Zoology Test 2a

Question 1

What are Platyhelminthes?

Answer 1

• flatworms

- acoelomates

Question 2

acelomates

Answer 2

without a body cavity (coelom)

Question 3

What is in between the epidermis and gastrodermis?

Answer 3

parenchyma

Question 4

How does embryo of Platyhelminthes differ form that of Cnidarians?

Answer 4

• triploblastic rather than diploblastic
• ectoderm, mesoderm and endoderm
• mesoderm gives rise to true muscle tissue, bones, circulatory system and other internal organs

Question 5

symmetry of platyhelminthes

Answer 5

bilaterally symmetrical

• must actively search for food and mates
• body flattened dorso-ventrally
• cephalization

Question 6

anterior

Answer 6

front

Question 7

posterior

Answer 7

back

Question 8

dorsal

Answer 8

back

Question 9

ventral

Answer 9

front

Question 10

cephalization

Answer 10

• possess head where central nervous system and sensory organs are located

Question 11

digestive system in platyhelminthes

Answer 11

incomplete digestive system

• mouth but no anus
• some of these worms don’t have a mouth and absorb nutrients through their specialized skin
• tegument with microtrix to enlarge surface area for absorption

Question 12

excretion and respiration in platyhelminthes

Answer 12

• simple diffusion

- flattened body aides in process, easier for diffusion to occur

Question 13

Platyhelminthes

Answer 13

• Turbellaria
• Monogenea
• Trematoda
• Cestoda

Question 14

types of turbellaria

Answer 14

• free living flatworms

- dugesia (planaria)

Question 15

types of monogenea

Answer 15

• small ectoparasites

Question 16

types of trematoda

Answer 16

• larger ‘flukes’

- endoparasites

Question 17

types of cestoda

Answer 17

• tapeworms

Question 18

Dugesia

Answer 18

• type of turbellaria
• also called planarian
• freshwater, tremendous powers in regeneration

Question 19

digestive system of dugesia

Answer 19

• y-shaped with reversible pharynx for feeding

Question 20

turbellaria reproduction (dugesia)

Answer 20

• asexually by fission (fragmentation)
• sexually via complex organ system (syngamy)
• monoecious

Question 21

characteristics of Monogenea

Answer 21

• ectoparasite
• don’t harm host
• attach via a haptor to host
• only sexual reproduction (only produce one adult at a time)

Question 22

characteristics of Trematoda

Answer 22

• parasitic flukes with two or three hosts per life cycle
• snail is always found in life cycle (intermediate host)
• vertebrate is almost always definitive host
• Clonorchis (human liver fluke)
• both asexual and sexual reproduction

Question 23

parasites

Answer 23

• loss of sensory structures
• loss of organ systems
• increased reproductive ability

Question 24

definitive host

Answer 24

where parasite has sexual reproduction

Question 25

intermediate host

Answer 25

parasite has asexual reproduction

Question 26

characteristics of cestoda

Answer 26

• includes tapeworms
• are endoparasites of vertebrate digestive system with highly specialized anatomy
• anatomy consists of series of proglottids and a ‘head’ bearing a scolex
• monoecious

Question 27

types of cestoda

Answer 27

• Taenia (beef tapeworm)

-

Question 28

scolex

Answer 28

hooks or suckers

Question 29

What is found inside a proglottid?

Answer 29

• reproductive organs (both male and female)
• nerve cords
• flame cells for excretion, excretory ducts, muscles and parenchyma

Question 30

characteristics of platyhelminthes nervous system

Answer 30

• have up to five pairs of nerve cords

- freshwater flatworms, there is a ladder-type = one pair of lateral nerve cords connected to cerebral ganglia

Question 31

osmoregulation in platyhelminthes

Answer 31

• flame cells lined with cilia drive fluids through a series of tubules which open to outside through series of pores

Question 32

life cycle of clonorchis

Answer 32

• ingested and burrows into the bile duct of the liver
• egg containing miracidium (larvae) travels through intestines and defecated
• snail ingests the egg
• the egg hatches and the miracidium feed on the snail tissue and becomes germ tissue (redia) via asexual reproduction
• this germ tissue is called a sporocyst, they release redia
• redia release cercaria via asexual reproduction which travel through water and imbed themselves in fish
• they become the metacercarial cyst in the fish muscle and wait to be ingested by final host
• cyst develops into adult and sexually reproduces to begin life cycle again

Question 33

Clonorchiasis

Answer 33

• caused by Clonorchis sinensis

- life cycle is broken by sanitary disposal of human feces and cooking fish throughly

Question 34

Schistosomiasis

Answer 34

• infects 300 million worldwide
• caused by human blood fluke, Schistosoma sp.
• female lives an external canal of male
• dioecious

Question 35

differences in life cycle of schistosoma

Answer 35

• cercariae burrow directly into skin of humans wading in water
• cercariae enter human blood stream and give rise directly to adults

Question 36

causes of eggs in schistosoma

Answer 36

• pass from circulatory system to digestive system and are voided in feces
• considerable damage occurs; eggs cause ulceration of linings of intestines and urinary bladder
• can cause cirrhosis of liver

Question 37

Swimmer’s Itch

Answer 37

• caused by cercaria of trematode fluke
• temporary dermatitis in human skin
• humans are the wrong definitive host for fluke, so cercariae penetrate human skin, but don’t survive

Question 38

life cycle of beef tapeworm

Answer 38

• gravid proglottid is released through fecal matter of humans
• shelled larvae is released
• contaminated grass is eaten by the cow and ingested
• cysts form in the muscle of the cow
• develop into a invaginated scolex/cysticercus
• the meat is then cooked and if not cooked throughly it will continue to live and then be ingested into human and repeat life cycle

Question 39

tapeworm facts

Answer 39

• only about 1% of cattle are infected with this in america
• throughly cook meet to avoid it
• can live in dogs, cats, humans
• can be found in meat, poultry or fish
• some encyst in organs
• some cause more serious pain