Samacheer Kalvi 10th Science Solutions Chapter 20 Breeding and Biotechnology

Samacheer Kalvi 10th Science Solutions Chapter 20 Breeding and Biotechnology

Tamilnadu Samacheer Kalvi 10th Science Solutions Chapter 20 Breeding and Biotechnology

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Samacheer Kalvi 10th Science Breeding and Biotechnology Textual Evaluation Solved

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) pure line selection
(d) hybridisation.
Answer:
(a) clonal selection

Question 2.
Pusa Komai is a disease resistant variety of:
(a) sugarcane
(b) rice
(c) cow pea
(d) maize
Answer:
(c) cow pea

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.

Question 4.
The miracle rice which saved millions of lives and celebrated its 50th birthday is:
(a) IR 8
(b) IR 24
(c) Atomita 2
(d) Ponni
Answer:
(a) IR 8

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).

Question 6.
We can cut the DNA with the help of:
(a) scissors
(b) restriction endonucleases
(c) knife
(d) RNAase
Answer:
(b) restriction endonucleases

Question 7.
rDNA is a ______.
(a) vector DNA
(b) circular DNA
(c) recombinant of vector DNA and desired DNA
(d) satellite DNA.
Answer:
(c) recombinant of vector DNA and desired DNA

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

Question 9.
Organisms with a 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:
(a) transgenic organisms

Question 10.
In hexaploid wheat (2n = 6x = 42) the haploid (n) and the basic(x) number of chromosomes are:
(a) n = 7 and x = 21
(b) n = 21 and x = 21
(c) n = 1 and x = 1
(d) n = 21 and x = 7
Answer:
(d) n = 21 and x = 7

II Fill in the blanks.

Question 1.
Economically important crop plants with superior quality are raised by ______.
Answer:
Breeding.

Question 2.
A protein rich wheat variety is ______.
Answer:
Atlas 66.

Question 3.
_______ is the chemical used for doubling the chromosomes.
Answer:
Colchicine.

Question 4.
The scientific process which produces crop plants enriched with desirable nutrients is called ______.
Answer:
Biofortification.

Question 5.
Rice normally grows well in alluvial soil, but _____ is a rice variety produced by mutation breeding that grows well in saline soil.
Answer:
Atomita – 2 rice

Question 6.
_____ technique made it possible to genetically engineer living organism.
Answer:
Recombinant DNA.

Question 7.
Restriction endonucleases cut the DNA molecule at specific positions known as ______.
Answer:
Molecular scissors.

Question 8.
Similar DNA fingerprinting is obtained for ______.
Answer:
Identical twins.

Question 9.
______ cells are undifferentiated mass of cells.
Answer:
Pleuripotent.

Question 10.
In gene cloning, the DNA of interest is integrated in a ______.
Answer:
Vector [plasmid].

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

Question 1.
Raphano brassica is a man – made tetraploid produced by colchicine treatment.
Answer:
True.

Question 2.
The process of producing an organism with more than two sets of chromosome is called mutation.
Answer:
False.
Correct statement: The process of producing an organism with more than two sets of chromosome is called polyploidy.

Question 3.
A group of plants produced from a single plant through vegetative or asexual reproduction are called a pureline.
Answer:
False.
Correct statement: A group of plants produced from a single plant through vegetative or asexual reproduction are called clones.

Question 4.
Iron fortified rice variety determines the protein quality of the cultivated plant.
Answer:
False.
Correct statement: Iron fortified rice variety determines the iron quality of the cultivated plant.

Question 5.
Golden rice is a hybrid.
Answer:
False.
Correct statement: Golden rice is a genetically modified plant.

Question 6.
Bt gene from bacteria can kill insects.
Answer:
True.

Question 7.
In vitro fertilisation means the fertilisation done inside the body.
Answer:
False.
Correct statement: In vitro fertilisation means the fertilisation done outside the body.

Question 8.
DNA fingerprinting technique was developed by Alec Jeffrey.
Answer:
True.

Question 9.
Molecular scissors refers to DNA ligases.
Answer:
False.
Correct statement: Molecular scissors refers to Restriction Enzymes.

IV. Match the following:

Question 1.

