2. What role does the notochord play during development?
a. It is a transient structure that defines the axis of symmetry of the organism.
b. It gives rise to cortical tissue.
c. It releases inductive signaling molecules.
d. It is the location of embryonic stem cell production.
e. It gives rise to the spinal cord.
13. From which structure do the neural crest cells arise?
a. Notochord
b. Pre-somitic mesoderm
c. Lateral endoderm
d. Dorsal aspect of the neural tube
e. Ventral aspect of the neural tube
17. What mechanism is necessary for growth cone motility?
a. Presence of netrins
b. Exposure to semaphorins
c. Blockage of calcium channels
d. Nuclear localization of integrins
e. Polymerization and depolymerization of actin and tubulin
Answer 2. Option a
Notochord is an essential structure of the chordates. It helps in the development of the brain and the vertebral column, thus helps in defining the axis of symmetry.
Answer 13. Option d
Neural crest lies between the epidermis and the neural tube during the organogenesis. The ectoderm layer formed during the gastrulation helps in the formation of the neural crest. The dorsal part of neural tube give rise to the neural crest.
Answer 17. Option e
Regulation of all the cytoskeleton structures is important for growth cone motility along with the turnover of the actin filaments at the leading edge.
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