What feature distinguishes male embryo from female at eight weeks of age?
a. males have a y chromosome
b. males have well developed primary reproductive organs
c. male testes have descended into the scrotum
d. in males, the ovaries have degenerated
e. all of the above

A, B & D

Explanation:

It is not possible to distinguish the sex of a fetus below seven (7)weeks. At this stage only observation of chromosomes through karyotype can determine the sex.  The male fetus will have an XY sex chromosome pair while females will have an XX chromosome pair. After the eighth weeks internal and external genitalia begins to differentiate. The testes and ovaries (the primary reproductive organs) begin to develop in males and females respectively. In males the paramesonephric ducts regresses while the mesonephric ducts begin to develop into testes. In females the mesonephric ducts regresses while the paramesonephric ducts begin to develop into ovaries.

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.