolic cooperation between the chromatophore and the host cercozoan
D) if there has been movement of genes from the chromatophore genome to the nuclear genome, such that these genes are no longer present in the chromatophore genome
D
The genome of modern chloroplasts is roughly 50% the size of the genome of the cyanobacterium from which it is thought to have been derived. In comparison, the genome of P. chromatophora's chromatophore is only slightly reduced relative to the size of the genome of the cyanobacterium from which it is thought to have been derived. What is a valid hypothesis that can be drawn from this comparison?
A) Lytic phage infections have targeted the chloroplast genome more often than the P. chromatophora genome.
B) P. chromatophora's chromatophore is the result of an evolutionarily recent endosymbiosis.
C) The genome of the chloroplast ancestor contained many more introns that could be lost without harm compared to the chromatophore's genome.
D) The genome of the cyanobacteria was smaller than the genome of P. chromatophora.
B
Plastids that are surrounded by more than two membranes are evidence of
A) evolution from mitochondria.
B) fusion of plastids.
C) origin of the plastids from archaea.
D) secondary endosymbiosis.
D
Biologists think that endosymbiosis gave rise to mitochondria before plastids partly because
A) the products of photosynthesis could not be metabolized without mitochondrial enzymes.
B) all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.
C) mitochondrial DNA is less similar to prokaryotic DNA than is plastid DNA.
D) without mitochondrial CO2 production, photosynthesis could not occur.
B
Which group is incorrectly paired with its description?
A) diatoms—important producers in aquatic communities
B) red algae—eukaryotes that acquired plastids by secondary endosymbiosis
C) apicomplexans—unicellular parasites with intricate life cycles
D) diplomonads—unicellular eukaryotes with modified mitochondria
D
According to the phylogeny presented in this chapter, which protists are in the same eukaryotic supergroup as plants?
A) green algae
B) dinoflagellates
C) red algae
D) both A and C
D
In a life cycle with alternation of generations, multicellular haploid forms alternate with
A) unicellular haploid forms.
B) unicellular diploid forms.
C) multicellular haploid forms.
D) multicellular diploid forms.
D
Based on the phylogenetic tree in Figure 28.2, which of the following statements is correct?
A) The most recent common ancestor of Excavata is older than that of SAR.
B) The most recent common ancestor of SAR is older than that of Unikonta.
C) The most basal (first to diverge) eukaryotic supergroup cannot be determined.
D) Excavata is the most basal eukaryotic supergroup.
C