BIO2231 - Bilateria → Flatworms Flashcards

Question 1

Q

How are Cnidaria and Ctenophora distinguished from other Eumetazoa?

3 points.

Answer

A

Eumetazoa are divided into two major branches on the basis of BODY SYMMETRY

<ul><li>Cnidaria and Ctenophora are radially symmetrical </li><li>All other animals are (at least in some life stages) bilaterally symmetrical </li><li>The Bilateria generally have an ANTERO POSTERIOR axis</li></ul>

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Question 2

Q

What are the key concepts in the Bilateria lineage?

5 points.

Answer

A

<ul><li>Cephalisation </li><li>Compartmentalisation </li><li>Development of organ systems </li><li>The coelom </li><li>Segmentation</li></ul>

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Question 3

Q

Bilateria

What is Cephalisation?

5 points.

Answer

A

Concentration of sense organs into a 'head'

<ul> <li>Associated with directional movement</li> <li>Directs sensory capabilities forward</li> <li>Development of the central nervous system (CNS)</li> <ul> <li>Longitudinal nerve chords evolve from a nerve net</li> <li>Increasing concentration of CNS in the head (brain)</li> </ul></ul>

_{BIO2231 3ac}

Question 4

Q

Bilateria

What is Compartmentalisation?

2 points.

Answer

A

<ul><li>Cephalisation is a case of specialisation of parts of the body for particular functions </li><li>Separation of the body into specialised sections is a feature of the bilateral animals</li></ul>

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Question 5

Q

What is Gastrulation?

Answer

A

Gut formation

<div>One end of the embryo folds inwards, expands and fills blastocoel, producing layers of embryonic tissue ECTODERM & ENDODERM</div>

_{BIO2231 3ae}

Question 6

Q

Describe

The development of the gut

3 points.

Answer

A

<ul> <li>Porifera : no gastrulation = no gut</li> <li>Cnidaria : gastrocoel is the gut and circulatory system (sac like sometimes with canals)</li> <li>Bilateria: Tube like gut develops from gastrocoel by the formation of an anus</li></ul>

_{BIO2231 3af}

Question 7

Q

What is Triploblastic?

5 points.

Answer

A

Having a body derived from three embryonic cell layers.

<ul> <li>Ectoderm</li> <li>Mesoderm</li> <li>Endoderm</li></ul>

<ul> <li>The mesoderm is derived from the endoderm</li> <li></li></ul>

_{BIO2231 3ag}

Question 8

Q

What is a Protostomia?

Answer

A

Early mesoderm cells form at junction between Ectoderm and Endoderm.

The mouth of the Protostomia (proto, “first”; stoma, “mouth”) develops from the first opening into the embryonic gut (blastopore)._{BIO2231 3ah}

Question 9

Q

What is a Deuterostomia?

Answer

A

Early mesoderm cells form from buds off the embryonic gut.

<div>During development the mouth of deuterostomes develops from an opening into the embryonic gut other than the blastopore.</div>

<div>The blastopore develops into the anus. </div>

<div>The coelom (a fluid-filled body cavity lined with mesoderm) develops from buds off the embryonic gut.</div>

_{BIO2231 3ai}

Question 10

Q

What are the different body plans of 
Bilateria?

5 points.

Answer

A

<ul> <li>Acoelomate</li> <li>Pseudocoelomate</li> <li>Coelomate</li> <ul> <li>Schizo-</li> <li>Entero-</li> </ul></ul>

_{BIO2231 3aj}

Question 11

Q

What is an acoelomate?

Answer

A

A Protostomia where the Mesoderm fills blastocoel.

_{BIO2231 3ak}

Question 12

Q

What is a pseudocoelomate?

Answer

A

A Protostomia where the Mesoderm lines one side of the blastocoel.

_{BIO2231 3al}

Question 13

Q

What is a schizocoelomate?

Answer

A

A Protostomia where the band of mesoderm surrounds gut and then splits open.

_{BIO2231 3am}

Question 14

Q

What is a Enterocoelomate?

Answer

A

A Deuterosomia

<div>The band of mesoderm surrounds the gut and opens</div>

<div>A similar form to schizocoelous but a different development process.</div>

_{BIO2231 3an}

Question 15

Q

Describe

The Coelom

7 points.

Answer

A

Development of the body cavity

<ul> <li>Provides support for muscular action (therefore also related to directional movement)</li> <li>Functions as a hydrostatic skeleton (using fluid pressure in the coelom</li> <li>see Annelids later in the course)</li> <li>Facilitates increased body size</li> <ul> <li>Room for organ development and cushioning</li> <li>Diffusion of gases, nutrients, wastes into & out of organs</li> <li>Used for storage</li> </ul></ul>

_{BIO2231 3ao}

Question 16

Q

Which phylums are Protostomia?

