IGCSE Biology / Selective breeding
Micropropagation and cloning animals
Edexcel International GCSE Biology (4BI1), chapter 20: Selective breeding, specification point 5.17B, 5.18B, 5.19B. Free lesson.
Read the revision notes · IGCSE Biology past papers
Micropropagation and nuclear transfer make genetically identical copies of plants or animals. They can preserve desirable traits, but clones have no genetic variation, so they cannot adapt to new challenges.
How micropropagation makes plants
Micropropagation grows many plants from a small piece of a parent plant. The tissue is often taken from a growing tip, where cells are actively dividing. Sterile conditions are needed throughout to stop microorganisms contaminating the tissue and growing medium.
How animal cloning by nuclear transfer works
In nuclear transfer, the nucleus comes from the animal being copied. The nucleus contains the genetic information, so the offspring is genetically identical to the animal that donated it.
Why cloning can be useful
Both methods can produce copies of organisms with desirable characteristics. Micropropagation is especially useful when many plants are needed quickly and there is little space. Micropropagation can produce thousands of identical plants in weeks. Animal cloning can copy an animal with a valuable trait or help produce copies of an endangered animal. Dolly the sheep was made using nuclear transfer.
Problems shared by both methods
Clones are genetically identical, so the population has no genetic variation. This means it cannot adapt through differences between individuals. If a new disease can infect one clone, it may affect every individual equally. A disease could destroy an entire crop of cloned plants. Cloned animals have the same vulnerability to disease. For animal cloning, the process is slow and has a low success rate. Many embryos fail. Animal cloning also raises ethical objections, including objections to its possible extension to humans.