Lesson 6.08 · Spec 4.6.2.5 · Paper 2
⚠ Biology Only
Cloning
Cloning has a notorious 1-mark trap: students asked to define tissue culture write "tissue culture is cloning" — a circular definition that earns zero marks. The mark scheme demands the mechanism: small groups of cells grown into new plants. In the next 10 minutes, you'll know all four named cloning techniques — and the precise spec wording for each.
By the End of This Lesson… Biology Only
You will be able to:
Define cloning as the production of genetically identical organisms
Describe tissue culture using the spec phrase "small groups of cells" — and state its uses
Describe cuttings as the gardener's method (older, simple, no lab)
Describe embryo transplants including "before they become specialised"
Describe the 5 spec-listed steps of adult cell cloning in order
Evaluate the benefits and risks of cloning with balanced consideration of ethical concerns
Spec Refs
4.6.2.5 — Cloning (4 techniques: tissue culture, cuttings, embryo transplants, adult cell cloning)
Paper 2 · Higher Tier · WS 1.3, 1.4
⚠ This content is on the Biology paper (8461) only — NOT on Combined Science.
What Is Cloning?
Definition
A clone is a genetically identical copy of an organism. Cloning produces offspring with the same genetic information as the parent (or donor cell).
Cross-module link — asexual reproduction
Cloning is a form of asexual reproduction (Lesson 6.01). One parent. No mixing of alleles. Offspring are identical to each other and to the parent — by mitosis only. This is the link the spec flags: "Advantages and disadvantages of sexual and asexual reproduction."
Why clone?
Cloning lets us mass-produce organisms with known, desired characteristics — useful for agriculture (high-yielding plants, productive livestock), conservation (rare species), and medical research. It is the natural extension of selective breeding (Lesson 6.07) — but instant rather than over many generations.
Spec scope
The spec names exactly 4 cloning techniques — 2 for plants and 2 for animals. You must know all four by name and be able to describe the mechanism of each.
The Four Spec-Named Methods
🌱 Tissue culture
For plants. Small groups of cells grown in lab conditions → new identical plants. Used commercially and for preserving rare species.
✂️ Cuttings
For plants. Older, simple gardener method. Stem or leaf cut from parent, planted, grows into new identical plant.
🧬 Embryo transplants
For animals. Cells from a developing embryo are split apart before they specialise, then transplanted into host mothers.
🐑 Adult cell cloning
For animals. A 5-step process: nucleus from adult body cell inserted into empty egg, electric shock, embryo, womb. Used for Dolly the sheep.
Memorisation pattern
Plants → tissue culture (modern, lab) + cuttings (old, simple). Animals → embryo transplants (split early embryo) + adult cell cloning (nucleus transfer from adult). Method must match organism type — tissue culture is not for animals.
Tissue Culture 🌱 Plants
Spec Definition
Tissue culture — using small groups of cells from part of a plant to grow identical new plants.
The process — in spec-aligned language:
1 Take a small group of cells from part of a plant (often stem or leaf)
2 Place on a sterile nutrient growth medium with plant hormones
3 Cells divide and grow into identical new plants
4 Plants transferred to soil to continue growing
Spec-listed uses
Preserving rare plant species — propagating endangered plants from a few cells
Commercial nurseries — producing thousands of identical plants quickly and cheaply
Definition trap — 1-mark question
For a 1-mark "define tissue culture" question, write the mechanism: "a small group of cells is grown into a new plant." NOT "tissue culture is cloning" — that's circular and scores zero. NOT "growing tissue" — too vague. The cells and the new organism must both appear.
Cuttings 🌱 Plants
Spec Definition
Cuttings — an older, but simple, method used by gardeners to produce many identical new plants from a parent plant.
1 Cut a stem (or leaf) from the parent plant
2 Optionally dip cut end in rooting powder
3 Plant in moist soil/compost
4 Roots develop → grows into a new identical plant
Why cuttings?
