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Exam 28: Protists

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Question 1

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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 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?

E) B) and C)
F) A) and C)

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Question 2

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Trypanosome infections evade attacks by host immune systems through which of the following mechanisms?

A) production of new cell-surface proteins with a different molecular structure by each new generation
B) production of toxins that kill lymphocytes
C) insertion of its DNA into the nuclear DNA of host cells
D) infection of lymphocytes leading to a decline in the host's ability to fight infection

E) B) and D)
F) A) and B)

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Question 3

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A particular species of protist has obtained a chloroplast via secondary endosymbiosis. You know this because the chloroplasts ________.

Use the following information to answer the question. 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 ________.

Use the following description and table to answer the question. 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 $\begin{array}{|c|c|}\hline \text { Material } & \begin{array}{c}\text { Specific Gravity } \\\left(\mathrm{kg} / \mathrm{m}^{3}\right) \end{array} \\\hline \text { Pure water } & 1000 \\\hline \text { Seawater } & 1026 \\\hline \text { Hydrated silica } & 2250 \\\hline \text { Diquid laminarin } & 1500 \\\hline \text { Diatom oil } & 910\\\hline \end{array}$ 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?

Which of the following organisms is a producer?

Which group is incorrectly paired with its description?

Dinoflagellates ________.

Which of the following approaches would be most likely to cause evolution of a drug-resistant strain of Plasmodium?

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, the taxon would ________.

A gelatinous seaweed that grows in shallow, cold water and undergoes heteromorphic alternation of generations is most probably what type of alga?

All protists are ________.

Imagine that some members of an aquatic species of motile, photosynthetic protists evolve to become parasitic to fish. They gain the ability to live in the fish gut, absorbing nutrients as the fish digests food. Over time, which of the following phenotypic changes would you expect to observe in this population of protists?

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?

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 ________.

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

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) ________.

Use the following information to answer the question. 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. Which term best describes the symbiotic relationship of well-fed P. bursaria to their zoochlorellae?

Many chlorophytes are unicellular, but others are bigger and more complex. The fact that increased size and complexity evolved in different ways indicates ________.

Which of the following results would be most likely if a layer of warm, light water caused by ocean surface warming blocks nutrient upwelling?