Archive for December 2016

In order to allude to the pharaoh's numerous attributes or qualities, the ruler on the Palette of Narmer is represented in all of the following ways EXCEPT

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In order to allude to the pharaoh's numerous attributes or qualities, the ruler on the Palette of Narmer is represented in all of the following ways EXCEPT




A) as a bull knocking down a city
B) as a falcon god subjugating his enemy
C) as a warrior ascending a mountain with his army
D) in hierarchical proportion with an idealized form









Answer: C

Which group is incorrectly paired with its description?

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Which group is incorrectly paired with its description? 




A) rhizarians?morphologically diverse group defined by DNA similarities
B) diatoms?important producers in aquatic communities
C) red algae?acquired plastids by secondary endosymbiosis
D) apicomplexans?parasites with intricate life cycles
E) diplomonads?protists with modified mitochondria






Answer: C

Biologists suspect that endosymbiosis gave rise to mitochondria before plastids partly because

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Biologists suspect 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.
E) mitochondrial proteins are synthesized on cytosolic ribosomes, whereas plastids utilize their own ribosomes.




Answer: B

Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. When within their hosts, the algae are referred to as zoochlorellae. In aquaria with light coming from only one side, P. bursaria gathers at the well-lit side, whereas other species of Paramecium gather at the opposite side. The zoochlorellae provide their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae with protection and motility. P. bursaria can lose its zoochlorellae in two ways: (1) if kept in darkness, the algae will die; and (2) if prey items (mostly bacteria) are absent from its habitat, P. bursaria will digest its zoochlorellae.

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Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. When within their hosts, the algae are referred to as zoochlorellae. In aquaria with light coming from only one side, P. bursaria gathers at the well-lit side, whereas other species of Paramecium gather at the opposite side. The zoochlorellae provide their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae with protection and motility. P. bursaria can lose its zoochlorellae in two ways: (1) if kept in darkness, the algae will die; and (2) if prey items (mostly bacteria) are absent from its habitat, P. bursaria will digest its zoochlorellae. 


Which term most accurately describes the nutritional mode of healthy P. bursaria? 

A) photoautotroph
B) photoheterotroph
C) chemoheterotroph
D) chemoautotroph
E) mixotroph


Answer: E


Which term accurately describes the behavior of Paramecium species that lack zoochlorellae in an aquarium with light coming from one side only? 

A) positive chemotaxis 
B) negative chemotaxis
C) positive phototaxis
D) negative phototaxis


Answer: D


Which term best describes the symbiotic relationship of well-fed P. bursaria to their zoochlorellae? 

A) mutualistic 
B) commensal
C) parasitic
D) predatory
E) pathogenic


Answer: A


The motility that permits P. bursaria to move toward a light source is provided by A) pseudopods. 

B) a single flagellum composed of the protein, flagellin.
C) a single flagellum featuring the 9 + 2 pattern.
D) many cilia.
E) contractile vacuoles.


Answer: D


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



Answer: 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) commensalistic
C) toxic
D) predator-prey
E) mutualistic


Answer: B


Theoretically, P.bursaria can obtain zoochlorella 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 what is true? 

A) The zoochlorellae also reproduced asexually, at an increasing rate over time.
B) The zoochlorellae also reproduced asexually, at a decreasing rate over time.
C) The zoochlorellae also reproduced asexually, at a fairly constant rate over time.
D) The zoochlorellae reproduced sexually, undergoing heteromorphic alternation of generations.
E) The zoochlorellae reproduced sexually, undergoing isomorphic alternation of generations.


Answer: C

Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "cyanelles." The cyanelles 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.

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Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "cyanelles." The cyanelles 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. What type of evidence permits biologists to make this claim about relatedness? 

A) morphological
B) ecological
C) biochemical
D) genetic
E) fossil
Answer: D


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? A) a threadlike pseudopod 

B) a pigmented central vacuole, surrounded by a tonoplast
C) a vacuole with food inside
D) a secretory vesicle
E) a contractile vacuole


Answer: C


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) all other amoeboid cells
D) all other rhizaria
E) diatoms


Answer: A


Which of the following represents the true significance of the finding that the cyanelles of P. chromatophora stem from a different type of cyanobacterium than gave rise to chloroplasts? A) This finding indicates that there is a second evolutionary lineage of photosynthetic eukaryotes. 

