Host parasite associations

Question 1

Key parasitic characteristics

Answer 1

• metabolically reliant on host
• lives in or on another species
• may not necessarily harm host
• usually smaller than host

Question 2

Distinguish between micro and macro parasites

Answer 2

MICRO - do not reproduce in their definitive hosts

• short generation time
• host is the unit of study
• often lasting immunity

MACRO- reproduce in definitive hosts

• long generation time
• no lasting immunity
• parasite unit of study

Question 3

Product of disease/ parasite interaction

Answer 3

• elevated temperature (fever)
• reduced food intake
• immune response
• decreased activity
• pain sensitivity

Question 4

3 ways to classify parasites

Answer 4

1) MACRO vs MICRO
2) Taxonomically
3) transmission strategy

Question 5

Protozoa are single celled (a) consisting of 4 classes, what are those classes? b)

EDDIE AND EVE DUCKED

Answer 5

a) eukaryotes

b) euglenozoa (extracellular)
apicomplexa (intracellular)
Entamoeba (amoeba like growth form)
Diplomonad (no mitochondiria)

Question 6

Helminth characterisitcs

Answer 6

• metazoan parasitic worms
• non- monophyletic group
• have complex lifestyles

Question 7

4 forms of Helminth

Answer 7

• nematoda (roundworms)
• trematoda (blood flukes)
• cestoda (tapewormds)
• acanthocephalans (thorny headed)

Question 8

DEFINE EACH

a) Direct/ simple/ monoxenic lifecycles

b) Indirect/ complex/ heteroxenic lifecycles

Answer 8

a) can complete development and reproduction using one host

b) requires 2 or more hosts to complete development and reproduction known as the intermediate stages

Question 9

Nematode worms lack (a) mechanisms and enter hosts through skin (b).

Answer 9

a) holdfast

b) penetration

Question 10

Distinguish between monogenean and digenean trematodes

Answer 10

mono- are fish ectoparasites with 2 suckers

dio- require multiple hosts

Question 11

Cestodes inhabit vertebrate (a) and attach to hosts with head like (b).

c) How do adults absorb nutrients as they lack a gut?

Answer 11

a) guts
b) scolex
c) through their body surface

Question 12

Acanthocephalans have thorny a (a) which is exerted into (b) walls.

Answer 12

a) proboscis

b) gut

Question 13

Why are non-parasitic arthropods crucial in the life cycles of many parasites?

Answer 13

• BLOOD FEEDING

- vectors or intermediate hosts

Question 14

Why be parasitic?

Answer 14

• constant source of processed food
• shelter from elements
• host movements help parasite dispersal
• presence of same species make finding mates easier

Question 15

Using examples, distinguish between facultative and obligate parasites.

Answer 15

FACULTATIVE - not always parasitic, doesn’t NEED host to complete life cycle
eg. fungi

OBLIGATE - need a host to complete life cycle, primarily for reproductive purposes

Question 16

Describe the life cycle of the obligate parasite: Entamoeba histolytica

Answer 16

• trophozoites multiply in mucosa crypts of large intestine
• amoebae from cysts which exit via faeces
• these are ingested and form associations with gut wall and cause ulcers

Question 17

Pros and Cons of being ECTOparasitic

Answer 17

PRO: - dispersal/ less attached to host immune system
CON: - can be dislodged and exposed

Question 18

Pros and Cons of being ENDOparasitic

Answer 18

PRO: - ease of feeding
- protection from predators

CON: - dispersal difficult/ vulnerable to immune system

Question 19

What is a parasitoid?

Super vs Hyper

Answer 19

• animal that feeds in or on a living host, consuming all of most of tissues and eventually killing it
  eg. wasps

Hyper: lays eggs in primary parasitoid larvae
Super: lays eggs in hyper parasitoid larvae

Question 20

What is brood parasitism?

Answer 20

• social parasitism among birds

- egg laying in other species nests