Column A	Column B
1. Sonalika	(a) Phaseolus mungo
2. IR-8	(b) Sugarcane
3. Saccharum	(c) Semi-dwarf wheat
4. Mung No. 1	(d) Groundnut
5. TMV-2	(e) Semi-dwarf Rice
6. Insulin	(f) Bacillus thuringienesis
7. Bt toxin	(g) Beta carotene
8. Golden rice	(h) the first hormone produced using rDNA technique

Answer:

1. (c) Semi – dwarf wheat
2. (e) Semi – dwarf Rice
3. (b) Sugarcane
4. (a) Phaseolus mungo
5. (d) Groundnut
6. (h) the first hormone produced using rDNA technique
7. (f) Bacillus thuringienesis
8. (g) Beta carotene.

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

(a) The assertion is correct and the reason is wrong.
(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason are correct.
(d) Both assertion and reason are wrong.

Question 1.
Assertion: Hybrid is superior to either of its parents.
Reason: Hybrid vigour is lost upon inbreeding.
Answer:
(a) The assertion is correct and the reason is wrong.

Question 2.
Assertion: Colchicine reduces the chromosome number.
Reason: It promotes the movement of sister chromatids to the opposite poles.
Answer:
(d) Both assertion and reason are wrong.

Question 3.
Assertion: rDNA is superior over hybridisation techniques.
Reason: Desired genes are inserted without introducing the undesirable genes in target organisms.
Answer:
(c) Both assertion and reason are correct.

VI. Answer in a Sentence

Question 1.
Give the name of the wheat variety having higher dietary fibre and protein.
Answer:
Atlas 66, a protein-rich variety, having higher dietary fibre and protein.

Question 2.
Semi-dwarf varieties were introduced in rice. This was made possible by the presence of dwarfing gene in rice. Name this dwarfing gene.
Answer:
Dee-geo-woo-gen a dwarf variety from China.

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 recombinant DNA (rDNA). Genetic engineering is also called recombinant DNA technology.

Question 4.
Name the types of stem cells.
Answer:
Embryonic stem cells and somatic stem cells are the types of stem cells.

Question 5.
What are transgenic organisms?
Answer:
Plants or animals expressing a modified endogenous gene or a foreign gene are called transgenic organisms.

Question 6.
State the importance of biofertiliser.
Answer:
Biofertilizer adds nutrients through the natural process of nitrogen fixation, stimulate the plant growth through the synthesis of growth-promoting substance.

VII. Short Answer Questions

Question 1.
Discuss the method of breeding for disease resistance.
Answer:
Plant diseases are caused by pathogens like viruses, bacteria and fungi. This affects crop yield. To develop disease-resistant varieties of crops, that would increase the yield and reduce the use of fungicides and bactericides are important. Some disease-resistant varieties are as follows:

Crop	Variety	Resistance to diseases
Wheat	Himgiri	Leaf and stripe rust, hill bunt
Cauliflower	Pusa Shubhra, Pusa Snowball K-1	Black rot
Cowpea	Pusa Komal	Bacterial blight

Question 2.
Name three improved characteristics of wheat that helped India to achieve high productivity.
Answer:
Sonalika, kalyan and sona are the three improved characteristic of wheat that helped India to achieve high productivity.

Question 3.
Name two maize hybrids rich in amino acid lysine.
Answer:
Protina, Shakti and Rathna are lysine – rich maize hybrids, which are developed in India.

Question 4.
Distinguish between
(a) Somatic gene therapy and germline gene therapy.
(b) Undifferentiated cells and differentiated cells.
Answer:
(a) Somatic gene therapy and germline gene therapy.

Somatic gene therapy	Germline gene therapy
Somatic gene therapy is the replacement of the defective gene in somatic cells.	Germline gene therapy is the replacement of the defective gene in the germ cell (egg and sperm).

(b) Undifferentiated cells and differentiated cells.

Undifferentiated cells	Differentiated cells
Our body is composed of over 200 specialised cell types, that can carry out specific functions, eg. Neurons or nerve cells that can transmit signals. Pancreatic cells to secrete insulin. These specialised cells are called as differentiated cells.	The cells which are variable potency, undifferentiated or unspecialised mass of cells are called stem cells. The stem cells are undifferentiated or unspecialised mass of cells.

