Variation & Evolution (AQA GCSE Biology): Revision Notes

6.2.5 Cloning

Methods of Plant Cloning

1. Tissue Culture:

• Used to preserve rare plant species or for commercial purposes.
• Plant cells are extracted and placed in a growth medium containing nutrients and hormones.
• These cells develop into new plants that are genetically identical to the parent plant, making them clones.

2. Cuttings:

• A traditional, simpler method of cloning plants.
• A section of the plant, such as a stem cutting, is taken from a plant with desirable traits.
• The cutting is planted and grows into a new plant that is genetically identical to the original.

Cloning in Animals

1. Embryo Transplants:

• Sperm and egg cells from parents with desirable traits are collected.
• Fertilisation occurs in the lab, creating an embryo.
• The embryo is allowed to divide multiple times before being implanted into a host mother.
• The resulting offspring are genetically identical, carrying the desirable traits of the parents.

2. Adult Cell Cloning:

• The nucleus is removed from an unfertilized egg cell.
• The nucleus from an adult body cell is inserted into the enucleated egg.
• An electric shock stimulates the egg cell to divide and form an embryo.
• The embryo is then implanted into a surrogate mother's womb.
• The offspring produced is a clone of the organism from which the adult body cell was taken.

Benefits and Risks of Cloning

Benefits of Cloning	Risks of Cloning
Enables the production of numerous offspring with specific desirable traits.	Reduces genetic diversity, which can make populations more vulnerable to diseases.
Can advance research into embryo development and genetic diseases.	Clones often have a lower survival rate and may suffer from genetic abnormalities.
Potentially helps in the conservation of endangered species or even the revival of extinct species.	Raises ethical concerns, including the possibility of human cloning.