Answer
Metamorphosis and growth in arthropods are controlled by two
hormones, which is juvenile hormone (JH) and ecdysone.
Neurosecretory cells in the pars intercerebralis of the
brain are used to detect external stimuli such as food,light and temperature.
Neurosecretory cells secrete a hormone called
prothoracicotrophic.
The hormone prothoracicotrophic transported by axoplasmic
streaming along the axons and stored in a pair of glands called corpora
cardiac.
When stimulated, impulses are transmitted down the
nervicorpora cardiac and stimulate the release of prothoracicotrophic from the corpora
cardiac into the haemolymph.
The prothoracicotrophic is then transported to the corpora
allata to produce juvenile hormone.
Juvenile hormone actives the genes that control the
retention of larval characteristic during development. It also suppresses the
genes which control the production of adult characteristics.
This causes the prothoracicotrophic be transported to the
prothracic glands. The prothoracic glands produce ecdysone.
The low level of juvenile hormone causes the level of
ecdysone to increase and thus moulting occurred.
Assignment submitted by L.Y., Kong, S. H., Lim, S. C., Soo, C. W. Tan and C.C.,Teh 2011/2012 (IBM)
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