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Bio102 > Lab 4: Phylum Platyhelminthes (flatworms) > Flashcards

Lab 4: Phylum Platyhelminthes (flatworms) Flashcards

1
Q

What clade(s) do Phylum Platyhelminthes belong to?

A

Metazoa, Eumetazoa, and Bilateria

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2
Q

What kind of symmetry of a flatworm?

A

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

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3
Q

What is the directional term for the head end?

A

anterior

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4
Q

What is the directional term for the tail end?

A

posterior

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5
Q

What is the directional term for the side facing up?

A

dorsal surface

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6
Q

What is the directional term for the side facing down?

A

ventral surface

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7
Q

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

A

Dorsoventrally flattened

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8
Q

What kind of movement do flatworms use?

A

undirectional movement

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9
Q

What is unidirectional movement?

A

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

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10
Q

What does triploblastic mean?

A

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

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11
Q

Platyhelminths have more ________ bodies than diploplastic animals

A

complex

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12
Q

During cleavage, the embryo is called a _______.

A

blastula

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13
Q

Where does the mesoderm layer form? (Inner, middle, outer?)

A

between the inner and outer layer; middle

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14
Q

What is the opening through which the cells move inward ?

A

blastopore

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15
Q

What does the mesoderm (middle layer) form?

A

muscles and loosely packed connective tissue called mesenchyme

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16
Q

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

A

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

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17
Q

What are auricles?

A

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

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18
Q

Sensory cells in the ____ detect changes in the environment

A

head

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19
Q

Do flatworms move with purpose?

A

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

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20
Q

What is a cilia?

A

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

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21
Q

What does the mesenchyme do?

A

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

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22
Q

The planaria has what kind of digestive system?

A

Incomplete; one opening serves as both the mouth and anus

23
Q

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

A

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

24
Q

What is asexual reproduction?

A

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

25
Q

What is a hermaphrodite?

A

each individual has both ovaries and testes

26
Q

Do flatworms fertilize their own eggs?

A

No, they exchange sperm with another worm

27
Q

What are two endoparasites?

A

-flukes
-tapeworms

27
Q

What is a definitive host?

A

the host in which sexual reproduction occurs

27
Q

What is an intermediate host

A

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

28
Q

Is Mesenchyme a non-living tissue.

A

No, it is made up of cells and considered to be living (unlike mesohyl and mesoglea)

29
Q

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

A

Gastrovascular cavity

30
Q

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

A

False

31
Q

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?

A

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.

32
Q

Can triploblasts only have incomplete digestive tracts?

A

No, some can have complete and others can have incomplete.

33
Q

What gives the flatworm shape and support?

A

the mesanchyme and body wall

34
Q

What are the steps involved in getting nutrients to the cells?

A
  1. obtaining food by scavenging or predation
  2. chemical digestion by the gastrodermis secreting digestive enzymes, then the food being digested in the GVC
  3. getting rid of undigested material
35
Q

What makes it possible to distribute food to the large surface area of a flatworm?

A

The highly branched GVC

36
Q

What helps a flatworm locate food?

A

Chemoreceptors

37
Q

What ingests the food in flatworms?

A

the pharnyx

38
Q

If an animal increases in size, the volume increases faster than the surface area, because volume is cubed while surface area is squared. So as volume increases, surface area to volume ratio decreases. Why is this significant for animals doing gas exchange?

A

When there is more volume and less surface area, the slow process of diffusion cannot occur at a rate fast enough to keep all cells alive.

39
Q

What is a flatworms solution to the surface area to volume dilemma?

A

By increasing the surface area to volume by being very flat, flatworms provide an extensive surface area for the volume of living cells and can provide oxygen at a rate that keeps up with the demand

40
Q

What is the nitrogenous waste in flatworms?

A

Ammonia

41
Q

What is asexual reproduction?

A

production of offspring from a single parent that occurs without the fusion of gametes; offspring are genetically identical

42
Q

What is the cost of hermaphroditism?

A

Energy expenditure

43
Q

What is the benefit of hermaphroditism?

A

They can reproduce with any planaria, not just male or female but either

44
Q

What is a tegument in a fluke and tapeworm?

A

tegument replaces the epidermis in larva and protect from hosts digestive enzymes and once cells fuse, there is no membrane between them so fewer ways for immune system or digestive enzymes to hurt them

45
Q

What are the bristle like projections in flukes and what do they do?

A

Spines; they help anchor themselves to host tissues

46
Q

What are the projections in tapeworms and what to they do?

A

microvilli; they increase surface area so more surface area more absorption of the already digested nutrients from the host’s digestive system

47
Q

What is the anterior end of a tapeworm called?

A

scolex; they also have suckers

48
Q

The segments in tapeworms are called

A

proglottids generated behind the scolex

49
Q

Mature proglottids

A

when proglottids mature and develop testes and ovaries

50
Q

Gravid proglottids

A

egg and sperm fuse forming fertilized eggs; at posterior end and break off and leave the definitive host with the feces and an intermediate host will ingest them

51
Q

What strategy do flukes use to increase the number of offspring produced and where does it occur in the life cycle?

A

they use asexual reproduction to increase offspring , occurring in the intermediate host during their life cycle

52
Q

What strategy do tapeworms use to increase the number of offspring produced?

A

They produce a large number of eggs using a segmented body structure to release them, enhancing survival chances

Bio102 (12 decks)

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