Question 5.
State the applications of DNA fingerprinting technique.
Answer:
Applications of DNA Fingerprinting:
(i) DNA fingerprinting technique is widely used in forensic applications like crime investigation such as identifying the culprit. It is also used for paternity testing in case of disputes.
(ii) It also helps in the study of genetic diversity of population, evolution and speciation.

Question 6.
How are stem cells useful in the regenerative process?
Answer:
Sometimes cells, tissues and organs in the body may be permanently damaged or lost due to genetic condition or disease or injury. In such situations, stem cells are used for the treatment of diseases, which is called stem – cell therapy. In treating neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease neuronal stem cells can be used to replace the damaged or lost neurons.

Question 7.
Differentiate between outbreeding and inbreeding.
Answer:
Inbreeding:
When breeding or mating takes place between animals of the same breed, for about 4 – 6 generations, then it is called inbreeding. Superior males and superior females of the same breed are identified and mated in pairs. It helps in the accumulation of superior genes and the elimination of undesirable genes. Inbreeding depression is the continued inbreeding, which reduces fertility and productivity. Inbreeding exposes harmful recessive genes that are eliminated by selection.

Outbreeding:
The breeding of unrelated animals is outbreeding. The offsprings formed are called hybrids. The hybrids are stronger and vigorous than their parents. Cross between two different species with desirable features of economic value is mated. Mule is superior to the horse in strength, intelligence, ability to work and resistance to diseases, but they are sterile.

VIII. Long Answer Questions

Question 1.
What are the effects of hybrid vigour in animals.
Answer:

1. Increased production of milk by cattle.
2. Increased production of egg by poultry.
3. High quality of meat is produced.
4. Increased growth rate in domesticated animals.

Question 2.
Describe mutation breeding with an example.
Answer:
The mutation is defined as the sudden heritable change in the nucleotide sequence of DNA in an organism. The genetic variations brings out changes in an organism. The organism which undergoes mutation is called a mutant.
The factors which induce mutations are known as mutagens or mutagenic agents. The mutagens are of two types:
(a) Physical mutagens: Radiations like X – rays, a, P and Y – rays, UV rays and temperature, etc, which induce, maturations are called physical mutagens.

(b) Chemical mutagens: Chemical substances that induce mutations are called chemical mutagens, eg. Mustard gas and nitrous acid. The utilization of induced mutation in crop improvement is called mutation inbreeding.
Achievements of mutation breeding:

• Sharbati Sonora wheat produced from Sonora – 64 by using gamma rays.
• Atomica – 2 rice with saline tolerance and pest resistance.
• Groundnuts with thick shells.

Question 3.
Biofortification may help in removing hidden hunger. How?
Answer:
Biofortification: Biofortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals. Some examples of crop varieties developed as a result of biofortification are given below:

1. Protina, Shakti and Rathna are lysine rich maize hybrids (developed in India).
2. Atlas 66, a protein rich wheat variety.
3. Iron rich fortified rice variety’.
4. Vitamin A enriched carrots, pumpkin and spinach.

Question 4.
With a neat labelled diagram explain the techniques involved in gene cloning.
Answer:
The carbon copy or more appropriately, a clone means to make a genetically exact copy of an organism. ‘Dolly’ is the cloned sheep.

In gene cloning, a gene or a piece of DNA fragment is inserted into a bacterial cell, where DNA will be multiplied (copied) as the cell divides.
The basic steps involved in gene cloning are:

• Isolation of desired DNA fragment by using restriction enzymes.
• Insertion of the DNA fragment into a suitable vector (plasmid) to make rDNA.
• Transfer of rDNA into the bacterial host cell (Transformation).
• Selection and multiplication of the recombinant host cell to get a clone.
• Expression of the cloned gene in the host cell.

Using this strategy several enzymes, hormones and vaccines can be produced.

Question 5.
Discuss the importance of biotechnology in the field of medicine.
Answer:
Using genetic engineering techniques medicinally important valuable proteins or polypeptides that form the potential pharmaceutical products for the treatment of various diseases have been developed on a commercial scale.
Pharmaceutical products developed by rDNA technique:

1. Insulin used in the treatment of diabetes.
2. Human growth hormone used for treating children with growth deficiencies.
3. Blood clotting factors are developed to treat haemophilia.
4. Tissue plasminogen activator is used to dissolve blood clots and prevent heart attack.
5. Development of vaccines against various diseases like Hepatitis B and rabies.

