Question 1

Trichocysts are
A) sharp darts produced by ciliates.
B) needlelike structures found in radiolarians.
C) spore-containing structures produced by slime molds.
D) resting stages in apicomplexan life cycles.
E) produced by coral animals.

Accepted Answer

Trichocysts are sharp, dart-like structures found in ciliates. They can be rapidly discharged for defense or immobilization of prey.

Question 2

Which of the following is not a means of locomotion in protists?
A) Amoeboid motion using pseudopods
B) Cilia, allowing movement both forward and backward
C) Flagella to push or pull a cell forward
D) Propulsion by means of expelling water from the contractile vacuole
E) Undulating membranes in parabasalids

Accepted Answer

Propulsion by means of expelling water from the contractile vacuole is not a means of locomotion in protists. The contractile vacuole primarily functions in osmoregulation, not locomotion.

Question 3

Which of the following can cause rats to lose their fear of cats?
A) Giardia, one of the excavates
B) Toxoplasma, an apicomplexan
C) Trichomonas vaginalis, a parabasalid
D) Amoebas of the heterolobosean genus Naegleria
E) Dinoflagellates of the genus Alexandrium

Accepted Answer

Toxoplasma is known to alter the behavior of rats and cause them to lose their fear of cats, which can make them more vulnerable to predation and increase the likelihood of the parasite being transmitted to its definitive host, the cat.

Question 4

Which of the following is many meters long, photosynthetic, and a protist?
A) Sphagnum moss
B) Macrocystis, a brown alga
C) Slime mold
D) Ginkgo tree
E) Euglena, one of the excavates

Accepted Answer

Macrocystis is a brown alga that can grow to be upwards of 60 meters long and is photosynthetic, making it the best choice among the options listed.

Question 5

Living foraminiferans have been found at the deepest depth of the world's oceans—10,896 m down in the Western Pacific's Challenger Deep.What explains why foraminiferans cannot secrete normal shells at these depths?
A) There is insufficient sunlight for photosynthesis.
B) There is insufficient calcium carbonate in the surrounding water.
C) It is too deep for coral animals.
D) There is insufficient silica in the surrounding water.
E) There is not enough organic matter to scavenge as an energy source for foraminiferans to build their shells.

Accepted Answer

Foraminiferans secrete shells made of calcium carbonate. At great depths, the surrounding water may not have sufficient amounts of calcium carbonate for foraminiferans to build their shells.

Question 6

Organelles called trichocysts are _______ organelles, and occur in _______.
A) defensive; radiolarians
B) defensive; ciliates
C) propulsive; radiolarians
D) propulsive; ciliates
E) propulsive; dinoflagellates

Accepted Answer

Trichocysts are defensive organelles that occur in ciliates.

Question 7

_______ possess(es) contractile vacuoles, which enable water balance in _______.
A) The malaria-causing parasite Plasmodium; red blood cells
B) Foraminiferans; salt water
C) Ciliates; fresh water
D) Kelp; salt water
E) Radiolarians; salt water

Accepted Answer

Ciliates possess contractile vacuoles which enable water balance in fresh water. The other options are incorrect because Plasmodium does not have contractile vacuoles and it lives inside red blood cells, foraminiferans and radiolarians live in salt water environments, and kelp does not have contractile vacuoles.

Question 8

Which is the best description of an absorptive heterotroph?
A) It secretes enzymes that digest large molecules into smaller molecules it can absorb.
B) It engulfs large molecules into food vacuoles where acids digest them into nutrients.
C) It absorbs sunlight energy used to digest food particles.
D) It is both photosynthetic and heterotrophic.
E) It is absorbed into other organisms for nutrients.

Accepted Answer

An absorptive heterotroph secretes enzymes that digest large molecules into smaller molecules it can absorb.

Answer: B 
 This description matches a phagocytic heterotroph, which engulfs large molecules into food vacuoles where acids digest them into nutrients.

Answer: C 
 This description matches a photoautotroph, which uses sunlight energy to produce food through photosynthesis.

Answer: D 
 This description matches a mixotroph, which is both photosynthetic and heterotrophic.

Answer: E 
 This description does not match any of the known types of heterotrophs.

