Question 1

Plastids that are surrounded by more than two membranes are evidence of

Accepted Answer

A)  evolution from mitochondria. 
B)  fusion of plastids. 
C)  origin of the plastids from archaea. 
D)  secondary endosymbiosis.

Question 2

Green algae differ from land plants in that many green algae ________.

Accepted Answer

A)  are unicellular 
B)  have plastids 
C)  have alternation of generations 
D)  have cell walls containing cellulose

Question 3

You are given the task of designing an aerobic, mixotrophic protist that can perform photosynthesis in fairly deep water (for example, 250 metres deep) and can also crawl about and engulf small particles. With which two of the following structures would you provide your protist?

Accepted Answer

A)  hydrogenosomes and apicoplasts 
B)  apicoplasts and pseudopods 
C)  pseudopods and chloroplasts from red algae 
D)  chloroplasts from both red and green algae

Question 4

When a mosquito infected with Plasmodium first bites a human, the Plasmodium ________.

Accepted Answer

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

Question 5

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 gather 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.
-The motility that permits P. bursaria to move toward a light source is provided by ________.

Accepted Answer

A)  pseudopods 
B)  a single flagellum featuring the 9 + 2 pattern 
C)  many cilia 
D)  contractile vacuoles

Question 6

Including the membrane of the surrounding vesicle, how many phospholipid (not lipopolysaccharide) bilayers should be found around each P. chromatophora's chromatophore, and which one of these bilayers should have photosystems embedded in it?

Accepted Answer

A)  two; innermost 
B)  two; outermost 
C)  three; innermost 
D)  three; outermost

Question 7

Which of the following phylogenetic trees appropriately groups organisms A to F? The asterisk shows the occurrence of a specific, rare mutation. The organisms that contain the rare mutation are also shown in bold.

Accepted Answer

A) 
 
B) 
 
C) 
 
D)

Question 8

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?

Accepted Answer

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 metabolise glucose. 
D)  The host cell was able to survive anaerobic conditions with the engulfed cell alive.

Question 9

Based on the phylogenetic tree in this figure, which of the following statements is correct?

Accepted Answer

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.

Question 10

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.
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 relabelling P. chromatophora as a mixotroph instead of an autotroph?

Accepted Answer

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

Question 11

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 ________.

Accepted Answer

A)  Paramecium 
B)  Pfiesteria (dinoflagellate) 
C)  Entamoeba 
D)  Triceratium (diatom)

Question 12

Prokaryotic and eukaryotic flagella ________.

Accepted Answer

A)  have the same evolutionary origin 
B)  have different structures 
C)  require different sources of energy 
D)  contain their own DNA

Question 13

"Rare events" can help us understand evolutionary events, as shown in the figure. Which of the following statements explains the logic of this approach?

Accepted Answer

A)  Organisms with the mutation evolved convergently. 
B)  The mutation provided an adaptive advantage to the organisms that contained it. 
C)  Because the mutation likely occurred only once, all organisms with the mutation have a common ancestor with the mutation. 
D)  "Reverse evolution" does not occur.

Question 14

Many parasitic members of the excavates lack plastids and have highly reduced mitochondria. Which of the following statements explains these observations?

Accepted Answer

A)  These parasites live in dark, low-oxygen conditions, and therefore it was adaptive to move all plastid and mitochondrial genes to the nucleus. 
B)  The original, eukaryotic ancestors of these parasites did not engulf prokaryotes. 
C)  These parasites live in dark, low-oxygen conditions and therefore loss of genes for plastids and mitochondria did not result in lower fitness. 
D)  In the future, natural selection will favour descendants that acquire new plastid genes from today's prokaryotes.

Question 15

Diatoms are encased in petri-plate-like cases (valves) made of translucent hydrated silica whose thickness can be varied. The material used to store excess calories can also be varied. At certain times, diatoms store excess calories in the form of the liquid polysaccharide, laminarin, and at other times as oil. The following are data concerning the density (specific gravity) of various components of diatoms, and of their environment.
Specific Gravities of Materials Relevant to Diatoms
$$\begin{array} { | l | c | } 
\hline \text { Material } & \begin{array} { c } 
\text { Specific Gravity } \
\left( \mathrm { kg } / \mathrm { m } ^ { \mathbf { 3 } } \right)
\end{array} \
\hline \text { Pure water } & 1000 \
\hline \text { Seawater } & 1026 \
\hline \text { Hydrated silica } & 2250 \
\hline \text { Liquid laminarin } & 1500 \
\hline \text { Diatom oil } & 910 \
\hline
\end{array}$$
-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?

Accepted Answer

A)  mid-winter 
B)  early spring 
C)  late summer 
D)  late autumn

Question 16

Use the following information to answer the question.
Giardia intestinalis 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 metabolise 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 cysts of Giardia function most like the ________.

Accepted Answer

A)  mitochondria of ancestral diplomonads 
B)  nuclei of archaeans 
C)  endospores of bacteria 
D)  capsids of viruses

Question 17

Which of the following groups is matched with a correct anatomical feature?

Accepted Answer

A)  foraminifera → silicon-rich tests 
B)  dinoflagellata → holdfast 
C)  diatoms → tests made of cellulose 
D)  brown algae → blade

Question 18

Diatoms are encased in petri-plate-like cases (valves) made of translucent hydrated silica whose thickness can be varied. The material used to store excess calories can also be varied. At certain times, diatoms store excess calories in the form of the liquid polysaccharide, laminarin, and at other times as oil. The following are data concerning the density (specific gravity) of various components of diatoms, and of their environment.
Specific Gravities of Materials Relevant to Diatoms
$$\begin{array} { | l | c | } 
\hline \text { Material } & \begin{array} { c } 
\text { Specific Gravity } \
\left( \mathrm { kg } / \mathrm { m } ^ { \mathbf { 3 } } \right)
\end{array} \
\hline \text { Pure water } & 1000 \
\hline \text { Seawater } & 1026 \
\hline \text { Hydrated silica } & 2250 \
\hline \text { Liquid laminarin } & 1500 \
\hline \text { Diatom oil } & 910 \
\hline
\end{array}$$
-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?

Accepted Answer

A)  cold fresh water 
B)  warm fresh water 
C)  cold seawater 
D)  warm seawater

Question 19

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 ________.

Accepted Answer

A)  Paramecium 
B)  Pfiesteria (dinoflagellate) 
C)  Entamoeba 
D)  Plasmodium

Exam 28: Protists