Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

8.2.4Topic 8 · Grey Matter

The Role of Animal Models in Research — Edexcel A Level Biology A (SNAB) 9BI0 Revision Notes & Topical Questions

5 min read 9 parts Lesson 15 of 22 1 quiz

📚 Edexcel A Level Biology A (SNAB) 9BI0 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

8.2.4 The Role of Animal Models in Research — Edexcel A Level Biology A (SNAB) 9BI0 notes: Evaluate the use of animals as models for studying the human brain and disease, including ethical issues and alternatives.An animal model is a non-human species used to investigate a biolog…

  • Replacement
  • Refinement
  • Exam-style question 1
  • Exam-style question 2
  • Exam-style question 3
  • Transgenic

Section 1 of 9What is an animal model?

An animal model is a non-human species used to investigate a biological process or disease so that the results can be applied to humans. In brain research, mice, rats and monkeys are used because their brains share the same basic structure and neurotransmitters as ours, and they have a nervous system whose development can be observed and manipulated.

Section 2 of 9Why animals are used

1
Experiments such as surgery, drug dosing or genetic changes would be unethical or impossible in healthy humans.
2
Many animals have short life cycles, so effects across the lifespan or over generations are seen quickly.
3
Genetics and environment can be controlled, giving valid, repeatable data. Inbred strains reduce variation.
4
Genes can be altered: transgenic or "knockout" mice allow the role of one gene in a condition such as Parkinson's disease to be tested.
5
Brain tissue can be examined directly after the experiment.

Examples include the kitten experiments on visual development, the use of rodents to test drugs for depression and the use of primates to study movement disorders.

Section 3 of 9Limitations and objections

No animal is identical to a human.

Limitations and objections
Differences in metabolism, brain size, complexity and genes mean that a drug may behave differently in humans, so results cannot be assumed to apply.
Some drugs that worked in animals have failed or caused harm in clinical trials.
Many conditions, including depression and schizophrenia, are difficult to reproduce in animals because they involve complex human thought.

Ethical objections focus on suffering and death of sentient animals, and the view that animals have rights and should not be used purely as tools. Others argue that human benefits justify use as long as suffering is minimised.

Section 4 of 9Regulation and the three Rs

In the UK, animal research is regulated by law and requires a licence. Researchers apply the 3Rs:

Replacement
Replacement use cell cultures, computer models or human volunteers instead of animals where possible.
Reduction
Reduction use the fewest animals that gives statistically valid results.
Refinement
Refinement change procedures to cause the least pain and distress, for example by using anaesthetics and good housing.

Alternatives include imaging in human volunteers, brain organoids grown from stem cells and computer simulation, but these cannot yet model a whole living nervous system.

Section 5 of 9Evaluating a use of animals

When asked to evaluate, give a balanced answer: state the benefit (new treatments, knowledge), the cost (suffering), the validity of the model (similarity to humans), whether alternatives exist and what regulation controls it.

Evaluating a use of animals
A conclusion should depend on the evidence rather than only on opinion.
Scientists, the public and regulators all weigh these factors, and the balance can change as new alternatives are developed.

Section 6 of 9Examples of brain research using animals

Studies in animals have produced several well-known findings.

Examples of brain research using animals
Recordings from single neurones in the visual cortex of cats and monkeys revealed how the cortex responds to lines and edges, and the monocular deprivation experiments revealed critical periods.
Studies of rats trained in mazes have shown the role of the hippocampus in forming spatial memories, because rats with a damaged hippocampus fail to remember the location of a hidden platform in a water maze.
Genetically modified mice carrying human genes linked to Alzheimer's disease have been used to test drugs that reduce the build-up of abnormal proteins in the brain.

Primates have been used to study Parkinson's disease, which led to the development of deep brain stimulation, a treatment in which a small electrode implanted in the brain reduces tremor.

Examples of brain research using animals
These examples show the benefits that supporters point to.
However, every example also has a cost, which is why each licence application is reviewed and a harm-benefit assessment is made before work is allowed to start.

When answering a question about the validity of a model, compare features directly: brain size, number of cortical folds, receptor types, lifespan, metabolism and whether the animal can show the symptom being studied. The closer the match, the more likely the results are to be relevant to humans, but closeness also usually means that a more sentient animal is being used, which creates a conflict between scientific value and ethical acceptability.

Section 7 of 9Exam-style questions

  1. Give two reasons why mice are used as models for human brain disease. [2]2 marks

  2. Explain what is meant by the 3Rs. [3]3 marks

  3. A drug that reduced symptoms in mice caused no benefit in humans. Suggest two reasons. [2]2 marks

Section 8 of 9Key terms

TermMeaning
Animal modelNon-human species used to study a process or disease relevant to humans
TransgenicContaining a gene from another organism or an altered gene
3RsReplacement, reduction and refinement in animal research
EthicsPrinciples about what is right or wrong
Clinical trialTesting a treatment in human volunteers
OrganoidSmall three-dimensional tissue culture grown from stem cells

Section 9 of 9Exam technique

1
Saying animal results always apply directly to humans.
2
Listing ethical objections only; a good evaluation also covers benefits and alternatives.
3
Confusing reduction (fewer animals) with replacement (no animals).
4
Forgetting that regulation and licensing control animal work.

Last updated: