HUMAN PARASITOLOGY - EXAM 1
QUESTIONS WITH CORRECT
ANSWERS
SECTION 1: SYMBIOSIS & PARASITE DEFINITIONS (Q1-25)
Q1. What are the four categories of symbiosis?
Answer: 1. Commensalism (+/0), 2. Phoresis - phorant (+) but
host (0), 3. Parasitism (exploitation) (+/-), 4. Mutualism (+/+).
Rationale: Symbiosis describes any close relationship between
different species. Commensalism benefits one without affecting
the other; phoresis involves transport without harm; parasitism
benefits the parasite while harming the host; mutualism benefits
both partners.
Q2. What is a symbiont?
Answer: An organism that lives in close association with another
organism of a different species.
Rationale: The term symbiont applies to any organism
participating in a symbiotic relationship, regardless of whether the
relationship is beneficial, neutral, or harmful to either party.
Q3. A pathogenic parasite is one that:
Answer: Can harm man.
Rationale: Not all parasites cause disease; pathogenicity refers
specifically to the ability to cause harm or disease in the host.
Q4. What is an obligate parasite?
Answer: An organism that is always parasitic, physiologically
dependent on the host, and cannot survive without it throughout
,most of its life cycle.
Rationale: Obligate parasites have evolved to the point where
they cannot complete their life cycle outside a host. Example:
ticks.
Q5. What is a facultative parasite?
Answer: An organism that can become parasitic if placed in a
conducive situation but does not require a host to complete its
life cycle.
Rationale: Facultative parasites are typically free-living organisms
that can opportunistically adopt a parasitic lifestyle when
conditions permit.
Q6. What is a parasitoid?
Answer: A parasite that kills its host, with offspring hatching
inside the host; it has only one host.
Rationale: Parasitoids represent an extreme form of parasitism
where host death is a normal part of the life cycle, commonly seen
in certain wasps and flies.
Q7. What is a parasite castrator?
Answer: A parasite strategy that inhibits host reproduction.
Rationale: Some parasites redirect host resources away from
reproduction toward parasite growth, effectively sterilizing the
host to enhance parasite survival.
Q8. What is an ectoparasite?
Answer: A parasite that lives on the outside surface of the host.
Rationale: Ectoparasites include ticks, lice, fleas, and mites that
infest the skin, hair, or feathers of their hosts.
,Q9. What is an endoparasite?
Answer: A parasite that lives inside the host's body.
Rationale: Endoparasites include protozoa like Plasmodium and
helminths like tapeworms that reside in internal organs, tissues, or
body cavities.
Q10. What is a hyperparasite?
Answer: A parasite of a parasite.
Rationale: Hyperparasitism occurs when a parasite is itself
infected by another parasite, representing a higher level of
parasitic complexity.
Q11. What is an accidental parasite?
Answer: A parasite that infects hosts it does not usually infect.
Rationale: Accidental (or incidental) parasites are those that find
themselves in a host species different from their normal one,
often with deleterious effects.
Q12. What is a micropredator?
Answer: An organism that attacks multiple organisms; attacks
rarely lead to death.
Rationale: Micropredators (like mosquitoes) feed on multiple
hosts during their lifetime, unlike true parasites that typically
remain on or in a single host.
Q13. Which organisms are traditionally considered parasites?
Answer: Helminths (trematodes, cestodes, nematodes), protozoa
(not all - depends on +/- relationship), and arthropods (especially
vectors).
Rationale: Bacteria, fungi, and viruses are NOT traditionally
considered parasites in parasitology, though they can be
pathogenic.
, Q14. Symbiosis is defined as:
Answer: A state in which two members of different species live
together.
Rationale: The key elements are close association and different
species; the relationship can be beneficial, neutral, or harmful.
Q15. The parasite has the _____ to harm the host.
Answer: Potential.
Rationale: Parasites have the potential to harm but don't always
cause disease; many infections are asymptomatic.
Q16. What is the pathway to parasitism in nematodes?
Answer: Free-living → phoresy → necromeny → parasitism.
Rationale: This evolutionary pathway shows how free-living
organisms gradually adapted to parasitic lifestyles through
intermediate stages of association.
Q17. What is phoresis?
Answer: A symbiotic relationship where one organism (phorant)
benefits from transport by another (host) without harming the
host.
Rationale: Phoresis is considered a precursor to parasitism in
evolutionary terms.
Q18. What is mutualism?
Answer: A symbiotic relationship where both species benefit
(+/+).
Rationale: Mutualism is the only symbiosis category where both
partners derive benefit.
Q19. What is commensalism?
