Question 1

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

Accepted Answer

The description matches that of a brown alga, which is known for its heteromorphic alternation of generations and growth in shallow, cold water. Red and green algae also undergo alternation of generations but do not typically grow in cold water. Yellow algae do not commonly exhibit heteromorphic alternation of generations.

Question 2

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

Accepted Answer

A primary producer is an organism that produces organic matter from inorganic substances through photosynthesis or chemosynthesis. Diatoms are unicellular algae that are known for their unique cell walls made of silica and are important primary producers in aquatic environments.

Question 3

Living diatoms contain brownish plastids. If global warming causes blooms of diatoms in the surface waters of Earth's oceans, how might this be harmful to the animals that build coral reefs?

Accepted Answer

The endosymbiotic dinoflagellates that live within the tissues of coral animals require light to perform photosynthesis and provide the coral with essential nutrients. If diatoms were to bloom in the surface waters above the coral, they could block light from reaching the dinoflagellates and disrupt the delicate balance of this symbiotic relationship. This could lead to stress, bleaching, and even death of the coral animals.

Question 4

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 28.1. 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 28.1
-Test tube 5 contains

Accepted Answer

Paramecium is a common organism that can be found in test tubes during laboratory experiments, often used to study protozoan behavior and characteristics.

Question 5

The next few questions refer to the following description and Table 28.1.
Diatoms are encased in Petri-platelike 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.
Table 28.1 Specific Gravities of Materials Relevant to Diatoms
 
-Water's 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?

Accepted Answer

The density of water decreases at warmer temperatures, so during late summer when the water is warmest, diatoms would store excess calories mostly as oil because oil has a lower density than water.

Question 6

Which of the following are actual mutualistic partnerships that involve a protist and a host organism?

Accepted Answer

A, B, and D describe mutualistic relationships involving protists. In these partnerships, both the protist and the host organism benefit from the relationship. For example, cellulose-digesting gut protists help wood-eating termites digest wood, dinoflagellates provide reef-building coral animals with nutrients through photosynthesis, and certain algae live in a mutualistic relationship with foraminiferans, providing them with energy through photosynthesis. Trichomonas and humans (C) do not have a mutualistic relationship; Trichomonas vaginalis is a pathogen in humans.

Question 7

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)

Accepted Answer

Diatoms are unicellular algae that are known for their silica-based cell walls, which make them very resistant to physical damage. They are photosynthetic and can be found in the upper layers of water where there is good light penetration. They cannot swim on their own and rely on ocean currents for transportation.

Question 8

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, what would be true of such a taxon?

Accepted Answer

The taxon would be polyphyletic because it would include organisms from multiple evolutionary lineages that do not share a recent common ancestor, but have independently evolved the trait of having pseudopods.

Question 9

Which of the following statements concerning protists is true?

Accepted Answer

Not all protists are autotrophs and some have modified mitochondria known as hydrogenosomes or mitosomes.

Answer: None of the statements are true except for the fact that slime molds have an amoeboid stage that may be followed by a stage during which spores are produced.

Therefore, the best choice is:
Answer: A

Question 10

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

For deep-water photosynthesis, chloroplasts from red algae are ideal because they can absorb light at longer wavelengths, which penetrates deeper into the water. Pseudopods would allow the protist to crawl and engulf particles, fitting the mixotrophic and mobile criteria.

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 28.1. 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 28.1
-Test tube 3 contains

Accepted Answer

The presence of substantial amounts of silica in chemical analysis of test tube 3 indicates the presence of diatoms, which have silica-based cell walls.

Question 12

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

Accepted Answer

Slime molds have been found to have significant differences in DNA sequences compared to true fungi, providing the best evidence for not classifying them as fungi.

Question 13

You are designing an artificial drug-delivery "cell" that can penetrate animal cells. Which of these protist structures should provide the most likely avenue for research along these lines?

Accepted Answer

The apical complex is a structure found in certain protists, such as those in the phylum Apicomplexa, which allows them to penetrate host cells. This makes it a relevant structure for research in designing drug-delivery systems that need to enter animal cells.

Question 14

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 28.1. 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 28.1
-Test tube 2 contains

Accepted Answer

The presence of a chemical toxic to fish and humans is a characteristic of Pfiesteria, a dinoflagellate known for producing toxins. The other organisms listed do not produce such toxins.

Question 15

Green algae differ from land plants in that many green algae

Accepted Answer

While some green algae may form multicellular colonies, the majority are unicellular. This distinguishes them from most land plants, which are multicellular.

Answer: C
 Like land plants, green algae have plastids, which are organelles that perform photosynthesis. In fact, it is believed that land plants evolved from a type of green algae.

Answer: D
 While some species of green algae have life cycles with both sexual and asexual phases, they do not have a complete alternation of generations like land plants do.

Answer: E
 Green algae (like most algae) have cell walls made of cellulose, but the specific composition and structure of their walls may be different than those of land plants.

Question 16

Which pair of alternatives is highlighted by the life cycle of the cellular slime molds, such as Dictyostelium?

Accepted Answer

The life cycle of cellular slime molds involves the transition from unicellular amoeboid cells to a multicellular stage where cells aggregate to form a slug-like structure. This slug then becomes a fruiting body that releases spores for dispersal. Therefore, the alternative highlighted by the life cycle of cellular slime molds is unicellular or multicellular.

Question 17

If the Archaeplastidae are eventually designated a kingdom, and if land plants are excluded from this kingdom, then what will be true of this new kingdom?

Accepted Answer

If land plants are excluded from this new kingdom, then it will be paraphyletic since it will include some but not all descendants of a common ancestor. Land plants, as a derived group, would be excluded from this new kingdom, causing it to be paraphyletic.

Question 18

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

Red algae are adapted to live in deeper water and can absorb blue light, allowing them to photosynthesize at greater depths. Additionally, red algae are typically multicellular, making this the most likely group for the described alga. Brown algae and green algae can also be multicellular, but brown algae typically do not live at such depths, and green algae do not typically absorb blue light. Dinoflagellates and golden algae are typically unicellular and may not be adapted to live at such depths.

Question 19

The chloroplasts of all of the following are thought to be derived from ancestral red algae, except those of

Accepted Answer

Green algae chloroplasts are derived from ancestral green algae, not red algae.

Question 20

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 28.1. 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 28.1
-Test tube 4 contains

Accepted Answer

The presence of an apicoplast in each organism is a defining characteristic of Plasmodium, a genus of parasitic protists responsible for causing malaria in humans.

Quiz 28: Protists