Unit 2: Microbial diversity - Practice Quiz

1 Which two domains together contain all prokaryotic organisms?

2 Archaea are best known for often living in which type of environment?

3 A key difference between Archaea and Eubacteria is found in their:

4 Which term describes organisms whose cells lack a membrane-bound nucleus?

5 A rod-shaped bacterium is classified as a:

6 The Gram staining technique is used to classify bacteria based on their:

7 Spherical bacteria are known as:

8 Gram-positive bacteria appear which color after Gram staining?

9 Which structure allows many bacteria to move?

10 Viruses can reproduce only when they are:

11 The protein coat that surrounds a virus's genetic material is called the:

12 The genetic material of a virus is composed of:

13 A virus that specifically infects bacteria is called a:

14 Why are viruses often described as being on the border of living and non-living?

15 The cell walls of most fungi are made mainly of:

16 How do fungi obtain their nutrition?

17 The thread-like filaments that make up the body of a multicellular fungus are called:

18 Which of the following is a single-celled fungus?

19 Protists are best described as:

20 Which protist uses pseudopodia (false feet) for movement?

21 A microbiologist isolates an organism from a hot acidic spring at 2 and . Cell wall analysis shows the absence of peptidoglycan, and membrane lipids contain ether-linked branched chains. To which group does this organism most likely belong?

22 Which feature is shared by both Eubacteria and Archaea but distinguishes them from Eukarya?

23 Carl Woese's three-domain classification was based primarily on the comparison of which molecule?

24 A methanogen isolated from cattle rumen produces methane and is strictly anaerobic. Which statement about this organism is correct?

25 A Gram stain of a clinical sample shows purple-stained cocci arranged in clusters. Which conclusion is most appropriate?

26 An organism appears pink after Gram staining. What does this indicate about its cell envelope?

27 Bacteria that grow only in the absence of oxygen and are killed by its presence are classified as:

28 A curved, comma-shaped bacterium that causes cholera would be described morphologically as a:

29 Endospore formation in genera such as Bacillus and Clostridium primarily serves what function?

30 Using the Baltimore classification, a virus with a positive-sense single-stranded RNA genome that is directly translated by host ribosomes belongs to which class?

31 A retrovirus such as HIV carries which enzyme essential for converting its RNA genome into DNA?

32 Which statement correctly distinguishes the lysogenic cycle from the lytic cycle of a bacteriophage?

33 The presence of a lipid envelope in some viruses generally makes them:

34 Which characteristic best explains why viruses are considered obligate intracellular parasites?

35 A fungus produces sexual spores enclosed within a sac-like structure called an ascus. To which phylum does it belong?

36 The rigid cell wall of most fungi is composed primarily of which polysaccharide?

37 Mushrooms and other members of Basidiomycota are characterized by producing sexual spores on which structure?

38 Which set of characteristics correctly describes fungal nutrition and structure?

39 A dimorphic fungus is one that:

40 A single-celled eukaryote moves and captures food using temporary cytoplasmic extensions called pseudopodia. This organism belongs to which group of protists?

41 A newly isolated prokaryote possesses membrane lipids composed of isoprenoid chains linked to glycerol via ether bonds, a cell wall lacking peptidoglycan, and an RNA polymerase with multiple subunits resembling the eukaryotic enzyme. Based on synthesis of these traits, which classification and reasoning is most accurate?

42 Carl Woese's three-domain system was established primarily on the basis of comparative analysis of a single conserved molecule. Why is this molecule ideal as a universal phylogenetic marker despite the availability of many other conserved genes?

43 Two bacterial isolates both stain Gram-positive but one retains crystal violet weakly and shows an acid-fast reaction with Ziehl-Neelsen staining. What structural feature best explains the acid-fast result and its clinical significance?

44 An obligate anaerobe is found to lack the enzymes catalase and superoxide dismutase. When cultured, adding which combination would best allow limited growth in the presence of trace oxygen?

45 A researcher observes a rod-shaped bacterium that forms a highly refractile, heat-resistant structure only when nutrients are depleted. Which statement about this structure is most accurate?

46 Bergey's Manual has increasingly shifted from purely phenotypic to phylogenetic classification. Which scenario best illustrates a limitation of relying solely on phenotypic traits like Gram reaction and metabolism?

47 According to the Baltimore classification, a virus with a (+) single-stranded RNA genome that must first be reverse-transcribed into DNA before replication belongs to which group, and what key enzyme distinguishes it from a standard (+)ssRNA virus?

48 A negative-sense ssRNA virus cannot use its genome directly as mRNA. What must the virion carry to initiate infection successfully, and why?

49 During a lysogenic-to-lytic switch in a temperate bacteriophage, prophage induction is triggered by host DNA damage. Which molecular event most directly initiates this transition?

50 Prions challenge conventional definitions of infectious agents. Which property most fundamentally distinguishes prion propagation from that of all nucleic acid-based viruses?

51 A fungal isolate produces sexual spores enclosed within a sac-like structure and also reproduces asexually via conidia. Based on the sexual spore type, to which phylum does it belong, and what is the diagnostic structure?

52 Coenocytic hyphae are characteristic of certain fungal groups. What is the functional consequence of lacking regular septa, and which phylum classically exhibits this feature?

53 A dikaryotic stage (n + n) with two genetically distinct nuclei per cell persisting over an extended period before karyogamy is a hallmark of which fungal group, and why is it evolutionarily significant?

54 Fungi imperfecti (Deuteromycota) is now considered an artificial, non-phylogenetic grouping. What is the primary reason these fungi were historically placed together, and how are they reclassified today?

55 A yeast and a filamentous mold of the same species can switch morphologies depending on temperature (mold at 25°C, yeast at 37°C). This dimorphism is most significant for which reason?

56 Protista is now recognized as a paraphyletic 'catch-all' kingdom. Which statement best explains why modern systematics considers it problematic?

57 An apicomplexan parasite possesses a non-photosynthetic plastid-like organelle called the apicoplast. What is the evolutionary and therapeutic significance of this structure?

58 Traditional classification of protists by mode of nutrition (algae, protozoa, slime molds) fails phylogenetically. Which example best demonstrates this failure?

59 A protist propels itself using rows of short, coordinated hair-like structures and possesses two distinct nuclei of different function. To which group does it belong, and what is the role of its nuclei?

60 Extreme halophiles, methanogens, and hyperthermophiles are all placed within Archaea. Which shared molecular or physiological feature—rather than their extreme habitats—provides the strongest justification for grouping them together?