AP Biology Chapter 28

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Protists

Protists are alike in that all are
A) unicellular.
B) eukaryotic.
C) symbionts.
D) monophyletic.
E) autotrophic.

b

Biologists have long been aware that the defunct kingdom Protista is paraphyletic. Which of these statements is
both true and 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 only once among the protists, and all eukaryotes are descendants of
that first eukaryotic cell.
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.

e

The strongest evidence for the endosymbiotic origin of eukaryotic organelles is the similarity between extant
prokaryotes and which of the following?
A) nuclei and chloroplasts
B) mitochondria and chloroplasts
C) cilia and mitochondria
D) mitochondria and nuclei
E) mitochondria and cilia

b

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 prokaryotes
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 protobiont

b

Which of these statements is false and therefore does not support the hypothesis that certain eukaryotic
organelles originated as bacterial endosymbionts? Such organelles
A) are roughly the same size as bacteria.
B) can be cultured on agar, because they make all their own proteins.
C) contain circular DNA molecules.
D) have ribosomes that are similar to those of bacteria.
E) have internal membranes that contain proteins homologous to those of bacterial plasma membranes.

b

Which process allowed the nucleomorphs of chlorarachniophytes to be first reduced, and then (in a few
species) lost altogether, without the loss of any genetic information?
A) conjugation
B) horizontal gene transfer
C) binary fission
D) phagocytosis
E) meiosis

b

Which organisms represent the common ancestor of all photosynthetic plastids found in eukaryotes?
A) autotrophic euglenids
B) diatoms
C) dinoflagellates
D) red algae
E) cyanobacteria

e

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 siliceous case.

c

Which of these was not derived from an ancestral alpha proteobacterium?
A) chloroplast
B) mitochondrion
C) hydrogenosome
D) mitosome
E) kinetoplast

a

A biologist discovers a new unicellullar organism that possesses more than two flagella and two small, but
equal-sized, nuclei. The organism has reduced mitochondria (mitosomes), no chloroplasts, and is anaerobic. To
which clade does this organism probably belong?
A) monera
B) the diplomonads
C) the ciliates
D) protista
E) the euglenids

b

Which two genera have members that can evade the human immune system by frequently changing their
surface proteins?
1. Plasmodium
2. Trichomonas
3. Paramecium
4. Trypanosoma
5. Entamoeba
A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 4 and 5

b

Which statement regarding resistance is false?
A) Many of the oomycetes that cause potato late blight have become resistant to pesticides.
B) Many of the mosquitoes that transmit malaria to humans have become resistant to pesticides.
C) Many of the malarial parasites have become resistant to antimalarial drugs.
D) Many humans have become resistant to antimalarial drugs.
E) Trichomonas vaginalis is resistant to the normal acidity of the human vagina.

d

Which of these taxa contains species that produce potent toxins that can cause extensive fish kills, contaminate
shellfish, and poison humans?
A) red algae
B) dinoflagellates
C) diplomonads
D) euglenids
E) golden algae

b

Which of the following pairs of protists and their characteristics is mismatched?
A) apicomplexans : internal parasites
B) golden algae : planktonic producers
C) euglenozoans : unicellular flagellates
D) ciliates : red tide organisms
E) entamoebas : ingestive heterotrophs

d

Which of these statements about dinoflagellates is false?
A) They possess two flagella.
B) Some cause red tides.
C) Their walls are composed of cellulose plates.
D) Many types contain chlorophyll.
E) Their dead cells accumulate on the seafloor, and are mined to serve as a filtering material.

e

Which group includes members that are important primary producers in ocean food webs, causes red tides that
kill many fish, and may even be carnivorous?
A) ciliates
B) apicomplexans
C) dinoflagellates
D) brown algae
E) golden algae

c

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

c

Which of the following is not characteristic of ciliates?
A) They use cilia as locomotory structures or as feeding structures.
B) They are relatively complex cells.
C) They can exchange genetic material with other ciliates by the process of mitosis.
D) Most live as solitary cells in fresh water.
E) They have two or more nuclei.

c

Which process results in genetic recombination, but is separate from the process wherein the population size of
Paramecium increases?
A) budding
B) meiotic division
C) mitotic division
D) conjugation
E) binary fission

d

Why is the filamentous morphology of the water molds considered a case of convergent evolution with the
hyphae (threads) of fungi?
A) Fungi are closely related to the water molds.
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 A and B are correct.

