Lecture 5 - Phylogeny 2 Animal architecture

Question 1

Morphology based tree divide….

Answer 1

Bilaterians into 2 clades (deuterostomes & protostomes)

Assume developmental modes reflect phylogenetic pattern.

Question 2

Recent molecular studies assign 2 taxa to deuterostomes…

Answer 2

Ecdysozoans : secrete external skeletons (exoskeletons) that are shed and replaced after they are outgrown (ecdysis)
Lophotrochozoans : Some phyla develop ciliated crown of tentacles to aid in feeding (lophophore) while others have distinct larvae stage (trochophore)

Question 3

What are the 5 major levels of organization?

Answer 3

1) protoplasmic lvl
2) cellular lvl
3) Cell-tissue lvl
4) Tissue-organ lvl
5) organ - system lvl

Question 4

Ecdysis

Answer 4

When exoskeleton are shed and replace after they are outgrown.

Question 5

Animals are categorized in which developmental mode ?

Answer 5

protostome or deuterostome

Question 6

Cellular lvl

Answer 6

multicellular organisms

cells show some division of labour

Question 7

Protoplasmic lvl

Answer 7

-unicellular organization
- differentiated in subcellular structures,
organelles , cell as a whole

Question 8

Cell-tissue lvl

Answer 8

cells grouped together & perform coordinated functions

Question 9

Tissue-organ lvl

Answer 9

• tissues assembled into even larger functional units (organs)
• parenchyma (chief functional cells), stroma ( support tissues)
• embryo becomes layered during gastrulation
• Germ layer form various tissues & organs

Question 10

Organ-system lvl

Answer 10

• different organs operate together as systems
• 11 different organ systems
• skeletal, muscular, integumentary, digestive, respiratory, circulatory, excretory, nervous,endocrine, immune, reproductive

Question 11

Bilateral symmetry animals have how many germ layer?

Answer 11

3 germ layer

Triploblastic body plan

Question 12

Radiata have how many germ layer ?

Answer 12

2 germ layer

Diploblastic body plan

Question 13

Bilateral animals usually exhibits which type of cleavage ?

Answer 13

Spiral or radial

Question 14

spiral cleaves ?

Answer 14

• planes of cell division diagonal to vertical axis
• smaller cells in large cell grooves
• early determination of each cell’s developmental fate (mosaic development)

Question 15

Radial cleavages ?

Answer 15

-planes of cell division either parallel or
perpendicular to vertical axis
-tiers of cells aligned directly above one another
- each cell in early divisions retains capacity to develop into a complete embryo. (regulative development)

Question 16

Why have a coelem ?

Answer 16

• protection
• skeletal substitute
• internal organ indépendance.

Question 17

segmented body plan

Answer 17

-serial repetition of similar body segments
- along longitudinal axis (metamerism)
- segment = metamere/somite
- characterizes only 3 phyla (Annelida,
Arthropoda, Chordata)
allows segment specialization

Question 18

What are the 4 tissue type ?

Answer 18

1. Epithelial
2. Connective
3. Muscular
4. Nervous

Question 19

1. epithelial

Answer 19

-covers internal/external
-protective covering on outside (e.g. skin)
also lines organs , ducts, passageways internally
- simple epithelia is found in all metazoan animals.
- stratified epithelia mostly restricted to vertebrates.

Question 20

2. Connective

Answer 20

-various binding & supportive functions
- relatively few cells but many extracellular
fibres & a ground substance ( MATRIX ) in
which fibres are embedded
- 2 basic types in vertebrates: loose & dense
also blood , lymph, interstitial fluid (lymph),
cartilage, bone

Question 21

3. Muscular

Answer 21

-most common tissue in most animals
-mostly originates from mesoderm
- comprised of muscle fibres
striated: skeletal & cardiac
smooth ( visceral)

Question 22

4. Nervous

Answer 22

• specialized for receiving stimuli & conducting impulses
• 2 basic types of cells
• neurons: basic functional unit
  neuroglia: insulate & support

Question 23

true tissues ?

Answer 23

Are collections of specialized cells isolated from other tissues by membranous layers. (not in sponges)

Question 24

Ectoderm forms…

Answer 24

outer covering and central nervous system.

Question 25

Endoderm form…

Answer 25

lines developing digestive tube & give rise to organs.

Question 26

Mesoderm form…

Answer 26

Muscles & separate set of organs.

Question 27

Cephalization

Answer 27

Central nervous system concentrated in head.

Question 28

Development

Answer 28

• body plan develops as part of an inherited developmental sequence after fertilization & zygote formation
• single-celled zygote then divides (cleavage ) into smaller cells (blastomeres)

Question 29

1 opening in gut is called

Answer 29

blind/incomplete gut

Question 30

2 opening in gut is called

Answer 30

complete gut

creates a tube that allow food movement from mouth to anus.

Question 31

Mesenteries

Answer 31

structures that suspend internal organs.

Question 32

The gut is surrounded by …

Answer 32

A fluid filled cavity.

Question 33

in 2 germ or 3 germ layer, which of the will the blastocoel persists ?

Answer 33

2 germ layers- blastocoel persists

3 germ layers - mesoderm can line the edge of the blastocoel.