IX. Higher Order Thinking Skills (HOTS) Questions

Question 1.
A breeder wishes to incorporate desirable characters into the crop plants. Prepare a list of characters he will incorporate.
Answer:
The list of character he will incorporate are:

1. High yielding and better quantity
2. Disease resistance
3. Insects pest resistance
4. Improved nutritional quality
5. Short duration

Question 2.
Organic farming is better than Green Revolution. Give reasons.
Answer:

• Dwarfness is desired in cereals, so fewer nutrients are consumed by the crops.
• Fertilizer is responsive.
• Disease resistant varieties.
• Insect and pest resistant crop varieties.
• High levels of desirable nutrients like vitamins, proteins and minerals.

Question 3.
Polyploids are characterised by gigantism. Justify your answer.
Answer:
An organism having more than two set of chromosome is called polyploidy. It can be induced by physical agents such as heat or cold treatment, X-rays and chemical agents like colchicine. As organisms produced by polyploidy have more than two set of chromosomes they are gigantic.

Question 4.
‘P’ is a gene required for the synthesis of vitamin A. It is integrated with the 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)  The P, Q and R:

• P – Beta – carotene gene.
• Q – Prevent vitamin A deficiency.
• R – Golden rice.

(ii) Importance of rice in India:

• Rice is the most important staple food for millions of people in developing countries like India.
• Beta – carotene is produced in the endosperm of the grain. It could control the chronic health problems caused by vitamin A deficiency, especially among the poor in developing countries like India.

Samacheer Kalvi 10th Science Breeding and Biotechnology Additional Questions Solved

I. Fill in the blanks.

Question 1.
Plant ______ is the art of developing economically important plants.
Answer:
Breeding.

Question 2.
Plant diseases are caused by ______ like viruses, bacteria and fungi.
Answer:
Pathogen.

Question 3.
______ is the first man – made cereal hybrid.
Answer:
Triticale.

Question 4.
The superiority of the hybrid obtained by cross-breeding is called _____ or ______.
Answer:
Heterosis
or
Hybrid vigour.

Question 5.
The other name for genetic engineering is ______.
Answer:
Recombinant DNA technology.

Question 6.
The organism which undergoes mutation is called a ______ and the factors which induce mutations are ______.
Answer:
Mutant; mutagenic agents.

Question 7.
The replacement of the defective gene in a germ cell (egg or sperm) is called ______.
Answer:
Germline gene therapy.

Question 8.
Blood clotting factors are developed to treat ______.
Answer:
Haemophilia.

Question 9.
Stem cells, which are undifferentiated or unspecialised mass of cells can be used for the treatment is called ______.
Answer:
Stem cell therapy.

Question 10.
_______ is used in the treatment of diabetes.
Answer:
Insulin.

II. Match the following:

Question 1.

1. Cowpea	(a) Joining the DNA fragments
2. UV rays	(b) New breed of sheep
3. Lady’s finger	(c) Bacterial blight
4. DNA ligase	(d) Flat bean
5. Pusasem 3	(e) Pusa Sawani
6. Hissardale	(f) Induce mutation

Answer:
1. (c) Bacterial blight
2. (f) Induce mutation
3. (e) Pusa Sawani
4. (a) Joining the DNA fragments
5. (d) Flat bean
6. (b) New breed of sheep.

III. Write “True or False” statements. Correct the false statements:

Question 1.
Modem Agricultural practices are activities carried out to improve the plants.
Answer:
True.

Question 2.
When breeding takes place between animals of the same breed, it is called outbreeding.
Answer:
False.
Correct statement: When breeding takes place between animals of the same breed, it is called inbreeding.

Question 3.
The process of introducing high yielding varieties of plants from one place to another is called a selection.
Answer:
False.
Correct statement: The process of introducing high yielding varieties of plants from one place to another is called Exotic species.

Question 4.
The mutation is a sudden inheritable change in the nucleus sequence of DNA in an organism.
Answer:
False.
Correct statement: Mutation is a sudden heritable change in the nucleotide sequence of DNA in an organism.

