Chapter 12 - Eukaryotes

The life cycle of the fish tapeworm is similar to that of the beef tapeworm. Which of the following is the most effective preventive measure?

cooking fish before eating

List the events in the cycle of the ascomycete Talaromyces in the sequence in which they occur, from early to late stages or events.

d-b-c-a-e-f A, Plasmogamy B, Conidium germinates to produce hyphae C, Vegetative mycelium grows D, Hypha produces conidiophore E, Karyogamy F, Ascus opens to release ascospores

In mid-December, a woman with insulin-dependent diabetes who had been on prednisone fell and received an abrasion on the dorsal side of her right hand. She was placed on penicillin. By the end of January, the ulcer had not healed, and she was referred to a plastic surgeon. On January 30, a swab of the wound was cultured at 35°C on blood agar. On the same day, a smear was made for Gram staining. The Gram stain showed large (10 µm) cells. Brownish, waxy colonies grew on the blood agar. Slide cultures set up on February 1 and incubated at 25°C showed septate hyphae and single conidia. The most likely cause of the infection is a

dimorphic fungus.

Ringworm is caused by a(n)

fungus.

Helminthic diseases are usually transmitted to humans by

gastrointestinal route.

How do pseudohyphae in yeasts differ from vegetative hyphae in filamentous fungi?

Yeasts use pseudohyphae to invade host tissue, whereas filamentous fungi use their vegetative hyphae for obtaining nutrients.

Which of the following arthropods does NOT transmit diseases by sucking blood from a human host?

houseflies

In the malaria parasite life cycle

humans are the intermediate host and mosquitoes are both the definitive host and the vector.

Which of the following could Tori's physician choose as a treatment for her yeast infection?

*a topical over-the-counter ointment, such as clotrimazole or miconazole *a single oral dose of fluconazole

Which of the following infections are also caused by C. albicans?

*fulminating disease *oral thrush

If a patient is diagnosed with ringworm, a cutaneous mycosis, which medically important phylum of fungi is implicated?

Ascomycota

Tori, a 24-year-old graduate student, had been suffering from a respiratory infection for over a week. She went to the student health center, where the physician prescribed her a broad-spectrum antibiotic. By the end of her round of antibiotics, Tori was no longer suffering from respiratory complications, but she had noticed an increase in itchiness in her genital region. Within a few days, the itchiness was getting worse and was accompanied by a vaginal discharge that had a cheesy consistency and foul odor. Tori returned to the student health center to discuss her condition with the physician. A sample of her discharge was taken and sent to the laboratory for microscopy and plating.

Above image shows the microscopy results for the vaginal sample. To confirm the identity of the organism, lab technicians also plated a sample of the organism on a nutrient media and on a Sabouraud dextrose agar plate.

Humans are not the definitive hosts for which parasitic helminth?

Anisakines

If one is examining the incidence of malaria in a third world country, which phylum of protozoa is involved, and must be eradicated?

Apicomplexa

How do blastoconidia and chlamydoconidia produced by yeast differ from bacterial endospores?

Blastoconidia and chlamydoconidia are spore structures produced by budding in yeasts, whereas bacterial endospores are produced by bacteria under extreme conditions.

Based on the lab results, which organism is most likely causing Tori's new symptoms?

Candida albicans

Yeast infections are caused by

Candida albicans.

Which statement regarding slime molds is false?

Cellular slime molds are typical aggregates of prokaryotic cells.

Which of the following statements best describes why the treatment for Tori's fungal infection may result in side effects to her own cells?

Fungal cells and human cells have a nucleus, multiple organelles, and 80S ribosomes for protein synthesis.

Which of the following statements is FALSE?

Fungal spores are highly resistant to heat and chemical agents

Which statement regarding the life cycle of Plasmodium vivax (the apicomplexan that causes malaria) is false?

Human beings are the definitive hosts.

Trichomonas vaginalis can be distinguished from other parasitic protozoa by which of the characteristics listed below?

It has an undulating membrane, infects the vagina, and is frequently transmitted by sexual contact.

Trichomonas vaginalis can be distinguished from other parasitic protozoa by which characteristic listed below?

It is responsible for urethritis and vaginitis in humans.

Regarding the life cycle of fungi, which of the following is the sexual spore phase that occurs when (+) and (-) nuclei fuse to form a diploid zygote nucleus?

Karyogamy phase

Which of the following statements regarding fungi is FALSE?

Most fungi are pathogenic for humans.

Which of the following statements regarding protozoa is FALSE?

Nearly all protozoa cause disease.

Which of the following best explains why Tori developed a new series of symptoms?

The antibiotics that treated Tori's primary respiratory infection also removed some of her normal bacterial flora, resulting in an overgrowth of other organisms.

Which of the following statements about helminths is FALSE?

They have eukaryotic cells. They are multicellular animals. Some have male and female reproductive organs in one animal. They are heterotrophic. *All are parasites. -right one

Arthropod vectors are blood-sucking animals such as ticks, lice, and fleas that transmit microbial pathogens.

True

Which of the following statements about protozoa is true?

When conditions become harsh, some protozoa can form a protective capsule, which is called a cyst.

If a patient has become ill from an infestation by the parasitic helminth Echinococcus granulosus, the intermediate host would be identified as ______, and the infected tissue to be examined in the patient would be ______.

humans; lungs and liver

What do tapeworms eat?

intestinal contents

Giardia and Trichomonas are unusual eukaryotes because they

lack mitochondria.

Which of the following pairs is mismatched?

mosquito - Pneumocystis

Dengue fever is transmitted by which of the following?

mosquitoes

Which of the following tends to be more complex in a parasitic helminth than in free-living helminths?

reproductive system