COMPLETE QUESTIONS AND ANSWERS/ VERIFIED/GRADED
A+/ 100% SOLVED
Cambrian explosion - ----Answers---535-525 million years
ago, marks earliest fossil appearance of many animal major
groups
Hox Genes - ----Answers---Control the development of body
form (Hox Gene "__" can tell to form an arm)
Protosome - ----Answers---Cell proliferation by spiral
cleavage
Coelom forms within the middle tissue germ layer
Initial opening of gut becomes the mouth
Deuterostome - ----Answers---Cell proliferation by radial
cleavage
Coelom forms from outpocket of the middle tissue germ layer
Initial opening of gut becomes the anus
Coelom - ----Answers---Body cavity surrounding the gut
Sessile - ----Answers---Do not exhibit locomotion
(Sponges)
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,Collar Cells - ----Answers---Flagella bearing cells that
create water currents that move through the body of the
sponge
Spicules - ----Answers---Tiny calcium/silica structures
Sponges (Phylum:Porifera) - ----Answers---Hermaphrodites
(release sperm into environment)
Jellyfish, Anemones, Corals
(Phylum: Cnidaria) - ----Answers---Have radial symmetry
Possess two specialized cell layers (tissues) and nerve cells
Two Body Forms: Sessile polyp and free swimming medusa
Nematocysts - ----Answers---Held under pressure (140
atmospheres) These are the microscopic venomous spines on
the tentacle
Animals - ----Answers---Multicellular eukaryotes
Heterotrophs: Ingest their food
Lack Cell Walls
Body held together by structural proteins
Collagen - ----Answers---Make up connective tissues (fibers)
Flexible and high tensile (stretching)
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, Skin - ----Answers---Dense irregular arrangement of
collagen
Ligament - ----Answers---Collagen arranged in sheets
(Connects Bones)
Tendon - ----Answers---Cable-like arrangement of collagen
(Connects muscle to bone)
Zygote - ----Answers---Fertilized egg
(Sperm+Egg=Zygote)
Undergoes rapid cell division called cleavage
Germ Layers - ----Answers---Give rise to tissues and organs
of animal embryo
Blastula - ----Answers---Cell that has undergone many cell
cleavages
Hollow blastula undergoes gastrulation, forming gastrula (has
layers of embryonic tissues)
Ectoderm - ----Answers---Germ layer covering embryo
surface
Endoderm - ----Answers---Innermost germ layer and lines
developing digestive tube (aka=Archenteron)
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