Question 1

After returning from a trip to Africa, Tom feels tired and weak and has severe anemia.A blood smear reveals a protozoan in his blood and the health care provider diagnoses malaria.Which of the following could be the causative agent of this disease?

Accepted Answer

Malaria is a parasitic disease caused by the Plasmodium species, which are transmitted to humans via the bite of infected Anopheles mosquitoes. Plasmodium vivax is one of the four species of Plasmodium that commonly cause malaria in humans. Giardia lamblia is a protozoan that causes gastrointestinal symptoms, not malaria. Trichophyton rubrum is a fungus that causes skin infections. Taenia solium is a tapeworm that causes pork tapeworm infection. HIV is a virus that attacks the immune system and causes AIDS, but it is not responsible for causing malaria.

Question 2

A specimen from a patient suffering diarrhea shows a one-celled organism in the microscope.The organism moves very slowly by protruding its cytoplasm.You would predict that the patient has an infection caused by ______.

Accepted Answer

Entamoeba is a one-celled organism that moves slowly by protruding its cytoplasm. It is commonly associated with gastrointestinal infections and can cause symptoms such as diarrhea, abdominal pain, and cramping. The other organisms listed do not typically cause diarrhea or move in the same way as Entamoeba.

Question 3

In producing beer and wine, humans have exploited the microbial ability to ferment sugar to alcohol.The microbes responsible for this process are ______.

Accepted Answer

The microbes responsible for fermenting sugar to alcohol in beer and wine are fungi, specifically yeast. This is because yeast is naturally adept at converting glucose into alcohol and carbon dioxide through fermentation. Therefore, the correct answer is D) fungi.

Question 4

Which pair is mismatched?

Accepted Answer

Plasmodium causes malaria, not Chagas disease.

Question 5

Protozoan cysts are

Accepted Answer

Protozoan cysts are analogous to bacterial endospores as they are a dormant, resistant form that helps the organism survive unfavorable conditions.

Question 6

Protozoan cells do not exhibit ______.

Accepted Answer

Protozoans do not have a cell wall. This feature distinguishes them from plant cells, which have a rigid cell wall made of cellulose.

Question 7

Algae are classified into divisions based principally on their type of motility.

Accepted Answer

Algae are classified into divisions based on various characteristics, such as pigments, cell wall composition, and reproduction, rather than just motility.

Question 8

A group of protozoa that are not motile are the ______.

Accepted Answer

Plasmodium species are non-motile protozoa that rely on vectors like mosquitoes for transmission.

Question 9

In humans, fungi can only infect the skin.

Accepted Answer

Fungi can infect not only the skin but also the nails, hair, and internal organs in humans. Examples of internal fungal infections include aspergillosis, candidiasis, and cryptococcosis.

Question 10

A protozoan cyst differs from a helminth egg in that

Accepted Answer

A protozoan cyst can germinate to form the organism, whereas an egg must be fertilized in order to develop. This is a fundamental difference between the two structures. A cyst is also not necessarily metabolically active, as it can remain dormant for extended periods of time. There is no significant difference in the morphology or structure of cysts and helminth eggs, and both can contain enclosed nuclei or free-floating chromosomes. Therefore, options A, B, and D are not correct answers to the question.

Question 11

A protozoan having a flagellum would be classified in the genus ______.

Accepted Answer

Trypanosoma is a genus of protozoa that have a flagellum. Entamoeba, Toxoplasma, Enterobius, and Plasmodium do not have a flagellum.

Question 12

The motile, feeding stage of protozoa is called the ______.

Accepted Answer

The trophozoite is the motile, feeding stage of protozoa which actively ingests food and reproduces through binary fission. Option A (oocyst) and B (cyst) refer to the non-motile and dormant stage of protozoa while option C (sporozoite) refers to the infective stage of certain protozoa. Option D (food vacuole) is a structure found within the protozoa cell that helps in digestion.

Question 13

Infections caused by fungi are called mycoses.

Accepted Answer

Infections caused by fungi are indeed called mycoses.

Question 14

Protozoa are classified into four groups based on ______.

Accepted Answer

Protozoa are classified into four groups based on how they move. The four groups are sarcodines, ciliates, flagellates, and sporozoans.

Question 15

Amoebic dysentery is most commonly contracted through

Accepted Answer

Amoebic dysentery is contracted through the fecal-oral route from contaminated food or water, typically from ingestion of fecal matter containing the amoeba Entamoeba histolytica.

Question 16

Protozoan endoplasm contains ______.

Accepted Answer

Endoplasm is the inner, more fluid part of the cytoplasm in a protozoan cell, which contains various organelles including mitochondria for energy production. Choice A and D refer to external structures used for movement, while choice B refers to a specialized area for feeding. Choice C refers to the outer part of the cytoplasm, which is more gel-like and involved in movement and support.

Question 17

During unfavorable growth conditions, many protozoa can convert to a resistant, dormant stage called a(n) ______.

Accepted Answer

Protozoa can convert to a resistant, dormant stage called a cyst during unfavorable growth conditions. This allows them to survive in unfavorable conditions, such as drought or extreme temperatures, until conditions become more favorable for growth and reproduction.

Question 18

All fungi cause some kind of disease in plants or animals.

Accepted Answer

This statement is false. While some fungi do cause diseases in plants or animals, not all fungi do. Some fungi have beneficial relationships with their hosts, such as mycorrhizal fungi that form symbiotic relationships with plant roots.

Question 19

Plankton are floating communities of helminths.

Accepted Answer

Plankton are not made up of helminths, which are parasitic worms. Plankton are tiny organisms that float in aquatic environments and include both plants (phytoplankton) and animals (zooplankton).

Question 20

There are no algae that can cause human disease.

Accepted Answer

Some algae, particularly certain types of cyanobacteria (often referred to as blue-green algae), can produce toxins that are harmful to humans, causing diseases or adverse health effects when people are exposed to or consume contaminated water.

Quiz 5: Eukaryotic Cells and Microorganisms