Q.(a) Define transgenic animals. Explain in detail any four areas where they can be used for human benefit.
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🔒 Start your 14-day free trial to unlock the full solution →Part (a)Concept understanding — Genetically Modified Organisms
Imagine you have a recipe for a simple sponge cake. Now, suppose you want that cake to also have chocolate chips inside it. You wouldn't throw away the original recipe and start from scratch. Instead, you would take the basic cake batter and deliberately add chocolate chips to it. You have modified the original recipe to give it a new, useful property.
A Genetically Modified Organism (GMO) works on the same principle, but instead of adding chocolate chips to batter, scientists add a specific gene (a tiny instruction manual inside a living cell) from one organism into the DNA of another organism. The result is a living thing — a plant, animal, or microbe — whose genetic material has been artificially altered in a way that does not occur naturally through mating or natural recombination.
The key word here is deliberate. GMOs are not the same as the natural evolution or selective breeding that farmers have done for thousands of years (like breeding wolves into dogs). Selective breeding mixes thousands of genes at once, like shuffling two entire decks of cards. Genetic modification is like taking a single, specific card from one deck and inserting it into a specific spot in another deck.
How does it actually work? (The core idea)
Every living thing — from a bacterium to a mango tree to a human — carries its hereditary information in a molecule called DNA. A gene is a specific segment of that DNA that contains the instructions for making one particular protein. That protein then gives the organism a particular trait, like the colour of a flower or the ability to resist a pest.
In genetic modification, scientists:
- Identify a useful gene from one organism (say, a gene from a soil bacterium that makes a protein toxic to certain insects).
- Isolate that gene and copy it.
- Insert that gene into the DNA of a different organism (say, a cotton plant).
- The cotton plant now reads that new gene and starts producing the insect-killing protein. The cotton plant has been genetically modified to be pest-resistant.
Why does this matter? (The real-world significance)
GMOs are not just a lab curiosity. They are a major part of modern agriculture and medicine. The NCERT textbook highlights two main areas where this technology has had a huge impact:
1. Agriculture: Making crops more useful
The most common GMOs you will encounter are crop plants. The goal is usually to give the plant a new, valuable trait without having to breed it for many generations.
- Pest resistance (Bt crops): A gene from the bacterium Bacillus thuringiensis (Bt) is inserted into crops like cotton and corn. This gene produces a protein that kills specific insect pests (like the cotton bollworm). The plant protects itself, so farmers need to spray fewer chemical pesticides.
- Herbicide tolerance: Some crops are modified to be resistant to a specific weed-killer (herbicide). This allows farmers to spray the herbicide to kill weeds without harming the crop itself.
- Increased nutritional value: A famous example is Golden Rice, which is genetically modified to produce beta-carotene (which the body converts to Vitamin A). This was developed to address Vitamin A deficiency in regions where rice is a staple food.
The NCERT textbook specifically mentions Bt cotton as a major success story in India. It has been widely adopted by farmers because it reduces the need for pesticides and can lead to higher yields. However, it also raises important questions about cost, seed patents, and long-term effects on soil and biodiversity — issues that are debated in economics and environmental studies.
2. Medicine: Producing life-saving drugs
This is where GMOs have had an arguably even more profound impact. Instead of modifying whole plants, scientists often modify microorganisms like bacteria or yeast to act as tiny factories.
- Human Insulin (Humulin): Before GMOs, people with diabetes used insulin from cows or pigs, which could cause allergic reactions. Scientists inserted the human gene for insulin into E. coli bacteria. The bacteria then multiplied and produced large quantities of pure human insulin. This was the first-ever commercial GMO product approved for human use.
- Vaccines and other proteins: Many modern vaccines (like the Hepatitis B vaccine) and other therapeutic proteins are now produced using genetically modified yeast or animal cells. This is safer, cheaper, and more scalable than extracting them from human or animal tissues.
A balanced perspective (What you should know) …
Part (b)Concept understanding — Bioreactor Scale-Up
Imagine you have a small kitchen blender that makes a perfect smoothie for one person. Now, your job is to make the same smoothie for a thousand people — but you can only use a giant industrial vat. You cannot just multiply every ingredient by a thousand and press the same button. The giant vat will not mix the same way; the heat will build up differently; the blades will not reach every corner. The smoothie might come out burnt, lumpy, or uneven.
That, in essence, is the core problem of bioreactor scale-up.
The Everyday Intuition
A bioreactor is a large, controlled tank where living cells (like yeast, bacteria, or animal cells) are grown to produce something useful — medicines, vaccines, enzymes, or even beer. In a lab, scientists work with tiny flasks or small reactors (a few litres). They figure out the perfect conditions: the right temperature, the right amount of oxygen, the right stirring speed, and the right nutrients.