B) This finding represents the first time that primary endosymbiosis has been directly observed.
C) This finding is the strongest evidence yet for the theory of endosymbiosis.
D) This finding is an example of the phenomenon known as "serial endosymbiosis."
E) This finding is the first evidence that eukaryotic cells do not necessarily digest prokaryotic cells that manage to gain access to their cytoplasm.


Answer: A


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 cyanelle 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 conclusion 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 cyanelle 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 cyanelle's genome.
D) All three of the conclusions above are valid.
E) Two of the conclusions above are valid.


Answer: B


If true, which of the following would be most important in determining whether P. chromatophora's cyanelle is still an endosymbiont, or is an organelle, as the term cyanelle implies? A) If P. chromatophora is less fit without its cyanelle than with it. 

B) If the cyanelle is less fit without the host cercozoan than with it.
C) If there is ongoing metabolic cooperation between the cyanelle and the host cercozoan.
D) If the magnesium-containing porphyrin ring in the cyanelle's chlorophyll molecules is built by the cyanelle, whereas the organic portion of the chlorophyll molecules is built by the host cercozoan.
E) If there has been movement of genes from the cyanelle genome to the nuclear genome, such that these genes are no longer present in the cyanelle genome.


Answer: E


If true, which of the following is the best evidence that the cyanelles are providing nutrition (in other words, calories) to the surrounding cercozoan? 

A) If the cyanelle performs aerobic photosynthesis. 
B) If the vesicle membrane that surrounds each cyanelle possesses glucose-transport proteins.
C) If the cyanelle performs aerobic respiration.
D) If radiolabeled 14CO2 enters the cyanelle and if, subsequently, radiolabeled glucose is present in cercozoan cytosol.
E) If radiolabeled "heavy" water, 2H2O, enters the cyanelle and if, subsequently, radiolabeled oxygen appears in cercozoan cytosol.


Answer: D


A crucial photosynthetic gene of the cyanobacterium that gave rise to the cyanelle is called psaE. This gene is present in the nuclear genome of the cercozoan, but is not in the genome of the cyanelle. This is evidence of A) reciprocal mutations in the cyanelle and nuclear genomes. 

B) horizontal gene transfer from bacterium to eukaryotes.
C) genetic recombination involving a protist and an archaean.
D) the origin of photosynthesis in protists.
E) transduction by a phage that infects both prokaryotes and eukaryotes.


Answer: B


What must occur for asexual reproduction to be successful in P. chromatophora? 

1. mitosis
2. S phase
3. meiosis
4. equal distribution of cyanelles during cytokinesis

A) 1 only
B) 1 and 2
C) 1, 2, and 3
D) 1, 2, and 4
E) 2, 3, and 4


Answer: D


Including the membrane of the surrounding vesicle, how many phospholipid (NOT lipopolysaccharide) bilayers should be found around each cyanelle, and which one of these bilayers should have photosystems embedded in it? A) two; innermost 

B) two; outermost
C) three; innermost
D) three; middle
E) three; outermost


Answer: A

Giardia lamblia is an intestinal parasite of humans and other mammals that causes intestinal ailments in most people who ingest the cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites. These attach to the small intestine's lining via a ventral adhesive disk. The trophozoites anaerobically metabolize glucose from the host's intestinal contents to produce ATP. Reproduction is completely asexual, occurring by longitudinal binary fission of trophozoites, with each daughter cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as it passes into the large intestine by secreting around itself a case that is resistant to cold, heat, and dehydration. Infection usually occurs by drinking untreated water that contains cysts.

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Giardia lamblia is an intestinal parasite of humans and other mammals that causes intestinal ailments in most people who ingest the cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites. These attach to the small intestine's lining via a ventral adhesive disk. The trophozoites anaerobically metabolize glucose from the host's intestinal contents to produce ATP. Reproduction is completely asexual, occurring by longitudinal binary fission of trophozoites, with each daughter cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as it passes into the large intestine by secreting around itself a case that is resistant to cold, heat, and dehydration. Infection usually occurs by drinking untreated water that contains cysts. 



The trophozoites of Giardia were first observed in 1681 in the diarrhea stools of the first known person to view protists with a microscope, a person named 

A) Robert Koch.
B) Robert Hooke.
C) Isaac Newton.
D) van Leeuwenhoek.
E) Louis Pasteur.


