C18 Sample Questions from Brock

Question 1

Primary endosymbioses gave rise to ______ and secondary endosymbioses gave rise to ______.
A) chloroplasts in algae / chloroplasts in plants
B) mitochondria in eukaryotes / chloroplasts in eukaryotes
C) chloroplasts and mitochondria in plants and red and green algae / chloroplasts in other eukaryotes
D) chloroplasts and mitochondria in green and red algae / chloroplasts and mitochondria in diatoms

Answer 1

B) mitochondria in eukaryotes / chloroplasts in eukaryotes.

Primary endosymbiosis led to the origin of mitochondria (from an alpha-proteobacterium) and chloroplasts in plants and algae (from a cyanobacterium). Secondary endosymbiosis involved a eukaryote engulfing another eukaryote that already possessed a chloroplast, leading to chloroplasts in other eukaryotic lineages.

Question 2

Evidence of _____ supports the hypothesis that eukaryotes are derived from bacteria.
A) antibiotic resistance
B) DNA content in the nucleus only
C) ribosome characteristics only
D) ribosome characteristics and DNA content in the nucleus

Answer 2

D) ribosome characteristics and DNA content in the nucleus.

Eukaryotic ribosomes (80S) share similarities with bacterial ribosomes (70S), distinct from archaeal ribosomes. The presence of a membrane-bound nucleus containing DNA is another shared feature, supporting the bacterial origin of mitochondria and chloroplasts.

Question 3

Which statement best describes our current understanding of the eukaryotic phylogenetic tree?
A) Ribosomal RNA data allowed the development of the current phylogeny with 6 supergroups.
B) Whole genome data was used to distinguish the 3 domains.
C) The most recent analyses have conclusively shown the relationships of the 6 supergroups.
D) New discoveries will probably lead to changes in the eukaryotic phylogenetic tree.

Answer 3

D) New discoveries will probably lead to changes in the eukaryotic phylogenetic tree.

Eukaryotic phylogeny is constantly being revised as new data become available. While ribosomal RNA and whole genome data have been instrumental in shaping our understanding, the relationships between the supergroups are still being debated and refined.

Question 4

Which group of Eukarya has complicated the phylogenetics of the domain by first being thought of as ancient as compared to the more recent view of them being highly derived eukaryotes?
A) dinoflagellates
B) fungi
C) hydrogenosome-containing eukaryotes
D) stramenopiles

Answer 4

C) hydrogenosome-containing eukaryotes

Initially, hydrogenosomes were thought to be ancient organelles, suggesting that the organisms possessing them were also ancient. However, later research revealed that hydrogenosomes are derived from mitochondria, placing these eukaryotes later in the evolutionary timeline.

Question 5

Of the taxa listed, which is NOT classified as a protist?
A) Amoeba
B) Euglena
C) Giardia
D) Saccharomyces

Answer 5

D) Saccharomyces

Saccharomyces is a genus of yeast, which belongs to the kingdom Fungi. Amoeba, Euglena, and Giardia are all protists.

Question 6

Which of the following is NOT a unifying characteristic of diplomonads and parabasalids?
A) having flagella
B) lacking chloroplasts
C) lacking mitochondria
D) being multicellular

Answer 6

D) being multicellular

Diplomonads and parabasalids are unicellular organisms. They share characteristics like flagella, lack of chloroplasts, and modified mitochondria (or lack thereof).

Question 7

Giardia are diplomonads which have nuclei that
A) appear as two separate chromosomes but are weakly joined.
B) contain one small and one large nucleus per cell.
C) have one nucleus enclosed in a mitosome and another nucleus in their cytoplasm.
D) occur as two similar sizes per cell.

Answer 7

D) occur as two similar sizes per cell.

Giardia have two nuclei of similar size and morphology per cell, a characteristic feature of diplomonads.

Question 8

Many parabasalids lack ___________, which makes them different than most other eukaryotes.
A) endoplasmic reticula
B) introns in their genomes
C) mitochondria and hydrogenosomes
D) Golgi complexes

Answer 8

C) mitochondria and hydrogenosomes

Parabasalids characteristically lack mitochondria. Some possess hydrogenosomes, which are analogous organelles involved in anaerobic metabolism.

Question 9

A thin, crescent-shaped organism with a single flagellum originating from a basal body and which folds back laterally across the cell would most likely be a member of the genus
A) Trypanosoma.
B) Glossina.
C) Entamoeba.
D) Gambiense.

Answer 9

A) Trypanosoma.

This description fits the morphology of Trypanosoma, a parasitic kinetoplastid known for its single flagellum that runs along the cell body.

