BIO 2 Chapter 32

tissue

groups of cells that work together to perform a specialized function

bilateral symmetry

body plan where an organism can be divided into 2 mirror image halves along a single plane

radial symmetry

body is organized around a central axis and can be equally sliced

dorsal

back side

ventral

front side

anterior

front end towards the head

posterior

back end towards the tail

diploblastic

2 germ layers (ectoderm and endoderm)

triploblastic

3 germ layers (ectoderm, endoderm, and mesoderm)

endoderm

lines the digestive tract and organs

ectoderm

outermost layer that covers the surface of the cell

mesoderm

creates muscles and organs

coelom

body cavity formed from tissue derived from the mesoderm

pseudocoelom

body cavity lined by tissue derived from tissue of mesoderm and endoderm

determinate

cell fate is set

indeterminate cleavage

cell fate is flexible or totipotent

blastopore

indentation that forms during the early stages of embyronic development (gastrulation)

choanoflagellates

single celled protists that are the closest living relatives to animals