But when you want to produce that medicine for millions of patients, you cannot just use a thousand tiny flasks. You need one giant reactor — maybe 10,000 litres or more. The challenge is: how do you take the small-scale success and make it work at a large scale without ruining the product?
This is bioreactor scale-up. It is the art and science of transferring a biological process from a small, well-controlled lab environment to a large, industrial-sized reactor while keeping the cells happy and the product quality identical.
The Precise Meaning
In technical terms, bioreactor scale-up is the process of increasing the volume of a bioreactor while maintaining the same environmental conditions that the cells need to grow and produce the desired substance. It is not about simply making everything bigger. It is about recreating the same micro-environment for every single cell, even when the reactor is a hundred times larger.
Why can't you just scale up by multiplying? Because physical forces do not scale linearly. Consider these three key problems:
- Mixing: In a small flask, a gentle swirl mixes everything instantly. In a giant tank, the liquid at the top may be perfectly stirred, but the liquid near the bottom may be stagnant. Cells at the bottom might starve or suffocate.
- Oxygen transfer: Cells need oxygen to breathe. In a small reactor, oxygen dissolves easily from the air. In a large reactor, the surface area relative to volume is much smaller. You need to pump in air and stir vigorously to get enough oxygen to the cells — but too much stirring can physically tear the cells apart.
- Heat removal: Cells generate heat as they grow. In a small flask, the heat escapes through the glass walls. In a large tank, the heat builds up inside. Without proper cooling, the temperature can rise and kill the cells.
The central rule of scale-up is: You cannot keep all parameters the same. You must choose one or two key parameters to hold constant (like the rate of oxygen transfer or the mixing time) and let others change. The choice depends on what the cells need most.
Why It Matters (The Real-World Impact)
Bioreactor scale-up is not a theoretical exercise. It is the bridge between a lab discovery and a life-saving product reaching the market. If scale-up fails, the product fails — and that can mean millions of rupees wasted, or worse, a medicine shortage.
Consider the production of insulin, vaccines, or monoclonal antibodies. These are made by genetically engineered cells. The process that works in a 5-litre lab reactor must be successfully transferred to a 10,000-litre production reactor. If the cells stop producing the protein at large scale, or if the protein gets contaminated, the entire batch is lost.
The NCERT textbook (Class 12 Biology, Chapter 11: Biotechnology – Principles and Processes) puts it this way: "The process of scaling up is a critical step in the commercialisation of a biotechnological product. It involves moving from a laboratory-scale process to a pilot plant and then to a full-scale production plant."
The Steps in a Nutshell
Scale-up is usually done in stages, not in one giant leap: …
Part (a)
Transgenic animals are animals whose genome has been deliberately altered to carry and express a foreign gene (a transgene) introduced by genetic engineering; the gene is present in all their cells and is passed to offspring.
Four areas of human benefit:
- Study of normal physiology and development - introducing/altering genes shows how they regulate normal body functions and development (e.g. the role of insulin-like growth factor in growth).
- Study of disease - transgenic models mimic human diseases (cancer, cystic fibrosis, Alzheimer's, rheumatoid arthritis), so disease mechanisms and treatments can be studied.
- Biological (pharmaceutical) products - animals act as bioreactors and secrete useful proteins, e.g. the first transgenic cow Rosie produced human-protein-enriched milk; alpha-1-antitrypsin (for emphysema) has been obtained from transgenic animals. …
Part (a): transgenic animals carry a deliberately introduced foreign gene; four uses are studying normal physiology/development, modelling human disease, producing biological/pharmaceutical products, and testing vaccine/chemical safety. Part (b): a sparged stirred-tank bioreactor is a stirred, air-sparged culture vessel with impeller, sparger, baffles and temperature/pH/foam/O2/sampling controls that grows microbes to make a product.
Part (a)
Definition. Transgenic (or genetically modified) animals are animals whose DNA has been manipulated to possess and express an additional, foreign gene - a transgene. The gene, often from another species, is introduced into the fertilised egg or early embryo, becomes integrated into every cell (including germ cells), and is therefore transmitted to the offspring. Transgenic mice, rats, rabbits, pigs, sheep, cows and fish have all been produced.
Four areas where they benefit humans:
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Normal physiology and development. Transgenic animals are used to study how genes regulate normal body functions and development. By adding or altering a gene one can follow its effect on the animal - for example, studying molecules such as the insulin-like growth factor helps reveal how growth and other physiological processes are controlled.