Question 10

A drug that specifically inhibits the replication of the large DNA mass present in large mitochondria would be most effective at killing
A) euglenids.
B) ciliates.
C) Trypanosoma
D) Toxoplasma

Answer 10

C) Trypanosoma

Trypanosoma species are kinetoplastids, which are characterized by a kinetoplast, a network of DNA contained within a large mitochondrion.

Question 11

Which group of eukaryotes LACKS alveoli?
A) apicomplexans
B) ciliates
C) dinoflagellates
D) oomycetes

Answer 11

D) oomycetes

Alveoli are membrane-bound sacs beneath the cell membrane, a characteristic of alveolates (ciliates, dinoflagellates, and apicomplexans). Oomycetes are stramenopiles and lack alveoli.

Question 12

Which statement BEST describes the habitats of the fungi?
A) Most fungi are aquatic, microscopic, and primarily freshwater.
B) Most fungi are aquatic and primarily marine.
C) Most fungi are terrestrial, microscopic, and inhabit soil or dead plant matter.
D) Most fungi are terrestrial and macroscopic.

Answer 12

C) Most fungi are terrestrial, microscopic, and inhabit soil or dead plant matter.

While some fungi are aquatic and some are macroscopic (like mushrooms), the vast majority are terrestrial and exist as microscopic filaments in soil or decaying organic matter.

Question 13

Oomycetes (ʺwater moldsʺ) contain ____ in their cell walls, while most fungi have ________ in their cell walls.
A) cellulose / chitin
B) chitin / cellulose
C) silica / chitin
D) cellulose / silica

Answer 13

A) cellulose / chitin

Oomycetes, despite their resemblance to fungi, have cell walls composed of cellulose, like plants. Most fungi have cell walls made of chitin.

Question 14

Which statement is TRUE regarding fungal spores?
A) Conidia and ascospores are sexual spores.
B) Ascospores and basidiospores are asexual spores.
C) Basidiospores and conidia are sexual spores.
D) Ascospores and basidiospores are sexual spores.

Answer 14

D) Ascospores and basidiospores are sexual spores.

Ascospores are formed within asci, and basidiospores are formed on basidia, both structures involved in sexual reproduction. Conidia are asexual spores.

Question 15

Which statement is TRUE regarding the ecological role of plant degradation by fungi?
A) In brown rot the cellulose is attacked preferentially, and the lignin is left unmetabolized.
B) In brown rot the lignin is attacked preferentially, and the cellulose is left unmetabolized.
C) In white rot the cellulose is attacked preferentially, and the lignin is left unmetabolized.
D) In white rot the lignin is attacked preferentially, and the cellulose is left unmetabolized.

Answer 15

B) In brown rot the lignin is attacked preferentially, and the cellulose is left unmetabolized.

Brown rot fungi preferentially degrade lignin, leaving behind the brown-colored cellulose. White rot fungi degrade both lignin and cellulose.

Question 16

Diatoms are
A) found only in freshwater.
B) more closely related to slime molds than to algae.
C) usually morphologically symmetric.
D) multicellular phototrophs.

Answer 16

C) usually morphologically symmetric.

Diatoms are known for their intricate, symmetrical silica shells. They are found in both freshwater and marine environments and are unicellular algae.

Question 17

Which algae are most closely related to plants?
A) red algae
B) green algae
C) brown algae
D) euglenoids

Answer 17

B) green algae

Green algae (Chlorophyta) and land plants share several key characteristics, including chlorophyll a and b, starch storage, and cellulose cell walls, suggesting a close evolutionary relationship.

Question 18

Endolithic phototrophic communities are most commonly found in environments.
A) dry
B) hot
C) humid
D) windy

Answer 18

A) dry

Endolithic communities, including phototrophic organisms, are often found in dry environments like deserts, where they inhabit the pores of rocks to protect themselves from harsh conditions.

Question 19

What would a fucoxanthin carotenoid stain be most useful in identifying?
A) brown or golden algae
B) flagellated algae
C) photosynthetic diatoms
D) slime molds from other molds

Answer 19

A) brown or golden algae

Fucoxanthin is a brown accessory pigment found in brown algae (Phaeophyta) and golden algae (Chrysophyta), giving them their characteristic color.

Question 20

A geologist going through a sediment core is likely to find remnants of ancient calcium carbonate containing ________ and silica containing ________.
A) diatoms / chlorarachniophytes
B) foraminiferans / diatoms
C) chlorarachniophytes / foraminiferans
D) foraminiferans / chlorarachniophytes

Answer 20

B) foraminiferans / diatoms

Foraminifera have calcium carbonate tests (shells), while diatoms have silica frustules (shells). Both contribute significantly to marine sediments.

