Chapter 18 and 15 Study Questions

Question 1

Sydney Brenner is known for his research with what specific nematodes?

Answer 1

Caenorhabditis elegans- C. elegans

Question 2

List 8 characteristics of nematodes as discussed in your text.

Answer 2

1. Eutely - consistant # of cells in all adults.
2. Cylindrical shape
3. flexible nonmoving cuticle
4. lack of motile cilia or flagella
5. Muscles of their body wall - have several unusual fetures such as running in a longitudnal direction only.
6. do not have protonephridia ( flame cells)
7. Muscular pahrynx
8. Outer body covering- thick, noncellular cuticle

Question 3

Breiflt describethe life cycle of Ascaris lumbricoides.

Answer 3

Embryonated eggs eaten uncooked vegetables or children with soiled fingers, dirt on toys
Life cycle: hatch in intestine—->larvae enter blood vessels through heart—->lungs growth occurs, may cause a serious pneumonia air passages—->bronchi, trachea—->pharynx—->intestine again for maturation to adult

Question 4

How common is Ascarisin some parts of Southeast Asia?

Answer 4

up to 25 % infection

Question 5

List some of the problems that may result from having Ascaris in your body?

Answer 5

abdominal symptoms
allergic reactions
large numbers may cause intestinal blockage
perforation of the intestine with resultant peritonitis is not uncommon
wandering worms may occasionally emerge from the anus, throat or may enter the trachea, eustachian tubes and middle ears

Question 6

Name two genera of hookworms and how do these worms enter the body?

Answer 6

Ancylostoma, Necator

Directly through skin

Question 7

What kind of damage may be caused to humans with hookworm infection?

Answer 7

hookworm infection in children may cause:
mental retardation
physical retardation
general loss of energy
may cause anemia in adults, many cases in the Southeastern U.S

Question 8

How may humans prevent from getting hookworms?

Answer 8

wear shoes, sanitary disposal of human feces

Question 9

Name the potentially lethal nematode that may be eaten in improperly cokked pork?

Answer 9

Trichinella spiralis

Question 10

Approximately how many cases of Trichinella are discovered annually in the U.S.?

Answer 10

12

Question 11

What is the scientific name for pinworms? How do children and adults get them?

Answer 11

Enterobius vermicularis
swallowed: Females, 12 mm long, migrate to anal region at night to lay eggs
Self-reinfection due to scratching, soiled bed clothing, pajamas
Eggs develop rapidly, become infective after 6 hours

Question 12

What percentage of adults and children in the U.S. are infected with pin worms?

Answer 12

30% of children, 16 % of adults in U.S. infected

Question 13

What are some of the ways for detecting pinworms and how may infections be prevented?

Answer 13

Examin feces for eggs or “scotch tape method” tape around anus
Wash hands.
if infected treat all family members.

Question 14

How many people in tropical countries are infected with the filarial worm?

Answer 14

120 million

Question 15

What human organs can be affected by the filarial worm? What is the name for this disease?

Answer 15

Filarial worm - Wuchereria bancrofti
lymphatic organs
Elephantiasis

Question 16

What is the common name and genus name for one of the common nematomorha?

Answer 16

Horsehair worms
Gordius
About 320 species worldwide in distribution
Long, slender, look like horsehair

Question 17

Describe the makeup of a rotifer?

Answer 17

External strucutures include:
Corona, characteristic ciliated crown
Mouth, foot, toes
Rotifers are dioecious

Question 18

Name the phylum to which rotifers belong?

Answer 18

Rotifera

Question 19

How are rotifers inportant in various ecosystems?

Answer 19

Very important link in the food chain for many other species of invertebrates and vertebrates

Question 20

Identify the common name nad briefly describe the general apperance of the members of the phylum acanthocephala, gastrotricha and entoprocta

Answer 20

1. Acanthocephala- Spiny headed worms- cylindrical, invaginable proboscis with rows of recurved spines
2. Gastrotricha- Gastrotrichs- look like rotifers
3. Entoprocta - Entoprocta- Look like hydroid cnidarians but have ciliated tentacles

Question 21

What are tardigrades? Describe these small creatures?

Answer 21

Very small, less than 1 mm long
“water bears”
Most of the 900 known species live in a water film around mosses and lichens or damp soils
Few are marine
Elongated, cylindrical or oval body is unsegmented
Head is the anterior part of trunk
Trunk bears four pairs of short, stubby, unjointed legs, each with four to eight claws
Body covered by non-chitinous cuticle that is molted four or more times during lifetime
Mouth leads to a muscular pharynx adapted for sucking
Two stylets protrude to pierce integument of nematodes or walls of plant cells and allow them to suck juices

Question 22

Approximately how many species of Tardigrades are found around the world?

Answer 22

900

Question 23

What is the specific habitat of Tardigrades?

Answer 23

a water film around mosses and lichens or damp soils