Biology 441, Spring 2013 Review for Second Hour Exam
You should be sure to know what subdivision of which germ layer each of the following develops from For example Lens develops from somatic ectoderm, more specifically from a placode.
Skeletal muscles Develop from myotomes of somites, paraxial mesoderm
Heart Lateral plate mesoderm
Adult kidney Metanephros; posterior part of intermediate mesoderm
Motor nerves Neural tube ectoderm
Sensory nerves Neural crest ectoderm
Postganglionic autonomic nerves Neural crest ectoderm
Facial Skeleton Neural crest ectoderm
Skeleton in the rest of the body Sclerotome off somites, and also lateral plate mesoderm
Pituitary gland Partly from stomodeal, somatic ectoderm.
Salivary glands Most are endoderm; one pair may be stomodeal ectoderm.
Thyroid gland Endoderm
Lungs Endoderm (plus some mesodermal mesenchyme)
Liver Endoderm (plus some mesodermal mesenchyme)
Pancreas Endoderm (plus some mesodermal mesenchyme)
Intestine Endoderm (plus some mesodermal mesenchyme)
Stomach Endoderm (plus some mesodermal mesenchyme)
Capillaries, veins, arteries Mesoderm (mostly or all from lateral plate mesoderm)
What symmetries do each of the following have? And for each one, name something else, NOT on the list, that also has that same symmetry or combination of symmetries.
A four bladed propeller
A plaid piece of cloth
The color pattern of a Copperhead snake
A snail shell
A frog egg before it is fertilized
A human embryo before it has formed its inner cell mass
A human embryo after it has formed its inner cell mass, but before a primitive streak has developed
A human embryo that is developing into identical twins
(Don't forget that there are three very different ways in which identical human twins develop)
A gastrulating or a neurulating embryo
Teeth in a mammal's mouth (difficult, but you can figure it out)
The individual vertebrae of your backbone
An individual Dictyostelium slug
An aggregating mass of Dictyostelium amoebae
A Dictyostelium fruiting body
Many Dictyostelium fruiting bodies, of different sizes, as compared with each other
The mechanism that controls the relative dimensions of fruiting divisions
The letter A
The letter N
The letter H
The symbol %
The symbol *
A zig-zag line
A pluteus larva
(Old fashioned) balances for weighing things
Wheatstone bridge electrical circuits for measuring small differences in electrical resistances
And why do they have this symmetry?
(Don't worry if you haven't had physics, or have forgotten about Wheatstone bridges; but it's no accident they are symmetrical, and I hope you will think about it.)
Cumulus clouds in the sky
The graphs of any equation in which x only occurs as x squared, x to the fourth, or x to other even powers?
The graphs of any equation in which x only occurs as x cubed, x to the fifth power, and simply as x?
The graphs of any equation in which both x and y only appear squared, or to the fourth power.
The graph of x times y is equal to a constant?
In general, how are the symmetries of x and y in an equation related to the symmetry of the graph of an equation? Relate this to Weyl's definition of symmetry.
Argue pro or con: Driesch discovered that whatever mechanisms control pluteus formation, these mechanisms have dilation symmetry.
Argue pro or con: Embryonic development depends on many mechanism that reduce/increase symmetry.
Argue pro or con: Any completely deterministic system keeps whatever symmetry it started with. It can only become less symmetrical by means of some external signal, or by becoming sensitive to random fluctuations, like Brownian movement.
Their lack of reflection symmetry (in flagella) is related to the asymmetry of the heart and stomach.
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