Deck 36: The Protists

Question 1

Which of the following groups of eukaryotes are considered most closely related?

A) Red algae and plants
B) Slime moulds and fungi
C) Brown algae and green algae
D) Choanoflagellates and dinoflagellates
E) Mycetozoa and euglenoids

Answer 1

Red algae and plants

Question 2

Which of the following protist groups move using pseudopodia?

A) Diatoms
B) Rhizopods
C) Cellular slime moulds
D) Diplomonads
E) Apicomplexans

Answer 2

Rhizopods

Question 3

In which of the following groups of protists do typical species have a sexual life cycle that includes motile gametes?

A) Ciliates
B) Diatoms
C) Red algae
D) Water moulds
E) Green algae

Answer 3

Diatoms

Question 4

Which of the following protist groups contain species that form symbiotic associations with unicellular algae?

A) Dinoflagellates
B) Actinopods
C) Forams
D) Diatoms
E) Euglenoids

Question 5

Which of the following statements provides evidence supporting the endosymbiotic origin of mitochondria?

A) Mitochondria are absent in the most primitive eukaryotes.
B) Replication of mitochondria occurs by binary fission.
C) Mitochondria are surrounded by a double membrane.
D) Replication of the mitochondria is independent of cell division.
E) Some of the proteins needed in mitochondria are encoded by nuclear genes, which are transcribed and translated within the cytoplasm.

Question 6

A biologist is asked to examine and describe a newly discovered species from a sample of fresh-water plankton. The organism is a heterotrophic unicell with a single flagellum surrounded by a collar of microvilli. The biologist correctly predicts that this organism has

A) an elaborate, proteinaceous skeleton composed of overlapping, helical strips.
B) a basket-like skeleton made of silica strips, cemented together and surrounded by a membranous web.
C) an intricate spherical skeleton composed of siliceous spines radiating out from a central capsule.
D) a cytoskeletal extension composed of actin.
E) no skeleton.

Question 7

You have been asked to identify an organism that is a unicellular, free-living heterotroph. It has a single flagellum and is surrounded by a basket-shaped structure composed of silica strips. You would conclude that the organism is a

A) choanoflagellate.
B) diatom.
C) dinoflagellate.
D) euglenoid.
E) apicomplexa.

Question 8

Unicellular amoebae that aggregate to form a migratory colony when their food supply runs short are characteristic of

A) forams.
B) rhizopods.
C) myxomycetes.
D) cellular slime moulds.
E) acellular slime moulds.

Question 9

Which is the correct sequence of stages in the lifecycle of a typical myxomycete?

A) Sporangium, myxamoebae, zygote, plasmodium
B) Plasmodium, zygote, sporangium, myxamoebae
C) Zygote, myxamoebae, plasmodium, sporangium
D) Zygote, plasmodium, myxamoebae, sporangium
E) Myxamoebae, sporangium, zygote, plasmodium

Question 10

Diplomonads are

A) unicellular protists with two nuclei, each associated with a pair of flagella.
B) normally involved in parasitic relationships with animals.
C) considered more primitive than other protists because they lack mitochondria.
D) internal, disease-causing parasites found in the blood of humans and other vertebrates.
E) All of the answers are correct.

Question 11

A medical laboratory isolates an intestinal parasite responsible for a local epidemic of severe dysentery. The organism is unicellular with a pair of nuclei and multiple flagella. You would expect that this organism would also have

A) a ventral sucker to allow attachment to the wall of the host's digestive system.
B) a conical arrangement of microtubules and secretory structures to enable forced penetration of the cells lining the host's intestine.
C) mitochondria with specialised biochemical pathways for respiration in the anaerobic conditions within the digestive system of the host.
D) an axostyle of microtubules running along the membrane.
E) All of the answers are correct.

Question 12

Parabasalids are a small group of protists involved in parasitic or commensal relationships with animals. Parabasalids are unusual in that

A) they lack mitochondria.
B) they have plasmids contain cytochromea.
C) their mitochondria lack DNA and carry out anaerobic respiration.
D) they have a single mitochondrion, containing a large rod-shaped mass of DNA, at the base of the flagella.
E) their mitochondria are surrounded by three membranes, suggesting that the ancestors of Parabasalids gained their mitochondria by secondary endosymbiosis.