Answer: A symbiotic relationship where one species benefits and
QUESTIONS WITH CORRECT
ANSWERS
SECTION 1: SYMBIOSIS & PARASITE DEFINITIONS (Q1-25)
Q1. What are the four categories of symbiosis?
Answer: 1. Commensalism (+/0), 2. Phoresis - phorant (+) but
host (0), 3. Parasitism (exploitation) (+/-), 4. Mutualism (+/+).
Rationale: Symbiosis describes any close relationship between
different species. Commensalism benefits one without affecting
the other; phoresis involves transport without harm; parasitism
benefits the parasite while harming the host; mutualism benefits
both partners.
Q2. What is a symbiont?
Answer: An organism that lives in close association with another
organism of a different species.
Rationale: The term symbiont applies to any organism
participating in a symbiotic relationship, regardless of whether the
relationship is beneficial, neutral, or harmful to either party.
Q3. A pathogenic parasite is one that:
Answer: Can harm man.
Rationale: Not all parasites cause disease; pathogenicity refers
specifically to the ability to cause harm or disease in the host.
Q4. What is an obligate parasite?
Answer: An organism that is always parasitic, physiologically
dependent on the host, and cannot survive without it throughout
,most of its life cycle.
Rationale: Obligate parasites have evolved to the point where
they cannot complete their life cycle outside a host. Example:
ticks.
Q5. What is a facultative parasite?
Answer: An organism that can become parasitic if placed in a
conducive situation but does not require a host to complete its
life cycle.
Rationale: Facultative parasites are typically free-living organisms
that can opportunistically adopt a parasitic lifestyle when
conditions permit.
Q6. What is a parasitoid?
Answer: A parasite that kills its host, with offspring hatching
inside the host; it has only one host.
Rationale: Parasitoids represent an extreme form of parasitism
where host death is a normal part of the life cycle, commonly seen
in certain wasps and flies.
Q7. What is a parasite castrator?
Answer: A parasite strategy that inhibits host reproduction.
Rationale: Some parasites redirect host resources away from
reproduction toward parasite growth, effectively sterilizing the
host to enhance parasite survival.
Q8. What is an ectoparasite?
Answer: A parasite that lives on the outside surface of the host.
Rationale: Ectoparasites include ticks, lice, fleas, and mites that
infest the skin, hair, or feathers of their hosts.
,Q9. What is an endoparasite?
Answer: A parasite that lives inside the host's body.
Rationale: Endoparasites include protozoa like Plasmodium and
helminths like tapeworms that reside in internal organs, tissues, or
body cavities.
Q10. What is a hyperparasite?
Answer: A parasite of a parasite.
Rationale: Hyperparasitism occurs when a parasite is itself
infected by another parasite, representing a higher level of
parasitic complexity.
Q11. What is an accidental parasite?
Answer: A parasite that infects hosts it does not usually infect.
Rationale: Accidental (or incidental) parasites are those that find
themselves in a host species different from their normal one,
often with deleterious effects.
Q12. What is a micropredator?
Answer: An organism that attacks multiple organisms; attacks
rarely lead to death.
Rationale: Micropredators (like mosquitoes) feed on multiple
hosts during their lifetime, unlike true parasites that typically
remain on or in a single host.
Q13. Which organisms are traditionally considered parasites?
Answer: Helminths (trematodes, cestodes, nematodes), protozoa
(not all - depends on +/- relationship), and arthropods (especially
vectors).
Rationale: Bacteria, fungi, and viruses are NOT traditionally
considered parasites in parasitology, though they can be
pathogenic.
, Q14. Symbiosis is defined as:
Answer: A state in which two members of different species live
together.
Rationale: The key elements are close association and different
species; the relationship can be beneficial, neutral, or harmful.
Q15. The parasite has the _____ to harm the host.
Answer: Potential.
Rationale: Parasites have the potential to harm but don't always
cause disease; many infections are asymptomatic.
Q16. What is the pathway to parasitism in nematodes?
Answer: Free-living → phoresy → necromeny → parasitism.
Rationale: This evolutionary pathway shows how free-living
organisms gradually adapted to parasitic lifestyles through
intermediate stages of association.
Q17. What is phoresis?
Answer: A symbiotic relationship where one organism (phorant)
benefits from transport by another (host) without harming the
host.
Rationale: Phoresis is considered a precursor to parasitism in
evolutionary terms.
Q18. What is mutualism?
Answer: A symbiotic relationship where both species benefit
(+/+).
Rationale: Mutualism is the only symbiosis category where both
partners derive benefit.
Q19. What is commensalism?
Answer: A symbiotic relationship where one species benefits and
