Biology Questions and Answers
- How are animals classified
according to the germ layers
present in their embryonic
development?
Cnidarians arpresent only e diploblastic,endoderm and ectod i.e., theyerm. (^)
With the exception oremaining animals are f poriferans, alltriploblastic.
Poriferans do not present differentiated
tissue oclassify regarding germ layrganization and so thers (althouey do notgh (^)
sometimes they are mentioned as
diploblastic).
- How does the embryo turn
from gastrula into neurula?
How is the neural tube
formed? What is the
embryonic origin of the
nervous system in
vertebrates?
The neurula stage is characterizethe appearance of the neural tube alongd by (^)
the dorsal region of the embryo. The
growth oinduces the differentiation of f mesoderm in that regionectodermal (^)
cells just above. These cells then
differentiate forming the neural tube. Sothe origin of the nervous system is the
ectoderm (the same germ layer that
gives birth to the skin).
- What is the notochord?
How is this structure formed?
The notochforms the supporting axis of the embryoord is a rodlike structure that (^)
and gives birth to the vertebral column
in vertebrates. It is formed by
differentiation of mesodermal cells.
- What is the coelom? To
which structures do coeloms
give birth? Are all animals
coelomate?
Coeloms are cavities delimited by
mesoderm. Cocavities where the internal oeloms originate thrgans oe (^) f the
body are located, like the pericardial
cavity,pleural cavity. the peritoneal cavity and the
Besides coelomate acoelomate animals, likeanimals, there are
platyhelminthes, and pseudocoelomate
animals, like nematodes.
- What is the germ layer
from which the coeloms
originate?
The coeloms armesoderm. e originated from - What are pleura,
pericardium and peritoneum?
Pleura is the membrane that covers thlungs and the inner wall of the chest; e
pericardicovers the heart; um is the membrane thatperitoneum is the (^)
membrane that covers most organs of
the gastrointestinalabdominal cavity. All these mem tract and part of thebranes
delimit coeloms (internal cavities).
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