21. Principles of Disease

Organisms that interact and live together on a permanent basis are in a relationship termed:

A relationship between two organisms in which one partner benefits and the other is harmed is termed:

Which of the following is an example of a commensal relationship?

Our microbiome is composed of a variety of microorganisms that live within and on our bodies. Research has shown our microbiota protects us against infectious pathogens, creates vitamins and minerals we need, and helps us digest our food. We act as a safe residence and food source for our microbiota. The relationship humans have with their microbiome could be described as?

a) A commensal relationship.

b) A resident relationship.

c) A mutual relationship.

d) A parasitic relationship.

The koala is a leaf-eating animal. What can you infer about its digestive system?

Briefly discuss the importance of lichens in nature. Briefly discuss the importance of algae in nature.

Why is it significant that Trichomonas does not have a cyst stage? Name a protozoan parasite that does have a cyst stage.

By what means are helminthic parasites transmitted to humans?

Use the following choices to answer questions 2 and 3:

1. metacercaria

2. redia

3. adult

4. miracidium

5. cercaria

If a snail is the first intermediate host of a parasite with these stages, which stage would be found in the snail?

a. 1

b. 2

c. 3

d. 4

e. 5

The definitive host for Plasmodium vivax is

a. human.

b. Anopheles.

c. a sporocyte.

d. a gametocyte.

Define symbiosis. Differentiate commensalism, mutualism, and parasitism, and give an example of each.

What best describes the relationship between host and pathogen?

a. Mutualism

b. Parasitism

c. Commensalism

d. Endosymbiosis

First label the following diseases as bacterial, viral, or protozoan, and then indicate which ones are vectorborne infections: dengue fever, AIDS, chikungunya, Lyme disease, malaria.