5.E: The Eukaryotes of Microbiology (Exercises)
5.1: Unicellular Eukaryotic Microorganisms
Protists are a diverse, polyphyletic group of eukaryotic organisms. Protists may be unicellular or multicellular. They vary in how they get their nutrition, morphology, method of locomotion, and mode of reproduction. Important structures of protists include contractile vacuoles, cilia, flagella, pellicles, and pseudopodia; some lack organelles such as mitochondria. Taxonomy of protists is changing rapidly as relationships are reassessed using newer techniques.
Multiple Choice
Which genus includes the causative agent for malaria?
- Euglena
- Paramecium
- Plasmodium
- Trypanosoma
- Answer
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C
Which protist is a concern because of its ability to contaminate water supplies and cause diarrheal illness?
- Plasmodium vivax
- Toxoplasma gondii
- Giardia lamblia
- Trichomonas vaginalis
- Answer
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C
Fill in the Blank
The plasma membrane of a protist is called the __________.
- Answer
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plasmalemma
Animals belong to the same supergroup as the kingdom __________.
- Answer
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Fungi
Short Answer
What are kinetoplastids?
Aside from a risk of birth defects, what other effect might a toxoplasmosis infection have?
What is the function of the ciliate macronucleus?
Critical Thinking
The protist shown has which of the following?
- pseudopodia
- flagella
- a shell
- cilia
(credit: modification of work by Richard Robinson)
Protist taxonomy has changed greatly in recent years as relationships have been re-examined using newer approaches. How do newer approaches differ from older approaches?
What characteristics might make you think a protist could be pathogenic? Are certain nutritional characteristics, methods of locomotion, or morphological differences likely to be associated with the ability to cause disease?
5.2: Parasitic Helminths
Helminth parasites are included within the study of microbiology because they are often identified by looking for microscopic eggs and larvae. The two major groups of helminth parasites are the roundworms (Nematoda) and the flatworms (Platyhelminthes). Nematodes are common intestinal parasites often transmitted through undercooked foods, although they are also found in other environments. Platyhelminths include tapeworms and flukes, which are often transmitted through undercooked meat.
Multiple Choice
A fluke is classified within which of the following?
- Nematoda
- Rotifera
- Platyhelminthes
- Annelida
- Answer
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C
A nonsegmented worm is found during a routine colonoscopy of an individual who reported having abdominal cramps, nausea, and vomiting. This worm is likely which of the following?
- nematode
- fluke
- trematode
- annelid
- Answer
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A
A segmented worm has male and female reproductive organs in each segment. Some use hooks to attach to the intestinal wall. Which type of worm is this?
- fluke
- nematode
- cestode
- annelid
- Answer
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C
Fill in the Blank
Flukes are in class _________.
- Answer
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Trematoda
A species of worm in which there are distinct male and female individuals is described as _________.
- Answer
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dioecious
Short Answer
What is the best defense against tapeworm infection?
Critical Thinking
Given the life cycle of the Schistosoma parasite, suggest a method of prevention of the disease.
5.3: Fungi
The fungi include diverse saprotrophic eukaryotic organisms with chitin cell walls. Fungi can be unicellular or multicellular; some (like yeast) and fungal spores are microscopic, whereas some are large and conspicuous. Reproductive types are important in distinguishing fungal groups. Medically important species exist in the four fungal groups Zygomycota, Ascomycota, Basidiomycota, and Microsporidia.
Multiple Choice
Mushrooms are a type of which of the following?
- conidia
- ascus
- polar tubule
- basidiocarp
- Answer
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D
Which of the following is the most common cause of human yeast infections?
- Candida albicans
- Blastomyces dermatitidis
- Cryptococcus neoformans
- Aspergillus fumigatus
- Answer
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A
Which of the following is an ascomycete fungus associated with bat droppings that can cause a respiratory infection if inhaled?
- Candida albicans
- Histoplasma capsulatum
- Rhizopus stolonifera
- Trichophyton rubrum
- Answer
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B
Fill in the Blank
Nonseptate hyphae are also called _________.
- Answer
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coenocytic
Unicellular fungi are called _________.
- Answer
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yeasts
Some fungi have proven medically useful because they can be used to produce _________.
- Answer
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antibiotics
Short Answer
Which genera of fungi are common dermatophytes (fungi that cause skin infections)?
What is a dikaryotic cell?
Critical Thinking
Which of the drawings shows septate hyphae?
Explain the benefit of research into the pathways involved in the synthesis of chitin in fungi.
5.4: Algae
Algae are a diverse group of photosynthetic eukaryotic protists. Algae may be unicellular or multicellular. Large, multicellular algae are called seaweeds but are not plants and lack plant-like tissues and organs. Although algae have little pathogenicity, they may be associated with toxic algal blooms that can harm aquatic wildlife and contaminate seafood with toxins that cause paralysis.
Multiple Choice
Which polysaccharide found in red algal cell walls is a useful solidifying agent?
- chitin
- cellulose
- phycoerythrin
- agar
- Answer
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D
Which is the term for the hard outer covering of some dinoflagellates?
- theca
- thallus
- mycelium
- shell
- Answer
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A
Which protists are associated with red tides?
- red algae
- brown algae
- dinoflagellates
- green algae
- Answer
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C
Fill in the Blank
Structures in chloroplasts used to synthesize and store starch are called ________.
- Answer
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pyrenoids
Algae with chloroplasts with three or four membranes are a result of ________ ________.
- Answer
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secondary endosymbiosis
Short Answer
What is a distinctive feature of diatoms?
Why are algae not considered parasitic?
Which groups contain the multicellular algae?
5.5: Lichens
Lichens are a symbiotic association between a fungus and an algae or a cyanobacterium. The symbiotic association found in lichens is currently considered to be a controlled parasitism, in which the fungus benefits and the algae or cyanobacterium is harmed. Lichens are slow growing and can live for centuries in a variety of habitats. Lichens are environmentally important, helping to create soil, providing food, and acting as indicators of air pollution.
Multiple Choice
You encounter a lichen with leafy structures. Which term describes this lichen?
- crustose
- foliose
- fruticose
- agarose
- Answer
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B
Which of the following is the term for the outer layer of a lichen?
- the cortex
- the medulla
- the thallus
- the theca
- Answer
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A
The fungus in a lichen is which of the following?
- a basidiomycete
- an ascomycete
- a zygomycete
- an apicomplexan
- Answer
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B
Short Answer
What are three ways that lichens are environmentally valuable?