What is reproductive cloning?

• A. Cloning produced by implanting a blastula into the uterus of an adult female.
• B. Cloning for the purposes of extracting stem cells with the same DNA as the donor cell.
• C. Cloning by fertilizing an egg with a donor sperm.
• D. Cloning by natural reproduction through identical twinning.

Answer: (A)

Reproductive cloning aims to produce a living organism that is genetically identical to the donor of the nucleus. This involves transferring a somatic cell nucleus into an egg that has had its own nucleus removed, letting the embryo begin to develop, and then implanting that embryo into the uterus of a surrogate mother so it can grow to term. Describing cloning produced by implanting a blastula into the uterus of an adult female fits this, because the embryo is placed in a womb to develop into a new individual who is genetically identical to the donor. The other scenarios describe different ideas: creating stem cells from an embryo for medical use (therapeutic cloning), fertilizing an egg with sperm (natural reproduction), or identical twinning that occurs naturally without cloning techniques.