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Study of disease. Many transgenic animals are designed to serve as models of human diseases so that the mechanism of the disease and possible treatments can be investigated. Transgenic models exist for cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's disease.
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Biological products. Medically useful proteins are expensive to make; transgenic animals can produce them cheaply, acting as living "bioreactors". The first transgenic cow, Rosie, produced human-protein-enriched milk (containing human alpha-lactalbumin). The human protein alpha-1-antitrypsin, used against emphysema, has been obtained from transgenic animals; similar attempts target phenylketonuria and cystic fibrosis. …
Showing the 12 most recent of 54 on this concept.
- CBSE 2026Set 57/3/11 markMCQQ.Golden rice is a promising transgenic crop. When released for cultivation, it will help in : (A) Producing petrol-like fuel (B) Reduction of Vitamin A deficiency in humans (C) Pest resistance (D) Herbicide tolerance
›Reveal solutionSolution
Golden rice is a genetically modified crop engineered to produce beta-carotene, which the human body converts into Vitamin A, making it a tool to combat Vitamin A deficiency.
Golden rice is one of the most well-known examples of a genetically modified organism (GMO) developed for humanitarian purposes. To understand what it does, we first need to step back and look at why it was created. Vitamin A deficiency is a serious public health problem in many developing countries, particularly in parts of Asia and Africa where rice is a dietary staple. Rice, however, contains no beta-carotene (the precursor to Vitamin A) in its polished grain. People who rely heavily on rice and lack access to diverse foods like carrots, leafy greens, or animal products often suffer from blindness, weakened immunity, and even death due to this deficiency.
Scientists addressed this by inserting two genes into the rice genome: one from a soil bacterium (Erwinia uredovora) and one from a daffodil plant. These genes enabled the rice plant to produce beta-carotene in the endosperm — the part of the grain we eat. The beta-carotene gives the rice a characteristic golden-yellow colour, hence the name "golden rice." When consumed, the human body converts this beta-carotene into Vitamin A.
NoteGolden rice is not intended to replace a balanced diet or Vitamin A supplements. It is designed as a supplementary intervention for populations where rice is the primary food and access to other sources of Vitamin A is limited. …
- CBSE 2026Set EG1 markQ.Write the name of any one transgenic animal.
›Reveal solutionSolution
A transgenic animal example: the cow Rosie (or a transgenic mouse).
A transgenic (genetically modified) animal is one that carries a foreign (manipulated) gene deliberately introduced into it. A well-known example is the transgenic cow Rosie, which produced human protein-enriched milk (containing human alpha-lactalbumin), making the milk more balanced for human babies.
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- CBSE 2026Set A1 markMCQQ.In which of the following is the large volume of culture processed to produce appreciable quantities of products?(a) Distillation unit(b) Bioreactor(c) PCR(d) Electrophoresis unit
›Reveal solutionSolution
A bioreactor processes large volumes of culture; the correct option is (b).
A bioreactor is a large vessel (often thousands of litres) in which raw materials are biologically converted into specific products (enzymes, proteins, etc.) using microbial, plant, animal or human cells. It provides optimum conditions — temperature, pH, substrate, salts, vitamins, oxygen — for large-scale produc …
- CBSE 2026Set A1 markMCQQ.Which technique was used to prevent infection of tobacco plants from Meloidegyne incognitia tapeworm?(a) RNA interference(b) Cry protein(c) Somatic hybridisation(d) Pesticide
›Reveal solutionSolution
RNA interference protected tobacco from the nematode; the correct option is (a).
The root parasite Meloidogyne incognita (a nematode, not a tapeworm as the stem loosely states) infects tobacco plants and reduces yield. Protection was achieved using RNA interference (RNAi). Using Agrobacterium as a vector, nematode-specific genes were introduced into the host plant to produce both sense and antisense RNA. These form a double-stranded RNA …
- CBSE 2026Set A1 markMCQQ.Which human protein is found in milk of the first transgenic cow-Rosie?(a) Alpha-1 antitrypsin(b) Alpha lactalbumin(c) Albumin(d) p53
›Reveal solutionSolution
Rosie's milk contained human alpha-lactalbumin; the correct option is (b).
Rosie, the first transgenic cow (1997), produced human protein-enriched milk containing about 2.4 grams per litre of human alpha-lactalbumin. This human protein made the milk nutritionally more balanced and suitable for human babies than ordinary cow's milk. It …
- CBSE 2026Set ANNUAL1 markQ.Which nematode infected the roots of tobacco plant and causes a great reduction in the yield?
›Reveal solutionSolution
The nematode Meloidogyne incognita infects tobacco roots and reduces yield; RNA interference (RNAi) technology has been used to make tobacco plants resistant to it.
