GCSE Biology revision

Cloning (biology only)

Variation and evolution

AQA 4.1.1.1

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AQA student objectives

Learning pathway

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ALL 🎯

Identify and describe What is Cloning?, Plant Cloning: Tissue Culture and Plant Cloning: Cuttings in the context of cloning (biology only).

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Explain the relationships between What is Cloning?, Plant Cloning: Tissue Culture and Plant Cloning: Cuttings and how they contribute to cloning (biology only).

SOME 🎯🎯🎯

Apply and analyse knowledge of What is Cloning?, Plant Cloning: Tissue Culture and Plant Cloning: Cuttings to interpret unfamiliar information about cloning (biology only).

Revision summary

Key knowledge

Read on screen, then print for Cornell-style active revision.

What is Cloning?

Cloning produces genetically identical organisms, meaning the offspring share the exact same genetic information as the parent.
Cloning can occur in both plants and animals, using a variety of techniques depending on the organism.

Plant Cloning: Tissue Culture

Tissue culture involves growing new, genetically identical plants from small parts of the parent plant, known as explants.
The explants are placed into sterile agar jelly containing all the nutrients needed for growth.
Once the explants develop into plantlets, they are transferred into nutrient-rich compost to continue growing into full plants.

2. Plant Cloning: Tissue CultureAQA

Notes

Tissue culture involves growing new, genetically identical plants from small parts of the parent plant, known as explants.
The explants are placed into sterile agar jelly containing all the nutrients needed for growth.
Once the explants develop into plantlets, they are transferred into nutrient-rich compost to continue growing into full plants.

Plant Cloning: Cuttings

Taking cuttings is an older, simpler method of plant cloning where parts of a plant — such as stems, leaves, or branches — are removed and replanted.
The cuttings are placed into damp compost, and plant hormones are added to encourage root growth.
Unlike tissue culture, cuttings do not require a sterile agar medium, making this method accessible to everyday gardeners.

3. Plant Cloning: CuttingsAQA

Notes

Taking cuttings is an older, simpler method of plant cloning where parts of a plant — such as stems, leaves, or branches — are removed and replanted.
The cuttings are placed into damp compost, and plant hormones are added to encourage root growth.
Unlike tissue culture, cuttings do not require a sterile agar medium, making this method accessible to everyday gardeners.

Animal Cloning: Embryo Transplantation

Embryo transplantation involves collecting sperm from one animal and an egg from another, then combining them through artificial insemination.
The fertilised egg, called a zygote, is allowed to develop into an early embryo before being removed from the uterus.
The embryo is split into smaller cells before specialisation occurs, so that each cell retains the ability to develop into a complete organism.
Each separated embryo is then transplanted into a surrogate (host) mother, producing offspring that are genetically identical clones of one another.

4. Animal Cloning: Embryo TransplantationAQA

Notes

Embryo transplantation involves collecting sperm from one animal and an egg from another, then combining them through artificial insemination.
The fertilised egg, called a zygote, is allowed to develop into an early embryo before being removed from the uterus.
The embryo is split into smaller cells before specialisation occurs, so that each cell retains the ability to develop into a complete organism.
Each separated embryo is then transplanted into a surrogate (host) mother, producing offspring that are genetically identical clones of one another.

Animal Cloning: Adult Cell Cloning

Adult cell cloning involves removing the nucleus from an unfertilised egg cell, a process known as enucleation, leaving an empty 'shell'.
A nucleus is then taken from an adult body cell (such as a skin cell) of the animal to be cloned.
The adult nucleus is inserted into the enucleated egg cell, and an electric shock stimulates the egg to divide and form an embryo.
The embryo is implanted into the womb of a surrogate mother, where it develops into a clone of the original adult animal.
Dolly the sheep, born in Edinburgh in 1996, was the first mammal to be successfully produced by adult cell cloning.

5. Animal Cloning: Adult Cell CloningAQA

Notes

Adult cell cloning involves removing the nucleus from an unfertilised egg cell, a process known as enucleation, leaving an empty 'shell'.
A nucleus is then taken from an adult body cell (such as a skin cell) of the animal to be cloned.
The adult nucleus is inserted into the enucleated egg cell, and an electric shock stimulates the egg to divide and form an embryo.
The embryo is implanted into the womb of a surrogate mother, where it develops into a clone of the original adult animal.
Dolly the sheep, born in Edinburgh in 1996, was the first mammal to be successfully produced by adult cell cloning.

Why Use an Egg Cell in Adult Cell Cloning?

Egg cells are used because they have the natural ability to divide and develop into an embryo, which adult body cells such as skin cells cannot do.
The adult body cell provides the nucleus containing the genetic information of the animal to be cloned, while the egg cell acts as the vehicle for development.

6. Why Use an Egg Cell in Adult Cell Cloning?AQA

Notes

Egg cells are used because they have the natural ability to divide and develop into an embryo, which adult body cells such as skin cells cannot do.
The adult body cell provides the nucleus containing the genetic information of the animal to be cloned, while the egg cell acts as the vehicle for development.

Advantages of Cloning

Cloned animals can be engineered to produce specific, required proteins, as their genetic characteristics can be precisely selected.
Cloning can help preserve endangered species by increasing their population numbers, with cloned individuals then able to breed naturally.

Disadvantages of Cloning

Cloning is a technically difficult and labour-intensive process that requires significant expertise and resources.
Producing genetically identical organisms reduces genetic variation in the gene pool, which is dangerous if a new disease emerges or the environment changes.
A reduced gene pool increases the risk of genetic diseases spreading through a population during reproduction.
There are significant ethical concerns around cloning, including debates about 'playing God', animal welfare, and the potential for cloning to lead to the genetic modification or selection of traits in humans (designer babies).

8. Disadvantages of CloningAQA

Notes

Cloning is a technically difficult and labour-intensive process that requires significant expertise and resources.
Producing genetically identical organisms reduces genetic variation in the gene pool, which is dangerous if a new disease emerges or the environment changes.
A reduced gene pool increases the risk of genetic diseases spreading through a population during reproduction.
There are significant ethical concerns around cloning, including debates about 'playing God', animal welfare, and the potential for cloning to lead to the genetic modification or selection of traits in humans (designer babies).

Key Terminology to Remember

An enucleated cell is a cell that has had its nucleus removed.
The gene pool refers to the total variety of genes and alleles present within a population.
Specialisation is the process by which cells develop into different types with specific functions — embryo splitting must occur before this stage.
Artificial insemination is the process of artificially combining sperm and egg outside of natural fertilisation.

9. Key Terminology to RememberAQA

Notes

An enucleated cell is a cell that has had its nucleus removed.
The gene pool refers to the total variety of genes and alleles present within a population.
Specialisation is the process by which cells develop into different types with specific functions — embryo splitting must occur before this stage.
Artificial insemination is the process of artificially combining sperm and egg outside of natural fertilisation.