invertebrates

Question 1

What are ecdysozoans?

Answer 1

group of animals that grow by ecdysis (moulting)

Question 2

What is a coelom

Answer 2

Fluid filled cavity that largely acts as a hydroskeleton

Lines with mesoderm and place for gas exchange and internal organs

Question 3

What are Hox genes

Answer 3

Group of genes common among all animals that designates regions of body plans along head to toe axis

Question 4

What is Cephalization?

Answer 4

The centralization of sense organs and nervous control at the anterior end of the body. Thus, creating a brain and head.

Question 5

Protostome

Answer 5

Mouth appears before anus during development of blastopore. Coelom is formed from splitting of mesoderm.

Question 6

Deusterostomes

Answer 6

First opening during development of blastula forms anus and coelom forms from outgrow of primitive gut.

Question 7

Lophotrocozoa

Answer 7

-Second largest group after arthropods
-Triploblastic and bilaterally symmetrical
ie, annelids and mollusks

Question 8

What are the 7 main characteristics of animals

Answer 8

• Eukaryotic
• Multicellularity
• Heterotrophic
• No cell wall
• Motile at some life stage
• Have diploid somatic cells
• Diplontic life cycle

Question 9

How is multicellularity an advantage?

Answer 9

• Allows organism to grow therefore have a longer lifespan
• Cells carry out specific functions
• Cells are small- better function because there is a high surface area to volume ratio

Question 10

Types of skeletons

Answer 10

• Hydrostatic (jellyfish, octopus)- limited possibility for attachment
• Exoskeleton- molt
• Endoskeleton

Question 11

What is the closest living relative to animals?

Answer 11

Choanoflagellates

Question 12

Proof that animals are monophyletic

Answer 12

• Similar gene sequences
• Similar extracellular matrix
• Unique junctions

Question 13

Germ layers

Answer 13

• Endoderm (inside)
• Mesoderm
• Ectoderm

Question 14

Triploblastic vs Diploblastic

Answer 14

Triploblastic= three germ layers
Diploblastic= Two germs layers (no mesoderm)

Question 15

Sponges

Answer 15

• Have endoskeleton (spicules for support)
• Sessile as adults motile larvae
• Filter feeders (choanocytes)
• Can be asexual and reproduce via fragmentation or internal budding (gemmules)
• Can reproduce sexually by being hermaphroditic BUT one at a time- sperm but find another “female” sponge

Question 16

What is the name for jellyfish, anemones, corals…

Answer 16

Cnidaria

Question 17

Cnidaria characteristics+

When do they stop development?

Answer 17

-Diploblastic
-No brain or ganglia
-Stop development at gastrula stage
Where mesoderm is we have the mesoglea
-Polyp is sessile form and medusa is motile form

Question 18

Four main groups of Cnidarians

Answer 18

• Hydrozoa (freshwater jellyfish, tentacles contain cnidocytes)
• Scyphozoa (true jellyfish, large amount of mesoglea)
• Cubozoa (box jellyfish-fatal sting)
• Anthozoa (coral, anemones- often form mutualistic relationships)

Question 19

Nervous system of Cnidarians

Answer 19

Little to no integration or processing of signals

• However, radial symmetry can be an advantage because sensory info comes from any direction
• Radial symmetry can be disadvantage because it does not favour locomotion

Question 20

3 types of body cavity plans

Answer 20

1) Coelomate - true coelom entirely surrounded by mesoderm (most triploblastic organisms)
2) PseudoCoelomate- “False Coelom” Mesoderm lines outside of pseudocoel
3) Acoelomate- NO CAVITY- Solid except for digestive space ie. flatworms

Question 21

Two ways to make a Coelom

Answer 21

1) Schizocoely- splitting of mesoderm within protostomes

2) Enterocoely- mesoderm forms pockets from gut within deuterostomes

Question 22

What is name for organisms such as flatworms? What are their main characteristics?

Answer 22

Platyhelminthes

• triploblastic, acoelomate, bilateral symmetry
• Directed movement due to cephalization
• Can be free living or parasitic

Question 23

What are the three groups within Lophotrocozoans?