Meloidogyne incognita is a nematode that infects the roots of tobacco plants, causing considerable reduction in yield. Using recombinant DNA technology, RNA interference (RNAi) was used to introduce nematode-specific genes into tobacco cells via Agrobacterium ve …
- CBSE 2026Set ANNUAL1 markQ.Large scale production of biotechnological products involve use of ............ .
›Reveal solutionSolution
Large-scale production of biotechnological products (enzymes, hormones, antibiotics, etc.) requires bioreactors, which provide optimum growth conditions for large volumes (100–1000 litres) of culture.
Once a gene of interest is cloned into a suitable host, the host cells must be grown on a large scale to produce the desired biotechnological product commercially. This is done in bioreactors, vessels in which raw materials are biologically converted by microbes, plant, animal, or human cells into specific products, …
- CBSE 2026Set ANNUAL1 markMCQQ.Assertion (A) : In bioreactors, raw materials are biologically converted into desired products. Reason (R) : In bioreactors optimum growth conditions for microbes such as temperature, pH, substrate, salt etc. are available.(a) Assertion (A) and Reason (R) both are true and Reason (R) is the correct explanation of Assertion (A).(b) Assertion (A) and Reason (R) both are true, but Reason (R) is not the correct explanation of Assertion (A).(c) Assertion (A) is true, but Reason (R) is false.(d) Assertion (A) is false, but Reason (R) is true.
›Reveal solutionSolution
Bioreactors do biologically convert raw materials into desired products (A), and they are able to do so specifically because they maintain the optimum growth conditions (temperature, pH, substrate, salts, etc.) microbes/cells need (R), which correctly explains A.
A bioreactor is a large vessel in which raw materials are biologically converted, using microbial, plant, animal, or human cells (or their enzyme systems), into specific products such as enzymes, hormones, antibodies or antibiotics — confirming Assertion (A). This large-scale, efficient conversion is possible precisely because a bioreactor provides and continuously monitors the optimum conditions …
- CBSE 2025Set ANNUAL1 markMCQQ.An important objective of biotechnology in the area of agriculture is -(a) to decrease seed number(b) to produce pest-resistant varieties of plants(c) to increase phosphorous, nitrogen production(d) to reduce the number of plants
›Reveal solutionSolution
Agricultural biotechnology mainly aims at developing pest-resistant crop varieties, such as Bt crops.
A key objective of biotechnology applied to agriculture is to reduce dependence on chemical pesticides by developing genetically modified, pest-resistant crop varieties — for example, Bt cotton and Bt brinjal, which carry cry genes from the soil bacterium Bacillus thuringiensis that make plant tissue toxic to specific insect larvae. This raises crop yield and lowers the …
- CBSE 2025Set KH1 markMCQQ.Bt cotton formed from:(a) Virus(b) Fungi(c) Bacteria(d) Insects
›Reveal solutionSolution
The Bt toxin gene (cry) comes from the bacterium Bacillus thuringiensis, so Bt cotton is formed using bacteria → option (c).
Concept. "Bt" stands for Bacillus thuringiensis, a soil bacterium that produces crystal (Cry) proteins toxic to certain insect larvae.
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- CBSE 2025Set ANNUAL1 markQ.Simple shake flasks are more effective than stirred-tank bioreactors for producing large quantities of recombinant proteins.
›Reveal solutionSolution
Small-scale culture in shake flasks cannot supply enough product; large-scale industrial production of proteins/biomolecules needs bioreactors with controlled aeration, mixing and nutrient/oxygen supply.
When genes are cloned to produce large quantities of useful proteins such as recombinant insulin, growth hormone or industrial enzymes, the desired gene is expressed in a suitable host organism (bacteria/yeast) which is then grown in large volumes (typically 100–1000 litres) of culture medium to obtain a sufficiently large biomass/yield of the product. Small shake flasks used in the laboratory can only support very limited culture volumes and provide poor control over oxygen, nutrients, pH and temperature, so they are unsuitable for large-scale product …
- CBSE 2025Set ANNUAL1 markMCQQ.Golden rice is a genetically modified crop where the incorporated gene is meant for biosynthesis of(a) vitamin B(b) vitamin A(c) vitamin E(d) vitamin C
›Reveal solutionSolution
Golden rice is engineered to produce beta-carotene in its grain, which the human body converts into vitamin A.
Golden rice is a transgenic variety of rice engineered by introducing genes for the biosynthesis of beta-carotene (which gives the grain its golden-yellow colour), a compound the human body can readily convert into vitamin A. It was developed specifically to …
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