Which stage of the embryo's tissue development becomes the nerves, brain, and spinal cord, and is ...

Which stage of the embryo's tissue development becomes the nerves, brain, and spinal cord, and is when any neural tube defects may occur?
 
  A) first
  B) second
  C) third
  D) fourth

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Which fetal support system links the mother's bloodstream to the baby's blood vessels?
 
  A) umbilical cord
  B) amniotic fluid
  C) placenta
  D) uterus

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Which fetal support system surrounds the baby and regulates its temperature and allows for free movement?
 
  A) umbilical cord
  B) amniotic fluid
  C) placenta
  D) uterus

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Which fetal support system allows the exchange of oxygen, nutrients, and wastes between the mother and baby?
 
  A) umbilical cord
  B) amniotic fluid
  C) placenta
  D) uterus

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Low maternal weight gain and low birth weight are associated with which of the following problems?
 
  A) obesity
  B) hemophilia
  C) Tay Sachs
  D) hepatitis