EXERCISES, LESSON 1
INSTRUCTIONS. Answer the following exercises by marking the lettered response that
best answers the question or best completes the incomplete statement.
After you have completed all of these exercises, turn to "Solutions to Exercises" at the
end of the lesson and check your answers. For each exercise answered incorrectly,
reread the material referenced with the solution.
Symbiosis is defined as:
a. A state in which two members of the same species band together to form a
group for hunting and protective reasons.
b. The close association or living together of two organisms of different species.
A type of commensalism in which a parasite lives off another organism (i.e.,
d. A condition in which two organisms must live together in order to exist.
A pathogenic parasite is one that:
a. Lives on the outer surface of the host organism.
b. Can harm man, crops, and domestic animals.
Lives on the inside of the host organism.
d. Has a long life span in the host organism.
Select the statement that describes the pathogenic effect produced by a parasitic
infection on a host.
a. Toxins produced by parasites inhibit the production of vitamins in the body of
b. Some parasites are so numerous that their presence in the intestines can
obstruct the flow of lymph in the lymphatic system.
Some parasitic infections can cause a loss of body fluids and blood.
d. All parasitic infections produce tumors in host tissues.