Samacheer Kalvi Class 10 Science Solutions Chapter 20 Breeding and Biotechnology

Samacheer Kalvi 10th Science Breeding and Biotechnology Text Book Back Questions and Answers

I. Choose the correct answer:

 

Question 1. Which method of crop improvement can be practised by a farmer if he is inexperienced?
(a) clonal selection
(b) mass selection
(c) pureline selection
(d) hybridisation
Answer: (b) mass selection
In simple words: An inexperienced farmer can easily use mass selection to improve crops. This method involves picking the best plants by looking at them and then breeding them together to get better seeds.

🎯 Exam Tip: Mass selection is the simplest and oldest method of crop improvement, making it suitable for beginners or small-scale farming.

 

Question 2. Pusa Komal is a disease resistant variety of _______.
(a) sugarcane
(b) rice
(c) cow pea
(d) maize.
Answer: (c) cow pea
In simple words: Pusa Komal is a special type of cowpea plant that has been bred to fight off diseases easily. This makes it a strong and healthy crop.

🎯 Exam Tip: Remember specific crop varieties and the diseases or traits they are resistant to for multiple-choice questions.

 

Question 3. Himgiri developed by hybridisation and selection for disease resistance against rust pathogens is a variety of:
(a) chilli
(b) maize
(c) sugarcane
(d) wheat
Answer: (d) wheat
In simple words: Himgiri is a type of wheat plant that was created by mixing different kinds of wheat and then choosing the best ones. It is specially made to resist a plant sickness called rust.

🎯 Exam Tip: Hybridisation combines desirable traits from two different parent plants to create a new, improved variety, often with disease resistance.

 

Question 4. _________ of lives and celebrated its 50th birthday is
(a) IR – 8
(b) IR – 24
(c) Atomita – 2
(d) Ponni.
Answer: (a) IR – 8
In simple words: IR-8 is a very important rice variety that has helped feed many people around the world. It was developed to produce a lot of grain, which is why it is famous.

🎯 Exam Tip: IR-8 is a significant variety in agricultural history, known for its high yield and impact on global food security.

 

Question 5. Which of the following is used to produce products useful to humans by biotechnology techniques?
(a) enzyme from organism
(b) live organism
(c) vitamins
(d) both (a) and (b)
Answer: (d) both (a) and (b)
In simple words: Biotechnology uses both enzymes taken from organisms and entire living organisms themselves to make things helpful for people. This can include medicines or other useful substances.

🎯 Exam Tip: Biotechnology harnesses biological processes, which often involves either isolating specific enzymes or utilizing whole microorganisms like bacteria or yeast.

 

Question 6. We can cut the DNA with the help of _________.
(a) scissors
(b) restriction endonucleases
(c) knife
(d) RNAase.
Answer: (b) restriction endonucleases
In simple words: Restriction endonucleases are special enzymes that act like tiny scissors to cut DNA at very specific places. These enzymes are crucial tools in genetic engineering.

🎯 Exam Tip: Restriction endonucleases are essential "molecular scissors" in genetic engineering, recognizing and cutting DNA at particular nucleotide sequences.

 

Question 7. rDNA is a:
(a) vector DNA
(b) plasmid DNA
(c) recombinant of vector DNA and desired DNA:
(d) satellite DNA
Answer: (c) recombinant of vector DNA and desired DNA:
In simple words: Recombinant DNA (rDNA) is a new DNA molecule made by joining a piece of DNA you want (desired DNA) with another DNA molecule that can carry it, called a vector DNA. This creates a combined DNA piece.

🎯 Exam Tip: Remember that "recombinant" means combining genetic material from different sources, typically a vector and a foreign gene.

 

Question 8. DNA fingerprinting is based on the principle of identifying _________ sequences of DNA.
(a) single-stranded
(b) mutated
(c) polymorphic
(d) repetitive.
Answer: (d) repetitive
In simple words: DNA fingerprinting works by looking for parts of DNA that repeat many times. These repeating parts are different for almost every person, helping to identify individuals.

🎯 Exam Tip: DNA fingerprinting relies on analyzing short tandem repeats (STRs) or variable number tandem repeats (VNTRs), which are highly polymorphic repetitive DNA sequences.

 

Question 9. Organisms with modified endogenous gene or a foreign gene are also known as:
(a) transgenic organisms
(b) genetically modified
(c) mutated
(d) both (a) and (b)
Answer: (d) both (a) and (b)
In simple words: An organism that has had its own genes changed, or has received genes from a different kind of organism, is called a transgenic organism or a genetically modified organism (GMO). Both terms refer to the same thing.

🎯 Exam Tip: Transgenic organisms are a specific type of genetically modified organism (GMO), where genes from another species have been introduced.

 

Question 10. In a hexaploid wheat (2n = 6x = 42) the haploid (n) and the basic (x) number of chromosomes respectively are _________.
(a) n = 7 and x = 21
(b) n = 21 and x = 21
(c) n = 7 and x = 7
(d) n = 21 and x = 7.
Answer: (d) n = 21 and x = 7.
In simple words: For hexaploid wheat, which has 42 chromosomes in total (2n = 42), the haploid number (n) is half of that, which is 21. The basic set of chromosomes (x) for wheat is 7, and since it is hexaploid (6x), it means it has 6 sets of 7 chromosomes each, making the total 42.

🎯 Exam Tip: In polyploids, 'n' refers to the haploid gametic number, while 'x' refers to the basic chromosome set number for the ancestral genome.

 

II. Fill in the blanks:

 

Question 1. Economically important crop plants with superior quality are raised by hybridization.
Answer: Hybridization
In simple words: Hybridization is a process where two different plants are crossed to create a new plant with better qualities. This helps farmers grow stronger and more useful crops.

🎯 Exam Tip: Hybridization is key to improving crop traits like yield, quality, and disease resistance by combining desirable genes.

 

Question 2. A protein rich wheat variety is Altas 66.
Answer: Altas 66
In simple words: Altas 66 is a type of wheat that has a lot of protein. This makes it a very nutritious food choice.

🎯 Exam Tip: Remember specific examples of biofortified crops and their enhanced nutritional value.

 

Question 3. Colchicine is the chemical used for doubling the chromosomes.
Answer: Colchicine
In simple words: Colchicine is a special chemical that can make a cell have twice the usual number of chromosomes. This is useful in plant breeding to create new types of plants.

🎯 Exam Tip: Colchicine inhibits spindle formation during cell division, leading to chromosome doubling and often polyploidy in plants.

 

Question 4. The scientific process which produces crop plants enriched with desirable nutrients are called Bio fortification.
Answer: Bio fortification
In simple words: Biofortification is a way to make crop plants more nutritious by adding more vitamins, minerals, and proteins to them. This helps make food healthier for people.

🎯 Exam Tip: Biofortification addresses hidden hunger by breeding crops with naturally higher levels of essential micronutrients.

 

Question 5. Rice normally grows well in alluvial soil, but Atomita 2 rice is a rice variety produced by mutation breeding that grows well in saline soil.
Answer: Atomita 2 rice
In simple words: Atomita 2 rice is a special kind of rice that can grow even in salty soil, unlike most rice plants. It was developed through a process called mutation breeding.

🎯 Exam Tip: Mutation breeding uses induced genetic changes to develop new crop varieties with improved traits, such as salinity tolerance.

 

Question 6. Recombinant technique made it possible to genetically engineer living organism.
Answer: Recombinant
In simple words: Recombinant DNA technology allows scientists to create new combinations of genetic material. This technique has made it possible to modify living organisms genetically, creating new characteristics.

🎯 Exam Tip: Recombinant DNA technology is the foundation of genetic engineering, enabling the transfer of genes between different organisms.

 

Question 7. Restriction endonucleases cut the DNA molecule at specific positions known as Phosphodiester.
Answer: Phosphodiester
In simple words: Restriction endonucleases are enzymes that cut DNA at specific points within its structure. They specifically break the phosphodiester bonds that link the sugar and phosphate parts of the DNA backbone.

🎯 Exam Tip: Restriction enzymes are highly specific, recognizing palindromic sequences and cutting phosphodiester bonds to produce DNA fragments.