Question 13

Heliozoans are radially symmetrical unicells with intricate siliceous skeletons, found mainly in freshwater plankton. They feed by engulfing food particles that become trapped on the surface of numerous thin ray-like extensions of the cytoplasm that radiate from the surface. Each cytoplasmic extension is made rigid by a central rod of microtubules. Based on this description, Heliozoans would be classified as

A) forams.
B) actinopods.
C) rhizopods.
D) chrysophytes.
E) diatoms.

Question 14

Radiolarians are single-celled radially symmetrical protists with elaborate skeletons commonly composed of

A) cellulose.
B) silica.
C) calcium carbonate.
D) chitin.
E) interlocking proteinaceous strips.

Question 15

The photosynthetic eukaryotes

A) form a monophyletic group because it appears likely that a single endosymbiotic event produced the many different-coloured chloroplasts observed in protists and plants.
B) contain chloroplasts that have evolved from the cyanelles of Glaucophytes.
C) share an acquired organelle rather than a common ancestor.
D) have diverged into three distinct lineages: the 'green lineage' (green algae and plants), the 'brown lineage' (brown algae, diatoms and other chromists), and the 'red lineage' (red algae and dinoflagellates).
E) All the answers are correct.

Question 16

The phycobilin pigments, phycocyanin and phycoerythrin, are accessory photosynthetic pigments in the plastids of

A) rhodophytes.
B) chlorophytes.
C) phaeophytes.
D) chrysophytes.
E) glaucophytes.

Question 17

The photosynthetic pigments found in the plastids of green algae are

A) chlorophyll a, chlorophyll c and fucoxanthin.
B) chlorophyll a, chlorophyll c and peridinin.
C) chlorophyll a, chlorophyll b and ß-carotene.
D) chlorophyll a and fucoxanthin.
E) chlorophyll a and phycobilins.

Question 18

An alga is collected from very deep water (150 m). It has a multicellular growth form and non-motile gametes, and therefore is most likely to be a

A) chlorophyte.
B) chrysophyte.
C) phaeophyte.
D) cryptomonads.
E) rhodophyte.

Question 19

Cryptomonads differ from other photosynthetic protists in that they

A) acquired their chloroplasts by primary endosymbiosis.
B) store the products of photosynthesis outside the chloroplast.
C) have a second, much-reduced nucleus associated with the chloroplast.
D) have reticulopodia linking individual cells in an amoeboid plasmodium.
E) contain plastids with cytochrome a and c

Question 20

Chlorophytes and phaeophytes share all of the following characteristics EXCEPT

A) the presence of chlorophyll a.
B) the absence of a vascular system.
C) a wide range of commercial uses.
D) motile gametes with one smooth and one hairy flagellum.
E) mainly marine and multicellular.

Question 21

Typical heterokont protists have plastids that were almost certainly acquired through secondary endosymbioses. In addition to this,

A) heterokonts can be both photosynthetic, in the presence of light, and heterotrophic, in the dark.
B) heterokonts have two different kinds of nuclei, the micronucleus, involved in sexual reproduction and the macronucleus, which controls the everyday functions of the cell.
C) heterokont plastids contain a nucleomorph, a remnant of the nucleus of the secondary endosymbiont.
D) most heterokonts have lost their plastid and reverted to heterotrophy.
E) heterokonts have two flagella, an anteriorly directed, hairy or tinsel flagellum and a posteriorly directed, whiplash or smooth flagellum.

Question 22

Phytophthora, the pathogen responsible for diseases such as forest dieback and potato blight, exists as a network of coenocytic hyphae with cellulosic cell walls that penetrate and absorb nutrients from cells of the host plant. Dispersal of Phytophthora is by swimming zoospores with

A) one posteriorly directed smooth flagellum and one anteriorly directed hairy flagellum.
B) one smooth flagellum anchored at the base of the anterior gullet; a second short flagellum does not usually emerge from the gullet.
C) a multitude of short cilia that are evenly distributed across the surface and beat in synchronous waves.
D) a single transverse flagellum which propels them through the water.
E) one posteriorly directed flagellum, and one spiral flagellum positioned inside a transverse groove.