Simple, cheap, no lab equipment needed
Quick — a working plant in weeks, not generations
Preserves the exact characteristics of the parent
Tissue culture vs cuttings
Tissue culture = small groups of cells, lab, mass production
Cuttings = whole stem/leaf, garden, small scale
Both produce identical clones of the parent plant
Embryo Transplants 🧬 Animals
Spec Definition
Embryo transplants — splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers.
Context — where the embryo comes from
Before the spec process begins, an embryo must already exist — typically formed by fertilising the egg of a high-quality female. This is a prerequisite, not a spec-listed step of the embryo-transplant mechanism itself.
The spec describes two actions for embryo transplants. Both must appear for full marks.
1
Split apart the embryo cells before they become specialisedThe spec phrase "before they become specialised" is essential — once cells specialise (differentiate), they can no longer form a whole new organism. Each unspecialised cell can still develop into a complete embryo.
2
Transplant the identical embryos into host mothersEach host mother gives birth to a clone of the original. One prize embryo can produce many identical offspring.
Applications (beyond spec scope)
The spec only describes the mechanism. In practice, embryo transplants are used for mass-producing offspring of high-quality breeding animals (e.g. prize cattle) — and conservation programmes for endangered animals. Note: the spec specifically mentions conservation in the context of tissue culture (rare plant species), not embryo transplants.
Adult Cell Cloning 🐑 Animals
The spec lists exactly 5 steps. Mark schemes award credit per step — learn them in order with the spec wording.
1
Remove the nucleus from an unfertilised egg cellThe egg cell is emptied of its own genetic material — this prepares it to receive the donor nucleus.
2
Insert the nucleus from an adult body cell (such as a skin cell) into the egg cellThe donor nucleus brings all the genetic information of the adult. The egg cell now contains the adult's complete genome.
3
An electric shock stimulates the egg cell to divide to form an embryoThe shock activates the egg, which begins to divide by mitosis — just as it would after fertilisation.
4
These embryo cells contain the same genetic information as the adult skin cellThe spec uses "skin cell" here as the example from step 2. The offspring is genetically identical to the adult donor — a true clone.
5
When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its developmentThe host female carries the pregnancy. She is not the genetic mother — the clone shares its DNA only with the original adult donor.
Dolly the Sheep — The Famous Example
Dolly (1996, Roslin Institute, UK)
The first mammal successfully cloned from an adult body cell. The donor nucleus came from a sheep's mammary gland cell. Dolly was born from a host mother (a different sheep) but genetically identical to the donor.
Dolly was the proof of concept that adult cells could be reprogrammed to form a whole new organism — overturning the previous belief that once a cell had specialised, the rest of its genetic information was permanently switched off.
Why the example matters for the exam
Questions on adult cell cloning often use Dolly as the worked example. If you can describe the 5 spec steps using sheep as the species ("nucleus from a sheep skin cell into an empty sheep egg cell…"), you'll handle any context the exam gives.
Issues with adult cell cloning
Dolly required 277 attempts to produce a successful clone. Many cloned animals show health problems — Dolly developed early-onset arthritis and lung disease. This high failure rate and welfare concerns feed directly into the ethical objections covered in the next slide.
Benefits and Concerns of Cloning
The spec (WS 1.3, 1.4) requires you to "explain the potential benefits and risks of cloning in agriculture and in medicine and that some people have ethical objections." Balance both sides.
✓ Benefits
Agriculture: mass-produce high-yielding crops or productive livestock with desired traits
Conservation: preserve rare or endangered species when natural breeding is too slow
Medical research: produce identical research subjects; potential therapeutic cloning for organ replacement (links to stem cells, Module 1)
Speed: mass-production of identical individuals far faster than selective breeding
✗ Risks & Ethical Concerns
Reduced genetic variation — entire cloned populations share the same vulnerabilities to disease or environmental change
Animal welfare — high failure rates and health problems in cloned animals
Ethical objections — some people object to interfering with natural reproduction; "playing God"
Religious or moral concerns — particularly regarding any extension to human cloning
Evaluation structure
At least one benefit + one risk + a balanced conclusion. One-sided answers cap at half marks. The spec explicitly mentions "some people have ethical objections" — this phrase should appear in any evaluation answer.