Answer: D


Given that Flagyl produces only minor side effects (if any) in humans, and given the set of parasites that it kills, Flagyl's mode of action probably involves 

A) peptidoglycan.
B) mitochondria or mitosomes.
C) anaerobic metabolic pathways.
D) nuclear envelopes.
E) microtubules.


Answer: C


Giardia's mitosome can be said to be "doubly degenerate," because it is a degenerate form of ________, an organelle that is itself a degenerate form of ________. 


A) nucleus; archaean
B) nucleus; bacterium
C) mitochondrion; proteobacterium
D) mitochondrion; spirochete
E) chloroplast; cyanobacterium


Answer: C


The mitosome of Giardia has no DNA within it. If it did contain DNA, then what predictions should we be able to make about its DNA? 

1. It is linear.
2. It is circular.
3. It has many introns.
4. It has few introns.
5. It is not associated with histone proteins.
6. It is complexed with histone proteins.

A) 1, 3, and 5
B) 1, 4, and 5
C) 2, 3, and 6
D) 2, 4, and 5
E) 2, 4, and 6


Answer: D



Given the putative ancestry of Giardia's mitosome, what should we predict is true of the mitosome? A) It has electron transport systems that use oxygen as the final electron acceptor. 

B) It has a double membrane.
C) It has thylakoids.
D) It contains microtubules, arranged in the "9 + 2 pattern."
E) It contains 80S (eukaryotic) ribosomes.


Answer: B


Given its mode of reproduction and internal structures, which of the following should be expected to occur in Giardia at some stage of its life cycle? 

1. separation (segregation) of daughter chromosomes
2. crossing over
3. meiosis

A) 1 only
B) 3 only
C) 1 and 2
D) 1 and 3
E) 2 and 3



Answer: A


Unlike most excavates, Giardia trophozoites have no oral groove and are unable to form food vacuoles. Thus, we should expect its nutrition (mostly glucose) to come from A) its mitosomes. 

B) endosymbiotic cyanobacteria.
C) the ventral disk by which it adheres to the intestinal lining.
D) osmosis involving aquaporins.
E) plasma membrane proteins that are transporters or pumps.


Answer: E


Diplomonads, such as Giardia, contain two haploid nuclei per trophozoite. Thus, during the G1 phase of the cell cycle, there should be a total of how many unreplicated chromosomes per trophozoite, and during the G2 phase, how many replicated chromosomes per trophozoite? A) 5; 5 

B) 5; 10
C) 10; 10
D) 10; 20
E) 20; 20


Answer: C


During passage through the large intestine, a trophozoite will often secrete a case around itself, forming a cyst. Cysts contain four haploid nuclei. When cysts "hatch" within a new host, two trophozoites are released. Thus, which of the following must happen within the cyst, prior to hatching? 

1. meiosis
2. nuclear division
3. S phase
4. binary fission

A) 1 only
B) 1 and 2
C) 2 and 3
D) 2 and 4
E) 2, 3, and 4


Answer: E


The cysts of Giardia are most analogous to the A) mitochondria of ancestral diplomonads. 

B) nuclei of archaeans.
C) endospores of bacteria.
D) capsids of viruses.


Answer: C


If the mitosomes of Giardia contain no DNA, yet are descendants of what were once free-living organisms, then where are we likely to find the genes that encode their structures, and what accounts for their current location there? A) plasmids; conjugation 

B) plasmids; transformation
C) nucleus; horizontal gene transfer
D) nucleus; S phase


Answer: C


The primary treatment for giardiasis (infection with Giardia), as well as for trichomoniasis (infection with Trichomonas vaginalis) and for amoebic dysentery (infection with Entamoeba histolytica), is a drug marketed as Flagyl (generic name is metronidazole). The drug also kills anaerobic gut bacteria. Consequently, which of these are cues that Flagyl's mode of action has nothing to do with attacking or disabling the parasites' flagella, as the drug's name might imply? 1. It would also harm the flagellated lining of the human intestine. 

2. Entamoeba possesses pseudopods, not flagella, yet it is killed by Flagyl.
3. Prokaryotic flagella and eukaryotic flagella are radically different from each other and unlikely to be harmed by the same chemical.
4. Not all anaerobic gut bacteria possess flagella, yet it kills these bacteria.

A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1, 2, and 4
E) 2, 3, and 4


Answer: E

Living diatoms contain brownish plastids. If global warming causes blooms of diatoms in the surface waters of Earth's oceans, how might this be harmful to the animals that build coral reefs?

