BiologyISC Class 12 · Biotechnology and its Applications

Transgenic Animals and Their Uses: ISC Class 12 Biology

Updated 15 October 2026 · Fact-checked

Transgenic animals have had their DNA manipulated to carry and express an extra (foreign) gene. Over 95 per cent are mice; rats, rabbits, pigs, sheep, cows and fish have also been made. They are used to study normal physiology and disease, to make biological products such as α-1-antitrypsin and α-lactalbumin, and to test vaccine and chemical safety.

Understand Transgenic Animals

Definition. Animals whose DNA has been manipulated to possess and express an extra (foreign) gene are transgenic animals. Transgenic rats, rabbits, pigs, sheep, cows and fish exist, but over 95 per cent are mice.

How a transgenic animal is made (outline). The foreign gene is joined to a suitable vector or prepared as DNA and microinjected into the nucleus of a fertilised egg (or an early embryo cell); the embryo is implanted in a surrogate mother; offspring are tested for the gene and its product. (Microinjection is the standard method for animal cells; disarmed retroviruses are another vector.)

Five uses (learn with one example each).

Use	What is done	Example
1. Normal physiology and development	genes from other species alter a factor; effects are studied to learn how genes are regulated and what they do	insulin-like growth factor studies
2. Study of disease	animals made as models for human diseases to investigate new treatments	transgenic models for cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer's
3. Biological products	gene for a useful (often human) protein introduced; product collected (often in milk)	α-1-antitrypsin for emphysema; attempts for phenylketonuria (PKU) and cystic fibrosis; Rosie the cow
4. Vaccine safety	transgenic mice test vaccine safety before use on humans	polio vaccine testing; could replace monkeys
5. Chemical safety (toxicity) testing	animals carry genes that make them more sensitive to toxic substances; exposed and studied	results obtained in less time

Rosie (1997). The first transgenic cow produced milk enriched with a human protein, about 2.4 grams per litre. The milk contained human alpha-lactalbumin and was nutritionally more balanced for human babies than natural cow milk.

Why make products in animals? Many medicines contain biological products that are expensive to make; an animal that secretes the product in its milk can make it continuously and in large amounts. Milk is easy to collect without harming the animal.

Ethical issues and regulation. Manipulating organisms needs ethical standards; GM organisms may have unpredictable results when released into ecosystems. India set up the GEAC (Genetic Engineering Approval Committee) to judge whether GM research is sound and whether GM organisms are safe to introduce for public use. Concerns include animal welfare, possible spread of transgenes, and patents on biological material (biopiracy).

Product-yield arithmetic. Amount of protein = concentration in milk (g/L) × volume of milk (L).

Flow chart: choose gene → clone it (rDNA) → microinject into fertilised egg → implant embryo → transgenic offspring → screen for gene and protein → use (study, product, testing).

Transgenic Animals: key facts

Five uses: Normal physiology insulin-like growth factor studies
Disease models cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer's
Biological products α-1-antitrypsin, α-lactalbumin
Vaccine safety polio vaccine in transgenic mice
Chemical safety sensitive animals give results faster; Give one example with each.
Products: α-1-antitrypsin emphysema
Human α-lactalbumin Rosie's milk (1997, 2.4 g/L), balanced for babies
Attempts under way phenylketonuria, cystic fibrosis; Both human proteins.
Yield: $protein (g) = c (g/L) \times V (L)$; Rosie: c = 2.4 g/L.
Regulator: GEAC Genetic Engineering Approval Committee
Judges whether GM research is sound
Also judges safety of releasing GM organisms for public use; Indian body for GM safety.

Normal physiology	insulin-like growth factor studies
Disease models	cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer's
Biological products	α-1-antitrypsin, α-lactalbumin
Vaccine safety	polio vaccine in transgenic mice
Chemical safety	sensitive animals give results faster

α-1-antitrypsin	emphysema
Human α-lactalbumin	Rosie's milk (1997, 2.4 g/L), balanced for babies
Attempts under way	phenylketonuria, cystic fibrosis

GEAC	Genetic Engineering Approval Committee
Judges	whether GM research is sound
Also judges	safety of releasing GM organisms for public use

How to answer Transgenic Animals questions

ISC asks the definition, uses of transgenic animals with examples, Rosie and α-lactalbumin, α-1-antitrypsin, vaccine and chemical safety testing, and the role of GEAC.

1Define with 'possess and express an extra (foreign) gene'.
2For uses, give each heading followed by its example: emphysema with α-1-antitrypsin, polio vaccine with transgenic mice.
3For Rosie, give year, animal, protein (human α-lactalbumin), amount (2.4 g/L) and why it helps babies.
4For chemical safety, explain 'more sensitive' animals and 'results in less time'.
5In yield sums, multiply concentration by volume and convert grams to kilograms if asked.
6For ethics, name GEAC and one concern.