 

Question 8. Similar DNA fingerprinting is obtained for Identical twins.
Answer: Identical twins
In simple words: Identical twins share almost the same DNA because they come from the same single egg. So, their DNA fingerprints will be very similar or practically identical.

🎯 Exam Tip: Identical twins are genetically almost indistinguishable, making their DNA fingerprints nearly identical, unlike fraternal twins or other siblings.

 

Question 9. Bacterial cells are undifferentiated mass of cells.
Answer: Bacterial
In simple words: Bacterial cells are simple, single-celled organisms that do not form complex tissues or organs. They remain as a group of cells without special functions.

🎯 Exam Tip: Bacteria are prokaryotes, meaning they lack a nucleus and other complex organelles, and do not undergo cellular differentiation like multicellular organisms.

 

Question 10. In gene cloning the DNA of interest is integrated in a bacterial cell.
Answer: bacterial cell
In simple words: When scientists want to make many copies of a specific piece of DNA, they often put it into a bacterial cell. The bacteria then copy this DNA as they grow and divide.

🎯 Exam Tip: Bacteria are widely used as host cells in gene cloning because they replicate rapidly and can easily take up and express foreign DNA.

 

III. State whether true or false. If false, write the correct statement:

 

Question 1. Raphanobrassica is a tetraploid man-made genus produced by colchicine treatment.
Answer: True
In simple words: Raphanobrassica is indeed a plant that humans created by using colchicine to double its chromosomes. This makes it a tetraploid, meaning it has four sets of chromosomes.

🎯 Exam Tip: Raphanobrassica is a classic example of an allopolyploid, a hybrid of two different species whose chromosome number was doubled to restore fertility.

 

Question 2. The process of producing an organism with more than two sets of chromosome is called mutation.
Answer: False – The process of producing an organism with more than two sets of chromosome is called polyploidy.
In simple words: When an organism has more than two sets of chromosomes, it is called polyploidy, not mutation. A mutation is a change in the DNA sequence, while polyploidy is about the number of entire chromosome sets.

🎯 Exam Tip: Distinguish between mutation (change in genetic sequence) and polyploidy (change in whole sets of chromosomes).

 

Question 3. A group of plants produced from a single plant through vegetative or asexual reproduction are called a pureline.
Answer: True
In simple words: A pureline is made up of plants that all came from one single plant through methods like cuttings or cloning. Because they come from one parent without mixing, they are all genetically identical.

🎯 Exam Tip: Purelines are genetically uniform populations derived from a single self-pollinated homozygous individual, while clones are genetically identical offspring from asexual reproduction.

 

Question 4. Iron fortified rice variety determines the protein quality of the cultivated plant.
Answer: False – Iron rich rice variety improves the iron content of the cultivated plant.
In simple words: Iron-fortified rice is made to have more iron, not necessarily to change the protein quality. Its main goal is to help people get enough iron in their diet.

🎯 Exam Tip: Biofortification targets specific nutrient deficiencies; iron-fortified rice focuses on increasing iron levels, while other varieties might target protein or vitamin A.

 

Question 5. Golden rice is a hybrid.
Answer: False – Golden rice is a genetically modified plant
In simple words: Golden rice is not a hybrid made by traditional cross-breeding. Instead, it is a genetically modified plant that has genes added to it to make vitamin A.

🎯 Exam Tip: Golden rice is a key example of a genetically modified organism (GMO) engineered to produce beta-carotene, a precursor to Vitamin A.

 

Question 6. Bt gene from bacteria can kill insects.
Answer: True
In simple words: The Bt gene comes from a type of bacteria. When this gene is put into plants, the plants can then make a special protein that is harmful to certain insects, effectively killing them.

🎯 Exam Tip: The Bt (Bacillus thuringiensis) gene produces insecticidal proteins that are specific to certain insect pests, making it a valuable tool in pest-resistant crop development.

 

Question 7. In vitro fertilisation means the fertilisation done inside the body.
Answer: False – In vitro fertilisation means the fertilisation done outside the body.
In simple words: "In vitro" means "in glass" or outside the living body, like in a test tube. So, in vitro fertilization is when an egg and sperm meet outside the body, not inside.

🎯 Exam Tip: "In vitro" literally means "in glass" and refers to biological processes that occur outside of a living organism, typically in a laboratory setting.

 

Question 8. DNA fingerprinting technique was developed by Alec Jeffrey.
Answer: True
In simple words: Alec Jeffrey is credited with developing the technique known as DNA fingerprinting. This method helps identify individuals based on their unique DNA patterns.

🎯 Exam Tip: Knowing key scientists and their contributions to major biological discoveries is important for general knowledge questions.

 

Question 9. Molecular scissors refers to DNA ligases.
Answer: False – Molecular scissors refers to Restriction enzymes
In simple words: Molecular scissors are actually restriction enzymes, which are used to cut DNA at specific places. DNA ligases, on the other hand, are enzymes that join DNA pieces together, acting like molecular glue.

🎯 Exam Tip: Differentiate between restriction enzymes (cuts DNA, "scissors") and DNA ligase (joins DNA, "glue").

 

IV. Match the following:

 

Question. Match the following.

Answer:
A. (iii) Semi-dwarf wheat
B. (v) Semi-dwarf Rice
C. (ii) Sugarcane
D. (i) Phaseolus mungo
E. (iv) Ground nut
F. (viii) First hormone produced using rDNA technique
G. (vi) Bacillus thuringienesis
H. (vii) Beta carotene
In simple words: This matching exercise links various crop varieties, biological products, and their characteristics or origins. For example, Sonalika is a type of semi-dwarf wheat, and IR 8 is a semi-dwarf rice. Insulin was the first hormone made using recombinant DNA technology.

🎯 Exam Tip: Memorize the common names of important crop varieties, their traits, and key biotechnological products and their associated scientific terms.

 

V. Understand the assertion statement, justify the reason given and choose the correct choice:

 

Question 1. Assertion : Hybrid is superior than either of its parents. Reason: Hybrid vigour is lost upon inbreeding.
(a) Assertion is correct and reason is wrong.
(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason is correct.
(d) Both assertion and reason is wrong.
Answer: (c) Both assertion and reason is correct.
In simple words: Both statements are true. A hybrid is usually stronger and better than its parent plants. This strength is called hybrid vigour, but it goes away if the hybrids are continuously bred with their close relatives (inbreeding).

🎯 Exam Tip: Hybrid vigor (heterosis) is the increased strength and growth often seen in hybrid offspring, but it is typically reduced by inbreeding due to increased homozygosity of recessive deleterious alleles.

 

Question 2. Assertion: Colchicine reduces the chromosome number. Reason: It promotes the movement of sister chromatids to the opposite poles.
(a) Assertion is correct and reason is wrong.
(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason is correct.
(d) Both assertion and reason is wrong.
Answer: (d) Both assertion and reason is wrong.
In simple words: Both the assertion and the reason are incorrect. Colchicine actually *doubles* the chromosome number, not reduces it. Also, it *prevents* the movement of sister chromatids by stopping the formation of the spindle fibers, not promotes it.

🎯 Exam Tip: Colchicine disrupts microtubule formation, which prevents the separation of sister chromatids during mitosis, leading to chromosome doubling (polyploidy), not reduction.

 

Question 3. Assertion: rDNA is superior over hybridisation techniques. Reason: Desired genes are inserted without introducing the undesirable genes in target organisms.
(a) Assertion is correct and reason is wrong.
(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason is correct.
(d) Both assertion and reason is wrong.
Answer: (a) Assertion is correct and reason is wrong.
In simple words: The assertion is true because rDNA technology is often better than traditional hybridization. However, the reason is not correct as rDNA technology precisely inserts only the desired genes, avoiding unwanted genes, which is a strength, not a problem. The given reason states that undesirable genes are inserted, which is false.

🎯 Exam Tip: Recombinant DNA technology allows for precise gene transfer, ensuring only beneficial traits are introduced, making it more targeted than traditional hybridization which transfers large segments of genetic material.

 

VI. Answer in a sentence:

 

Question 1. Give the name of the wheat variety having higher dietary fibre and protein.
Answer: Triticale is a hybrid of wheat having dietary fibre and protein. Triticale is the first man-made cereal that combines the qualities of both wheat and rye.
In simple words: Triticale is a special kind of wheat that has more fiber and protein, making it very nutritious.

