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13 Cards in this Set

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  • Back
what does it mean to be ametabolous?
egg - instars - adult. little looks like big. only difference between adult and nymph is that the adult has external genetalia
What does it mean to be hemimetabolous?
egg - nymph - adults
immature insect looks alot like adult but not identical. adults sometimes change habitats. adults have external genitalia, wings, shape change)
What does it mean to be homometabolous?
egg-larva-pupa-adult --> little insect look nothing like adult
Why is there metamorphosis?
specialization in body form -- between egg/larave/pupa/adult
Sir V.B. Wigglesworth experiment
rhodnius - blood sucking bug that causes chagas disease. triatoma is rhodnius relative. hemimetablous insects. proved that the head is importnat early on, but is no longer needed after a certain time. (decapitated 5th instar pf 1 day no molt, decapitated 5th instar of 4 days did molt)
What is parabiosis?
Connecting the blood supplies. allows to check for blood borne hormones
wigglesworth exp. w/ parabiosis...
connected 1 day and 4 day decapitated -- they both molt. evidence for a molting hormone.
What was Carroll William's experiment?
loose brain -- place brain in bottom and top halfs. bottom no mold - evidence for something else besides hormone. Found to be the prothoracic glands. Ecdyson released by prothoracic to control molting. PTTH release from corpora cardiaca and causes prothoracic to release ecdysone
corpora cardiaca
neurohemal organ -- implanted brain and gland in abdomen and the insect molted. proved brain and prothoracic gland are sufficient for molting.
How do they know what to become?
JH causes insect to become another of what it is. So JH not present in 5th instar -> adult molt.
Where does JH come from?
corpora allatum (true endocrine gland)
How does JH work?
-concentration hypothesis -- lowering concentrations cause molting to diff. stages.
-critical period switch - JH is either one or off. (**Correct**)
How did metamorphosis evolve?
Jim Truman -- larval stages are like embryos. homometabolous insects got rid of nymph stage. (hormones of pupa match nymphs)