Question 23

Which of the following describes the skeleton of a dinoflagellate?

A) An elaborate array of trumpet-shaped calcium carbonate plates, forming a sphere.
B) A multichambered shell made of organic material hardened with calcium carbonate. The spirally arranged chambers have many tiny pores.
C) Spherical, with a distinctive equatorial constriction. The surface is covered by a complex pattern of projecting ridges, reinforced by internal plates of cellulose.
D) Long slender radial projections with scales of silica.
E) A pair of glass-like valves that fit together like the two halves of a Petri dish. The surface is highly ornamented with pores and spines.

Question 24

A biologist discovers an aquatic organism that is unicellular with well-developed organelles, including two kinds of nuclei. The organism is an active predator that engulfs smaller unicellular organisms. The biologist also observes that occasionally individuals are found in pairs that remain connected for several hours. Based on this information, the biologist concludes that the organism is a

A) euglenoid.
B) ciliate.
C) kinetoplast.
D) heterokont.
E) dinoflagellate.

Question 25

Euglenoids

A) have an anterior gullet with emergent and non-emergent flagella.
B) excrete undigested material through the cytoproct.
C) secrete an elaborate proteinaceous cell wall.
D) store the products of photosynthesis as paramylon granules inside their chloroplasts.
E) have a cytoskeleton composed of actin.

Question 26

All Euglenoids

A) have chloroplasts similar to green algae.
B) are fresh-water organisms.
C) are occasionally heterotrophic.
D) swim using a single long flagellum.
E) are parasitic.

Question 27

A biologist was asked to identify a unicellular organism collected from shallow marine waters. The organism secreted a multichambered porous test and extending through the pores were slender, brownish-coloured pseudopodia forming a protoplasmic net. Experiments showed that the growth of the test was greatest in the presence of light. Based on this information, the biologist concluded that the organism was a

A) diatom.
B) actinopod.
C) foram.
D) cercozoa.
E) dinoflagellate.

Question 28

The malarial parasite

A) contains a plastid
B) lacks a plastid.
C) retains a vestigial plastid.
D) has a double-membrane plastid.
E) has a non-photosynthetic plastid.

Question 29

Protists are diverse organisms and some store starch. Protists which store starch include

A) cryptomonads.
B) chrysophytes.
C) red algae.
D) diatoms.
E) haptophytes.

Question 30

Trypanosomes

A) are multicellular parasites which have two flagella.
B) are transmitted by sandflies and cause disease due to infection of human macrophage cells.
C) are free-swimming in the blood of humans, and avoid the host immune system by constantly changing their surface proteins.
D) contain a structure called a kinetoplast is located at the base of the flagella, adjacent to the mitochondrion.
E) store paramylon, a $\beta$ -(1 $\rightarrow$ 3) glucan, as granules in the cytoplasm.

Question 31

Forams

A) occur in great abundance as plankton, but do not occur in deepwater.
B) are mostly marine heterotrophs that produce elaborate calcareous (CaCO3) shells.
C) contain DNA that is composed of tiny DNA circles linked in a chain and forming an elongated rod-like structure.
D) are similar to green algae with fucoxanthin in the chloroplase, as well as chlorophyll a.
E) some cause a human disease called African Sleeping Sickness.

Question 32

Diplomonads are all of the following, EXCEPT

A) they are unicellular heterotrophic flagellates.
B) they have two nuclei.
C) they have two flagella.
D) they contain a sucker-like central disc which they use to attach to the gut of animals.
E) they have a large mitochondrion, and are restricted to anaerobic environment.

Question 33

Haptophytes

A) are extremely abundant in inland waters, frequently forming massive blooms.
B) contain a haptonema, s thread-like extension between the flagella, which is used to capture prey.
C) are close relatives of the chrysophytes as they also have heterokont flagellation.
D) contain spectacular, star-shaped silica skeletons.
E) use starch as a storage molecule.