🎯 Exam Tip: Triticale is an important example of an intergeneric hybrid, demonstrating successful breeding between two different genera (wheat and rye).

 

Question 2. Semi-dwarf varieties were introduced in rice. This was made possible by the presence of the dwarfing gene in rice. Name this dwarfing gene.
Answer: The dwarfing gene is Sd-I. This gene helps rice plants grow shorter, which prevents them from falling over in strong winds or rain.
In simple words: The special gene that makes rice plants shorter is called Sd-I.

🎯 Exam Tip: The Sd-1 gene significantly contributed to the Green Revolution by enabling the development of high-yielding, semi-dwarf rice varieties.

 

Question 3. Define genetic engineering.
Answer: Genetic engineering is the manipulation and transfer of genes from one organism to another organism to create a new DNA called as recombinant DNA (rDNA). It is a process of directly changing an organism's genes.
In simple words: Genetic engineering is about moving genes from one living thing to another to make new types of DNA.

🎯 Exam Tip: Emphasize "manipulation and transfer of genes" and "recombinant DNA" as key terms in defining genetic engineering.

 

Question 4. Name the types of stem cells?
Answer: Embryonic stem cell and Adult stem cell or somatic stem cell, are the two types of stem cells. These cells have the amazing ability to become many different cell types.
In simple words: The two main types of stem cells are embryonic stem cells and adult stem cells.

🎯 Exam Tip: Differentiate between embryonic stem cells (pluripotent, can become any cell type) and adult stem cells (multipotent, can become limited cell types).

 

Question 5. What are transgenic organisms?
Answer: Plants or animals expressing a modified endogenous gene or a foreign gene is known as transgenic organism. These organisms have DNA that has been changed by adding genes from another species.
In simple words: Transgenic organisms are living things that have genes from a different species put into them.

🎯 Exam Tip: A transgenic organism contains foreign DNA that has been introduced into its genome, allowing it to express new traits.

 

Question 6. State the importance of bio-fertiliser.
Answer: Bio-fertilizers are important because they increase harvest yields, improve soil structure, enhance water retention, and are economical and eco-friendly. They help farms become more efficient by adding natural nutrients to the soil.
In simple words: Bio-fertilizers help crops grow bigger, make the soil healthier, save water, and are good for the environment and farmers' money.

🎯 Exam Tip: Bio-fertilizers are living microorganisms that enrich soil nutrient quality, offering an environmentally sustainable alternative to chemical fertilizers.

 

VII. Short Answers Questions:

 

Question 1. Discuss the method of breeding for disease resistance.
Answer: Breeding for disease resistance involves selecting plants that naturally resist certain diseases and then crossing them to create new varieties that are stronger. This process helps produce crops that can fight off common plant illnesses like rust or blight without needing many chemicals. For example, the Himgiri wheat variety is resistant to leaf and stripe rust, while Pusa Komal is a disease-resistant cowpea variety.

In simple words: To breed for disease resistance, scientists find plants that naturally do not get sick. They then breed these strong plants together to create new types of crops that can fight off diseases better.

🎯 Exam Tip: Focus on the selection and hybridization processes in breeding for disease resistance, and be ready to provide examples of resistant crop varieties.

 

Question 2. Name three improved characteristics of wheat that helped India to achieve high productivity.
Answer: Three improved characteristics of wheat that helped India achieve high productivity are: 1. High yielding, 2. Semi-dwarf, and 3. Fertilizer responsive. These traits, developed in varieties like Sonalika and Kalyan Sona, allowed for a significant increase in food production, greatly contributing to the Green Revolution.
In simple words: Wheat was improved by making it grow a lot of grain, keeping it short so it would not fall over, and making it respond well to fertilizers.

🎯 Exam Tip: The "Green Revolution" largely relied on developing semi-dwarf, high-yielding, and fertilizer-responsive varieties of wheat and rice.

 

Question 3. Name two maize hybrids rich in amino acid lysine.
Answer: Protina and Shakti are two maize hybrids that are rich in the amino acid lysine. Lysine is an essential nutrient that our bodies need for good health.
In simple words: Two maize types that have a lot of lysine, an important nutrient, are Protina and Shakti.

🎯 Exam Tip: Lysine is an essential amino acid often deficient in cereal grains; identifying lysine-rich varieties like Protina and Shakti demonstrates biofortification efforts.

 

Question 4. Distinguish between (a) somatic gene therapy and germ line gene therapy.
Answer:
(a) Somatic gene therapy and Germ line gene therapy:
* **Somatic gene therapy:** This involves replacing a defective gene in somatic cells, which are any body cells other than egg or sperm. The changes made only affect the treated individual and are not passed on to their children.
* **Germ line gene therapy:** This involves replacing a defective gene in germ cells (egg and sperm). The genetic changes made here are permanent and will be passed down to future generations.
In simple words: Somatic gene therapy fixes genes in body cells, so it does not pass to children. Germ line gene therapy fixes genes in egg/sperm cells, so it does pass to children.

 

Question 4. Distinguish between (b) undifferentiated cells and differentiated cells.
Answer:
(b) Undifferentiated cells and Differentiated cells:
* **Undifferentiated cells:** These are cells that have not yet become specialized for a specific function or job. For example, cells in early embryos are undifferentiated and can become many different cell types.
* **Differentiated cells:** These are cells that have become specialized to do a particular job. For example, muscle cells are specialized for movement, and nerve cells are specialized for sending signals. These cells often lose the ability to change into other cell types.
In simple words: Undifferentiated cells are like blank slates; they have not chosen a job yet, like early embryo cells. Differentiated cells are cells that have a specific job, like muscle or nerve cells.

🎯 Exam Tip: The key difference between somatic and germline therapy is the heritability of the genetic change. For cells, differentiation means specialization.

 

Question 5. State the applications of DNA fingerprinting technique.
Answer: DNA fingerprinting is widely used in forensic applications to identify criminals and in paternity testing for legal disputes. It also helps in studying the genetic diversity within a population, understanding evolution, and the formation of new species. This technique uses unique patterns in DNA to distinguish individuals.
In simple words: DNA fingerprinting is used to solve crimes, confirm who a child's parents are, and study how different groups of living things are related.

🎯 Exam Tip: The primary applications of DNA fingerprinting are in forensics (crime scene investigation) and paternity testing due to its high accuracy in individual identification.

 

Question 6. How are stem cells useful in regenerative process?
Answer: Stem cells are crucial in regenerative processes because they can replace damaged or lost cells, tissues, and organs caused by genetic conditions, diseases, or injuries. In stem cell therapy, these special cells are used to regenerate and repair the body, restoring lost functions. This is because stem cells have the unique ability to both renew themselves and develop into many different types of specialized cells.
In simple words: Stem cells can fix or replace parts of the body that are broken or lost due to sickness or injury. They are like repair cells that can grow into new tissues.

🎯 Exam Tip: Stem cells' ability to self-renew and differentiate into specialized cell types makes them invaluable for regenerative medicine and tissue repair.

 

Question 7. Differentiate between outbreeding and inbreeding.
Answer:

Outbreeding involves breeding animals that are not closely related, which helps to increase genetic diversity and can lead to hybrid vigor. Inbreeding, on the other hand, involves breeding closely related animals, which can help to fix desirable traits but also increases the risk of genetic disorders due to inbreeding depression.
In simple words: Outbreeding means breeding animals that are not related to get strong offspring. Inbreeding means breeding animals that are closely related, which can make good traits show up but also has risks.

🎯 Exam Tip: Outbreeding increases genetic variation and can lead to hybrid vigor, while inbreeding decreases variation, can fix desirable traits, but risks inbreeding depression.

 

VIII. Long Answers Questions:

 

Question 1. What are the effects of hybrid vigour in animals?
Answer: Hybrid vigour, also known as heterosis, describes the superior qualities of a hybrid offspring compared to its parents, usually obtained through cross-breeding. This improved performance is observed in several ways in animal breeding: increased production of milk by cattle, higher egg production in poultry, better quality of meat, and an increased growth rate in domesticated animals. These benefits lead to more efficient and productive livestock farming.
In simple words: Hybrid vigour makes animal offspring stronger and better than their parents. This means cows produce more milk, chickens lay more eggs, meat quality improves, and animals grow faster.