Question 5.
A breed is a group of animals of common origin within a species, which has certain characters, that are not found in other members of the same species.
Answer:
True.

IV. Choose the correct answer.

Question 1.
The high yielding rice variety from Indonesia and China are ______.
(a) Peta and DGWG
(b) IR-8 and Gold rice
(c) Hexaploid Triticale and Triticum durum
(d) Sonalika and Kalyan Sona.
Answer:
(a) Peta and DGWG

Question 2.
First artificially synthesized hormone is:
(a) Secretin
(b) Insulin
(c) Glucagon
(d) Renin
Answer:
(b) Insulin

Question 3.
The presence of this substance in bacteria can undergo replication independently along with chromosomal DNA ______.
(a) heritable
(b) colchicine
(c) mutation
(d) plasmid.
Answer:
(d) plasmid.

Question 4.
Bacillus thuringiensis (Bt) stains have been used for designing novel.
(a) Bio-metallogical techniques
(b) Bio-insecticidal plants
(c) Bio-mineralization
(d) Bio-fertilizer
Answer:
(b) Bio-insecticidal plants

Question 5.
A group of plants produced from a single plant through vegetative or asexual reproduction is called ______.
(a) Transgenic
(b) Hexaploid
(c) clones
(d) mutation.
Answer:
(b) Hexaploid

V. Answer the following briefly:

Question 1.
What is the green revolution? Who is the “Father of Green Revolution”?
Answer:
Green Revolution is the process of increasing food production through high yielding crop varieties and modem agricultural techniques in underdeveloped and developing nations. Dr Norman. E. Borlaug, an American agronomist is the “Father of Green Revolution”.

Question 2.
Write the role of polyploidy in crop improvement.
Answer:
The role of polyploidy in crop improvement are production of:

1. Seedless watermelons (3n) and bananas (3n).
2. TV-29 (triploid variety of tea) with larger shoots and drought tolerance.
3. Triticale (6n) is a hybrid of wheat and rye. To make this plant fertile polyploidy is induced. It has higher dietary fibre and protein.
4. Raphanobrassica is an allotetraploid by colchicine treatment.

Question 3.
What is Bio – fortification? Give any two examples.
Answer:
Bio – fortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals.
Examples of crop varieties developed as a result of bio – fortification are:

• Protina, Shakti and Rathna are lysine – rich maize hybrids.
• Atlas 66, A protein – rich wheat variety.

Question 4.
Give two examples of cross-breeding in animals.
Answer:
Cross breed of fowls: White Leghorn X Plymouth Rock
↓
Hybrid fowl – yield more eggs

Cross breed of cows : Developed by mating the bulls of exotic breeds and cows of indigenous breeds.
Brown Swiss X Sahiwal
↓
Karan Swiss – yield 2-3 times more milk than indigenous cows.

Question 5.
What is hybridization? Explain the hybridization experiment.
Answer:
The process of crossing two or more types of plants for bringing their desired characters together into one progeny hybrid is called hybridization. Hybridization is creating a genetic variation to get improved varieties.

Hybridization Experiment:
Triticale is the first man-made cereal hybrid. It is obtained by crossing wheat (Triticum durum, 2n = 28) and rye (Secale cereal, 2n = 14). The F, a hybrid is sterile (2n = 21). Then the chromosome number is doubled using colchicine and it becomes hexaploid triticale (2n = 42). The cycle of crop raising and selection continues until the plants with the desired characters are finally obtained.

Question 6.
Name the methods of plant breeding for crop improvement.
Answer:
The methods of plant breeding to develop high yielding varieties, for crop improvement, are as follows:

• Introduction of new varieties of plants
• Selection
• Polyploid breeding
• Mutation breeding
• Hybridization.

Question 7.
Explain briefly about gene therapy.
Answer:
The replacement of a defective gene by the direct transfer of functional genes into humans to treat genetic disease or disorder is referred to as gene therapy.
The recombinant DNA technology is used for gene therapy:

• Somatic gene therapy is the replacement of the defective gene in somatic cells.
• Gene line gene therapy is the replacement of the defective gene in the germ cell (egg or sperm).