c

The Irish potato famine was caused by an organism that belongs to which group?
A) ciliates
B) oomycetes
C) diatoms
D) apicomplexans
E) dinoflagellates

b

If one were to apply the most recent technique used to fight potato late blight to the fight against the malarial
infection of humans, then one 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 ʺcocktailʺ of at least three different pesticides against Anopheles mosquitoes.
E) insert genes from a Plasmodium-resistant strain of mosquito into Anopheles mosquitoes.

e

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 waterʹs 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?

c

A large seaweed that floats freely on the surface of deep bodies of water would be expected to lack which of the
following?
A) thalli
B) bladders
C) blades
D) holdfasts
E) gel-forming polysaccharides

d

The following are all characteristic of the water molds (oomycetes) except
A) the presence of filamentous feeding structures.
B) flagellated zoospores.
C) a nutritional mode that can result in the decomposition of dead organic matter.
D) a morphological similarity to fungi that is the result of evolutionary convergence.
E) a feeding plasmodium.

e

Waterʹs density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration
and using data from Table 28.1, 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

Judging from Table 28.1 and given that waterʹs density and, consequently, its buoyancy decrease at warmer
temperatures, in which environment should diatoms (and other suspended particles) sink most slowly?
A) cold freshwater
B) warm freshwater
C) cold seawater
D) warm seawater
E) warm brackish water

c

Using dead diatoms to ʺpumpʺ CO2 to the seafloor is feasible only if dead diatoms sink quickly. Consequently,
application of mineral fertilizers, such as iron, should be most effective at times when diatom
A) valves are thickest, and laminarin is being produced rather than oil.
B) valves are thickest, and oil is being produced rather than laminarin.
C) valves are thinnest, and laminarin is being produced rather than oil.
D) valves are thinnest, and oil is being produced rather than laminarin.

a

Theoretically, which two of the following present the richest potential sources of silica?
1. marine sediments consisting of foram tests
2. marine sediments consisting of diatom cases (valves)
3. marine sediments consisting of radiolarian shells
4. marine sediments consisting of dinoflagellate plates
A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 3 and 4

c

Thread-like pseudopods that can perform phagocytosis are generally characteristic of which group?
A) radiolarians and forams
B) gymnamoebas
C) entamoebas
D) amoeboid stage of cellular slime molds
E) oomycetes

a

Which of the following produce the dense glassy ooze found in certain areas of the deep-ocean floor?
A) forams
B) dinoflagellates
C) radiolarians
D) ciliates
E) apicomplexans

c

A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group?
A) diatoms
B) foraminiferans
C) radiolarians
D) gymnamoebas
E) ciliates

b

Typically as cells grow, their increase in volume outpaces their increase in surface area, and continued survival
requires undergoing asexual reproduction to reestablish a healthy surface area to volume ratio. Thus, which of
these is least likely to contribute to the ability of a single-celled foraminiferan to grow to a diameter of several
centimeters?
A) Its threadlike pseudopods dramatically increase its surface area to volume ratio.
B) Its symbiotic algae provide oxygen to the cytoplasm.
C) Its symbiotic algae absorb metabolic waste products from the cytoplasm.
D) Its symbiotic algae provide glucose to the cytoplasm.
E) Its calcium carbonate test contributes extra mass.

e

What makes certain red algae appear red?
A) They live in warm coastal waters.
B) They possess pigments that reflect and transmit red light.
C) They use red light for photosynthesis.
D) They lack chlorophyll.
E) They contain the pigment bacteriorhodopsin.

b

The largest seaweeds belong to which group?
A) red algae
B) green algae
C) brown algae
D) golden algae

c

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) red algae → cyanobacteria → land plants
E) cyanobacteria → red algae → green algae → land plants

a

The chloroplasts of all of the following are derived from ancestral red algae, except those of
A) golden algae.
B) diatoms.
C) dinoflagellates.
D) green algae.
E) brown algae.

d

A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. This
alga probably belongs to which group?
A) red algae
B) brown algae
C) green algae
D) dinoflagellates
E) golden algae

a

Green algae often differ from land plants in that some green algae
A) are heterotrophs.
B) are unicellular.
C) have plastids.
D) have alternation of generations.
E) have cell walls containing cellulose.

b

Which taxon of eukaryotic organisms is thought to be directly ancestral to the plant kingdom?
A) golden algae
B) radiolarians
C) foraminiferans
D) apicomplexans
E) green algae

e

If the Archaeplastidae are eventually designated a kingdom, and if the 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.