🎯 Exam Tip: Hybrid vigor results from heterozygosity masking undesirable recessive alleles and often leads to improved growth, fertility, and disease resistance in offspring.

 

Question 2. Describe mutation breeding with an example.
Answer: Mutation is a sudden, inheritable change in the DNA sequence of an organism, leading to genetic variations. Mutation breeding uses these induced mutations to create new crop varieties with improved traits. It involves exposing plants to mutagens (factors that cause mutations) like X-rays or certain chemicals. Physical mutagens include radiations (X-rays, gamma rays) and temperature, while chemical mutagens include substances like mustard gas and nitrous acid. For example, Sharbati Sonora wheat was produced from Sonora-64 using gamma rays, and Atomita 2 rice was developed with saline tolerance and pest resistance through mutation breeding. Another achievement is groundnuts with thick shells.
In simple words: Mutation breeding is a way to make new plant types by causing small, sudden changes in their DNA. Scientists use things like radiation or chemicals to do this. For example, a type of wheat called Sharbati Sonora was made this way.

🎯 Exam Tip: Mutation breeding is an important technique for crop improvement, often used to develop new varieties with resistance to disease, pests, or improved nutritional content.

 

Question 3. Biofortification may help in removing hidden hunger. How?
Answer: Biofortification is a scientific process of breeding crop plants to enrich them with high levels of desirable nutrients like vitamins, proteins, and minerals. Micronutrient malnutrition, also known as "hidden hunger," occurs when there is a lack of essential micronutrients such as vitamin A, zinc, and iron in the diet. Biofortification effectively removes hidden hunger by providing nutrient-dense foods. Scientists breed crops whose edible parts (seeds, tubers, roots) have improved nutritional value. These biofortified foods can significantly contribute to building the body's stores of micronutrients throughout a person's life cycle. Examples include Protina, Shakti, and Rathna (lysine-rich maize), Atlas 66 (protein-rich wheat), iron-fortified rice, and vitamin A-enriched carrots, pumpkin, and spinach.
In simple words: Biofortification helps fight "hidden hunger" by making staple crops richer in important nutrients like vitamins and minerals. By breeding crops to have more of these good things, people can get the nutrients they need just by eating their regular food.

🎯 Exam Tip: Connect biofortification directly to the problem of "hidden hunger" (micronutrient deficiencies) and provide examples of crops and the nutrients they are enriched with.

 

Question 4. With a neat labelled diagram explain the techniques involved in gene cloning.
Answer: Gene cloning involves inserting a specific gene or a piece of DNA fragment into a bacterial cell. In the bacterial cell, this DNA is then multiplied (copied) as the cell divides. This process creates many identical copies of the desired gene. The basic steps involved in gene cloning are:
1. **Isolation of desired DNA fragment:** The specific DNA piece you want to clone is cut out using restriction enzymes.
2. **Insertion into a vector:** The DNA fragment is then inserted into a suitable carrier molecule, usually a plasmid (a small, circular DNA molecule in bacteria), to create recombinant DNA (rDNA).
3. **Transfer to host cell:** The recombinant DNA is transferred into a bacterial host cell, a process called transformation.
4. **Selection and multiplication:** The recombinant host cells are selected and multiplied to create many clones, each containing the desired gene.
5. **Expression of cloned gene:** Finally, the cloned gene is expressed in the host cell to produce the desired protein or product. This strategy allows for the large-scale production of enzymes, hormones, and vaccines.

In simple words: Gene cloning is like copying a specific gene many times. First, you cut out the gene you want. Then, you put it into a small circle of DNA called a plasmid, which goes into a bacteria. The bacteria then makes many copies of this gene as it multiplies.

🎯 Exam Tip: When explaining gene cloning, make sure to clearly define the roles of restriction enzymes (cutting), plasmids (vectors), and host bacteria (multiplication).

 

Question 5. Discuss the importance of biotechnology in the field of medicine.
Answer: Biotechnology has revolutionized medicine by using genetic engineering techniques to produce valuable proteins and polypeptides. These serve as potential pharmaceutical products for treating various diseases on a commercial scale. Pharmaceutical products developed using recombinant DNA (rDNA) technology include: insulin for treating diabetes, human growth hormone for children with growth deficiencies, blood clotting factors for haemophilia, and tissue plasminogen activator to dissolve blood clots and prevent heart attacks. Biotechnology also plays a crucial role in developing vaccines against various diseases like hepatitis B and rabies, significantly improving global health.
In simple words: Biotechnology is very important in medicine because it helps make many new medicines. It uses special genetic methods to create things like insulin for diabetes, growth hormones for children, and treatments for blood problems. It also helps make vaccines to stop many diseases.

🎯 Exam Tip: Highlight specific examples of biotech-derived medicines (insulin, growth hormone, vaccines) to illustrate the broad impact of biotechnology on human health.

 

IX. Higher Order Thinking Skills: (HOTS)

 

Question 1. A breeder wishes to incorporate desirable characters into the crop plants. Prepare a list of characters he will incorporate.
Answer: A breeder aims to incorporate a range of desirable characteristics into crop plants to improve their productivity and resilience. For fodder crops, tallness and profuse branching are desired traits as they mean more plant material for animals to eat. Other general desirable characteristics include: high yield, resistance to diseases and pests, tolerance to environmental stresses (like drought, salinity, or extreme temperatures), improved nutritional quality (e.g., higher protein or vitamin content), early maturity, and better shelf-life for harvested products. These traits make crops more efficient and beneficial.
In simple words: A breeder would want crops that grow tall and bushy, produce a lot of food, do not get sick easily, can handle bad weather, and are full of nutrients.

🎯 Exam Tip: When listing desirable traits, categorize them into yield, quality, resistance, and adaptability to cover a comprehensive range of breeding objectives.

 

Question 2. Organic farming is better than Green Revolution. Give reasons.
Answer: Organic farming is often considered better than the Green Revolution due to its eco-friendly and pollution-free approach. The Green Revolution significantly increased food production through high-yielding varieties and modern agricultural techniques, but it heavily relied on chemical fertilizers and pesticides, which caused environmental pollution and degraded soil quality over time. Organic farming, in contrast, is a method of crop production that avoids synthetic pesticides, herbicides, and fertilizers, focusing instead on natural methods to maintain soil fertility and control pests. This approach helps release nutrients naturally to crops, promotes biodiversity, and results in healthier food and a sustainable environment, making it a more balanced and long-term solution.
In simple words: Organic farming is better because it does not use harmful chemicals, so it is cleaner for the earth and makes healthier food. The Green Revolution made a lot of food but used many chemicals that hurt the environment.

🎯 Exam Tip: Compare organic farming and the Green Revolution by highlighting the environmental impact, sustainability, and reliance on chemicals versus natural processes.

 

Question 3. Polyploids are characterised by gigantism. Justify your answer.
Answer: An organism with more than two sets of chromosomes is called a polyploid. Polyploidy can be induced by physical treatments like heat, cold, X-rays, or chemical agents such as colchicine. Polyploid cells or organisms have three or more times the haploid chromosomal number. This increased chromosome number often leads to larger cell size, which in turn results in larger plant parts, bigger fruits, and overall larger organisms, a phenomenon known as gigantism. For instance, increased size and woodiness have been observed in some insular plants. Therefore, polyploids are characterized by gigantism due to their larger cell volume and increased biomass.
In simple words: Polyploids are organisms with extra sets of chromosomes, which makes their cells bigger. Because their cells are bigger, the whole organism often grows much larger than normal, which is called gigantism.

🎯 Exam Tip: Link polyploidy to increased cell size and gene dosage, which collectively contribute to the observed gigantism in polyploid organisms.

