Form 5 · Worked answers

Genetic Technology, worked answers

Fully worked answers for Genetic Technology, original structured and essay questions with mark-scheme keywords highlighted.

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How this topic is examined

Giving a detailed worked example of genetic engineering rather than only naming the technique.
Explaining step by step how bacteria are used to produce a human protein such as insulin.
Weighing a specific benefit of genetic technology against a specific concern in a balanced answer.
Explaining how gene therapy could correct a genetic disease at the cell level.
Describing why DNA fingerprinting can identify one individual from a DNA sample.
Distinguishing reproductive cloning from therapeutic cloning and their different purposes.

Model answer structure

Read the command word and answer to the marks, one clear point per mark.
Define the key biological term precisely before you explain it.
Explain the process or reason in the correct sequence, using the right terms.
Where useful, add a labelled diagram or a worked example.
End with the link the question asks for (cause → effect, structure → function).

Fully worked answers

Explain how genetic engineering differs from selective breeding.

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**Genetic engineering** directly alters an organism's genes in the laboratory, most often by transferring a gene from one organism into a completely different one, so it can cross species boundaries. **Selective breeding** instead works only with genetic variation that already exists within a population, choosing which individuals to breed over many generations, and cannot introduce a gene from an unrelated species. Genetic engineering therefore achieves in one laboratory step a change selective breeding could never achieve at all.

genetic engineeringselective breedingexisting variationspecies boundaries

Describe, step by step, how bacteria are used to produce human insulin.

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The human gene that codes for **insulin** is cut out of human DNA using a specific enzyme. This gene is then inserted into a bacterial **plasmid**, a small circular piece of bacterial DNA, using another enzyme, forming **recombinant DNA**. The recombinant plasmid is returned to a bacterium, which is allowed to reproduce under controlled conditions. As the bacteria multiply, each one reads the human gene and produces human insulin, which is then collected and purified for use by patients with diabetes.

geneenzymeplasmidrecombinant DNAbacteriuminsulin

Explain what is meant by a vector in genetic engineering, using a plasmid as your example.

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A **vector** is a carrier used to transfer a chosen gene into a host cell so that the gene can be copied and expressed there. A **plasmid**, a small circular piece of bacterial DNA separate from the bacterium's main chromosome, is the standard example of a vector: once a gene is inserted into it, the plasmid carries that gene into a host bacterium, and the gene is automatically copied every time the host cell divides.

vectorplasmidhost cellcarrier

Explain how Bt cotton is produced and what benefit it provides to farmers.

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**Bt cotton** is produced by inserting a gene from a soil bacterium into the cotton plant's DNA, so that the plant itself produces a natural **toxin** that is effective against a specific pest caterpillar. Because the toxin is produced inside the plant, farmers growing Bt cotton need to apply much less chemical **pesticide** to protect the crop from this pest, which reduces both cost and the amount of pesticide released into the environment.

Bt cottongenetoxinpestpesticide

Give one example of biotechnology that does not involve genetic engineering, and explain why it still counts as biotechnology.

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**Fermentation** by yeast, used to make bread rise or to produce yoghurt, is an example of biotechnology that involves no genetic engineering at all. It counts as **biotechnology** because it uses a living organism, yeast, and its natural products for a practical purpose, which is the definition of biotechnology; genetic engineering is only one modern branch of this much wider field.

biotechnologyfermentationyeastliving organismpractical purpose

Discuss one benefit and one concern of genetic technology in a balanced way.

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One **benefit** of genetic technology is that bacteria engineered with the human insulin gene can produce insulin more cheaply and reliably than extracting it from animal organs, helping more patients with diabetes access treatment. One **concern** is the unknown long-term effect of a genetically modified organism on the surrounding environment, such as an inserted gene spreading from a crop to a wild relative of that plant. A balanced answer states both points and briefly explains why each matters, rather than arguing only one side.

benefitconcernbalancedspecific example

Explain why gene therapy does not automatically change every cell in a patient's body.

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**Gene therapy** treats a genetic disease by inserting a working copy of a gene into **specific cells or tissues**, aiming to replace or support the function of one faulty gene in that location, rather than altering the whole body at once. Because the treatment is targeted rather than body-wide, it does not automatically change every cell a patient has, and it is not automatically passed on to the patient's children.

gene therapyspecific cellsfaulty genenot passed on

Explain how DNA fingerprinting can identify a person without changing any of their genes.