Question 34

Laminarin is

A) a $\beta$ -(1 $\rightarrow$ 3) glucan, used as a storage compound by brown algae.
B) a unicellular golden-brown algae with a silica wall.
C) the elongated rod-like structure composed of tiny DNA circles linked in a chain.
D) an organism , the skeleton of which forms the chalk deposits such as the white cliffs of Dover.
E) the silica hoops that interconnect the silica valves of diatoms.

Question 35

Oomycetes

A) have distinctive vesicles of endoplasmic reticulum, corticol alvioli, beneath the plasma membrane.
B) store paramylon, a $\beta$ -(1 $\rightarrow$ 3) glucan, as granules in the cytoplasm.
C) have elaborate skeletons of silica.
D) have coenocytic hyphae with cellulose walls.
E) are extremely abundant in inland waters, frequently forming massive blooms.

Question 36

A molecular biologist is studying the physical structure of DNA from various eukarya when, much to her surprise, she notices the DNA from one organism is not packaged in nucleosomes. What type of organism could this be?

A) Diatom
B) Phaeophyte
C) Oomycete
D) Dinoflagellate
E) Cilliate

Question 37

A parasitic protist of mammalians contains a plastid that is necessary for the synthesis of at least one critical compound. How could this information be used in combatting this protist?

A) The plastid can be specifically targeted by a drug, thus killing the parasite without harming the host.
B) The host could be treated with a protisticide.
C) Plastids are not normally found in protists, therefore they are particularly susceptible to chemical interference.
D) The premise of the question is factually incorrect - protists cannot contains plastids.
E) Plastids do not have plastid-specific functions, therefore are not able to be manipulated to combat the host.

Question 38

What is the main function of the large mass of DNA present in the single mitochondrion near the base of the flagella in kinetoplasts?

A) Motion
B) Energy
C) E^- donation
D) Protein synthesis
E) Protein tagging, secretion and external targeting

Question 39

The phylogeny of protists was traditionally based on nutrition. Which of the following features is NOT used in more recent work to group protists?

A) Morphology
B) Biochemistry
C) Molecular features
D) Gene sequence
E) Protein structure

Question 40

A large prokaryotic organism engulfs a smaller one, but does not consume it. This is an example of

A) phagocytosis.
B) endosymbiosis.
C) exosymbiosis.
D) mutualistic engulfment.
E) an organelle.

Question 41

Sponges have collar cells called choanocytes that consist of a central flagellum surrounded by a microvilli collar. What organism does this bear a striking resemblance too?

A) Phytophthora
B) Slime mould
C) Choanoflagellate
D) Cercozoa
E) Euglenoid

Question 42

Two scientists working in the field discover a small slug-like creature which is approximately 1mm long. The two scientists disagree on the origins of the organism: one believes it to be a true mollusc, the other suspects it could be a pseudoplasmodium. How could it be most simply determined what the true nature of the organism is?

A) Place the 'slug' in an environment favourable to cellular slime moulds with sufficient food sources and observe if the slug differentiates into a fruiting body.
B) Perform DNA analysis and look for molecular markers specific to molluscs.
C) Dissect the slug under microscopy and analyse the internal anatomy of the organism.
D) Place the 'slug' in an environment favourable to cellular slime moulds with sufficient food sources and observe if the slug differentiates into a mass of individual amoeba.
E) Using a classical Linnaean system, use physiological and morphological features to key out the organism to genus and species.

Question 43

A hiker drinks fresh water from a stream in a forest. Two days later he experiences violent diarrhoea and examines a sample of his own stool. Under the microscope he observes an organism approximately 15µm long with what appears to be two nuclei. The hiker's diarrhoea is most likely caused by

A) Giardia
B) Diplomonads
C) Parabasalids
D) Shigella
E) Entamoeba

Question 44

Dunaliella salina, under certain environmental conditions, can produce high levels of $\beta$ , $\beta$ -carotene. This orange-red pigment has applications in neutraceuticals as it can be readily converted to

A) Vitamin A.
B) Vitamin C.
C) Vitamin D.
D) linoleic acid.
E) tryptophan.