Transgenic Animals in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Producing a human protein in milk

Suppose a dairy research station keeps a transgenic cow that, like Rosie, gives milk containing 2.4 g of human α-lactalbumin per litre, and she gives 20 litres of milk a day.

How much α-lactalbumin does she produce in a day and in a week, and why is this route attractive?

Try it first, then show the solutionSolution

Daily: 2.4 g/L × 20 L = 48 g.
Weekly: 48 g × 7 = 336 g.
The protein is collected simply by milking, without harming the animal, and production continues every day.
It gives a nutritionally balanced milk for human babies or a source to purify the protein.

Answer: 48 g a day and 336 g a week, collected easily through milk.

Memory hook: Milk as a protein factory.

Tricks to remember Transgenic Animals

Short memory aids. Say each one aloud once, then use it on a question the same day.

P-D-B-V-C
Physiology, Disease, Biological products, Vaccine safety, Chemical safety.
Use it when: Five uses in order.
Rosie's recipe
1997, 2.4 grams per litre, human alpha-lactalbumin.
Use it when: Rosie questions.
Antitrypsin for airy lungs
α-1-antitrypsin treats emphysema (damaged air sacs).
Use it when: Matching product to disease.

Transgenic Animals: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Definition and examples · 2 marks · Short answerBoard level

What are transgenic animals? Name the animal that makes up most of them and three others that have been made transgenic.

Try it first, then show the solutionSolution

Animals whose DNA has been manipulated to possess and express an extra (foreign) gene (1 mark).
Over 95 per cent are mice; others: rats, rabbits, pigs, sheep, cows, fish (any three) (1 mark).

Answer: Animals expressing a foreign gene; mostly mice; also rats, rabbits, cows, etc.

Example 2: Rosie · 2 marks · Short answerBoard level

Who was Rosie? What was special about her milk?

Try it first, then show the solutionSolution

Rosie was the first transgenic cow, produced in 1997 (1 mark).
Her milk contained human α-lactalbumin (about 2.4 g per litre) and was nutritionally more balanced for human babies than natural cow milk (1 mark).

Answer: First transgenic cow; milk with human α-lactalbumin, better for babies.

Example 3: Uses with examples · 3 marks · Short answerHarder board level

Explain three uses of transgenic animals with one example each.

Try it first, then show the solutionSolution

Biological products: a gene for a human protein is introduced so the animal makes it, e.g. α-1-antitrypsin for emphysema (1 mark).
Vaccine safety: transgenic mice test the safety of vaccines such as the polio vaccine before human use, possibly replacing monkeys (1 mark).
Study of disease: animals serve as models for human diseases, e.g. cancer or cystic fibrosis, to test new treatments (1 mark).

Answer: Products (α-1-antitrypsin), vaccine safety (polio), disease models (cancer).

Example 4: Toxicity testing · 2 marks · Short answerHarder board level

How are transgenic animals used for chemical safety testing, and what is their advantage over ordinary animals?

Try it first, then show the solutionSolution

Animals carrying genes that make them more sensitive to toxic substances are exposed to the chemical, and the effects are studied (as in drug toxicity testing) (1 mark).
Because they react more strongly, results are obtained in less time (1 mark).

Answer: Sensitised animals reveal toxicity faster.

Example 5: Yield from a herd · 3 marks · Short answerHarder board level

Suppose a herd of 10 transgenic cows each gives 15 litres of milk a day containing 2.4 g/L of a human protein. How many kilograms of the protein does the herd produce in 30 days? How many litres of milk are needed for 1 kg?

Try it first, then show the solutionSolution

Per day: 10 × 15 L × 2.4 g/L = 360 g (1 mark).
In 30 days: 360 × 30 = 10 800 g = 10.8 kg (1 mark).
For 1 kg: 1000 g ÷ 2.4 g/L ≈ 417 L (1 mark).

Answer: 10.8 kg in 30 days; about 417 L of milk per kg.

Example 6: Weighing benefits and risks · 4 marks · Short answerHOTS / competency

Suppose a company proposes releasing transgenic fish that grow twice as fast into village ponds that drain into a river. (a) Give two possible benefits. (b) Give two ecological risks. (c) Which Indian body must approve the release and what does it check?

Try it first, then show the solutionSolution

(a) More fish protein from the same pond; higher income for fish farmers in less time (1 mark).
(b) Escaped fish may outcompete native species for food; transgenes may spread to wild fish by interbreeding, with unpredictable effects (2 marks).
(c) GEAC (Genetic Engineering Approval Committee), which judges whether the GM research is sound and whether releasing the GM organism is safe (1 mark).

Answer: Benefits: more protein and income; risks: competition and gene spread; GEAC approves.

Where students lose marks in Transgenic Animals

The slips examiners see most often, and what to write instead.

