Parasitic protozoans are microscopic single celled eukaryotes.
Correct Answer: Unicellular
There are four species of the protozoan parasite Plasmodium that can cause malaria symptoms to different degrees, with P. falciparum being the most pathogenic.
Correct Answer: Is the most dangerous of the malaria-causing parasites
Parasitic infections affect hundreds of millions of people. Parasites can have life cycles that involve single or multiple hosts. Parasites can be protozoans and helminths, and there are three classes of helminth that infect humans.
Correct Answer: All the choices are true
Budding is a reproductive measure used by yeast. All the other methods are used by various species of protozoa. Gametogony is the reproductive phase simple fission (schizogony) which is used by protozoa such as toxoplasma. Some protozoa, such as trypanosome, use binary fission.
Correct Answer: Budding
The body of the worm is covered by a tough cuticle, which may be smooth or may possess ridges, spines, or tubercles.
Correct Answer: Cuticle
Nematodes are round worms with a cylindrical body and an alimentary canal that goes from the anterior mouth to the posterior anus.
Correct Answer: Roundworms
Trematodes are flukes and are leaf-shaped with a blind-branched alimentary tract (with an opening at one end only).
Correct Answer: Flukes
The severity of a helminthic infection is related to the number of worms acquired by repeated infection over time — the smaller the number, the greater the chance of asymptomatic infection. However, many worms are long-lived, and repeated infections with these worms will drive up the number in the host. The resulting large worm loads result in increased disability of the host.
Correct Answer: The number of worms that are present
Malaria is transmitted to humans by the bite of the Anopheles mosquito. Failures in mosquito control have increased the incidence of malaria.
Correct Answer: The bite of a mosquito
Plasmodium, the causative agent of malaria, is transmitted to humans by the Anopheles mosquito. However, for Plasmodium the mosquito is the organism in which sexual reproduction occurs and is therefore the definitive host. Humans are the intermediate host.
Correct Answer: A human
Merozoites are found in humans only. They are released from infected hepatocytes and then attach to specific receptors on red blood cells and are carried into the cells by endocytosis. They can then travel round the body in the blood.
Correct Answer: The blood of an infected human
The bite of the tsetse fly deposits the trypomistagote form of the Trypanosoma parasites, which begin to multiply causing localized inflammation. This develops into a chancre from which parasites spread into the blood and lymph of the host. Host antibodies destroy the parasites but they reappear several days later, causing recurrent parasitaemia. These reappearances become less frequent but can last for years and are accompanied by fever. During parasitemia, the Trypanosoma trypomastigotes localize in the small blood vessels of the heart and the central nervous system, and can cause brain hemorrhage and inflammation.
Correct Answer: Short-lived disease
Enterobius is a pinworm entirely restricted to humans, and infection can be readily transmitted in places where large numbers of children gather together.
Correct Answer: Pinworm
Eggs are passed into feces but must mature in the soil before the eggs can become infectious. The larvae of the worms penetrate the intestinal mucosa of the human host and invade the liver. The larvae are still small enough to exit through the hepatic vein, be carried to the right side of the heart and subsequently be pumped into the lung.
Correct Answer: Eggs must mature in the digestive tract before they can become infectious
Cercariae, metacercaria, and miracidia are seen in the life cycle of shistosomes, a kind of trematode.
Correct Answer: Trematodes
Cryptococcus is a fungus, the other choices are all protozoans.
Correct Answer: Cryptococcus
Tapeworms are helminths and are nourished by absorbing soluble intestinal contents.
Correct Answer: Intestinal contents
Ringworm is a fungal disease.
Correct Answer: Fungus
Fungi contain ergosterol in their plasma membranes.
Correct Answer: Ergosterol
Fungal cell walls contain both mannan and glucan.
Correct Answer: Mannan and glucan
All other choices are spores or associated with spores.
Correct Answer: Hyphae
Superficial mycoses are fungal infections of the superficial skin and are associated with hair follicles. They are not systemic and do not affect inner organs or destroy tissue. Coccidioides cause deep mycoses.
Correct Answer: They are associated with hair follicles
Mucocutaneous candidiasis is not a deep mycoses infection. It is an infection of the mucous membranes caused by Candida albicans and can be seen as thrush and vulvovaginitis.
Correct Answer: It is a deep mycosis
Tinea corporis is a form of ringworm which is found between the fingers, in wrinkles in the palm, and on scaly skin.
Correct Answer: A form of ringworm
The most commonly seen yeast infections are caused Candida albicans.
Correct Answer: Candida albicans
Parasites can be divided into two groups, protozoans and helminthes.
Correct Answer: True
Malaria is just one example of a parasitic disease and if affects more than 500 million people; more than 2 million people, mostly children, die of this disease each year.
Correct Answer: False
Malaria is caused by the protozoan parasite Plasmodium.
All helminths have differentiated organs.
All helminths are bilaterally symmetrical.
There are three classes of helminth that infect humans: nematodes, cestodes, and trematodes.
Some parasitic organisms use a single host; others require multiple hosts.
The pathogenic mechanisms of parasitic protozoa and helmiths vary from species to species
Blind-ended branched alimentary tracts are not part of nematodes. They are part of trematodes.
Correct Answer: A blind branched alimentary tract
Plasmodium sporozpoies penetrate the salivary glands of mosquitos and infect humans when the mosquito bites.
Correct Answer: Sporozoite
Many protozoans possess a trophozoite stage, but the trophozoite form of Trichomonas can survive outside the host and is transmitted from host to host.
Correct Answer: Trophozoite
The protozoan Entamoeba histolytica lives in the human gut and produces strong cysts that are passed in the stool and transmitted through the fecal–oral route of contamination.
Correct Answer: Cyst
The parasitic helminth Ascaris lumbricoides, produces highly resistant eggs that are passed in the stool of the infected host. These eggs are not immediately infectious and must mature in the soil for a period.
Correct Answer: Egg