Question 9

Which of the statement about diatoms is false?
A) They produce a large portion of Earth's oxygen through photosynthesis.
B) They are endosymbiotic with corals.
C) They can form a major component of sedimentary rocks.
D) They have a great variety of intricate forms.
E) Their fossil remains are used in ecologically-friendly pesticides.

Accepted Answer

Diatoms are not endosymbiotic with corals. Instead, they are photosynthetic organisms that can form partnerships with various other organisms, such as planktonic copepods or invertebrates living in reef ecosystems.

Question 10

Radiolarians have long, thin pseudopods stiffened by microtubules that help increase surface area.What is most likely to be the function of the stiff pseudopods?
A) Capturing prey
B) Helping the cell float
C) Coordinating movement for locomotion
D) Storing oil
E) Spearing marine amoebas, their main prey

Accepted Answer

Helping the cell float. The stiff pseudopods increase the surface area of the cell, which helps it to float in water.

Question 11

Which statement about dinoflagellates is false?
A) They have elaborate shells composed of calcium carbonate.
B) They produce red tides that are toxic to shellfish.
C) They are important primary producers in plankton.
D) They contribute an important component of atmospheric oxygen.
E) They are common endosymbionts in both animals and other protists.

Accepted Answer

Dinoflagellates have shells that are composed of cellulose plates called "thecae," not calcium carbonate.

Question 12

Which of the following can be large enough that an individual organism is easily visible to the naked eye?
A) Brown algae
B) Dinoflagellates
C) Toxoplasma
D) Foraminiferans
E) Diatoms

Accepted Answer

Brown algae can be very large, some species can grow up to 50 meters in length. This makes them large enough that an individual organism is easily visible to the naked eye. Dinoflagellates, Foraminiferans, and Diatoms are all unicellular organisms and are too small to be easily visible without the aid of a microscope. Toxoplasma is a protozoan parasite that is also too small to be visible without magnification.

Question 13

What feature of unicellular eukaryotes is associated with breakdown of ingested food materials by acids, particularly in ciliates?
A) Endosymbiosis
B) Nuclear membrane
C) Digestive vacuole
D) Flexible cell membrane
E) Complex cytoskeleton

Accepted Answer

The feature associated with breakdown of ingested food materials by acids, particularly in ciliates, is a digestive vacuole. In unicellular eukaryotes, such as ciliates, specialized organelles called digestive vacuoles can form around ingested food particles. These vacuoles are capable of breaking down the food through the use of digestive enzymes and low pH levels.

Question 14

A whitish, cottony mold growing on dead fish or dead insects in water is likely to be produced by a(n)
A) member of the oomycetes, such as Saprolegnia.
B) amoebozoan.
C) radiolarian.
D) brown alga.
E) ciliated alveolate.

Accepted Answer

The whitish, cottony mold growing on dead fish or dead insects in water is most likely to be produced by an oomycete, specifically the genus Saprolegnia. Oomycetes are a group of water molds that are commonly found in freshwater and marine environments. Saprolegnia is known to be a common saprophytic oomycete that grows on dead or decaying aquatic animals, plants, and invertebrates.

Question 15

Two members of the excavate clade that can cause disease are
A) euglenids and kinetoplastids.
B) dinoflagellates and apicomplexans.
C) loboseans and plasmodial slime molds.
D) cercozoans and foraminiferans.
E) diplomonads and parabasalids.

Accepted Answer

Diplomonads and parabasalids are two members of the excavate clade that can cause disease. Diplomonads are responsible for causing gastrointestinal infections such as giardiasis, while parabasalids can cause sexually transmitted diseases such as trichomoniasis.

Question 16

The malaria-causing organism Plasmodium is a member of the group called Apicomplexans, which
A) are all parasites. 
B) have simple life cycles.
C) contain multiple contractile vacuoles.
D) typically have a single host.
E) reproduce only asexually.

Accepted Answer

The text explicitly states that Apicomplexans are parasites.

Answer: D
 The text suggests that Apicomplexans typically have a single host.

The other choices are incorrect based on the information provided.

Question 17

Certain protists have a contractile vacuole, which collects and expels excess pure water (H₂O).This is most useful for A) slime molds locomoting on dry land. B) protists in salt water maintaining a hypotonic internal environment. C) dinoflagellates evading predators. D) protists in fresh water maintaining a hypertonic internal environment. E) radiolarians moving by jet propulsion.

