Tutorial lab 3

Question 1

The name cnidaria refers to the specialized cells called _______

Answer 1

Cnidocytes

Question 2

Describe nematocysts

Answer 2

Stinging structures in cnidocytes used to immobilize prey

Question 3

Give examples of members of the phylum cnidocytes

Answer 3

Jellyfish, sea anemones, sea fans, corals, hydras

Question 4

Cnidarians are composed of ___ cellular layers

Answer 4

2

Question 4

What is meant by the term “radially symmetrical”?

Answer 4

Symmetrical down the middle

Question 5

Name the mature and embryonic forms of the layers of cnidarians

Answer 5

Outer - epidermis (developed from ectoderm)

Inner - Gastrodermis (developed from endoderm)

Question 6

What is meant by the term diploblastic organisms?

Answer 6

The organism has two germ layers of cells (very little differentiation)

Question 7

In cnidarians, what lies between the epidermis and gastrodermis

Answer 7

A gelatinous layer of poorly developed mesoglea

Question 8

Animals with three germ layers of cells are called ______

Answer 8

Triploblastic organisms

Question 9

What are the two forms of cnidarians?

Answer 9

Polyp or medusa

Question 10

A ______ is a tubular organism closed at one end with a mouth surrounded by tentacles at the other end

Answer 10

Polyp

Question 11

A ______ is an umbrella-shaped, jellylike, free swimming organism with a mouth at the end of a central projection called a manubrium

Answer 11

Medusa

Question 12

Why do cnidarians not need a specialized respiratory or circulatory system?

Answer 12

Because they live only in water and can use osmosis to obtain water and diffusion to obtain nutrients and oxygen

Question 13

Polyps used for feeding within a colony of Obelia are ______ and contain ______ to increase surface area

Answer 13

Nutritive polyps, tentacles

Question 14

Within a colony of Obelia, ______ polyps are club-shaped and lack tentacles

Answer 14

Reproductive

Question 15

Describe the perisarc in a colony of Obelia

Answer 15

The perisarc is a transparent sheath covering the branches of the colony, called the hydrothecae around the nutritive polyps and the gonothecae around the reproductive polyps

Question 16

Describe the tentacles of Obelia

Answer 16

They are long projections containing cnidocytes (with nematocysts inside them)

Question 17

The _______ extends into the cavity of the medusa, containing a mouth at its tip surrounded by four oral lobes.

Answer 17

Manubrium

Question 18

Flatworms are _____blastic

Answer 18

Triploblastic

Question 19

Where can gonads be seen on the medusa?

Answer 19

Underside

Question 20

What is the third cellular layer in flatworms and what does it develop from (embryonicly)?

Answer 20

Parenchyma tissue developed from embryonic mesoderm between the epidermis and gastrodermis

Question 21

What is the term for having no body cavity except the digestive cavity?

Answer 21

Acoelomate

Question 22

Parasitic flatworms also belong to the phylum ________

Answer 22

Platyhelminthes

Question 23

Describe the pharynx of dugesia sp.

Answer 23

It is a protrusible pharynx (meaning it sticks out from the organism) with a mouth at the end of it

Question 29

What type of digestive tract does Dugesia sp. have? What does this mean?

Answer 29

Blind digestive tract - A digestive tract with only one opening

Question 31

Describe the mouth and pharynx of Clonorchis sinensis (human liver fluke)

Answer 31

Clonorchis sinensis has an anterior mouth under a muscular sucker. Attached to the mouth is a muscular pharynx

Question 32

What makes the digestive tract of other Platyhelminthes different from Clonorchis sinensis?

Answer 32

It is nonexistent because they are often submerged in food and can directly absorb nutrients

Question 33

True or false: marine Platyhelminthes have an excretory system.

Answer 33

False. They don't have one because they can diffuse. Therefore, the primary function of it is thought to be osmoregulation.

Question 34

Describe the discrete excretory system of planarians

Answer 34

There is an excretory pore which is at the end of a tubule. The other end has a spherical structure with long cilia called flame cells

Question 35

Describe a flame cell of a planarian

Answer 35

A spherical structure within the body containing long cilia

Question 35

The ________ system serves to transport nutrient materials in Platyhelminthes

Answer 35

Gastrovascular system

Question 35

What is the symmetry of Cnidaria?

Answer 35

Radially symmetrical

Question 36

Describe reproduction in Platyhelminthes

Answer 36

They are hermaphroditic and have both male and female sex organs.

Question 36

Describe digestion in Hydra

Answer 36

Hydra use tentacles to capture food and bring it towards the mouth

Question 37

Describe reproduction in Hydra

Answer 37

``` Asexual = budding Sexual = sperm and ova (made from spermaries and ovaries) ```

Question 38

Briefly describe Obelia sp.

Answer 38

They are colonial and alternate between both Cnidarian stages. Polyp = asexual and medusa = sexual

Question 39

What is the common name of Dugesia sp.?

Answer 39

Planarian

Question 40

What is the function of setae in an earthworm's natural habitat?

Answer 40

Providing the grip required for movement

Question 40

Platyhelminthes are ______ symmetrical

Answer 40

Bilaterally

Question 41

Describe the tracheal system (for respiration)

Answer 41

Air enters small openings called spiracles which lead to a system of branching tracheae. These branch into extremely fine tubules (tracheoles) that reach the individual cells or small groups of cells within the body

Question 41

On a cross-section of Ascaris sp., how does one locate the following structures: cuticle, epidermis, pseudocoelom, muscle cells, pharynx

Answer 41

``` Cuticle - outer covering Epidermis - more inner covering Pseudocoelom - fluid-filled interior Muscle cells - long cells stretched out from walls Pharynx - odd-looking centre portion ```

Question 42

On a cross section of an earthworm, how does one locate the following structures: cuticle, epidermis, goblet cells, circular muscle layer, longitudinal muscle layer, peritoneum, coelom, intestine, chloragogue cells, dorsal blood vessel, ventral blood vessel, nephridia, setae

Answer 42

Cuticle - thin external layer Epidermis - outer cellular layer filled with goblet cells Circular muscle layer - located just beneath the epidermis Longitudinal muscle layer - bundles of muscle beneath circular muscle Peritoneum - thin epithelial lining separating the body cavity from wall Coelom - body cavity Intestine - large central portion with unfolding called typhlosole Chloragogue cells - surround intestine Dorsal blood vessel - above intestine Ventral blood vessel - below intestine Nephridia - between intestine and body wall, look like wavy lines Setae - projections from body wall

Question 43

What is the function of the chloragogue cells?

Answer 43

Glycogen synthesis, deamination of proteins, production of ammonia and urea

Question 44

The trachea tubes have ______ thickening to them

Answer 44

Spiral

Question 45

What is the symmetry of Cnidaria?

Answer 45

Radially symmetrical