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Living diatoms contain brownish plastids. If global warming causes blooms of diatoms in the surface waters of Earth's oceans, how might this be harmful to the animals that build coral reefs? 





A) The coral animals, which capture planktonic organisms, may be outcompeted by the diatoms.
B) The coral animals' endosymbiotic dinoflagellates may get "shaded out" by the diatoms.
C) The coral animals may die from overeating the plentiful diatoms, with their cases of silica.
D) The diatoms' photosynthetic output may over-oxygenate the water.





Answer: B

You are designing an artificial drug-delivery "cell" that can penetrate animal cells. Which of these protist structures should provide the most likely avenue for research along these lines?

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You are designing an artificial drug-delivery "cell" that can penetrate animal cells. Which of these protist structures should provide the most likely avenue for research along these lines? 




A) pseudopods
B) apical complex
C) excavated feeding grooves
D) nucleomorphs
E) mitosomes



Answer: B

Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as do some of the white blood cells of animals (monocytes). If one were to erect a taxon that included all organisms that have cells with pseudopods, what would be true of such a taxon?

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Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as do some of the white blood cells of animals (monocytes). If one were to erect a taxon that included all organisms that have cells with pseudopods, what would be true of such a taxon? 




A) It would be polyphyletic.
B) It would be paraphyletic.
C) It would be monophyletic.
D) It would include all eukaryotes.






Answer: A

You are given the task of designing an aquatic protist that is a primary producer. It cannot swim on its own, yet must stay in well-lit surface waters. It must be resistant to physical damage from wave action. It should be most similar to a(n)

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You are given the task of designing an aquatic protist that is a primary producer. It cannot swim on its own, yet must stay in well-lit surface waters. It must be resistant to physical damage from wave action. It should be most similar to a(n) 






A) diatom.
B) dinoflagellate.
C) apicomplexan.
D) red alga.
E) radiolarian.





Answer: A

You are given the task of designing an aerobic, mixotrophic protist that can perform photosynthesis in fairly deep water (for example, 250 m deep), and can also crawl about and engulf small particles. With which two of the following structures would you provide your protist? 1. hydrogenosome 2. apicoplast 3. pseudopods 4. chloroplast from red alga 5. chloroplast from green alga

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You are given the task of designing an aerobic, mixotrophic protist that can perform photosynthesis in fairly deep water (for example, 250 m deep), and can also crawl about and engulf small particles. With which two of the following structures would you provide your protist?
1. hydrogenosome
2. apicoplast
3. pseudopods
4. chloroplast from red alga
5. chloroplast from green alga 





A) 1 and 2
B) 2 and 3
C) 2 and 4
D) 3 and 4
E) 4 and 5






Answer: D

Which of the following statements concerning protists is true?

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Which of the following statements concerning protists is true? 






A) All protists have mitochondria, though in some species they are much reduced and known by different names.
B) The primary organism that transmits malaria to humans by its bite is the tsetse fly.
C) All apicomplexans are autotrophic.
D) All slime molds have an amoeboid stage that may be followed by a stage during which spores are produced.
E) Euglenozoans that are mixotrophic lack functional chloroplasts.






Answer: A

If the Archaeplastidae are eventually designated a kingdom, and if land plants are excluded from this kingdom, then what will be true of this new kingdom?

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If the Archaeplastidae are eventually designated a kingdom, and if land plants are excluded from this kingdom, then what will be true of this new kingdom? 






A) It will be monophyletic.
B) It will more accurately depict evolutionary relationships than does the current taxonomy.
C) It will be paraphyletic.
D) It will be a true clade.
E) It will be polyphyletic.






Answer: C

Which of the following is a characteristic of the water molds (oomycetes)?

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Which of the following is a characteristic of the water molds (oomycetes)? 





A) the presence of filamentous feeding structures
B) zoospores that are spread by breezes
C) the same nutritional mode as possessed by cyanobacteria
D) a morphological similarity to fungi that is the result of common ancestry
E) a feeding Plasmodium






Answer: A

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?

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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 does carbon dioxide get into these protists with their glasslike valves?
B) How do diatoms get transported from one location on the water's surface layers to another location on the surface?
C) How do diatoms with their glasslike valves keep from sinking into poorly lit waters?
D) How do diatoms with their glasslike valves avoid being shattered by the action of waves?
E) How do diatom sperm cells locate diatom egg cells?