6 points.

Answer

A

<div>Lophotrochoza (spiral cleavage)</div>

<ul> <li>Platyhelminthes</li> <li>Mollusca</li> <li>Annelida</li> <li>Bryozoa</li></ul>

<div>Ecdysozoa (cuticle moulting</div>

<ul> <li>Arthropoda</li> <li>Nematoda</li></ul>

_{BIO2231 3ap}

Question 17

Q

Which phylums are Deuterostomia?

2 points.

Answer

A

<ul> <li>Chordata (Coelomates with endoskeleton, dorsal neural tube</li> <li>Echinodermata ( sea stars, sea urchins, sea cucumbers etc)</li></ul>

_{BIO2231 3aq}

Question 18

Q

What is Metamerism?

5 points.

Answer

A

= segmentation

<ul><li>A form of compartementalisation </li><li>Serial repetition of segments </li><li>Can involve internal/external structures </li><li>Linked to increased mobility </li><li>Allows complexity and specialised functions</li></ul>

_{BIO2231 3ar}

Question 19

Q

Describe

Bilateria - Tissues

4 points.

Answer

A

<div>Groups of similar cells + cell products organised to perform a specific function </div>

<ul> <li>Epithelial </li> <li>Connective </li> <li>Muscular </li> <li>Nervous</li></ul>

_{BIO2231 3as}

Question 20

Q

Describe

Bilateria - Organ systems

3 points.

Answer

A

<div>Compartmentalisation of the body at finer scales into organ systems </div>

<ul> <li>Digestive system - uptake of nutrients </li> <li>Circulatory system - move nutrients, respiratory gasses and waste products around </li> <li>Excretory system - osmoregulation and getting rid of waste products</li></ul>

_{BIO2231 3at}

Question 21

Q

Describe

Digestive systems

3 points.

Answer

A

Regionalisation of Gut (Foregut, Midgut & Hindgut)

<ul> <li>foregut and hindgut - ectodermal</li> <li>midgut - endodermal</li> <li>Local differences in pH and enzymes</li> <li>Mainly associated with one way gut with separate mouth and anus</li> <li>Provides "disassembly line" </li> <li>Typically physical breakdown, chemical breakdown, absorption, egestion</li></ul>

_{BIO2231 3au}

Question 22

Q

Circulatory systems

4 points.

Answer

A

<ul><li>Most basic form = circulation of fluid within the coelom </li><li>Intermediate form open circulatory system with contractile elements </li><li>Developed form closed system </li><li>Circulatory systems are usually less developed in small animals</li></ul>

_{BIO2231 3av}

Question 23

Q

Excretory systems

Answer

A

Function to remove waste products of metabolism Often linked to osmoregulation due to disposal of wastes in solution_{BIO2231 3aw}

Question 24

Q

What are Nephridia?

Answer

A

Ciliated tubules

<div>Nephridia remove metabolic wastes from an animal's body. Nephridia come in two basic categories: metanephridia and protonephridia.</div>

_{BIO2231 3ax}

Question 25

Q

Definition

Phylum Platyhelminthes

11 points.

Answer

A

Flatworms

<ul> <li>Tissue organ organisation</li> <li>Bilaterally symmetrical</li> <li>Triploblastic acoelomate</li> <li>Gastrulation</li> <ul> <li>Digestive cavity (gut)</li> <li>No anus!</li> </ul> <li>Dorsoventrally flattened</li> <li>Cephalized (head present)</li> <li>Two major groups </li> <ul> <li>Free living </li> <li>Parasitic forms (show secondary loss of features)</li> </ul></ul>

_{BIO2231 3ay}

Question 26

Q

Describe

Platyhelminthes systems - musular system

Answer

A

<ul> <ul> <li>Below the epidermis are layers of circular and longitudinal muscle fibres</li> </ul></ul>

_{BIO2231 3az}

Question 27

Q

Describe

Platyhelminthes systems - nervous

6 points.

Answer

A

<ul> <li>Ladder shaped:</li> <ul> <li>longitudinal nerve cords</li> <li>transverse nerves</li> <li>Cerebrial ganglia (brain)</li> </ul> <li>Sensory organs:</li> <ul> <li>Eye spots, statocysts</li> </ul></ul>

_{BIO2231 3ba}

Question 28

Q

Describe

Platyhelminthes systems - excretory

2 points.

