Developmental biology test 3 || with 100% Errorless Answers.

Polyphenisms correct answers Discontinuous phenotypes that are elicited by the environment. Multiple ways an organism can develop due to the effects of its environment during development. Theme of polyphenism correct answers The endocrine system will meduate which of the phenotypes develop. Sensory organs send a nuerological signal back to the brain to change the events of development. Endocrine system is a testimony to the different hormones that are present. Signaling from sensory organs to the brain ragulates hormone release and changes in hormones. Example of polyphenism: Locusts correct answers Stationary vs gregarious locusts. Statonary has front wings and halters. Migratory has front and hindwings. Results from different expression of the UBX gene. Which phenotype that develops is due to environmental cues during development. This environmental cue is population density. If a certain neruon is stimulated by neighboring insects in development, than it changes its morph. Example: Lots of other inscets bumping into it stimulates a particular neuron that will determine the migratory morph. Lots of neuron stimulation means overcrowded environment gives migratory morph. Less stimulation gives stationary morph. Example of polyphenism: Spadefoot toads correct answers Environmental cues: Water volume which tadpole will sense. Somites correct answers Blocks of dorsal mesoderm. Transient structures that give rise to various cell fates. What do somites give rise to correct answers The somites give rise to the body and limb muscles, the cartilage that forms the vertebrae and ribs, and the dermis. Their patterning provides much of the A-P organization of the body. Somite fates correct answers Signals from surrounding tissues induce various fates within the somite. In an experiment when the somite was isolated it was found that it produced mesenchyme. Somite + notochord = cartilage. Somite + ventral neural tube = Cartilage. Somite + dorsal neural tube = Striated muscle. Somite + ectoderm or lateral mesoderm = Delayed formation of striated muscle. Dermomyotome correct answers Expresses Pax-3 and MyoD (TF). Gives rise to the dermis and muscle (trunk and limb bud) Sclerotome correct answers Ventral medial cells express Pax-1 (TF) and migrate ventrally to surround the notochord and develop into vertebrea and ribs.