Answer 23

-Annelids, Mollusks, Rotifers

Question 24

Advantages of segmentation and example of Lophotrocozoans that have it

Answer 24

Annelids have segmentation and closed circulatory system

• Multiple copies of organs
• Efficient nervous control
• Increases body size
• Regeneration

Question 25

What are Trocophore

Answer 25

Larvae form of lophotrochozoans that are small translucent and free swimming

Question 26

What are Radula

Answer 26

Radula are small tooth-like structures that most mollusks have other than bivalvia

Question 27

Main mollusk groups

Answer 27

- Polyplacophora "many plates" - Bivalvia ie Scallops (have siphon) for water flow-Filter feeders - Gastropoda (snails) (dioecious or hermaphroditic) - Cephalopods - Squids- large head reduced foot. Females die after laying eggs, No trocophore

Question 28

What is hemocoel?

Answer 28

Body cavity in arthropods that contains blood or hemolymph. Part of circulatory system.

Question 29

What is cryptobiosis?

Answer 29

Physiological state in which metabolic activity is reduced to an undetectable level. Used to survive extreme conditions

Question 30

Types of ecdysozoa and characteristics

Answer 30

- Nematoda (round worm) mainly parasitic, can sustain the extreme - Tardigrada (water bears) Go into cryptobiosis to survive the extreme - Onychophora (velvet worms) segmented, spit really far for defense - Arthropods MOST DIVERSE EUKARYOTIC GROUP

Question 31

Characteristic features of Arthropods

Answer 31

- Segmented body - Jointed appendages - Highly developed sense organs (eyes of a fly) - Rigid exoskeleton

Question 32

Advantages and Disadvantages of an exoskeleton

Answer 32

``` Advantages: -Physical protection and support -Location of pigment (camo or sexual selection) -faster locomotion Disadvantages: -Inflexible -Heavy -Growth is periodic rather than continuous (wait until shedding of shell) -Requires energy -No respiration through skin ```

Question 33

Types of metamorphosis

Answer 33

Metamorphosis enables change in morphology -Incomplete metamorphosis: gradual change (egg -> nymph -> adult) -Complete metamorphosis: specific abrupt morphological changes in which morphology is fully altered (egg -> larva -> pupa -> adult)

Question 34

What hormones regulate moulting? How was this discovered through the experiment on R. prolixus?

Answer 34

-The heads of the same R. prolixus were cut off within the hour of feeding and within two weeks of feeding. The R. prolixus that got it's head cut off right away did not moult. This experiment led to the conclusion that the hormone that triggers moulting is in the head. PTTH (in head) --> Ecdysone( in prothoracic gland)

Question 35

Phenotypic Plasticity

Answer 35

Ability of one genotype to produce more than one phenotype when exposed to a different environment.

Question 36

Parthenogenesis

Answer 36

Form of asexual reproduction in which embryo develops without fertilization by sperm.

Question 37

Four majors arthropod groups

Answer 37

- Myriapods (millipedes, centipedes...) - Chelicerates (6 pairs of appendages, separate sexes, pedipalps) - Crustaceans ( PARAPHYLETIC) can reproduce by cyclical parthenogenesis - Insects Wings come from crayfish gills, unique trait is their external mouth parts

Question 38

Respiratory system of arthropods

Answer 38

- Insects and myriapods have tubular tracheae instead of lungs called spiracles - Crustaceans breathe through gills - Chelicerates breathe through book lungs or gills

Question 39

Arthropod circulatory system

Answer 39

Open (hemolymph fills cavity) | One way valves.

Question 40

Sexual Reproduction of Arthropods

Answer 40

Most arthropods are dioecious, most lays eggs. Some (like scorpions), care for their young

Question 41

What are spermatophores?

Answer 41

Packets of sperm used by some arthropods when sexual reproduction isn't fully internal. (may also be external in water, but this case doesn't require spermatophores)

Question 42

What is a nemotocyst?

Answer 42

Spear like structure of most cnidarians