The first organ system that shows any sign of activity is the: respiratory system. digestive ...

The first organ system that shows any sign of activity is the:
 
  respiratory system.
  digestive system.
  nervous system.
  cardiovascular system.

Question 2

The neural tube will become the
 
  reproductive organs.
  intestinal tract.
  brain and spinal cord.
  backbone, legs, and arms.

Question 3

Which period begins three weeks after conception?
 
  the embryonic period
  the fetal period
  the gestational period
  the germinal period

Question 4

Which of the following structures is the first sign of a human body forming during the embryonic period?
 
  the neural tube
  the spinal cord
  the primitive streak
  the blood vessels

Question 5

What percentage of embryos are aborted spontaneously?
 
  5 percent
  20 percent
  31 percent
  40 percent

Question 6

The third period of gestation is the:
 
  zygotic period.
  embryonic period.
  germinal period.
  fetal period.