c

The best evidence for not classifying the slime molds as fungi comes from slime moldsʹ
A) DNA sequences.
B) nutritional modes.
C) choice of habitats.
D) physical appearance.
E) reproductive methods.

a

Which pair of alternatives is highlighted by the life cycle of the cellular slime molds, such as Dictyostelium?
A) prokaryotic or eukaryotic
B) plant or animal
C) unicellular or multicellular
D) diploid or haploid
E) autotroph or heterotroph

c

Which of the following correctly pairs a protist with one of its characteristics?
A) diplomonads : micronuclei involved in conjugation
B) ciliates : pseudopods
C) apicomplexans : parasitic
D) gymnamoebas : calcium carbonate test
E) foraminiferans : abundant in soils

c

Which of the following statements concerning protists is false?
A) All protists are eukaryotic organisms; many are unicellular or colonial.
B) The primary organism that transmits malaria to humans by its bite is the tsetse fly.
C) All apicomplexans are parasitic.
D) Cellular slime molds have an amoeboid stage that may be followed by a stage during which spores are
produced.
E) Euglenozoans that are mixotrophic contain chloroplasts.

b

Which of the following is correctly described as a primary producer?
A) oomycete
B) kinetoplastid
C) apicomplexan
D) diatom
E) radiolarian

d

A certain unicellular eukaryote has a siliceous (glasslike) shell and autotrophic nutrition. To which group does
it belong?
A) dinoflagellates
B) diatoms
C) brown algae
D) radiolarians
E) oomycetes

b

You are given the task of designing an aerobic, mixotrophic protist that can perform photosynthesis in fairly
deep water (e.g., 250 m deep), and can also crawl about and engulf small particles. With which two of these
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

d

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.

a

Some protists, formerly united as the ʺamitochondriateʺ clade, have recently been shown to be rather diverse.
Some of them possess neither mitochondria nor mitochondrial genes (and have been classified as fungi). Others
possess no mitochondria, but do have mitochondrial genes in their nuclear genome. Still others have modified
mitochondria (viz. mitosomes or hydrogenosomes). Which statement(s) represent(s) consequences of these
recent findings?
1. The amitochondriates do not comprise a true clade.
2. The ʺamitochondriate hypothesisʺ concerning the root of the eukaryotic tree has been strengthened.
3. Just as there is a diversity of cyanobacterial descendants among eukaryotes, so too is there a diversity of
alpha-proteobacterial descendants among the eukaryotes.
4. If the amitochondriate organisms continued to be recognized as a taxon, this taxon would be polyphyletic.
5. Horizontal gene transfer involving mitochondrial genes has occurred in some amitochondriate organisms.
A) 1 only
B) 1 and 4
C) 2 and 3
D) 1, 3, and 5
E) all except 2

e

Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as do the white blood
cells of animals. If one were to erect a taxon that included all organisms that have cells with pseudpods, 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.

a

You are designing an artificial drug-delivery ʺcellʺ 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

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

Test tube 2 contains
A) Paramecium
B) Navicula (diatom)
C) Pfiesteria (dinoflagellate)
D) Entamoeba
E) Plasmodium

c

Test tube 4 contains
A) Paramecium
B) Navicula (diatom)
C) Pfiesteria (dinoflagellate)
D) Entamoeba
E) Plasmodium

e

Test tube 5 contains
A) Paramecium
B) Navicula (diatom)
C) Pfiesteria (dinoflagellate)
D) Entamoeba
E) Plasmodium

a

Test tube 3 contains
A) Paramecium
B) Navicula (diatom)
C) Pfiesteria (dinoflagellate)
D) Entamoeba
E) Plasmodium

b

Test tube 1 contains
A) Paramecium
B) Navicula (diatom)
C) Pfiesteria (dinoflagellate)
D) Entamoeba
E) Plasmodium

d

Which of these are actual mutualistic partnerships that involve a protist and a host organism?
A) cellulose-digesting gut protists : wood-eating termites
B) dinoflagellates : reef-building coral animals
C) Trichomonas : humans
D) algae : certain foraminiferans
E) all except C

e

Which of the following statements concerning living phytoplanktonic organisms are true?
1. They are important members of communities surrounding deep-sea hydrothermal vents.
2. They are important primary producers in most aquatic food webs.
3. They are important in maintaining oxygen in Earthʹs seas and atmosphere.
4. They are most often found growing in the sediments of seas and oceans.
5. They can be so concentrated that they affect the color of seawater.
A) 1 and 4
B) 1, 2, and 4
C) 2, 3, and 4
D) 2, 3, and 5
E) 3, 4, and 5

d

Which term most accurately describes the nutritional mode of healthy P. bursaria?
A) photoautotroph
B) photoheterotroph
C) chemoheterotroph
D) chemoautotroph
E) mixotroph

