Parasitology

Question 1

What is meant by phoresis?

Answer 1

• two symbionts travel together
• no harm
• no physiological or biochemical dependence

Question 2

What is meant by mutualism?

Answer 2

• no harm
• both partners benefit
• association is not obligatory (some dependence)

Question 3

What is meant by commensalism?

Answer 3

• usually one partner benefits
• no harm
• association is not obligatory

Question 4

What is meant by parasitism?

Answer 4

• oner partner benefits at the expense of the other
• obligatory dependence

Question 5

List the types of location of parasites within the host

Answer 5

ectoparasite - external
endoparasite - internal

Question 6

What is meant by a facultative parasite?

Answer 6

can become parasitic if ingested or enter a wound

Question 7

What is the definitive host?

Answer 7

• parasite reaches sexual maturity

Question 8

What is the intermediate host?

Answer 8

• parasite develops and often reproduces asexually

Question 9

What is the paratenic host?

Answer 9

• parasite undergoes no development but remains infective to another host

Question 10

What is the reservoir host?

Answer 10

• animal that harbors a parasite which can be transmitted to humans (zoonosis)

Question 11

What are microparasites?

Answer 11

• viruses, bacteria, protozoa
• epidemic disease
• specific resistance to infection
• high reproductive potential

Question 12

What are macroparasites?

Answer 12

• endemic disease
• non-specific host resistance
• low reproduction potential
• transmission dependent upon stages

Question 13

List some major microparasites and what they cause

Answer 13

• prions - creutzfeldt-jakob disease, BSE
• viruses - HIV, covid-19, flu, measles
• bacteria - tuberculosis, anthrax, typhoid
• protozoa - malaria, trypanosomiasis, leishmaniasis

Question 14

Describe the life cycle of a malarial parasite

Answer 14

1. pre-erthrocytic cycle (liver) - asexual
2. post-erthrocytic cycle (blood) - asexual and gamete formation –> haemozoin (waste product)

Question 15

List the major macroparasites

Answer 15

• phylum platyhelminthes (flatworms)
• phylum nematoda (round worms)
• phylum arthropoda

Question 16

Where does the miracidium stage of digenea occur?

Answer 16

in snails

Question 17

Where does the carcaria stage of digenea occur?

Answer 17

in humans

Question 18

Where does trichinella spiralis inhabit in humans?

Answer 18

• adult in gut wall
• cyst in muscle cell

Question 19

Describe monogenean attachment

Answer 19

• posterior opisthaptor
• has suckers, clamps, hooks and/or glands

Question 20

Describe digenean attachment

Answer 20

oral and ventral suckers

Question 21

Describe cestode attachment

Answer 21

• scolex
• strobila = chain of proglottids

Question 22

List the ways in which macroparasites feed

Answer 22

1. surface browsing
2. blood feeding
3. bulk tissue feeding
4. nutrient uptake across body wall

Question 23

List some of the problems associated with blood feeding

Answer 23

• waste products of blood digestion
• lack of B vitamins
• clotting agents
• exposure to host’s immune system

Question 24

Where are microthrix found?

Answer 24

cestodes

Question 25

Where are microvilli found?

Answer 25

monogeneans and larval digeneans

Question 26

Describe some adaptations that aid nutrition

Answer 26

- micro-organisms to counteract vitamin B deficiency - production of anti-coagulants - release of endogenous enzymes and binding of exogenous enzymes - acidification of host's gut - migration along gut

Question 27

What is meant by premunition?

Answer 27

host recovers from disease and is resistant to re-infection

Question 28

What is meant by concomitant immunity?

Answer 28

parasite elicits protection against re-infection but itself remains unaffected by immune response

Question 29

List some evasion mechanisms of host's immune response

Answer 29

1. inaccessibility 2. antigen disguise/mimicry 3. antigen polymorphism 4. shedding agents 5. immunomodulation of host 6. anticomplementary activity

Question 30

What is meant by oviparous?

Answer 30

eggs released into environment and develop outside parent's body

Question 31

What is meant by ovoviviparous?

Answer 31

encapsulated embryos develop within parent's body (elongated uterus)

Question 32

What is meant by viviparous?

Answer 32

embryos develop within parent's body (no egg shell)

Question 33

List the types of sequential hermaphrodites

Answer 33

protandry - male organs before female protogyny - female organs before male

Question 34

List some obligate parasites

Answer 34

- monogenea - trematoda - cestoda

Question 35

List some features of the aceolomate

Answer 35

- tegument - ectoderm - parenchyma - mesodermal organ - endoderm

Question 36

List some features of the pseudocoelomate

Answer 36

- mesoderm - mesodermal organ - pseudocoel - endoderm

Question 37

What is the closest relative to the proto-mitochondrion?

Answer 37

rickettsia