Cloning
Revise Cloning for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. A separate (triple) biology topic covering tissue culture, cuttings, embryo transplants and adult cell cloning.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Cloning produces genetically identical offspring. Four methods must be known, and two of them apply only to plants. This is a Triple-only topic.
Tissue culture uses small groups of cells from part of a plant to grow identical new plants. It is useful for preserving rare plant species and for commercial nurseries producing plants quickly. Cuttings is an older, simpler method in which a branch is taken from a parent plant and planted to produce a genetically identical new plant.
In animals, embryo transplants split a developing embryo before its cells become specialised, and the identical embryos are transplanted into host mothers. Adult cell cloning replaces the nucleus of an unfertilised egg cell with the nucleus from an adult body cell, producing a clone of the adult.
Revision notes
Plant cloning
Tissue culture: small groups of cells from a plant are grown into identical new plants. Useful for preserving rare species and for rapid commercial production.
Cuttings: an older, simpler method in which a branch from a parent plant is planted and grows into a genetically identical new plant.
Embryo transplants
Cells are split apart from a developing animal embryo before they become specialised.
The identical embryos are then transplanted into host mothers, producing several genetically identical offspring.
Adult cell cloning
The nucleus is removed from an unfertilised egg cell and replaced with the nucleus from an adult body cell.
An electric shock stimulates the egg to divide, forming an embryo with the same genes as the adult. The embryo is inserted into the womb of an adult female to develop.
Key points
- Cloning produces genetically identical offspring.
- Tissue culture grows plants from small groups of cells.
- Cuttings produce identical plants from a branch.
- Embryo transplants split an embryo before specialisation.
- Adult cell cloning replaces an egg nucleus with a body cell nucleus.
- An electric shock stimulates the egg to divide.
Worked examples
Example 1
Describe the process of adult cell cloning. [4 marks]
Model answer
The nucleus is removed from an unfertilised egg cell (1 mark). The nucleus from an adult body cell is inserted into the egg cell (1 mark). An electric shock stimulates the egg cell to divide and form an embryo (1 mark). When the embryo is a ball of cells it is inserted into the womb of an adult female to continue developing (1 mark).
Example 2
Give one use of tissue culture. [2 marks]
Model answer
It can be used to preserve rare plant species (1 mark), because many identical plants can be produced quickly from a small amount of tissue (1 mark).
Example 3
Explain why the offspring produced by embryo transplant are genetically identical. [2 marks]
Model answer
The embryo cells are split apart before they become specialised (1 mark), so each cell contains exactly the same genetic information as all the others (1 mark).
Common mistakes
Saying adult cell cloning uses a fertilised egg.
The egg is unfertilised, and its nucleus is removed before the body cell nucleus is inserted.
Confusing embryo transplants with adult cell cloning.
Embryo transplants split an existing embryo; adult cell cloning starts from a body cell nucleus.
Forgetting the electric shock.
It stimulates the egg to begin dividing and usually carries a mark.
Saying clones are identical in every way.
They are genetically identical, but the environment can still produce differences.
Exam tips
- Learn all four methods and which apply to plants or animals.
- Give the adult cell cloning steps in order.
- Say genetically identical rather than just identical.
- Remember this is a Triple-only topic.
Key terms
- Clone
- An organism genetically identical to another.
- Tissue culture
- Growing new plants from small groups of cells.
- Embryo transplant
- Splitting an embryo to produce identical offspring.
- Adult cell cloning
- Replacing an egg nucleus with an adult body cell nucleus.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.