craniates and vertebrates

Question 1

synapomorphic traits of clade craniata

Answer 1

“big 4” +

• -cranium - usually cartilage/bone, fibrous connective tissue
• -brain with unique set of sensory and motor cranial nerves
• -nephrons = functional unit of excretion
• -neural crest cells
• -epidermal placodes
• -hox gene complex

Question 2

neural crest cells

Answer 2

are mesenchymal = undifferentiated “wandering” cell population, pluripotent

Question 3

neural crest cells form

Answer 3

–a part of the peripheral nervous system - dorsal root ganglia of spinal nerves and postganglionic neurons in the dorsal root, Schwann cells

–part of head skeleton (cartilage and bone of lower jaw, cells that produce dentin)

–meninges of CNS

Question 4

epidermal placodes

Answer 4

–special cells in head integument (natural covering of an organism) of developing embryo

–neurogenic (form part of CNS) epithelia outside of CNS

–contribute to formation of sense organs of head (vision, audition, olfaction)

–placode cells are mesenchymal, develop from ectoderm

Question 5

Homeobox (Hox) gene complex

Answer 5

–control pattern of body formation (overall body plan) during early embryonic development

–Hox genes control developmental fate of cell groups

–Hox genes code for proteins that control transcription of other genes

Question 6

synapomorphic traits of clade vertebrata

Answer 6

“big 4” + craniata traits +

• -vertebral column - segmentally arranged endoskeletal elements flanking the spinal cord
• -extrinsic eye muscles (anchor eyeball to orbital wall)
• -nervous regulation of heartbeat/HR - aneural in embryo, innervated by branch of vagus nerve in adult

Question 7

additional craniate/vertebrate features

Answer 7

• -integument - 2 layers
• -paired kidneys and paired gonads; ducts usually empty to cloaca
• -metamerism/segmentation - the body is segmented - serial repetition along longitudinal axis (ex: ribs, spinal nerves)
• -regional body differentiation
• -Eucoelomate - body cavity forms within mesoderm
• -Tripoblastic Enterocoelous Deuterostomes - 3 germ layer, mouth opens second

Question 8

cloaca

Answer 8

=sewer
posterior chamber of gut
most mammals do not have

Question 9

regional body differentiation

Answer 9

head: principle sense organs, brain, anterior gut opening
trunk: between head and anus/cloaca
tail: posterior to trunk, skeleton and muscle, no viscera; locomotion and balance

Question 10

coelom

Answer 10

body cavity

Question 11

viscera

Answer 11

organs

Question 12

embryological origins of the anus and mouth

Answer 12

a dent forms in the embryo, this dent forms the blastopore, deepens to become the archenteron (early gut), and becomes the anus (in deuterostomes - mouth forms second)

Question 13

somatopleure

Answer 13

mesoderm external to coelom + ectoderm

contributes to body wall (muscle, skin), kidneys, parietal peritoneum

Question 14

splanchnopleure

Answer 14

mesoderm internal to coelom + endoderm

contributes to digestive system, lungs, visceral peritoneum

Question 15

contributions of ectoderm

Answer 15

superficial skin
nervous tissue
eye, ear, brain
spinal cord

Question 16

contributions of mesoderm

Answer 16

muscle
skeleton
urogenital system
connective tissue

Question 17

contributions of endoderm

Answer 17

digestive
respiratory
thyroid
urinary bladder