Accepted Answer

Protists in fresh water need to maintain a hypertonic internal environment, which means that they have a higher concentration of solutes than their surrounding environment. This results in water moving into their cells, which can cause them to burst if they do not have a mechanism to expel excess water. The contractile vacuole allows these protists to collect and expel excess pure water, thereby maintaining a proper internal environment. Slime molds, dinoflagellates, and radiolarians do not specifically require a contractile vacuole to survive in their respective environments. Protists in saltwater require a mechanism to pump ions out of their cells to maintain a hypertonic internal environment, but the contractile vacuole is not involved in this process.

Question 18

The locomotor organelles of dinoflagellates occur in the equatorial and longitudinal grooves of the cell.Members of the genus Paramecium have a form of locomotion that is generally more precise than locomotion by dinoflagellates.This is because paramecia use _______ in locomotion.
A) flagella
B) trichocysts
C) digestive vacuoles
D) the oral groove
E) rows of cilia

Accepted Answer

Paramecia use rows of cilia in a precise and coordinated manner for locomotion, allowing them to move in a certain direction and change direction quickly.

Question 19

_______ secrete external shells of calcium carbonate, which formed much of the world's limestone, as used in the ancient pyramids of Egypt.Long pseudopods extend through pores in the shells for locomotion.
A) Foraminiferans
B) Diatoms
C) Dinoflagellates
D) Water molds
E) Radiolarians

Accepted Answer

Foraminiferans secrete external shells of calcium carbonate and use long pseudopods for locomotion through pores in the shells. Diatoms and dinoflagellates have cell walls made of silica. Water molds are not capable of secreting shells. Radiolarians also secrete external shells of silica, rather than calcium carbonate.

Question 20

After a long vacation you return to find your goldfish has died.Its body is covered in white filaments that are resistant to the fungicide you added to the tank to prevent organisms with cell walls made of chitin from growing.The mystery filaments are likely part of which organism?
A) A dinoflagellate
B) An oomycete
C) A diatom
D) A cellular slime mold
E) A plasmodial slime mold

Accepted Answer

Oomycetes, also known as water molds, have cell walls made of cellulose and glucans which are resistant to many fungicides. Their filamentous structures could explain the appearance of the white filaments on the goldfish's body. The other choices (A, C, D, E) do not have cell walls made of chitin and are therefore unlikely to be the source of the mystery filaments.

Quiz 26: The Origin and Diversification of Eukaryotes

Trichocysts are

Which of the following is not a means of locomotion in protists?

Which of the following can cause rats to lose their fear of cats?

Which of the following is many meters long, photosynthetic, and a protist?

Living foraminiferans have been found at the deepest depth of the world's oceans—10,896 m down in the Western Pacific's Challenger Deep.What explains why foraminiferans cannot secrete normal shells at these depths?

Organelles called trichocysts are _ organelles, and occur in _.

_ possess(es) contractile vacuoles, which enable water balance in _.

Which is the best description of an absorptive heterotroph?

Which of the statement about diatoms is false?

Radiolarians have long, thin pseudopods stiffened by microtubules that help increase surface area.What is most likely to be the function of the stiff pseudopods?

Which statement about dinoflagellates is false?

Which of the following can be large enough that an individual organism is easily visible to the naked eye?

What feature of unicellular eukaryotes is associated with breakdown of ingested food materials by acids, particularly in ciliates?

A whitish, cottony mold growing on dead fish or dead insects in water is likely to be produced by a(n)

Two members of the excavate clade that can cause disease are

The malaria-causing organism Plasmodium is a member of the group called Apicomplexans, which

Certain protists have a contractile vacuole, which collects and expels excess pure water (H₂O) .This is most useful for

The locomotor organelles of dinoflagellates occur in the equatorial and longitudinal grooves of the cell.Members of the genus Paramecium have a form of locomotion that is generally more precise than locomotion by dinoflagellates.This is because paramecia use _______ in locomotion.

_______ secrete external shells of calcium carbonate, which formed much of the world's limestone, as used in the ancient pyramids of Egypt.Long pseudopods extend through pores in the shells for locomotion.

After a long vacation you return to find your goldfish has died.Its body is covered in white filaments that are resistant to the fungicide you added to the tank to prevent organisms with cell walls made of chitin from growing.The mystery filaments are likely part of which organism?