 

Question 4. 'P' is a gene required for the synthesis of vitamin A. It is integrated with genome of 'Q' to produce genetically modified plant 'R'. (i) What is P, Q and R? (ii) State the importance of 'R' in India.
Answer:
(i) Based on the description:
* **P** is the Beta-carotene gene (responsible for Vitamin A synthesis).
* **Q** refers to Biofortification, which is the process used to enhance the nutritional content of crops.
* **R** is Golden rice, the genetically modified plant produced.
(ii) The importance of **R** (Golden rice) in India is significant because it can produce beta-carotene, which the body converts into vitamin A. This helps prevent vitamin A deficiency, a major public health problem in many developing countries, including parts of India. Vitamin A deficiency can lead to blindness and weakened immune systems, so Golden rice offers a way to improve public health through dietary means.
In simple words: (i) P is the gene for beta-carotene, Q is the process of making crops more nutritious (biofortification), and R is Golden rice. (ii) Golden rice is important in India because it helps people get enough vitamin A, which prevents blindness and keeps them healthy.

🎯 Exam Tip: Golden rice is a prime example of how biotechnology can address micronutrient deficiencies, especially Vitamin A, in populations that rely heavily on rice as a staple food.

 

IX. Higher Order Thinking Skills: (HOTS)

 

Question 1. A breeder wishes to incorporate desirable characters into the crop plants. Prepare a list of characters he will incorporate.
Answer: For a fodder crop, a breeder would want to include traits like tallness and profuse branching. These characteristics help the plant produce more green matter, which is important for animal feed. Healthy, well-branched plants mean more food for livestock.
In simple words: A breeder would choose plants that grow tall and have many branches, especially for crops used to feed animals.

🎯 Exam Tip: When listing desirable characters for specific crops, always consider the purpose of the crop (e.g., fodder, grain, oil) to select relevant traits.

 

Question 2. Organic farming is better than Green Revolution. Give reasons.
Answer: Organic farming is superior to the Green Revolution because it uses eco-friendly methods that do not harm the environment or cause pollution. It focuses on maintaining the natural balance of the soil and ecosystem. The Green Revolution, while increasing food production, often relied on chemical fertilizers and pesticides which can damage soil health and pollute water. Organic methods avoid these harmful chemicals, leading to healthier soil and produce.
In simple words: Organic farming is better because it doesn't use chemicals that harm the earth, unlike the Green Revolution which used many chemicals to grow more food.

🎯 Exam Tip: Emphasize sustainability, environmental protection, and long-term soil health as key advantages of organic farming over the Green Revolution's short-term yield focus.

 

Question 3. Polyploids are characterised by gigantism. Justify your answer.
Answer: An organism that has more than two complete sets of chromosomes is known as a polyploid. These extra sets of chromosomes, often three or more times the normal haploid number, cause the cells to be larger. This increase in cell size leads to the characteristic "gigantism," meaning the polyploid organisms, whether plants or animals, are generally larger in size compared to their diploid counterparts. This effect is very noticeable in plants, where polyploidy often leads to larger fruits, flowers, and overall plant structures.
In simple words: Polyploid organisms have extra sets of chromosomes, which makes their cells bigger. Because of larger cells, these organisms grow larger overall, a trait called gigantism.

🎯 Exam Tip: Remember that gigantism in polyploids is a result of increased cell size due to more chromosome sets, impacting overall organism size.

 

Question 4. 'P' is a gene required for the synthesis of vitamin A. It is integrated with genome of 'Q' to produce genetically modified plant 'R'
(i) What is P, Q and R?
(ii) State the importance of 'R' in India.
Answer:
(i) P is the Beta carotene gene.
Q is Bio fortification.
R is Golden rice.
(ii) Golden rice is a genetically modified type of rice that can produce beta carotene, which the body converts into vitamin A. This is very important in India because it can help prevent vitamin A deficiency, a common nutritional problem that can cause blindness and other health issues, especially in children.
In simple words: (i) P is the gene for beta carotene, Q is making crops better with nutrients, and R is Golden rice. (ii) Golden rice helps stop vitamin A deficiency in India by providing a nutrient that makes vitamin A.

🎯 Exam Tip: Clearly identify each component (P, Q, R) and link Golden Rice's beta carotene production directly to combating vitamin A deficiency.

 

I. Choose the Correct Answer:

 

Question 1. Modern biotechnology consist:
(a) Genetic engineering
(b) Tissue culture
(c) Gene cloning
(d) All of the options
Answer: (d) All of the options
In simple words: Modern biotechnology includes changing genes, growing cells in labs, and making copies of genes.

🎯 Exam Tip: Modern biotechnology is a broad field encompassing many advanced techniques, so "All of the options" is often a strong indicator for such questions.

 

Question 2. The disease-resistant cauliflower variety is -
(a) Himgiri
(b) Pusa Shubhra
(c) Pusa Komal
(d) IR – 8.
Answer: (b) Pusa Shubhra
In simple words: Pusa Shubhra is a type of cauliflower that can resist diseases.

🎯 Exam Tip: Memorizing specific disease-resistant varieties for common crops is important for these types of questions.

 

Question 3. Transgenic animals has:
(a) Foreign DNA in all its cell
(b) Foreign RNA in all its cells
(c) Foreign DNA in some of the cells
(d) Both (b) and (c)
Answer: (a) Foreign DNA in all its cell
In simple words: Transgenic animals have new DNA from a different species in every single one of their cells.

🎯 Exam Tip: The key characteristic of a transgenic organism is that the foreign genetic material is integrated into the germline, meaning it is present in all cells and can be passed to offspring.

 

Question 4. The gamete cells, which have only one set of chromosomes is called ______.
(a) diploid
(b) polyploid
(c) triploid
(d) haploid.
Answer: (d) haploid.
In simple words: Gamete cells, like sperm or egg, only have one set of chromosomes, so they are called haploid.

🎯 Exam Tip: Distinguish between haploid (one set of chromosomes, as in gametes) and diploid (two sets of chromosomes, as in somatic cells).

 

Question 5. A kind of Biotechnology involving manipulation of DNA is:
(a) DNA replication
(b) Denaturation
(c) Genetic Engineering
(d) Renaturation
Answer: (c) Genetic Engineering
In simple words: Genetic engineering is a type of biotechnology where scientists change DNA.

🎯 Exam Tip: Genetic engineering is the direct manipulation of an organism's genes, often to introduce new traits.

 

Question 6. A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant plasmid using:
(a) ECORI
(b) Taq polymerase
(c) Polymerase III
(d) Ligase
Answer: (d) Ligase
In simple words: Ligase acts like a molecular glue, joining different DNA pieces together to make a new recombinant DNA molecule.

🎯 Exam Tip: Understand the specific roles of enzymes in genetic engineering: restriction endonucleases cut DNA, and ligases join DNA fragments.

 

Question 7. _________lowing foods can prevent the kind of blindness associated with Vitamin 'A' deficiency?
(a) Golden Rice
(b) Bt-Brinjal
(c) Flaver savr tomato
(d) Canolla
Answer: (a) Golden Rice
In simple words: Golden Rice is a special kind of rice that has extra Vitamin A, which helps stop a type of blindness caused by not having enough Vitamin A.

🎯 Exam Tip: Associate Golden Rice specifically with Vitamin A enrichment and its role in preventing related deficiencies.

 

Question 8. Restriction endonucleases are enzymes which:
(a) Remove nucleotides from the ends of the DNA molecule.
(b) Make cuts at specific positions within the DNA molecule.
(c) Recognise a specific nucleotide sequence for binding of DNA ligase.
(d) Restrict the action of the enzyme DNA polymerase.
Answer: (b) Make cuts at specific positions within the DNA molecule.
In simple words: Restriction endonucleases are enzymes that cut DNA at exact spots, like tiny molecular scissors.

🎯 Exam Tip: The precise cutting action of restriction endonucleases at specific recognition sites is fundamental to genetic engineering.

 

Question 9. __________ is the Father of Indian Green Revolution.
(a) Nammalvar
(b) Dr Borloug
(c) Dr M.S.Swaminathan
(d) Dr Sultan Ismail
Answer: (c) Dr M.S.Swaminathan
In simple words: Dr M.S. Swaminathan is known as the father of the Green Revolution in India because of his important work in making sure India had enough food.

🎯 Exam Tip: It is crucial to remember key figures associated with significant scientific and agricultural movements.