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

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

a

If both host and alga can survive apart from each other, then which of these best accounts for their ability to
live together?
A) genome fusion
B) horizontal gene transfer
C) genetic recombination
D) conjugation
E) metabolic cooperation

e

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.

d

If the chloroplasts of the zoochlorellae are very similar to those found in the photosynthetic cells of land plants,
then Chlorella is probably what type of alga?
A) red
B) green
C) brown
D) golden

b

A P. bursaria cell that has lost its zoochlorellae is said to be ʺaposymbiotic.ʺ It might be able to replenish its
contingent of zoochlorellae by ingesting them without subsequently digesting them. Which of these situations
would be most favorable to the re-establishment of resident zoochlorellae, assuming compatible Chlorella are
present in P. bursariaʹs 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 ʺaposymbiotic.ʺ 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

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.

c

Can P. bursaria live in association with any and all strains/species of Chlorella? In an experiment to help answer
this question, Chlorella was collected, and cultured separately, from three different sources: (1) P. bursaria
cytoplasm, (2) free-living Chlorella, and (3) from cytoplasm of other protist species. A population of P. bursaria
was treated with the herbicide, paraquat, which killed all of its zoochlorellae, but otherwise left P. bursaria
unharmed. The zoochlorella-free paramecia were then introduced to a 1:1:1 mixture of Chlorella from the three
cultures listed above, and subsequently reestablished a contingent of zooclorellae. Two weeks later,
zoochlorellae were collected from the P. bursaria cells and tested to determine which Chlorella strain(s) had been
maintained within P. bursaria.
The different strains of Chlorella are morphologically indistinguishable. Consequently, which of these would be
the best test to perform on Chlorella, both before and after re-establishment of zoochlorellae, to determine
which Chlorella strains had been maintained within P. bursaria?
A) Determine the chemical composition of its cell wall.
B) Determine the absorption spectrum of its photosynthetic pigments.
C) Determine the sequence of a portion of its mitochondrial DNA.
D) Determine the sequence of an exon of a ribosomal RNA gene.
E) Determine the endosymbiontʹs diameter.

c

Which conclusion is consistent with the data presented in Figure 28.2 above?
A) Co-adaptation between P. bursaria and the native strain of Chlorella has occurred.
B) All types of Chlorella tested are tolerated equally well by P. bursaria.
C) P. bursaria cannot reproduce in the absence of zoochlorellae as well as it can when zoochlorellae are
present.
D) Zoochlorellae derived from other protists are well adapted to survive within P. bursaria, relative to the
native strain.

a

Which of these precautions would have been most important to insuring the validity of the results?
A) Chlorella in the three cultures were genetically identical.
B) Roughly equal numbers of each strain of Chlorella were present in the reintroduction mixture.
C) The Chlorella cultures were free of bacteria.
D) The P. bursaria culture was free of bacteria.
E) The Chlorella DNA contained no introns.

b

Is P. bursariaʹs ability to detect and move toward light an innate ability, or is it due to the presence of
zoochlorellae? Arrange the following steps in the proper sequence needed to answer this question.
1. Introduce P. bursaria from both the experimental and control populations to an aquarium that lacks
free-living Chlorella, but that contains bacterial prey.
2. Remove equal amounts of water from the well-lit side of the aquarium and the poorly lit side of the
aquarium, census the number and kind of P. bursaria present in each sample.
3. Shine light on only one side of the aquarium containing aposymbiotic P. bursaria.
4. Expose one population of P. bursaria (the experimental population) to an herbicide to kill its zoochlorellae.
5. Collect healthy P. bursaria from the well-lit side of an aquarium and divide it into two equal populations: a
control population and an experimental population.
A) 5 → 4 → 1 → 2 → 3
B) 5 → 4 → 1 → 3 → 2
C) 4 → 1 → 5 → 3 → 2
D) 2 → 5 → 4 → 1 → 3
E) 2 → 5 → 4 → 3 → 1

b

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