Question 1

The manufacture of which of the following products involves using materials that once belonged to a protist?

Accepted Answer

Diatomaceous earth, derived from the fossilized remains of diatoms (a type of protist), is used in cosmetics, filters, and as a component in chalk. Marble, however, is not related to protists.

Question 2

You discover a new lineage of protists.You examine several species of this lineage under the microscope and find a distinctive feature that sets them apart from other protists.Following the nomenclature style used to name the lineage Discicristata,you decide to name this new lineage Spherocristata.What is the distinctive feature that is reflected in the name?

Accepted Answer

The name Spherocristata reflects the distinctive feature of spherical cristae within the mitochondria of the protists in this lineage.

Question 3

Consider the following points: (a)All excavates live in environments where oxygen availability is low;(b)all excavates lack mitochondria;and (c)all excavates have some mitochondrial genes.Based on this information,which of the following statements is true of the excavate lineage?

Accepted Answer

Since all excavates have some mitochondrial genes, it is likely that their ancestors had mitochondria. However, the fact that they lack mitochondria today suggests that they lost them over time. This loss may have been adaptive in environments with low oxygen availability, as mitochondria rely on oxygen to produce energy.

Question 4

What is the major distinguishing feature of Amoebozoa?

Accepted Answer

Amoebozoa is characterized by the absence of a cell wall, which allows the cell to extend and form large lobes for movement. This distinguishes it from other protists which generally have a more defined cell shape.

Question 5

Which of the following groups is matched with an incorrect anatomical feature?

Accepted Answer

The answer of Which of the following groups is matched...

Question 6

The data graphed in Figure 29.3 could be an artifact if latrunculin A kills this species of diatoms (i.e.,that may be why the cells are not moving).Which of the following would be the best evidence that latrunculin A is not killing the cells?

Accepted Answer

If washing off the toxin from the culture allows the cells to move again, it indicates that the cells were not killed by the toxin but rather their movement was inhibited temporarily. This would provide evidence that latrunculin A is not killing the cells. Option B suggests that there were still some cells moving, but it is not clear if they were the same cells as before treatment or if they were a different, unaffected population. Option C is not relevant in determining if the toxin is killing the cells. Option D only indicates that another species of diatom may not be affected by the toxin, but it does not provide evidence about the species in question.

Question 7

Which of the major lineages of eukaryotes contain pronounced "feeding grooves" for digesting prey or organic debris?

Accepted Answer

The major lineage of eukaryotes that contain pronounced "feeding grooves" for digesting prey or organic debris is Excavata. Excavates have feeding grooves on their surface, which allows them to feed on various types of organic matter. The other lineages listed do not have this characteristic feature. Plantae are photosynthetic organisms, while Alveolata and Rhizaria have different feeding strategies.

Question 8

How was primary productivity measured in the phytoplankton experiment?

Accepted Answer

Primary productivity was measured by measuring the net CO₂ uptake by the phytoplankton. This is because primary productivity refers to the amount of organic matter produced by photosynthesis in a given time period, and this can be determined by measuring the rate of CO₂ uptake. Option B, the number of cells produced, is not a direct measure of primary productivity since cell abundance can be influenced by factors such as cell division and mortality. Option C, net CO₂ production, is the opposite of primary productivity since it refers to the amount of CO₂ released during respiration. Option D, accumulation of mutations, is not relevant to primary productivity since it relates to genetic changes in the phytoplankton population over time.

Question 9

Latrunculin A is a reversible toxin that disrupts the formation of actin fibers.A culture of a particular species of diatom was treated with this toxin diluted in a buffer,while another culture was treated only with the buffer (no toxin;control).The motility of cells in each culture was assessed by counting the number of cells that were moving during a defined period of time.Which of the following conclusion statements is reasonable based on the data in the bar graph presented below?

Accepted Answer

The bar graph shows that treatment with Latrunculin A, which disrupts the formation of actin fibers, greatly reduces the motility of cells in the culture. This suggests that actin fibers play an important role in the movement of this species of diatom. The control group also shows some decrease in motility relative to the untreated cells, but the effect is not as large as that observed in the Latrunculin A-treated group. This could indicate that some baseline level of actin fiber formation is necessary for movement, but full formation of actin fibers is required for optimal motility. Therefore, the best conclusion statement is that in this species of diatom, fully formed actin fibers are necessary for movement (Choice C).

Question 10

Which of the following best describes what scientists (the Bell research group)concluded about the effect of atmospheric CO₂ increases on phytoplankton's primary productivity?

Accepted Answer

The Bell research group found that after 1000 generations, phytoplankton showed a moderate increase in primary productivity in response to increased atmospheric CO₂ levels.

Question 11

Alternation of generations occurs in protists.Which of the following represents the correct sequence of events for this mode of reproduction?

Accepted Answer

Alternation of generations involves a cycle between a haploid gametophyte phase and a diploid sporophyte phase. In the gametophyte phase, gametes are produced by mitosis. These gametes fuse during fertilization to form a diploid zygote, which develops into a sporophyte. The sporophyte undergoes meiosis to produce haploid spores, which then develop into gametophytes.

Question 12

What is meant by the term "high-selected" lines in the phytoplankton experiment?

Accepted Answer

"High-selected" lines refer to phytoplankton lines that were subjected to high levels of environmental selection pressures, including high CO2 conditions. Therefore, both option A and B are correct, and the answer is E. Option C is not accurate as there is no indication in the passage that high-selected lines were allowed to grow at a faster rate than other lines of phytoplankton.

Question 13

Assume 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?

Accepted Answer

The photosynthetic protists would no longer need their chloroplasts since they would be living inside the fish gut and absorbing nutrients from the fish.

Question 14

Cultures of the same species of diatom referred to in the previous question were treated with BDM,a reversible inhibitor of myosin function.Which of the following predictions is consistent with the hypothesis that an actin-myosin interaction is necessary for motility?

Accepted Answer

The hypothesis states that an actin-myosin interaction is necessary for motility. If BDM, a reversible inhibitor of myosin function, is added, it should decrease the motility of the cells in culture if the hypothesis is correct. Therefore, choice A is the best option. BDM inhibits myosin function, which is required for movement in diatoms. If myosin is not functioning correctly, movement is impacted, and this would decrease the motility of the cells in culture.

Question 15

The dinoflagellate Pfiesteria piscicida can feed off algae and bacteria.They can also "steal" intact chloroplasts from algae and become photosynthetic.In the presence of large amounts of fish,Pfiesteria can secrete a toxin that kills fish,allowing it to feed on decaying fish matter.How would you classify this species?

Accepted Answer

Pfiesteria can act as a predator by secreting a toxin to kill fish, a primary producer by acquiring intact chloroplasts and becoming photosynthetic, and a detritivore by feeding on decaying fish matter. Therefore, the best choice is D, all of the above.

Question 16

Protists belong to the domain Eukarya.Which of the following is not a protist?

Accepted Answer

Yeast is a fungus, which belongs to a different kingdom (Fungi) from Protists. The other three options (kelp, red algae, and diatoms) are all examples of protists.

Quiz 29: Protists