Exam 4 Flashcards
Animals are…
Heterotrophic, multicellular, and have tissues
What are tissues?
Layers of cells that act as a functional unit
During cleavage there is rapid ____ but no ____
division; cell growth
There is no cell growth during cleavage because…
The cells are dividing so quickly that there is no time for the cell to grow
Steps of creating and embryonic layer
Zygote –> cleavage –> eight cell stage –> cleavage –> blastula –> gastrulation (becomes a gastrula)
Blastocoel
The hallow inside of a blastula
What is Gastrulation?
When the embryo folds inward, expands and fills in the blastocoel. Germ layers form through gastrulation.
Ectoderm
Outer layer of an animal
Endoderm
Inner layer of an animal that can make up the inside of the digestive tract
Archenteron
The hallow space inside the endoderm
Animals origin
750 million years ago
Animals closest relative are ___ because…
Choanoflagellates; their genetic similarity and behavioral similarities such as signaling and adhesion
Sponges lack
True tissues
___ of sponges have been found in other animals but not plants, fungi, or non-choanoflagellates
Collar cells
Proterozoic Era
1 billion - 542 million years ago; Ediacaran Period (560 mya)
Paleozoic Era
541 - 242 mya; Cambrian Period (525 mya)
During the Cambrian period, there is rapid diversification of ____
Bilaterians
450 mya
Arthropods are discovered
365 mya
Vertebrates colonize
Radial symmetry
has a top & bottom, but no left/right or front/back
Bilateral symmetry
Has a top/bottom and a left/right
Ectoderm
Germ layer on the outside surface embryo; for some phyla the ectoderm can form the central nervous system
Endoderm
Inner germ layer that lines the archenteron and gives rise to the lining of the digestive tract
Diploblastic
Two germ layer (the endoderm and ectoderm); cnidarians
Triploblastic
Three germ layer (endoderm, ectoderm, mesoderm); all bilaterians
Mesoderm
Forms muscles and other internal organs
Coelom
A fluid or air-filled space located between the digestive tract (endoderm) and outer body wall
Acoelomate
Lack internal body cavity
Coelomate
Have an internal body cavity with the inside and outside by mesoderm-derive tissues
Pesudocoelomate
Have an internal body cavity with the outside surrounded by mesoderm and the inside derived by endoderm
Spiral and determinate cleavage
Seen in protostomes; where spiral division is diagonal to the vertical axis and determinate development casts the developmental fate of each embryonic cell very early
Radial and indeterminate cleavage
Seen in deuterostomes; where radial has parallel or perpendicular cell division and indeterminate development early cleavage divisions retain capacity to develop into a complete embryo
In a protostome the ___ develops where as in a deuterstome the ___ develops
mouth; anus
Basal eumetozoas are
Cnidara and Ctenophora and are diploblastic with radial symmetry
Eumetozoas have…
True tissues
Bilateria clades
Deuterostomia, lophotrochoza, and ecdysozoa