Flashcards in Embryonic Development and Symmetry Deck (79)
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1
a zygote is a
multicellular organism
2
A zygote cell is a diploid cell resulting from the union of two what?
two haploid gametes
3
an embryo is a young animal or plant while..
it is still contained within a protective structure
4
the embryoe is NOT exposed to...
the environment
5
what are the two major processes occurring during embryonic development
cleavage and gastrulation
6
what is cleavage
first cell divisions in the embryo
7
what is gastrulation
in-folding, invagination
- the process forms embryonic tissue layers (2-3) from the first layer of cells
8
Gastrula
layers of embryonic cells are formed = germ layers
9
the ectoderm is the
outer skin
- epidermis
- nervous system
10
the endoderm is the
inner skin
- lining of digestive AND respiratory system
11
organisms with 2 germ layers are
diploblastic (with two buds)
12
Mesoderm is the
middle skin
- most internal organs: muscles, skeletal system, heart, stomach
13
Organisms with 3 germ layers are
triploblastic - three buds
14
Archenteron =
old gut
- digestive spaces (gut cavity)
15
blastopore is the
mouth or anus
16
what do tissues enable?
complex body organization
17
what does the gut enable?
extracellular digestion - large food items possible
18
cnidaria are
diplobasltic, blind gut, radial symmetry, multicellular
19
flatwroms are
triploblastic, blind gut, bilaterally symetrical
20
3 types of symmetry
asymmetrical
radially symmetrical
bilaterally symmetrical
21
asymmetrical
no axis divides body into equal halves
22
radially symmetrical
along one axis - as long as one cuts through centre- body can be divided into equal halves from many angles
23
bilaterally symmetrical
-single axis divides body in equal hlaves
24
examples of cnidarians
-jellyfish, sea anemones, corals, hydrozoans
25
how many species of cnidarians are there
11,000
26
cnidarians are...
diploblastic
27
cnidarians have what kind of tissues?
nervous and muscular
28
most life cycles include both of these body forms
polyp - sessile
medusa - motile
29
how do cnidarians obtain energy
- carnivorous
- using cnidocytes to caputre prey, inject prey with venom and stick to prey
30