Worked Example
Adult cell cloning — 5 marks5 marks
Scientists want to produce a clone of a prize bull using adult cell cloning. Describe the process they would use. Use information about cells and embryos in your answer.
1
The nucleus is removed from an unfertilised egg cell (from a female cow).
2
The nucleus from an adult body cell of the prize bull (e.g. a skin cell) is inserted into the empty egg cell.
3
An electric shock stimulates the egg cell to divide to form an embryo.
4
The embryo cells contain the same genetic information as the adult skin cell donor from the prize bull — so the clone will be genetically identical to the bull.
5
When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female (a host cow) to continue its development.
One mark per step (5 total). The most commonly missed step is step 4 — explicitly stating that the embryo contains the donor's genetic information. Skipping it costs the "this produces a clone" mark.
Examiner Alerts
Alert 1 — Definitions must give the mechanism
For 1-mark definition questions, writing "tissue culture is cloning" or "tissue culture makes clones" is a circular definition and scores zero. The mark scheme demands the mechanism: a group of cells is grown into a new (organism). The same rule applies to any cloning method — describe what happens, not just relabel the term.
Alert 2 — Adult cell cloning step order is critical
The 5 spec steps are sequential: remove nucleus from egg → insert nucleus from body cell → electric shock → embryo forms → insert into womb. Mark schemes award one mark per step. Skip a step or put them out of order, and you lose marks. Practise writing them in order until you can do it without prompts.
Alert 3 — Method must match organism type
Tissue culture and cuttings are plant techniques only. Embryo transplants and adult cell cloning are animal techniques. Writing "Dolly the sheep was made by tissue culture" is wrong — Dolly was adult cell cloning. Check the organism in the question before choosing the method.
Common Errors
✗ Wrong
"Tissue culture is cloning"
✓ Right
"Tissue culture is when a small group of cells is grown into a new plant" — mechanism, not relabel
✗ Wrong
"Dolly was made by tissue culture"
✓ Right
"Dolly was made by adult cell cloning — nucleus from a skin cell into an empty egg cell, electric shock, embryo, host womb"
✗ Wrong
"Cloning makes offspring with different DNA"
✓ Right
"Clones are genetically identical to the donor — same nuclear DNA"
✗ Wrong
"Embryo cells are split after they specialise"
✓ Right
"Embryo cells must be split before they become specialised — once specialised, they can no longer form a whole new organism" (spec wording)
Recap: Three Takeaways
1
Plant cloning — tissue culture (small groups of cells in a lab → many identical plants; for rare species and commercial nurseries); cuttings (older, simple gardener method; stem/leaf in soil → new plant). Both give genetically identical offspring.
2
Animal cloning — embryo transplants (split early embryo cells before they specialise; transplant into host mothers); adult cell cloning (5 spec steps: remove egg nucleus → insert adult body cell nucleus → electric shock → embryo → insert into womb). Dolly the sheep is the canonical example.
3
Evaluation — benefits include agriculture (productive crops/livestock), conservation, medical research. Risks include reduced genetic variation, animal welfare problems, and ethical objections. Always give both sides + a balanced conclusion (WS 1.3, 1.4).
Checkpoint
You should now be able to:
✓ Define cloning as producing genetically identical organisms (link to asexual reproduction)
✓ Name and pair the four spec techniques with the correct organism type (plant vs animal)
✓ Define tissue culture using the spec phrase "small groups of cells" — and avoid the circular trap
✓ Distinguish cuttings (simple, gardener) from tissue culture (lab, mass production)
✓ Describe embryo transplants using the spec phrase "before they become specialised"
✓ List the 5 spec steps of adult cell cloning in correct order
✓ Use Dolly the sheep as a worked example of adult cell cloning
✓ Evaluate cloning with benefits, risks, and reference to ethical objections (WS 1.3, 1.4)
Next lesson
Lesson 6.09 — Theory of Evolution & Speciation & Understanding of GeneticsBiology Only: Darwin and Wallace, why the theory was slow to be accepted, and how Mendel's pea experiments laid the foundation for genetics.
Next: By the End of This Lesson… Biology Only