25. What are twins?
Genetically what are the two
types of twins that can be
generated?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Twins are simultaneously generated
( the mother’s uterus) offspring.
classify according to zygosity
monozygotic or as dizygotic .
Monozygotic twins, also known
identical twins, are those
from one single fertilized
(therefore from one single );
monozygotic twins are genetically
, i.e., they have identical
and are necessarily of
same sex. Dizygotic twins, known
as fraternal twins, those generated
from two ova fecundated by
two sperm cells; so they
not genetically identical and are
not necessarily of same sex.