Rare species can be cloned to protect from extinction. • Crop plants with…

The idea

Cloning produces genetically identical offspring from a single parent cell or organism. In conservation, cloning a rare species can increase numbers when natural breeding is difficult, creating a genetic backup that may protect the species from extinction. In agriculture, cloning a crop plant that shows a special feature, such as disease resistance, produces many identical plants for farmers. Because the offspring are genetically identical, each should show the same useful feature, giving a reliable crop. However, identical plants share the same weaknesses, so a new disease could affect the whole crop. Cloning therefore supports conservation and food production but reduces genetic variation, which can make populations vulnerable to changing conditions.

What earns the marks

• Cloning produces genetically identical offspring from one parent, so the offspring have the same genes as the parent.
• Cloning a rare species can increase its population size and provide a genetic backup, which may help protect it from extinction.
• Cloning a crop plant with a special feature, such as disease resistance, produces many identical plants that should all show that feature.
• Farmers benefit because a uniform, reliable crop can be grown from cloned plants with desirable characteristics.
• A limitation is that cloned populations have little genetic variation, so they may all be vulnerable to the same disease or environmental change.

Common mistakes and how to put them right

• Thinking cloning creates genetic variation.

  Put it right by stating that cloning produces genetically identical offspring, so variation is not increased.

• Assuming cloning guarantees survival of a rare species.

  Put it right by explaining that cloning can increase numbers but does not remove the need to protect habitats and maintain genetic diversity.

• Confusing cloning with selective breeding.

  Put it right by noting that cloning copies one parent's genome, whereas selective breeding combines genetic material from two parents over generations.

Exam tips

• Link each example to the reason for cloning: conservation for rare species and reliable crop production for farmers.
• Use the phrase genetically identical when explaining why cloned crop plants all show the same special feature.
• Give one benefit and one limitation of cloning to show balanced understanding, especially in longer answers.