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**DNA fingerprinting** extracts a sample of a person's DNA, cuts it at specific points using enzymes, and compares the resulting **pattern** of repeated sequences with a reference sample; it only reads and compares patterns that already exist and does not add, remove or alter any gene. Because this pattern is unique to each person, other than identical twins, a close match between two patterns strongly suggests the samples came from the same person or from close relatives.

DNA fingerprintingunique patterncomparesno gene changed

Phrasing that earns marks

Genetic engineering: Genetic engineering is the deliberate, direct alteration of an organism's genes in the laboratory, most often by transferring a useful gene from one organism into another so the recipient gains a new characteristic it did not have before. This differs from selective breeding, which only works with genetic variation that already exists in a population. The transferred gene can come from a bacterium, a plant or an animal, and it is moved across species boundaries for a specific purpose.
Recombinant DNA: Recombinant DNA is formed by cutting a gene from one source and joining it into DNA from another, often a bacterial plasmid, using specific enzymes. Once inserted into a host cell, the recombinant DNA is copied and read along with the host's own genes. The plasmid acts as a vector, a carrier that ferries the new gene into the host and allows it to be copied whenever the host cell divides.
Applications: Practical applications include bacteria engineered to produce human insulin and growth hormone, crops modified for pest resistance, herbicide tolerance or improved nutrient content, and enzymes engineered for use in industrial processes such as detergents and food production. Each application starts from the same basic technique: identifying a useful gene, then transferring and expressing it in a new host. Bt cotton, for example, is engineered to produce a natural toxin against a specific pest caterpillar, making it one of the most widely grown genetically modified crops in the world.
Biotechnology: Biotechnology is the broader use of living organisms, cells or their products for a practical purpose, and includes traditional processes such as fermentation for bread and yoghurt alongside modern techniques such as genetic engineering and enzyme technology used at an industrial scale. Genetic engineering can therefore be described as one modern branch within the wider field of biotechnology, not a separate subject.
Benefits: Benefits include cheaper, more reliable production of medicines such as insulin and vaccines, higher and more resilient crop yields that support food security, and new treatments for some genetic diseases through approaches such as gene therapy. Industrial enzymes produced through biotechnology can also make manufacturing processes faster and use less energy.
Ethical and safety issues: Concerns include unknown long-term effects of a genetically modified organism on health or on other species in the environment, unequal access to expensive new technology between rich and poor countries, and broader questions about how far it is acceptable to alter living things. A strong exam answer names a specific concern, such as an inserted gene spreading to a wild relative of a crop, rather than describing the worry in general terms.
Gene therapy: Gene therapy treats a genetic disease by inserting a working copy of a gene into a patient's cells to replace or support a faulty one. It targets specific cells rather than the whole body, so it does not automatically change every cell or get passed on to the patient's children. Research in this field is still active, and the number of widely approved gene therapy treatments remains small compared with conventional medicine.
Genetically modified (GM) crops: A genetically modified crop has had a useful gene inserted, for example for resistance to a specific pest or tolerance of a herbicide, or for higher levels of a nutrient. Each GM crop is tested and regulated individually rather than judged as automatically safe or unsafe as a category.

Frequently asked questions

What is genetic engineering?

Genetic engineering is the deliberate changing of an organism's genes, usually by taking a gene from one organism and inserting it into another so that the second organism gains a new characteristic. For example, the human gene for insulin can be put into a bacterium, which then produces human insulin. It is done directly in the laboratory, unlike selective breeding. This lets scientists transfer a characteristic across very different species, something impossible to achieve through natural breeding.

How is insulin produced using bacteria?

The human gene that codes for insulin is cut out and inserted into a small circle of bacterial DNA called a plasmid, forming recombinant DNA. The plasmid is put back into a bacterium, which is then allowed to reproduce. As the bacteria multiply, they read the human gene and produce human insulin, which is collected and purified for use by people with diabetes.

What are the concerns about genetic technology?

Genetic technology brings clear benefits such as medicines and improved crops, but it also raises concerns. These include possible effects on human health, unknown long-term effects on the environment and other species, and ethical questions about how far it is right to change living things. A good answer weighs the benefits against these concerns rather than taking only one side, and names a specific example for each point instead of speaking only in general terms.