 

Question 10. New lined of sheep developed in Punjab is:
(a) Sahiwal
(b) Hisardale
(c) Mareno
(d) Sharbati sonara
Answer: (b) Hisardale
In simple words: Hisardale is a new type of sheep that was created in Punjab.

🎯 Exam Tip: Familiarize yourself with examples of new crop varieties or animal breeds developed through specific breeding programs in India.

 

II. Fill in the Blanks:

 

Question 1. .......... is a cross between Male Donkey and Female Horse.
Answer: Mule
In simple words: A mule is born when a male donkey and a female horse breed together.

🎯 Exam Tip: Remember common animal hybrids and the parent species involved in their creation.

 

Question 2. .......... is a DNA molecule found in the cytoplasm of bacterial cell.
Answer: Plasmid
In simple words: Plasmids are small, circular DNA pieces found inside bacterial cells, separate from the main chromosome.

🎯 Exam Tip: Plasmids are key vectors in genetic engineering because they can carry and replicate foreign DNA in bacteria.

 

Question 3. .......... was the first cloned female sheep.
Answer: Dolly
In simple words: Dolly was the very first sheep created by cloning.

🎯 Exam Tip: Dolly the sheep is a landmark example in the history of cloning.

 

Question 4. Human insulin can be synthesized by using ..........
Answer: rDNA technology
In simple words: Scientists can make human insulin using special DNA technology.

🎯 Exam Tip: Recombinant DNA (rDNA) technology is crucial for producing many therapeutic proteins like insulin.

 

Question 5. In genetic engineering, a DNA segment is transfered to the host cell through ..........
Answer: Vector
In simple words: In genetic engineering, a vector is like a delivery vehicle that carries a piece of DNA into a new cell.

🎯 Exam Tip: Common vectors include plasmids and viruses, which are chosen based on the host cell and size of the DNA to be transferred.

 

Question 6. Genetically identical individuals are ..........
Answer: Clones
In simple words: Clones are living things that are genetically exactly the same as another living thing.

🎯 Exam Tip: Understand that cloning results in genetically identical copies, important in both natural processes and artificial reproduction.

 

Question 7. Ligase is used for joining two ..........
Answer: DNA fragments
In simple words: Ligase is an enzyme that helps stick two pieces of DNA together.

🎯 Exam Tip: Ligase plays a critical role in DNA repair and replication, as well as in recombinant DNA technology.

 

Question 8. Enzyme that cleaves nucleic acids within the polynucleotide chain is known as ..........
Answer: Endonuclease
In simple words: An endonuclease is an enzyme that cuts the DNA chain from the inside.

🎯 Exam Tip: Differentiate endonucleases (cut internally) from exonucleases (cut from the ends of nucleic acids).

 

Question 9. The bacterium used as biopesticide is ..........
Answer: Bacillus thuringiensis.
In simple words: Bacillus thuringiensis is a type of bacteria used as a natural pest killer.

🎯 Exam Tip: Bt-toxin, from Bacillus thuringiensis, is a common biological pesticide used in organic farming and genetic modification of crops.

 

Question 10. A strain of golden rice contains high content of ..........
Answer: Vitamin A
In simple words: Golden rice has a lot of Vitamin A in it.

🎯 Exam Tip: Reinforce the connection between Golden Rice and its enhanced Vitamin A content, which is achieved through biotechnology.

 

III. State Whether True or False. If False, Write the Correct Statement:

 

Question 1. The structure used to transfer the piece of DNA attached to it into a host ceil is vector.
Answer: True
In simple words: A vector is indeed used to carry DNA into a host cell.

🎯 Exam Tip: Always remember that a vector is the carrier molecule in genetic transfers.

 

Question 2. Restriction endonucleases are used to join the DNA fragments having sticky ends.
Answer: False. Restriction endonucleases are used to *cut* the DNA fragments, while ligase enzymes are used to join them.
In simple words: No, restriction endonucleases cut DNA, they don't join it. Ligase is the enzyme that joins DNA pieces together.

🎯 Exam Tip: Clearly differentiate the functions of restriction endonucleases (cutting) and DNA ligase (joining) in molecular biology.

 

Question 3. The progeny of a single individual obtained by self breeding is clonal selection.
Answer: False. The progeny of a single individual obtained by self-breeding is called pureline selection. Clonal selection involves propagating plants vegetatively from a single desirable parent.
In simple words: This is false. Plants from one self-bred parent are pureline, while clonal selection means making copies from a plant without seeds.

🎯 Exam Tip: Understand the difference between pureline selection (from self-pollinated individuals) and clonal selection (from vegetative propagation of a single plant).

 

Question 4. The aim of crop improvement is to develop improved crop varieties.
Answer: True
In simple words: Yes, crop improvement aims to create better types of crops.

🎯 Exam Tip: Crop improvement encompasses goals like higher yield, disease resistance, and better nutritional quality.

 

Question 5. International Rice Research institute (IRRI) is in Indonesia.
Answer: False. The International Rice Research Institute (IRRI) is located in the Philippines.
In simple words: This is false. The International Rice Research Institute is actually in the Philippines.

🎯 Exam Tip: Knowing the locations of major research institutes is helpful for general knowledge questions.

 

IV. Match the Following:

Answer:
A. (v) unspecialised mass of cell
B. (i) Blood clotting
C. (ii) Cloned shape
D. (iii) World war II
E. (iv) Triticale
In simple words: Stem cells are unspecialized, haemophilia involves blood clotting, Dolly was a cloned sheep, a Gamma Garden was used after World War II, and hybridization led to Triticale.

🎯 Exam Tip: Practice matching questions by understanding the core concept or association for each pair, not just memorizing the sequence.

 

V. Understand the assertion statement, justify the reason given and choose the correct choice:

 

Question 1. Assertion: Bacillus thuringiensis is toxic to many insects. Reason: It inhibits ion transport in the mid gut.
(a) Assertion is correct and reason is wrong
(b) Reason is correct and the assertion is wrong
(c) Both assertion and reason is correct
(d) Both assertion and reason is wrong
Answer: (a) Assertion is correct and reason is wrong
In simple words: The statement that Bacillus thuringiensis kills insects is true, but the reason given for how it works (by stopping ion transport) is incorrect.

🎯 Exam Tip: For Assertion-Reason questions, first check if each statement is individually true, then check if the reason correctly explains the assertion.

 

Question 2. Assertion: Recombinant DNA technology has become successful due to restriction endonucleases present in Eukaryotic cells. Reason: Restriction endonucleases cut the DNA molecule to form blunt ends.
(a) Assertion is correct and reason is wrong
(b) Reason is correct and the assertion is wrong
(c) Both assertion and reason is correct
(d) Both assertion and reason is wrong
Answer: (d) Both assertion and reason is wrong
In simple words: Both the assertion (that eukaryotic cells have restriction endonucleases) and the reason (that these enzymes only make blunt cuts) are incorrect. Recombinant DNA technology uses restriction endonucleases primarily from prokaryotes (bacteria), and they can produce both blunt and sticky ends.

🎯 Exam Tip: Remember that restriction enzymes are primarily found in prokaryotes (bacteria) and can produce both sticky and blunt ends, depending on the enzyme.

 

VI. Answer in a Sentence:

 

Question 1. Name two neurodegenerative disorders.
Answer: Two neurodegenerative disorders are Parkinson's disease and Alzheimer's disease. These conditions involve the progressive damage or death of neurons in the brain, leading to declines in cognitive and motor functions.
In simple words: Parkinson's and Alzheimer's are two diseases that damage brain cells over time.

🎯 Exam Tip: Be able to recall specific examples of diseases for different categories, such as neurodegenerative disorders.

 

Question 2. Name two chemical mutagens.
Answer: Two chemical mutagens are mustard gas and nitrous acid. These substances can cause changes in the DNA, leading to mutations.
In simple words: Mustard gas and nitrous acid are two chemicals that can cause changes in an organism's genes.

🎯 Exam Tip: Remember that mutagens are agents that cause mutations, and they can be both physical (like X-rays) and chemical.

 

Question 3. What is plant breeding?
Answer: Plant breeding is the skillful process of developing economically important plants with improved quality. This art aims to create new plant varieties that are more productive, disease-resistant, or have better nutritional value.
In simple words: Plant breeding is the method of creating better and more useful plant types.