Answer

A

<ul> <li>Osmoregulation </li> <ul> <li>A network of water collecting tubules adjacent to flame cells or protonephridia</li> </ul></ul>

_{BIO2231 3bb}

Question 29

Q

Describe

Platyhelminthes systems - Digestive

3 points.

Answer

A

<ul> <li>Some species possess a digestive system</li> <li>Mouth, pharynx and branching gut where nutrients are absorbed</li> <li>Intestine: one opening, blind ending</li></ul>

_{BIO2231 3bc}

Question 30

Q

Describe

Platyhelminthes - outer body covering

2 points.

Answer

A

<div>In free living forms: ciliated epidermis </div>

<ul> <li>Rhabdites (epidermal cells) produce mucous </li></ul>

<div>Parasitic forms: non ciliated syncytial tegument </div>

<ul> <li>Resistance to immune system and/or gut enzymes</li></ul>

_{BIO2231 3bd}

Question 31

Q

Platyhelminthes

Class Turbellaria

12 points.

Answer

A

<ul> <li>Almost all free living</li> <li>Most are marine (planarians are freshwater)</li> <li>Movement by ciliated epidermis and mucous</li> <li>Muscle contractions permit turning, folding twisting and swimming</li> <li>Nutrition</li> <ul> <li>Live prey or dead animal remains </li> <li>Muscular pharynx insert into prey and pump to bring in food fragments </li> <li>Highly divided guts </li> <li>Triclad and Polyclad </li> <ul> <li>Branching of gut </li> <li>Tri --: three main branches e.g., planarians </li> <li>Poly --: many branches</li> </ul> </ul></ul>

_{BIO2231 3be}

Question 32

Q

Platyhelminthes

Superorder:Neodermata

10 points.

Answer

A

Flukes ( Trematoda & Monogenea ) Tapeworms (Cestoda)

<ul> <li>Advantages</li> <ul> <li>protected from predators</li> <li>Reduced locomotion</li> <li>Stable environment</li> <li>Abundance of nutrients</li> </ul> <li>Problems</li> <ul> <li>How to stay in place? (i.e. avoid being physically removed)</li> <li>How to resist host defences ? (digestive enzymes / immune system)</li> <li>How to find a mate?</li> <li>How disperse and locate another host?</li> </ul></ul>

_{BIO2231 3bf}

Question 33

Q

What is the tegument?

Answer

A

The integument of an organism, especially a parasitic flatworm

<div>Integument = a tough outer protective layer, especially that of an animal or plant.</div>

<div>e.g. "this chemical compound is found in the integument of the seed"</div>

_{BIO2231 3bg}

Question 34

Q

Describe

Class Trematoda

8 points.

Answer

A

Flukes

<ul> <li>Tegument ( syncitial)</li> <li>Layer of glycoproteins to avoid detection by host immune system</li> <li>Possess 2 suckers</li> <ul> <li>Oral sucker (feeding)</li> <li>Ventral sucker (attachment)</li> </ul> <li>Complex life cycles</li> <ul> <li>Intermediate hosts</li> <li>Molluscs > vertebrates</li> </ul></ul>

_{BIO2231 3bh}

Question 35

Q

What is a Schistosoma?

5 points.

Answer

A

Blood Fluke

<ul> <li>Common blood fluke of SE Asia causes Schistosomiasis</li> <li>Eggs penetrate intestinal tissue and bladder</li> <li>Schistosomiasis (Bilharzia ) is a major infectious disease</li> <ul> <li>400-600 million people infected</li> <li>280,000 deaths/year</li> </ul></ul>

_{BIO2231 3bi}

Question 36

Q

Definition

Class Cestoda

6 points.

Answer

A

Tapeworms

<ul> <li>Similar Tegument to Flukes</li> <ul> <li>Body in two parts</li> <li>Anterior Scolex for attachment (hooks & suckers)</li> </ul> <li>Posterior series of proglottids (contain sex organs and eggs)</li> <li>No digestive system !</li> <ul> <li>Absorption of nutrients through body wall</li> </ul></ul>

_{BIO2231 3bj}

Question 37

Q

Describe

Other flatworm like things

4 points.

Answer

A

<ul> <li>Nemertea (ribbon worms)</li> <ul> <li>Possess a specialized coelom</li> <li>through gut with anus</li> <li>anterior mouth</li> </ul> <li>Xenacoelomorpha (acoels , nemertodermatids, and xenoturbellids)</li> <ul> <li>Flattened</li> <li>acoelomates (an animal that does not possess a body cavity)</li> <li>ventral mouth</li> <li>no anus or discrete organs</li> </ul></ul>

_{BIO2231 3bk}

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BIO2231 - Bilateria → Flatworms Flashcards

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