Parasitology Exam 1

Question 1

direct life cycle

Answer 1

no intermediate host

Question 2

indirect life cycle

Answer 2

definitive host + 1 or more intermediate hosts
transmission often linked to predator-prey relationships or vector-vertebrate interactions

Question 3

symbiosis
4 types

Answer 3

any 2 organisms living in close association, commonly one living in or on the body of the other
commensalism, mutualism, phoresis, parasitism

Question 4

commensalism

Answer 4

one benefits and the other is not helped or harmed
facultative

Question 5

mutualism

Answer 5

both benefit, usually obligatory where one cannot survive without the other
cleaning phenomena between fish

Question 6

phoresis

Answer 6

travel together with no physiological/biochemical dependence; mechanically carried
bacteria on legs of flies

Question 7

parasitism

Answer 7

either harms the host or lives at the expense of the house = mechanical injury or robbing host of nutrition

Question 8

endoparasites

Answer 8

helminths, flukes

Question 9

exoparasites

Answer 9

fleas, ticks

Question 10

obligatory parasites

Answer 10

cannot complete life cycle without spending part of time in parasitic relationship; many have free-living stages outside of host or time in environment with protective egg wall or cyst

Question 11

facultative parasites

Answer 11

not usually parasitic but can become so if accidentally eaten or enter a wound
e.g. free living amoebas or nematodes

Question 12

accidental parasites

Answer 12

do not survive in wrong host but may be pathogenic
e.g. toxoplasma

Question 13

temporary/intermittent parasites

Answer 13

mosquitos or bedbugs

Question 14

definitive host

Answer 14

parasite reaches sexual maturity
often vertebrates

Question 15

intermediate host

Answer 15

required for development, sexual maturity is not reached

Question 16

paratenic or transport host

Answer 16

no development, parasite remains alive and is infective to next host
bridge an ecological gap

Question 17

reservoir host

Answer 17

animal harboring infection that can be transmitted to humans

Question 18

host specificity

Answer 18

some parasites are host specific
e.g. Coccidia

Question 19

What are some examples where we are seeing anthelmintic resistance in our animal populations?

Answer 19

coccidia resistance in poultry

Question 20

How might parasites contribute to financial loss in herds?

Answer 20

By killing numerous animals in a herd, the production will decrease

Question 21

How do crowded stressful conditions contribute to parasitism?

Answer 21

In pastures/pens of domesticated animals, eggs/larvae/cysts can become dense in the soil and if adult parasites infect the host it can be devastating

Coccidia thrives in crowded conditions

Question 22

What are life stages? Can you provide examples?

Answer 22

trophozite: active, feeding, multiplying stage (e.g. giardia)
cyst: protective membrane/thickened wall so they can survive outside the host
oocysts: coccidian form of a cyst

Question 23

Why are cysts an important life stage adaptation?

Answer 23

Helps parasites live in environments with harsh conditions (food deficiency, desiccation, low O2, pH or temperature change)

Question 24

Nematodes

Answer 24

bilaterally symmetrical
elongated
tapered at both ends
pseudocoelomate
complete digestive system

Question 25

Platyhelminths

Answer 25

found in many environments
bilaterally symmetrical
dorsoventrally flattened, some elongated
lead-shaped or ovoid in form
acoelomate
distinct anterior end
sensory/motor elaborate nervous system
cestodes have no digestive system
trematodes have a digestive system

Question 26

cestodes

Answer 26

tapeworms
-no digestive system
-monoecious organisms
-strobila (segments)
-sucker/grooves/hook/spine/glands /tentacles

Question 27

trematodes

Answer 27

fluke
-digestive system is blind sac w/ anterior mouth, muscular pharynx, EC digestion
-undigested waste go through mouth

Question 28

protozoans

Answer 28

most habitats
commensal & parasitic
microscopic, single-celled, 1+ nuclei
immunologic, varibale size, surface proteins
use pseudopodia, flagella, cilia for locomotion
sexual/asexual reproduction
trophozoites or cysts

Question 29

3 types of protozoans

Answer 29

diplomonadidae - flagellates (giardia)
trichomonadidae - thousands of flagella
trypanosomatidae - kinetoplasts

Question 30

arthropods

Answer 30

vectors several groups of pathogens
invertebrates
segmentation
hard exoskeleton + appendages
discrete mm.

Question 31

monoecious/hermaphroditic

Answer 31

having both male and female reproductive organs in the same individual

e.g. nematodes, trematodes, cestodes

Question 32

dioecious

Answer 32

male and female reproductive organs in separate individuals

e.g. nematodes & trematodes

Question 33

acetabula

Answer 33

specialized sucker for parasitic adaptation to attach to host; cup shaped, ovoid, muscular structure

e.g. cestode (tapeworm)

Question 34

name parts of a tapeworm

Answer 34

proglottids (each segment of strobila)
strobila (segmented part)
scolex (head of tapeworm)
rostellum (knob-like protrusion at anterior end)

Question 35

holdfast organ

Answer 35

an organ by which a parasitic organism attaches itself to a host

cestodes

Question 36

parthenogenetic

Answer 36

asexual reproduction

nematodes

Question 37

oviparous

Answer 37

producing young by the means of eggs that are hatched after laid by parent

nematodes

Question 38

ovoviviparous

Answer 38

producing young by the means of eggs that are hatched within the body of the parent

nematodes

Question 39

triradiate

Answer 39

having or consisting of three rays or radiating branches

pharynx or esophagus of nematodes

Question 40

kinetoplasts

Answer 40

protozoans with DNA containing region in a single large mitochondrian

Question 41

flagellates

Answer 41

protozoans that have flagella