🎯 Exam Tip: Define plant breeding by focusing on its dual nature as both an "art" (skill) and a "science" (systematic improvement) for economic benefit.

 

Question 4. What is the aim of Animal husbandry?
Answer: The main aim of animal husbandry is to improve the genetic traits of animals to make them more useful for human welfare. This includes breeding for higher milk production, better meat quality, or increased disease resistance, ultimately benefiting mankind.
In simple words: Animal husbandry's goal is to make animals better through breeding so they can help people more.

🎯 Exam Tip: Connect animal husbandry directly to improving animal genotypes for human benefit, such as food production or other resources.

 

Question 5. What are exotic species?
Answer: Exotic species are high-yield varieties of plants that are introduced from one place to another. These species are often brought in to improve local crop production due to their superior performance in specific traits.
In simple words: Exotic species are plant types that come from another region and are brought in because they grow very well.

🎯 Exam Tip: Remember that "exotic" in this context refers to non-native species, often introduced for beneficial agricultural purposes.

 

Question 6. List the two main aspects of hybridization.
Answer: The two main aspects of hybridization are combining desirable traits from two different plants into one new plant, and utilizing hybrid vigor. Hybrid vigor, also known as heterosis, is the increased strength, growth, and productivity often seen in hybrid offspring compared to their parents.
In simple words: Hybridization mainly aims to combine good qualities from two different plants into one new plant and to use the extra strength that hybrids often show.

🎯 Exam Tip: Identify combining characters and exploiting hybrid vigor (heterosis) as the primary objectives of hybridization.

 

Question 7. What is heterosis?
Answer: Heterosis, also known as hybrid vigor, refers to the superiority of a hybrid offspring compared to its parents, specifically when produced through cross-breeding. This superiority can manifest as increased growth rate, yield, fertility, or resistance to disease. When two different purebred parents are crossed, their hybrid offspring often show enhanced traits beyond what either parent possesses, a phenomenon that has been widely utilized in agriculture.
In simple words: Heterosis is when a hybrid plant or animal is stronger, grows better, or produces more than its parents, happening because of cross-breeding.

🎯 Exam Tip: Define heterosis as the "superiority" or "vigor" of hybrids over their parents, resulting from cross-breeding.

 

Question 8. What are plasmids?
Answer: Plasmids are small, circular, self-replicating DNA molecules that are found in the cytoplasm of bacteria, separate from the main bacterial chromosome. These extrachromosomal DNA elements often carry genes that provide bacteria with advantages, such as antibiotic resistance. In biotechnology, plasmids are widely used as vectors to carry and replicate foreign DNA inside host cells.
In simple words: Plasmids are small, round pieces of DNA that can make copies of themselves, found inside bacteria, and separate from the main DNA.

🎯 Exam Tip: Highlight the key features of plasmids: circular, self-replicating, extrachromosomal, and found in bacteria.

 

Question 9. What is transgene?
Answer: A transgene is a gene that has been transferred from one organism into another different organism using genetic engineering techniques. The recipient organism is then called a transgenic organism. This transfer allows the new organism to express a trait or produce a product that it wouldn't naturally.
In simple words: A transgene is a gene that scientists move from one living thing to another using genetic engineering.

🎯 Exam Tip: Emphasize that a transgene is a gene that has been *artificially transferred* and is distinct from naturally acquired genes.

 

Question 10. Name the Research institute found by Nammalvar.
Answer: Nammalvar founded the Nammalvar Ecological Foundation for Farm Research and Global Food Security Trust. This organization focuses on promoting ecological farming and food security. He was an Indian organic farming scientist.
In simple words: Nammalvar started the Nammalvar Ecological Foundation for farm research and food security.

🎯 Exam Tip: Connect the name Nammalvar with his significant contributions to organic farming and food security in India.

 

VII. Short Answers Questions:

 

Question 1. List out the pest-resistant crop varieties.
Answer: Here are some pest-resistant crop varieties:

These varieties have been developed to naturally resist common pests, reducing the need for chemical pesticides. This is a crucial strategy in sustainable agriculture.
In simple words: Some crops that can fight off pests are Brassica (Pusa Gaurav) against aphids, Flat Bean (Pusa Sem 2, Pusa Sem 3) against leaf hoppers, and Lady's finger (Pusa Sawani, Pusa A4) against shoot and fruit borers.

🎯 Exam Tip: When asked to list examples, ensure you provide both the crop name, the specific variety, and the pest it resists for full marks.

 

Question 2. What does the nutritional quality of crop depend on?
Answer: The nutritional quality of crops depends on the amount and type of nutrients they contain. To improve a crop's nutritional quality, farmers and breeders focus on increasing its:
• Protein content and the overall quality of those proteins.
• Oil content, particularly healthy fats.
• Mineral content, such as iron, zinc, and other essential elements. This helps ensure people get a balanced diet from the crops they eat.
In simple words: A crop's nutritional quality depends on how much protein, oil, and minerals it has.

🎯 Exam Tip: Focus on the main macronutrients (protein, fats/oils) and micronutrients (minerals) as key indicators of nutritional quality.

 

Question 3. Write a note on Gamma Garden.
Answer: A Gamma Garden, also known as an Atomic Garden, is a concept that became popular after World War II. It involves the peaceful use of atomic energy to improve crops. In a Gamma Garden, radioactive sources like Cobalt-60 or Caesium-137 are used to expose plants to gamma rays. These gamma rays induce desirable mutations in crop plants, which can lead to new varieties with improved traits such as disease resistance or higher yield. This method is a type of induced mutation breeding, aiming to harness natural genetic variation.
In simple words: A Gamma Garden uses radiation from things like Cobalt-60 to cause changes in plants. These changes, called mutations, can create better types of crops.

🎯 Exam Tip: Explain Gamma Gardens by mentioning their purpose (crop improvement), the method (induced mutation using gamma rays), and the key radioactive sources (Cobalt-60, Caesium-137).

 

Question 4. An organism having more than two sets of chromosomes is called polyploid. It can be induced by physical events such as heat or cold treatment, X-rays and chemical agents like colchicine.
Answer: Achievements of polyploidy breeding:
• Seedless watermelons (3n) and bananas (3n) are examples of polyploids that are sterile and do not produce seeds, which is desirable for consumption.
• TV – 29 (triploid variety of tea) shows larger shoots and has tolerance to drought. This makes it a more robust and productive tea plant.
• Triticale (6n) is a hybrid of wheat and rye. It has higher dietary fibre and protein content compared to its parent grains, making it nutritionally superior.
• Rapuano brassica is an allotetraploid created through colchicine treatment. Colchicine interferes with cell division, leading to an increase in chromosome number.
In simple words: Polyploidy breeding has created seedless fruits like watermelons, drought-tolerant tea (TV-29), a nutritious wheat-rye hybrid called Triticale, and Rapuano brassica, all by increasing chromosome sets.

🎯 Exam Tip: For achievements, provide specific examples of polyploid crops and clearly state the improved traits (e.g., seedless, drought tolerance, nutritional value).

 

Question 5. Mention the two important properties of stem cells.
Answer: The two important properties of stem cells are:
1. Their ability to divide and create more stem cells through a process called self-renewal. This means they can maintain their population over a long period.
2. Their ability to develop into specialized cells with specific functions through a process called differentiation. This makes them capable of forming various tissues and organs. Stem cells have the potential to replace damaged cells in the body.
In simple words: Stem cells can make more copies of themselves (self-renewal) and can turn into different types of specialized cells (differentiation).

🎯 Exam Tip: The terms "self-renewal" and "differentiation" are key vocabulary for describing stem cell properties and should be clearly explained.

 

Question 6. Illustrate hybridization with example.
Answer: Hybridization is the process of crossing two genetically different individuals to produce offspring with combined desirable traits. A classic example is the creation of Triticale, which is the first man-made cereal hybrid. It was obtained by crossing durum wheat (\(Triticum\ durum\), \(2n = 28\)) with rye (\(Secale\ cereal\), \(2n = 14\)). The initial hybrid was sterile, but by doubling its chromosomes using colchicine treatment, a fertile hexaploid Triticale (\(2n = 42\)) was produced, combining the disease resistance of rye with the grain quality of wheat.

