Lab 4

Question 1

What clade(s) do Phylum Platyhelminthes belong to?

Answer 1

Metazoa, Eumetazoa, and Bilateria

Question 2

What kind of symmetry of a flatworm?

Answer 2

Bilateral symmetry; meaning that the animal can be divided into mirror image left and right halves by a single plane that passes along the midline of its body

Question 3

What is the directional term for the head end?

Answer 3

anterior

Question 4

What is the directional term for the tail end?

Answer 4

posterior

Question 5

What is the directional term for the side facing up?

Answer 5

dorsal surface

Question 6

What is the directional term for the side facing down?

Answer 6

ventral surface

Question 7

What is the term that means worms are flattened from the top down?

Answer 7

Dorsoventrally flattened

Question 8

What kind of movement do flatworms use?

Answer 8

undirectional movement

Question 9

What is unidirectional movement?

Answer 9

moving with one part of the body primarily leading the way, identified as the anterior end

Question 10

What does triploblastic mean?

Answer 10

development from three germ layers; the endoderm, ectoderm, and mesoderm

Question 11

Platyhelminths have more ________ bodies than diploplastic animals

Answer 11

complex

Question 12

During cleavage, the embryo is called a _______.

Answer 12

blastula

Question 13

Where does the mesoderm layer form?

Answer 13

between the inner and outer layer

Question 14

What is the opening through which the cells move inward ?

Answer 14

blastopore

Question 15

What does the mesoderm (middle layer) form?

Answer 15

muscles and loosely packed connective tissue called mesenchyme

Question 16

What kind of nervous system do platyhelminthes have? What does it mean?

Answer 16

Centralized; consists of a mass of nerve cells (brain), and a nerve cord

Question 17

What are auricles?

Answer 17

sensory cells that detect water currents, solid objects, and chemicals located in two flap-like projections on the head

Question 18

Sensory cells in the ____ detect changes in the environment

Answer 18

head

Question 19

Do flatworms move with purpose?

Answer 19

Yes, their sensory structures repond to stimuli such as food or light. They choose where to go.

Question 20

What is a cilia?

Answer 20

hairlike structures that exist on a flatworms surface that together move too propel an organism

Question 21

What does the mesenchyme do?

Answer 21

acts as a modified hydrostatic skeleton and is referred to as a mesenchymal hydrostatic skeleton

Question 22

The planaria has what kind of digestive system?

Answer 22

Incomplete; one opening serves as both the mouth and anus

Question 23

What is the feeding strategy of most free-living flatworms?

Answer 23

carnivorous predators (hunt other animals) or scavengers (find and eat dead animals)

Question 24

What is asexual reproduction?

Answer 24

the animal splits in two parts and then through regeneration, grow two whole organisms. The two individuals are genetically identical to one another

Question 25

What is a hermaphrodite?

Answer 25

each individual has both ovaries and testes

Question 26

Do flatworms fertilize their own eggs?

Answer 26

No, they exchange sperm with another worm

Question 27

What are two endoparasites?

Answer 27

-flukes
-tapeworms

Question 27

What is a definitive host?

Answer 27

the host in which sexual reproduction occurs

Question 27

What is an intermediate host

Answer 27

host in which additional development occurs, but maturation and sexual reproduction do not occur

Question 28

Is Mesenchyme a non-living tissue.

Answer 28

No, it is made up of cells and considered to be living.

Question 29

The part of the free-living flatworm’s body that distributes ingested nutrients to all parts of the body is the:

Answer 29

Gastrovascular cavity

Question 30

T/F: An animal that feeds by predation (hunting food) does not require a centralized nervous system

Answer 30

False

Question 31

Which of the following is true about the way gas exchange constrains the body plans of a sponge, an anemone, and a free-living flatworm?

Answer 31

A sponge and anemone are constrained to each layer of the body wall being only one cell thick, while a flatworm is constrained to having a body plan that has a very high surface area to volume ratio by being very flat and thin.