Dolly the sheep was produced by

  • A. fertilising an egg in a test tube
  • B. transferring the nucleus of an adult body cell into an enucleated egg cell
  • C. inserting a human gene into a sheep embryo
  • D. splitting a very early embryo into two

Explanation

Somatic cell nuclear transfer showed for the first time that the nucleus of a fully differentiated adult cell can be reprogrammed to direct the development of a whole new animal. The lamb was genetically identical to the sheep that donated the nucleus rather than to the egg donor or the surrogate mother. Splitting an early embryo also gives clones, but that is how natural identical twins arise, not how Dolly was made.

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