This process demonstrates how hybridization and chromosome doubling can create entirely new, fertile species with desired traits from both parents, such as the hardy Triticale.
In simple words: Hybridization mixes traits from two different plants. For example, Triticale was made by crossing wheat and rye, and then doubling its chromosomes to make it fertile, giving it good traits from both parents.

🎯 Exam Tip: Use the Triticale example to clearly illustrate the steps: cross-breeding, initial hybrid (often sterile), and chromosome doubling for fertility and stability.

 

VIII. Long Answer Questions:

 

Question 1. Explain the following methods of plant breeding for crop improvement.
(a) Introduction of new varieties in plants:
(b) Selection:
(i) Mass selection:
(ii) Pure line selection:
(iii) Clonal selection:

Answer:
(a) Introduction of new varieties in plants: This method involves bringing in high-yielding plant varieties from one geographical area and introducing them to another. These imported plants are known as exotic species. Before these new varieties can be widely grown, they must be thoroughly checked for any pathogens or pests they might carry to prevent the spread of diseases. For example, Phaseolus mungo (a type of bean) was successfully introduced from China, bringing new genetic traits to local agriculture.
(b) Selection: Selection is a fundamental plant breeding technique where individual plants or groups of plants are chosen from a mixed population based on their desirable physical characteristics. The goal is to isolate and multiply plants that exhibit superior traits. There are several methods of selection:
(i) Mass selection: In this method, seeds are collected from a large number of plants that show desired characteristics within a mixed population. These collected seeds are then sown to grow the next generation. This process is repeated for seven to eight generations. Over time, the population becomes more uniform for the chosen traits. Finally, the improved seeds are multiplied and distributed to farmers. Common examples of groundnut varieties developed by mass selection include TMV-2 and AK-10. This method relies on the observable traits of plants in a field.
(ii) Pure line selection: A pureline is defined as the offspring of a single self-pollinated individual. This method is also known as individual plant selection. Here, a large number of plants from a self-pollinated crop are selected individually, and their seeds are harvested separately. The progeny of each selected plant forms a pure line. Plants within a pure line are genetically identical (genotypically) and also look the same (phenotypically). This method aims to achieve genetic uniformity.
(iii) Clonal selection: Clonal selection involves selecting a group of plants that are produced from a single parent plant through vegetative or asexual reproduction. These groups of plants are called clones. All plants within a clone are genetically identical (genotype) and appear the same (phenotype). This method is particularly useful for vegetatively propagated crops where desirable clones are chosen from a mixed population and then multiplied. This ensures that beneficial traits are maintained without genetic variation from sexual reproduction.
In simple words: Plant breeding improves crops in a few ways. (a) New varieties are brought from other places after checking for diseases. (b) Selection involves picking plants with good traits. (i) Mass selection picks many good plants from a mixed group. (ii) Pure line selection picks plants from one self-pollinated parent to get exact copies. (iii) Clonal selection picks good plants that grow without seeds, making many identical copies.

🎯 Exam Tip: For each method, clearly state its definition, the process involved, and provide a relevant example or application to illustrate your explanation.

 

Question 2. In what way transgenic organisms are better?
Answer: Transgenic organisms are those plants or animals that express a modified gene (either their own altered gene or a gene from another species). These organisms are better in several ways:
Transgenic plants are generally more stable and offer improved nutritional quality. They can be engineered to be resistant to diseases and tolerant to various environmental stresses like drought or salinity. For example, some transgenic plants are designed to resist specific pests, reducing the need for chemical pesticides. Similarly, transgenic animals are used to produce valuable proteins that have medicinal importance, often at a lower cost. They can also be bred to improve livestock quality, such as faster growth rates or leaner meat. This technology helps address food security and health challenges by providing enhanced organisms.
In simple words: Transgenic organisms are better because they have changed genes. Transgenic plants can be stronger, fight diseases, and have more nutrients. Transgenic animals can make medicines or grow better for food.

🎯 Exam Tip: When discussing the advantages of transgenic organisms, categorize the benefits into plants (e.g., disease resistance, nutrition, stress tolerance) and animals (e.g., medicinal products, improved livestock traits).

 

Question 3. Describe the tools of recombinant DNA technology.
Answer: Recombinant DNA (rDNA) technology, or genetic engineering, relies on several basic requirements and tools to manipulate and transfer genes. Key tools include:
1. **Plasmids:** These are small, circular DNA molecules found in bacteria that can replicate independently alongside the main chromosomal DNA. Plasmids are crucial as vectors because they can carry foreign DNA into a host cell. Their ability to replicate autonomously allows the transferred gene to multiply within the host.
2. **Restriction Enzymes:** Also known as molecular scissors, these enzymes cut or break DNA at specific recognition sites. Different restriction enzymes recognize unique DNA sequences and make precise cuts, which can result in either "sticky ends" (overhanging single-stranded portions) or "blunt ends" (even cuts). These cuts are essential for isolating the desired gene and creating openings in the vector DNA.
3. **DNA Ligases:** These are enzymes that act like molecular glue. They help in ligating (joining) the broken DNA fragments together. After restriction enzymes cut the DNA, ligases form phosphodiester bonds to covalently link the desired gene into the vector DNA, creating a recombinant DNA molecule. This joining process is critical for inserting the target gene into the vector. The combination of these tools allows scientists to precisely cut, paste, and replicate DNA fragments, forming the backbone of modern genetic engineering.
In simple words: Recombinant DNA technology uses special tools. Plasmids are small, circular DNA in bacteria that carry new genes. Restriction enzymes are like tiny scissors that cut DNA at exact spots. DNA ligases are like glue that stick the cut DNA pieces back together.

🎯 Exam Tip: For each tool, clearly define its nature (e.g., plasmid is DNA, restriction enzyme is an enzyme) and its specific function in the rDNA technology process.

 

Question 4. Give the Schematic representation of Mass selection.
Answer: Mass selection is a process where seeds from the best plants with desired characteristics are collected from a mixed group. These collected seeds are then used to grow the next generation of plants. This process is repeated for seven or eight generations to improve the crop. Finally, the improved seeds are distributed to farmers for cultivation. For example, groundnut varieties like TMV-2 and AK-10 were developed this way. This method visually represents the steps of choosing the best plants from a mixed group and breeding them over generations to get improved varieties.
In simple words: Farmers pick seeds from the strongest plants in a mixed group. They grow these seeds again and again for many generations. This helps them get better plants that yield more and are shared with other farmers.

🎯 Exam Tip: When asked for a schematic representation, it is important to clearly describe the sequential steps involved in the process, even if a visual diagram is not directly drawn.

 

Question 1. Although 'green revolution' increases the food production, it is not enough to feed growing population. This probelm is overcomed by 'X' crops.
(a) What is 'X'?
(b) Explain it with examples.
Answer:
(a) 'X' stands for Genetically Modified (GM) crops.
(b) Genetic modification means changing the genes of an organism in a lab using special techniques (rDNA techniques). This helps to create plants with desired new traits. For example, GM crops can be made resistant to pests, tolerate salty soil, or have better nutrients, which helps to feed more people. Another example is golden rice, which is modified to produce beta-carotene to prevent Vitamin A deficiency.
In simple words: The "X" crops are Genetically Modified crops. These are made by changing a plant's genes to give it new, useful features, like being stronger against bugs or having more vitamins.

🎯 Exam Tip: Remember to clearly define genetic modification and provide specific examples of how GM crops help address food security challenges.

 

Question 2. What is Gamma garden?
Answer: A Gamma garden, also known as an atomic garden, is a special outdoor area used for a type of breeding called induced mutation breeding. In these gardens, radioactive sources like Cobalt-60 or Caesium-137 are used to create useful changes (mutations) in crop plants. This method was popularized after World War II for the peaceful use of atomic energy to improve crops.
In simple words: A Gamma garden is a special field where plants are exposed to radiation to make new, better types of crops by changing their genes.

🎯 Exam Tip: Highlight that Gamma gardens use radiation to induce mutations, which can lead to new, desirable traits in plants for crop improvement.