Question 21

What phenomenon accounts for the appearance of chloroplasts in some unicellular phototrophic eukaryotes?
A) transformation of hydrogenosomes
B) secondary endosymbioses of green or red algae
C) primary endosymbioses of green or red algae
D) horizontal gene transfer

Answer 21

B) secondary endosymbioses of green or red algae

Some phototrophic eukaryotes acquired chloroplasts by engulfing a green or red alga that already possessed a primary chloroplast (derived from cyanobacteria). This is known as secondary endosymbiosis.

Question 22

Which group of amoebozoans is most likely to cause illness in humans?
A) dictyostelium
B) entamoebas
C) gymnamoebas
D) slime molds

Answer 22

B) entamoebas

Entamoebas include species like Entamoeba histolytica, which causes amoebic dysentery in humans.

Question 23

How can the amebozoans and radiolarians be distinguished from each other with microscopy?
A) Amebozoans have lobe-shaped pseudopodia, and radiolarians have threadlike pseudopodia, and radiolarians have radial symmetry.
B) Amebozoans have lobe-shaped pseudopodia, amebozoans have radial symmetry, and radiolarians have unusually large, thick pseudopodia.
C) Amebozoans have large but thin pseudopodia and radiolarians have thick, lobe-shaped pseudopodia.
D) Amebozoans have radial symmetry and threadlike pseudopodia, whereas radiolarians have lobe-shaped pseudopodia.

Answer 23

A) Amebozoans have lobe-shaped pseudopodia, and radiolarians have threadlike pseudopodia, and radiolarians have radial symmetry.

This accurately describes the morphological differences between these two groups.

Question 24

Which microbial group is responsible for massive amphibian die-offs worldwide?
A) cercozoans
B) ciliates
C) chytrids
D) zygomycetes

Answer 24

C) chytrids

Chytridiomycosis, caused by chytrid fungi like Batrachochytrium dendrobatidis, is a major factor in amphibian decline globally.

Question 25

Which of the following is NOT a member of the Eukarya?
A) protists
B) fungi
C) spirochetes
D) red algae

Answer 25

C) spirochetes

Spirochetes are bacteria. Protists, fungi, and red algae are all members of the domain Eukarya.

Question 26

The function of the parabasal body is to
A) allow for photosynthesis to occur.
B) give structural support to the Golgi complex.
C) allow for the formation of energy from aerobic respiration.
D) give structural support to the endoflagellum.

Answer 26

D) give structural support to the endoflagellum.

The parabasal body is a Golgi-like structure that provides support to the flagella in parabasalids.

Question 27

The amoebozoa use what structures for movement and feeding?
A) threadlike pseudopodia
B) cilia
C) flagella
D) lobe-shaped pseudopodia

Answer 27

D) lobe-shaped pseudopodia

Amoebozoa, as their name suggests, use lobe-shaped pseudopodia for both movement and engulfing food particles.

Question 28

The amoebozoa that are parasitic for humans are the
A) gymnamoebas.
B) radiolarians.
C) entamoebas.
D) oomycetes.

Answer 28

C) entamoebas.

Entamoeba histolytica is a significant human parasite.

Question 28

One of the earliest diverging lineages of fungi is the
A) chytridiomycetes.
B) zygomycetes.
C) glomeromycetes.
D) ascomycetes.

Answer 28

A) chytridiomycetes.

Chytridiomycetes are considered one of the earliest diverging lineages of fungi.

Question 29

A fungal mycelium is a large accumulation of ____, which may appear dusty or fuzzy due to the presence of _________.
A) coenocytes / conidia
B) coenocytes / mycorrhizae
C) hyphae / conidia
D) hyphae / mycorrhizae

Answer 29

C) hyphae / conidia

A mycelium is a network of hyphae (filaments). Conidia are asexual spores that can give the mycelium a dusty or fuzzy appearance.

Question 30

What are the most abundant biomolecules in a typical fungal cell wall?
A) amino acids
B) carbohydrates
C) lipids
D) porins and channels

Answer 30

B) carbohydrates

Chitin, a carbohydrate polymer, is the major component of fungal cell walls, along with other polysaccharides like glucans.

Question 31

Which spores are NOT involved in sexual reproduction of fungi?
A) ascospores
B) basidiospores
C) conidia
D) zygospores

Answer 31

C) conidia

Conidia are asexual spores, while ascospores, basidiospores, and zygospores are all involved in sexual reproduction.

Question 32

In contrast to bacterial endospores, fungal spores have substantially less resistance to
A) chemicals.
B) desiccation.
C) heat.
D) freezing.

Answer 32

C) heat.

Fungal spores are generally less resistant to high temperatures than bacterial endospores.