Answer: C

If we were to apply the most recent technique used to fight potato late blight to the fight against the malarial infection of humans, then we would

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If we were to apply the most recent technique used to fight potato late blight to the fight against the malarial infection of humans, then we would 






A) increase the dosage of the least-expensive antimalarial drug administered to humans.
B) increase the dosage of the most common pesticide used to kill Anopheles mosquitoes.
C) introduce a predator of the malarial parasite into infected humans.
D) use a "cocktail" of at least three different pesticides against Anopheles mosquitoes.
E) insert genes from a Plasmodium-resistant strain of mosquito into Anopheles mosquitoes.




Answer: E

Why is the filamentous morphology of the water molds considered a case of convergent evolution?

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Why is the filamentous morphology of the water molds considered a case of convergent evolution? 






A) Water molds evolved from filamentous fungi.
B) Body shape reflects ancestor-descendant relationships among organisms.
C) In both cases, filamentous shape is an adaptation for the absorptive nutritional mode of a decomposer.
D) Filamentous body shape is evolutionarily ancestral for all eukaryotes.
E) Both the first and second responses above are correct.







Answer: C

Which of the following is characteristic of ciliates?

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Which of the following is characteristic of ciliates? 






A) They use pseudopods as locomotory structures or as feeding structures.
B) They are relatively specialized cells.
C) They can exchange genetic material with other ciliates by the process of mitosis.
D) Most live as solitary autotrophs in fresh water.
E) They are often multinucleate.





Answer: E

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 three nuclei, one large and two small. This organism is most likely to be a member of which group?

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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 three nuclei, one large and two small. This organism is most likely to be a member of which group? 






A) foraminiferans
B) radiolarians
C) ciliates
D) kinetoplastids
E) slime molds





Answer: C

Which of the following statements about dinoflagellates is true?

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Which of the following statements about dinoflagellates is true? 





A) They possess two flagella.
B) All known varieties are autotrophic.
C) Their walls are usually composed of silica plates.
D) Many types lack mitochondria.
E) Their dead cells accumulate on the seafloor, and are mined to serve as a filtering material.





Answer: A

An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?

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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.
E) It is protected by a case made of silica.






Answer: C

According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate?

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According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate? 





A) from infoldings of the plasma membrane, coupled with mutations of genes for proteins in energy-transfer reactions
B) from engulfed, originally free-living proteobacteria
C) by secondary endosymbiosis
D) from the nuclear envelope folding outward and forming mitochondrial membranes
E) when a protoeukaryote engaged in a symbiotic relationship with a protocell






Answer: B

Biologists have long been aware that the defunct kingdom Protista is polyphyletic. Which of these statements is most consistent with this conclusion?

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Biologists have long been aware that the defunct kingdom Protista is polyphyletic. Which of these statements is most consistent with this conclusion? 





A) Many species within this kingdom were once classified as monerans.
B) Animals, plants, and fungi arose from different protist ancestors.
C) The eukaryotic condition has evolved more than once among the protists.
D) Chloroplasts among various protists are similar to those found in prokaryotes.
E) Some protists, all animals, and all fungi share a protist common ancestor, but these protists, animals, and fungi are currently assigned to three different kingdoms.






Answer: C

All protists are

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All protists are 




A) unicellular.
B) eukaryotic.
C) symbionts.
D) monophyletic.
E) mixotrophic.





Answer: B

Which of the following statements is not true?

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Which of the following statements is not true? 






A) Archaea and bacteria have different membrane lipids.
B) Both archaea and bacteria generally lack membrane-enclosed organelles.
C) The cell walls of archaea lack peptidoglycan.
D) Only bacteria have histones associated with DNA.
E) Only some archaea use CO2 to oxidize H2, releasing methane.






Answer: D

Photoautotrophs use

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Photoautotrophs use 





A) light as an energy source and CO2 as a carbon source.
B) light as an energy source and methane as a carbon source.
C) N2 as an energy source and CO2 as a carbon source.
D) CO2 as both an energy source and a carbon source.
E) H2S as an energy source and CO2 as a carbon source.







Answer: A

Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O2 reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O2. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocytes are described as having "…a thickened cell wall that restricts entry of O2 produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates."

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Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O2 reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O2. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocytes are described as having "…a thickened cell wall that restricts entry of O2 produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates." 

Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen? 