Mistake: Uses without examples
Listing 'study of disease' or 'biological products' alone earns little when the question asks for examples.
Do this: Attach an example to every use.
Usually costs: ½ mark per use.
Mistake: Wrong protein for Rosie
Writing α-1-antitrypsin for Rosie mixes up two products.
Do this: Rosie: human α-lactalbumin; emphysema: α-1-antitrypsin.
Usually costs: 1 mark.
Mistake: Confusing transgenic with cloned animals
A cloned animal (copy of a donor) need not carry a foreign gene.
Do this: Transgenic = carries and expresses an extra, foreign gene.
Usually costs: 1 mark.
Mistake: Expanding GEAC wrongly
Variants such as 'Genetic Engineering Advisory Council' are seen.
Do this: Genetic Engineering Approval Committee.
Usually costs: 1 mark.

Exam tips

Use the Greek letters: α-1-antitrypsin, α-lactalbumin.
State 'over 95 per cent are mice' for the definition question.
Link vaccine safety to polio and to replacing monkeys.
Show units (g/L, L, g) in yield sums.
Mention GEAC in any ethics or regulation question.

Practice questions on Transgenic Animals

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
α-1-antitrypsin produced by transgenic animals is used to treat:
(a) emphysema (b) diabetes (c) SCID (d) haemophilia
Hint
Lungs.
Answer
(a) emphysema.
Q2 · 2 marks · Short answerBoard level
Name two diseases, other than emphysema, for which treatment through transgenic animal products is being attempted.
Hint
One is a metabolic disorder.
Answer
Phenylketonuria (PKU) and cystic fibrosis.
Q3 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Transgenic mice may replace monkeys in testing batches of polio vaccine.
Reason (R): Transgenic mice are being developed so that a vaccine can be shown to be safe before people receive it.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
If found reliable.
Answer
(a).
Q4 · 2 marks · Short answerHarder board level
How do transgenic animals help in understanding normal physiology? Give the example used in NCERT.
Hint
Growth factor.
Answer
Genes from other species that alter the formation of a factor are introduced, and the resulting biological effects reveal the role of the factor and how its genes are regulated. Example: insulin-like growth factor.
Q5 · 2 marks · Short answerHarder board level
Why are transgenic animals described as 'more sensitive' in toxicity testing, and why is that useful?
Hint
Faster results.
Answer
They carry genes that make them react more strongly to toxic substances than ordinary animals, so harmful effects appear sooner and at lower doses, giving results in less time.
Q6 · 2 marks · Short answerHarder board level
Each litre of a transgenic goat's milk carries 2.4 g of a human protein, and she is milked for 3 litres daily. Find the protein collected over 10 days.
Hint
c × V × days.
Answer
Per day: 2.4 × 3 = 7.2 g; in 10 days: 72 g.
Q7 · 3 marks · Short answerHOTS / competency
Suppose a scientist wants a transgenic mouse model to test new drugs for a human inherited disease. Outline how she would make it and how it would be used.
Hint
Microinjection; disease model.
Answer
She would clone the human disease-causing allele, microinject it into the nucleus of fertilised mouse eggs, implant the embryos in a surrogate mother and screen offspring for the gene. Mice that develop the disease serve as a model: new drugs are given to them and their effects on symptoms studied before human trials.
Q8 · 3 marks · Case-basedHOTS / competency
Read and answer.
Suppose a cow, like Rosie, produces milk with 2.4 g/L of human α-lactalbumin and gives 15 litres a day.
(a) How much α-lactalbumin is produced per day? (1)
(b) Why is such milk better for human babies? (1)
(c) Name the committee in India that judges the safety of such GM products. (1)
Hint
2.4 × 15.
Answer
(a) 2.4 × 15 = 36 g. (b) It contains human α-lactalbumin, making it nutritionally more balanced for human babies than ordinary cow milk. (c) GEAC, the Genetic Engineering Approval Committee.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Which animal makes up most transgenic animals?Show answer
Mice (over 95 per cent).
2.Which human protein did Rosie's milk contain?Show answer
Alpha-lactalbumin.
3.Which vaccine is tested with transgenic mice?Show answer
Polio vaccine.
4.What does α-1-antitrypsin treat?Show answer
Emphysema.
5.Expand GEAC.Show answer
Genetic Engineering Approval Committee.
6.Concentration of α-lactalbumin in Rosie's milk?Show answer
About 2.4 g per litre.

Transgenic Animals: frequently asked questions

What is a transgenic animal?

An animal whose DNA has been manipulated so that it carries and expresses an extra, foreign gene.

What are the uses of transgenic animals?

Studying normal physiology and development, modelling human diseases, producing biological products, testing vaccine safety and testing chemical safety.

Who was Rosie?

The first transgenic cow (1997), whose milk contained human α-lactalbumin at about 2.4 g per litre.

Why are transgenic mice used for vaccine testing?

To test vaccine safety before human use; if reliable, they could replace monkeys in testing batches of polio vaccine.

Who regulates GM organisms in India?

The Genetic Engineering Approval Committee (GEAC).