4.2.4 Evaluating the Use of Genetic Engineering · 4. Natural Selection and Genetic Modification | Edexcel GCSE Combined Science 1SC0: Biology

Section 1 of 9How to evaluate

To evaluate means to consider evidence for and against and reach a judgement. A strong answer states benefits and risks, who is affected, whether the evidence is reliable, and gives a conclusion linked to the points made. The same method applies to GM crops, GM animals, and medical uses such as gene therapy.

Section 2 of 9Applications in medicine

Applications in medicine

Medicines from GM microorganisms

Medicines from GM microorganisms bacteria make human insulin and growth hormone. These are pure, produced in large amounts, and avoid the allergic reactions that animal-derived insulin could cause.

Gene therapy

Gene therapy inserting a working allele into the cells of a patient with a genetic disorder such as cystic fibrosis or severe combined immunodeficiency.

It has treated some conditions but is limited: the gene may not reach enough cells, the effect may not last,
- and the body may respond to the viral vector.

Disease models

Disease models animals such as mice are modified so that they develop a human disease, allowing treatments to be tested.

In every case, ask whether the benefit could be achieved another way, such as by selective breeding or improved farming, and whether the harm can be reversed if it appears.

A condition treated by gene therapy also needs careful trials, because a patient cannot easily be returned to their original state if something goes wrong.

Section 3 of 9Applications in agriculture

GM crops can improve yield, nutrition and resistance, as covered in the lesson on food demand. The main risks cited are cross-pollination with wild plants, harm to non-target organisms, increased reliance on a few herbicide-resistant varieties, and the cost of seed. Reduced pesticide spraying can benefit wildlife, but herbicide-resistant crops may lead to heavy use of weedkillers.

Section 4 of 9Ethical, social and economic issues

Issue	Points
Ethical	Is it right to alter the genes of living things? Concerns about animal welfare and about future uses such as altering human embryos for appearance or ability (designer babies).
Health	Possible allergens or unknown long-term effects; people want the right to choose through labelling.
Environmental	Gene transfer to wild species, loss of biodiversity, effects on other organisms; but potentially less land and chemical use.
Economic	Patents and costs may give large companies control; better yields can raise farmers' incomes and lower food prices.

Section 5 of 9Reaching a conclusion

A balanced conclusion might say that the medical uses are widely accepted because the benefit is large and the risk is controlled in a laboratory, whereas environmental release of GM crops needs careful testing and monitoring because organisms cannot be recalled once released. Evidence should come from peer-reviewed studies, large trials and independent regulators, and you should note when evidence comes from a source with a financial interest, such as a seed company or an opposing campaign group.

Section 6 of 9Applying the method to a scenario

General structure of an amino acid (labelled)

General structure of amino acids (labelled)

Suppose a company wants to grow herbicide-resistant oilseed rape.

1

Benefits: weeds can be sprayed in a single treatment, labour and fuel use fall, and yields rise because the crop competes less with weeds.

2

Risks: the resistance gene could be passed by pollen to wild relatives, creating weeds that survive spraying; wildlife that feeds on weeds, such as seed-eating birds and insects, may decline when fields are kept very clean; the farmers must buy new seed and weedkiller each year from the same company.

3

Evidence: field-scale trials comparing GM and conventional fields can measure insect numbers and weed seed production.

4

A conclusion could be that the crop should be grown only with buffer zones, monitoring and regulation, or not grown at all, depending on how the evidence is weighted.

5

Whichever you choose, link it to specific points made, and avoid vague words such as bad or unnatural.

6

Examiners reward precise biological reasoning, such as naming the process of gene flow, rather than general opinion.

Finally, remember that regulation differs between countries.

Applying the method to a scenario

Some require GM foods to be labelled or have restricted their growth, while others have approved many varieties.

Public attitudes, trade rules and the strength of the scientific evidence all influence these decisions, and an evaluation can mention that different groups, such as farmers, consumers, conservationists and companies, will weigh the same evidence differently because their priorities differ.

Section 7 of 9Exam-style questions

Evaluate the use of genetic engineering to produce human insulin in bacteria. [4]4 marks
Suggest why scientists should publish GM crop safety trials in peer-reviewed journals. [2]2 marks
State two ethical objections some people have to genetic engineering. [2]2 marks

Section 8 of 9Key terms

Term	Meaning
Evaluate	Consider the evidence for and against and reach a judgement.
Gene therapy	Introducing a working allele into a person's cells to treat a genetic disorder.
Peer review	Checking of scientific work by other experts before publication.
Ethical issue	A question of right and wrong raised by a technology.
Transgenic	An organism containing a gene from another species.
Patent	A legal right giving a company sole use of an invention.
Designer baby	An embryo selected or altered for chosen characteristics.

Section 9 of 9Exam technique

1

Writing a list of facts with no judgement. An evaluate question needs a conclusion.

2

Treating all genetic engineering as the same. Contained microbial production and open-field crops carry very different risks.

3

Using opinion without evidence, such as saying GM is unnatural and so dangerous.

4

Confusing gene therapy (changing a patient's cells) with producing a protein in bacteria.