1. couple them with photosystem II (the photosystem that splits water molecules)
2. package them in membranes that are impermeable to all gases
3. be obligate anaerobes
4. be strict aerobes
5. package these enzymes in specialized cells or compartments that inhibit oxygen entry

A) 1 and 4
B) 2 and 4
C) 2 and 5
D) 3 and 4
E) 3 and 5


Answer: E


Which two questions below arise from a careful reading of this quotation, and are most important for understanding how N2 enters heterocysts, and how O2 is kept out of heterocysts? 


1. If carbohydrates can enter the heterocysts from neighboring cells via the "intracellular connections," how is it that O2 doesn't also enter via this route?
2. If the cell walls of Anabaena's photosynthetic cells are permeable to O2 and CO2, are they also permeable to N2?
3. If the nuclei of the photosynthetic cells contain the genes that code for nitrogen fixation, how can these cells fail to perform nitrogen fixation?
4. If the nuclei of the heterocysts contain the genes that code for photosynthesis, how can these cells fail to perform photosynthesis?
5. If the cell walls of Anabaena's heterocysts are permeable to N2, how is it that N2 doesn't diffuse out of the heterocysts before it can be fixed?
6. If the thick cell walls of the heterocysts exclude entry of oxygen gas, how is it that they don't also exclude the entry of nitrogen gas?

A) 1 and 3
B) 1 and 6
C) 2 and 5
D) 3 and 4
E) 4 and 6



Answer: B

A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.

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A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 



This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of 

1. penicillin-resistance genes
2. a secretory system that removes penicillin from the cell
3. a gram-positive cell wall
4. a gram-negative cell wall
5. an endospore

A) 1 or 5
B) 2 or 3
C) 4 or 5
D) 2, 3, or 5
E) 2, 4, or 5


Answer: D


Adherence to the intestinal lining by this bacterium is due to its possession of A) fimbriae. 

B) pili.
C) a capsule.
D) a flagellum.
E) a cell wall with an outer lipopolysaccharide membrane.


Answer: C


What should be true of the cell wall of this bacterium? A) Its innermost layer is composed of a phospholipid bilayer. 

B) After it has been subjected to Gram staining, the cell should remain purple.
C) It has an outer membrane of lipopolysaccharide.
D) It is mostly composed of a complex, cross-linked polysaccharide.
E) Two of the responses above are correct.


Answer: C


Some of the proteins that allow this bacterium to swim are related (in an evolutionary sense) to proteins that 

A) attach to the single chromosome.
B) act as restriction enzymes.
C) synthesize peptidoglycan for the cell wall.
D) move penicillin out of the cell.
E) comprise its ribosomes.


Answer: D


In which feature(s) should one be able to locate a complete chromosome of this bacterium? 1. nucleolus 

2. prophage
3. endospore
4. nucleoid

A) 4 only
B) 1 and 3
C) 2 and 3
D) 3 and 4
E) 2, 3, and 4


Answer: D


The cell also lacks F factors and F plasmids. Upon its death, this bacterium should be able to participate in A) conjugation. 

B) transduction.
C) transformation.
D) Three of the responses above are correct.
E) Two of the responses above are correct.



Answer: C


This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Thus, this bacterium should be an 

A) aerobic chemoheterotroph.
B) aerobic chemoautotroph.
C) anaerobic chemoheterotroph.
D) anaerobic chemoautotroph.


Answer: C


This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Humans lacking this bacterium have no measurable reproductive advantage or disadvantage relative to humans who harbor this bacterium. Consequently, the bacterium can be properly described as which of the following? 

1. symbiont
2. endosymbiont
3. mutualist
4. commensal

A) 4 only
B) 1 and 2
C) 1 and 4
D) 2 and 3
E) 2 and 4



Answer: C

Broad-spectrum antibiotics inhibit the growth of most intestinal bacteria. Consequently, assuming that nothing is done to counter the reduction of intestinal bacteria, a hospital patient who is receiving broad-spectrum antibiotics is most likely to become

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Broad-spectrum antibiotics inhibit the growth of most intestinal bacteria. Consequently, assuming that nothing is done to counter the reduction of intestinal bacteria, a hospital patient who is receiving broad-spectrum antibiotics is most likely to become 







A) unable to fix carbon dioxide.
B) antibiotic resistant.
C) unable to fix nitrogen.
D) unable to synthesize peptidoglycan.
E) deficient in certain vitamins and nutrients.






Answer: E

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