Question 33

The unusual ability of _______ being flagellated and motile enables _____.
A) ascospores / their dispersal in aquatic systems
B) ascospores / spreading of those pathogens in blood
C) zoospores / dispersal in aquatic systems
D) zoospores / spreading of those pathogens in blood

Answer 33

C) zoospores / dispersal in aquatic systems

Zoospores are motile spores, typically found in aquatic fungi like chytrids, that facilitate dispersal in water.

Question 34

Spoilage of bread, which appears dark green-blue to black in color, is most likely caused by the fungus
A) Aspergillus niger.
B) Batrachochytrium dendrobatidis.
C) Glomus
D) Rhizopus nigricans.

Answer 34

D) Rhizopus nigricans.

Rhizopus nigricans is a common bread mold, often appearing as black or dark green fuzzy growth.

Question 35

Obligate symbiotic fungi that form associations with plants by entering their cortical cells without invading the plant cellʹs membrane are called _____ and include the genus ____.
A) ectomycorrhizae / Agaricus
B) ectomycorrhizae / Glomus
C) endomycorrhizae / Agaricus
D) endomycorrhizae / Glomus

Answer 35

D) endomycorrhizae / Glomus

Endomycorrhizae penetrate the cortical cells of plant roots, forming arbuscules. Glomus is a common genus of arbuscular mycorrhizal fungi. Ectomycorrhizae do not penetrate the cell walls.

Question 36

Microsporidia were previously thought to be an early-branching taxon of Eukarya due to their parasitic lifestyle. However, new evidence suggests that they are more closely related to the
A) ascomycetes.
B) chytridiomycetes.
C) glomeromycetes.
D) zygomycetes.

Answer 36

A) ascomycetes.

While initially thought to be primitive eukaryotes, molecular evidence now places microsporidia closer to fungi, specifically the ascomycetes.

Question 37

Ascospores are produced in all of the following taxa EXCEPT
A) Aspergillus.
B) Candida.
C) Rhizopus.
D) Saccharomyces.

Answer 37

C) Rhizopus.

Rhizopus belongs to the Zygomycetes, which produce zygospores during sexual reproduction. Aspergillus, Candida, and Saccharomyces are all ascomycetes, which produce ascospores.

Question 38

For a pure culture of Saccharomyces cerevisiae cells that were all derived from a single cell to mate
A) a mating-type switch in one or more cells in the culture must occur.
B) both the α and the a gene must be fully expressed in the initial population.
C) the α gene must be fully repressed in the population.
D) some cells must exist as diploids.

Answer 38

A) a mating-type switch in one or more cells in the culture must occur.

Saccharomyces cerevisiae can switch mating types, allowing cells derived from a single cell to eventually mate and form diploids.

Question 39

The majority of basidiomycetes living in soil occur as
A) diploid mycelia.
B) diploid basidiocarps.
C) haploid mycelia.
D) haploid basidiocarps.

Answer 39

C) haploid mycelia.

The majority of the basidiomycete life cycle is spent as haploid mycelia. The diploid stage is relatively short-lived and primarily associated with the basidiocarp (fruiting body).

Question 40

The accessory pigment phycoerythrin is dominant in the ________ group of algae, which mostly lack flagella, have multicellular lifestyles, and occur in marine waters. Those in particular which deposit calcium carbonate in coral reef systems are classified as ________ algae.
A) chlorophyte / coralline
B) chlorophyte / rhodolithic
C) rhodophyte / coralline
D) rhodophyte / rhodolithic

Answer 40

C) rhodophyte / coralline

Red algae (rhodophytes) are characterized by the accessory pigment phycoerythrin, which gives them their red color. Coralline red algae are important in coral reef ecosystems due to their calcium carbonate deposition.

Question 41

What are the two main groups of green algae?
A) chlorophytes and chrysophytes
B) chlorophytes and charophyceans
C) chrysophytes and charophyceans
D) chlorarachniophytes and chlorophytes

Answer 41

B) chlorophytes and charophyceans

These are the two main lineages of green algae.

Question 42

In a freshwater pond, a green alga is likely to be
A) only colonial.
B) only filamentous.
C) only unicellular.
D) colonial, filamentous, multicellular, or unicellular.

Answer 42

D) colonial, filamentous, multicellular, or unicellular.

Green algae exhibit a wide variety of morphologies, including all of the listed forms.

Question 43

The green alga Botryococcus braunii is a candidate for production of biofuel due to its ability to produce
A) and withstand large amounts of alcohols.
B) hydrogen gas.
C) long-chain (C30-C36) hydrocarbons.
D) Short-chain (C8-C14) hydrocarbons.

Answer 43

C) long-chain (C30-C36) hydrocarbons.

Botryococcus braunii produces large amounts of long-chain hydrocarbons, making it a potential source of biofuel.