Flashcards in Embryonic Development and Symmetry Deck (79)
a zygote is a
A zygote cell is a diploid cell resulting from the union of two what?
two haploid gametes
an embryo is a young animal or plant while..
it is still contained within a protective structure
the embryoe is NOT exposed to...
what are the two major processes occurring during embryonic development
cleavage and gastrulation
what is cleavage
first cell divisions in the embryo
what is gastrulation
- the process forms embryonic tissue layers (2-3) from the first layer of cells
layers of embryonic cells are formed = germ layers
the ectoderm is the
- nervous system
the endoderm is the
- lining of digestive AND respiratory system
organisms with 2 germ layers are
diploblastic (with two buds)
Mesoderm is the
- most internal organs: muscles, skeletal system, heart, stomach
Organisms with 3 germ layers are
triploblastic - three buds
- digestive spaces (gut cavity)
blastopore is the
mouth or anus
what do tissues enable?
complex body organization
what does the gut enable?
extracellular digestion - large food items possible
diplobasltic, blind gut, radial symmetry, multicellular
triploblastic, blind gut, bilaterally symetrical
3 types of symmetry
no axis divides body into equal halves
along one axis - as long as one cuts through centre- body can be divided into equal halves from many angles
-single axis divides body in equal hlaves
examples of cnidarians
-jellyfish, sea anemones, corals, hydrozoans
how many species of cnidarians are there
cnidarians have what kind of tissues?
nervous and muscular
most life cycles include both of these body forms
polyp - sessile
medusa - motile
how do cnidarians obtain energy
- using cnidocytes to caputre prey, inject prey with venom and stick to prey