Parasitology

Question 1

Define parasite

Answer 1

A smaller organism that lives on or in and at the expense of a larger organism (host).

Question 2

What is the phylum and class of “roundworms”?

Answer 2

Phylum nemathelminths

Class Nematoda

Question 3

What is the phylum and class of “tapeworms”?

Answer 3

Phylum platyhelminthes

Class Cestoda

Question 4

What is the phylum and class of “flukes”?

Answer 4

Phylum platyhelminthes

Class trematoda

Question 5

Nematodes:

• Free-living or parasitic?
• Shape/conformation?
• Ailmentary canal present?
• Separate sexes or hemaphroditic?

Answer 5

• Both free-living and parasitic
• Elongate/cylindrical
• Ailmentary canal present
• Separate sexes

Question 6

Cestodes:

• Shape/conformation?
• Alimentary canal present?
• Separate sexes or hermatphroditic?

Answer 6

• Flat body
• No alimentary canal
• Hermaphroditic

Question 7

What is a scolex and who has one?

Answer 7

Scolex is the “holdfast organ” in cestodes. It’s the head

Question 8

What is a strobila and who has it?

Answer 8

Strobila is the body with proglottids found in cestodes

Question 9

What is a proglottid and who has it?

Answer 9

Egg packets found in cestodes

Question 10

Trematodes:

• Shape/conformation?
• Separate sexes or hermaphroditic?

Answer 10

• Dorso-ventrally flattened - Leaf-like

* separate sexes

Question 11

Common name for diptera.

Answer 11

Flies

Question 12

Common name for siphonaptera

Answer 12

Fleas

Question 13

Common name for Phthiraptera

Answer 13

Lice

Question 14

What are the physical characteristics of insects?

Answer 14

Adults have 3 pairs of legs
3 body segments: head, thorax and abdomen
Antenna present

Question 15

What are the physical characteristics of adult arachnids (acari)?

Answer 15

4 pairs of legs
2 body segments: cephalo-thorax and abdomen
No antennae, but palps

Question 16

How many pairs of legs are found in nymph acari? Larvae acari?

Answer 16

4 pairs in nymphs

3 pairs in larvae

Question 17

How are protozoa classified?

Answer 17

Classified based on their mode of locomotion.

Question 18

What are the ways in which protozoa accomplish locomotion?

Answer 18

Pseudopodia
Flagella
Gliding movements
Cilia

Question 19

Define Definitive Host.

Answer 19

Harbors adult (sexual) stage of the parasite

Question 20

Define Intermediate Host

Answer 20

Harbors larval (asexual) stage of the parasite

Question 21

Define Incidental Host

Answer 21

An unusual host, unnecessary for the maintenance of the parasite in nature.

Question 22

In what ways can parasites cause mechanical tissue damage?

Answer 22

Blockage of internal organs
Pressure atrophy
Migration through tissues

Question 23

Give examples of toxic parasite products

Answer 23

Destructive enzymes 
Endotoxins
Toxic secretions (tick paralysis)

Question 24

Define premunition

Answer 24

A type of acquired immunity in which the host is able to prevent superinfection by keeping parasite numbers in check without eliminating the infection (i.e. marlia, toxoplasmosis)

Question 25

Define concomitant immunity

Answer 25

A type of acquired immunity in which the parasite elicits a protection against reinfection, but the parasite itself remains in the host, unaffected by the immune response (i.e. schistosomiasis).