Question

Twins that derive from a single zygote that has split into two are called:

Answer 1

They are colloquially known as identical twins. Technically, they are monozygotic twins.

Answer 2

Hey there!

These are known as identical twins because since they derive from a single zygote, they have the same DNA. This rarely happens. If two sperm cells fertilizes 2 eggs, they are fraternal twins. This means they are twins, but not similar.

I hope this helps!