Protozoa

Question 1

List the defining characteristics of protozoa

Answer 1

unicellular eukaryotes; reproduce asexually by schizogony, fission, or budding. Reproduce sexually by syngamy

Question 2

Define schizogony

Answer 2

Asexual reproduction by multiple fission

Question 3

Define protozoan conjugation

Answer 3

The sexual reproduction of a protozoa where two protozoan cells (specifically the nuclei) fuse together to create a zygote.

Question 4

Define cyst

Answer 4

A growth stage with a protective membrane or a thickened wall; often the infectious form and is durable in harsh environments

Question 5

Define oocyst

Answer 5

The thick-walled stage of some Apicomplexa

Question 6

Define trophozoite

Answer 6

A general term for the active, feeding, and multiplying stage of most protozoa

Question 7

Define pseudopod

Answer 7

A structure that is a protrusion from the surface of the cell that amoeboid cells use for movement and feeding

Question 8

Define undulating membrane

Answer 8

A fin-like extension of the cytoplasmic membrane that Apicomplexa use for gliding motility

Question 9

Define definitive host

Answer 9

The host organism in which sexual reproduction occurs

Question 10

Define intermediate host

Answer 10

The host organism that houses the asexual or immature stages.

Question 11

Describe the life cycle of Plasmodium spp.

Answer 11

Asexual: An infected mosquito bites a human; the sporozoites migrate through the bloodstream to the liver. They undergo schizogony in a liver cell and merozoites are produced, then released into the bloodstream, where they can then infect red blood cells. In a red blood cell, a merozoite develops into its ring stage, which grows and divides, producing merozoites, which are released when the erythrocyte ruptures. Some merozoites infect new red blood cells and some develop into male and female gametocytes.
Sexual: Another mosquito bites the infected human and ingests the gametocytes. In the mosquito’s digestive tract, the gametocytes unite to form a zygote, and the resulting sporozoites migrate to the salivary glands of the mosquito.

Question 12

Is a sporozoite part of the sexual or asexual reproduction of Plasmodium spp.?

Answer 12

Produced by sexual reproduction and can undergo asexual reproduction

Question 13

Is a merozoite part of the asexual or sexual reproduction of Plasmodium spp.?

Answer 13

Asexual reproduction

Question 14

Is a ring stage part of the sexual or asexual reproduction of Plasmodium spp.?

Answer 14

Asexual reproduction

Question 15

Describe the four groups of medically relevant protozoa

Answer 15

Characterized by movement:

• Amoeba have pseudopods.
• Flagellates have flagella.
• Ciliates have cilia.
• Apicomplexa have no obvious motility structures but use their undulating membrane for gliding motility.

Question 16

What group of medically relevant protozoa is the genera Giardia in?

Answer 16

Flagellates

Question 17

What group of medically relevant protozoa is the genera Trichomonas in?

Answer 17

Flagellates

Question 18

What group of medically relevant protozoa is the genera Entamoeba in?

Answer 18

Amoeba

Question 19

What group of medically relevant protozoa is the genera Acanthamoeba in?

Answer 19

Amoeba

Question 20

What group of medically relevant protozoa is the genera Plasmodium in?

Answer 20

Apicomplexa

Question 21

What group of medically relevant protozoa is the genera Toxoplasma in?

Answer 21

Apicomplexa

Question 22

What group of medically relevant protozoa is the genera Cryptosporidium in?

Answer 22

Apicomplexa

Question 23

What group of medically relevant protozoa is the genera Cyclospora in?

Answer 23

Flagellates

Question 24

What group of medically relevant protozoa is the genera Balantidium in?

Answer 24

Ciliates

Question 25

List the methods commonly used to identify protozoa in the lab.

Answer 25

Cannot be cultured. Identified through microscopic morphology, and rarely immunologic tests