Question 1

Given the putative ancestry of Giardia's mitosome, what should we predict is true of the mitosome?

Accepted Answer

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. B

Question 2

The evolution of complex multicellularity in eukaryotes

Accepted Answer

A)   occurred only once, in the common ancestor of all eukaryotes.
B)   occurred only once, in the common ancestor of all multicellular eukaryotes.
C)   occurred only once, in the animal lineage.
D)   is not documented by the fossil record.
E)   occurred independently in several different eukaryotic lineages. E

Question 3

Which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells?

Accepted Answer

A)   the existence of structural and molecular differences between the plasma membranes of prokaryotes and the internal membranes of mitochondria and chloroplasts
B)   the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts
C)   the size disparity between most prokaryotic cells and most eukaryotic cells
D)   the observation that some eukaryotic cells lack mitochondria B

Question 4

The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?

Accepted Answer

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

Question 5

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?

Accepted Answer

A)   red algae
B)   brown algae
C)   green algae
D)   dinoflagellates
E)   golden algae

Question 6

The next few questions refer to the following description.
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.
-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?

Accepted Answer

A)   parasitic
B)   commensalistic
C)   toxic
D)   predator-prey
E)   mutualistic

Question 7

Multicellular colonies of plant cells adhere to each other primarily by ________, whereas multicellular colonies of animal cells are typically held together by ________.

Accepted Answer

A)   fusion of cellular membranes; cell walls
B)   cell walls; fused cellular membranes
C)   cell walls; proteins
D)   interlocking chloroplasts; interlocking mitochondria
E)   interlocking cellular shapes (like puzzle pieces) ; large, calcified capsules

Question 8

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

Accepted Answer

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.

Question 9

All protists are

Accepted Answer

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

Question 10

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

Accepted Answer

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

Question 11

You are given five test tubes, each containing an unknown protist, and your task is to read the following description and match these five protists to the correct test tube.
In test tube 1, you observe an organism feeding. Your sketch of the organism looks very similar to Figure 25.1. When light, especially red and blue light, is shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 2 and 3. Chemical analysis of test tube 3 indicates the presence of substantial amounts of silica. Chemical analysis of test tube 2 indicates the presence of a chemical that is toxic to fish and humans. Microscopic analysis of organisms in test tubes 2, 4, and 5 reveals the presence of permanent, membrane-bounded sacs just under the plasma membrane. Microscopic analysis of organisms in test tube 4 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 5 reveals the presence of one large nucleus and several small nuclei in each organism.  Figure 25.1
The next few questions refer to the following description and Figure 25.1.
-Test tube 5 contains

Accepted Answer

A)   Paramecium.
B)   Navicula (diatom) .
C)   Pfiesteria (dinoflagellate) .
D)   Entamoeba.
E)   Plasmodium.

Question 12

The evolution of multicellularity in animals required adaptations that promoted

Accepted Answer

A)   cellular migration and intercellular communication.
B)   cellular migration and cellular adhesion.
C)   cellular adhesion and intercellular communication.
D)   photosynthesis and cellular migration.
E)   cellular fusion and regeneration.

Question 13

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.

Accepted Answer

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

Question 14

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

Accepted Answer

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

Question 15

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.

Accepted Answer

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

Question 16

A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group?

Accepted Answer

A)   diatoms
B)   foraminiferans
C)   radiolarians
D)   gymnamoebas

Question 17

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 ________.

Accepted Answer

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

Question 18

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

Accepted Answer

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.

Question 19

The best evidence for not classifying the slime molds as fungi comes from slime molds'

Accepted Answer

A)   DNA sequences.
B)   nutritional modes.
C)   choice of habitats.
D)   physical appearance.
E)   reproductive methods.

Question 20

Which of the following is correctly described as a primary producer?

Accepted Answer

A)   oomycete
B)   kinetoplastid
C)   apicomplexan
D)   diatom
E)   radiolarian

Exam 25: The Origin and Diversification of Eukaryotes