Question 8.
What were the important discoveries that led to the stepping stones of recombinant DNA technology?
Answer:

1. Presence of plasmid in bacteria that can undergo replication independently along with chromosomal DNA.
2. Restriction enzymes cuts or break DNA at specific sites and are also called as molecular scissors.
3. DNA ligases are the enzymes which help in ligating (joining) the broken DNA fragments.

Question 9.
What does modern agriculture include?
Answer:
Modem agricultural practices are activities carried out to improve the cultivation of plants. It includes:

1. Preparation of soil
2. Sowing
3. Application of manures and fertilizers
4. Proper irrigation
5. Protection from weeds and pests
6. Harvesting and threshing
7. Storage

Question 10.
What is the aim of crop improvement?
Answer:
The aim of crop improvement is to develop improved crop varieties possessing higher yield, better quality, resistance to diseases and shorter duration.

Question 11.
(a) What are the two important properties of stem cells?
(b) Write a short note on two types of stem cells.
Answer:
(a) Properties of stem cells:
It’s the ability to divide and give rise to more stem cells by self-renewal.
It’s the ability to give rise to specialised cells with specific functions by the process of differentiation.

(b) Types of cells:

• Embryonic stem cells: Embryonic stem cells are derived from the inner cell mass of the blastocyst, which can be extracted from the early embryos. These cells can be developed into any cell in the body.
• Adult stem cell or somatic stem cell: These cells are found in the newborn and adults. They have the ability to divide and give rise to specific cell types. Sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.

Question 12.
What are bulk genomic DNA and satellite DNA?
Answer:
In human beings, 99 % of the DNA base sequences are the same and this is called a bulk genomic DNA. The remaining 1 % of the DNA sequence differs from one individual to another. This 1 % DNA sequence is present as a small stretch of repeated sequences, which is called satellite DNA.

VI. Answer the following in detail.

Question 1.
What are stem cells? Explain its types.
Answer:
Stem cells are undifferentiated or unspecialised mass of cells. The stem cells are the cells of variable potency. The two important properties of stem cells that differentiate them from other cells are:

1. Its ability to divide and give rise to more stem cells by self-renewal.
2. Its ability to give rise to specialised cells with specific functions by the process of differentiation.

Types of stem cells Embryonic stem cells can be extracted and cultured from the early embryos. These cells are derived from the inner cell mass of the blastocyst. These cells can be developed into air, cell in the body.

Adult stem cell or somatic stem cell are found in the neonatal (new bom) and adults. They have tne ability to divide and give rise to specific cell types. Sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.

Question 2.
Explain with examples the inbreeding and outbreeding of animal breeding.
Answer:
Animal breeding aims at the genotypes of domesticated animals to increase their yield and improve the desirable qualities to produce milk, egg and meat. When breeding takes place between animals of the same breed, it is called inbreeding.
The cross between different – breeds is called outbreeding.

1. Inbreeding:
Inbreeding refers to the mating of closely related animals within the same breed for about 4 – 6 generations. Superior males and superior females of the same breed are identified and mated in pairs. It helps in the accumulation of superior genes and elimination of genes, which are undesirable. Hissardale is a new breed of sheep developed in Punjab by crossing Bikaneri (Magra) ewes and Australian Marino rams.

2. Inbreeding depression:
Continued inbreeding reduces fertility and productivity. Inbreeding exposes harmful recessive genes that are eliminated by selection.

3. Outbreeding:
It is the breeding of unrelated animals. The offsprings formed are called hybrids. The hybrids are stronger and vigorous than their parents. Cross between two different species with desirable features of economic value are mated. Let’s see what cross produce a mule. Mule is superior to a horse in strength, intelligence, ability to work and resistance to diseases but they are sterile

Question 3.
Explain the DNA fingerprinting technology with an illustration.
Answer:
The DNA pattern of two individuals cannot be the same except for identical twins. Each persons DNA sequence is unique, due to the small difference in the base pairs. DNA fingerprinting is the easier and quicker method, to compare the genetic difference among the two individuals. This technique was developed by Alec Jeffrey.

Each individual’s unique DNA sequences provides distinct characteristics of an individual, which helps in identification. A variable number of tandem repeat sequences [VNTRs] serve as molecular markers for identification.

In human beings, 99 % of DNA base sequences are the same and this is called as bulk genomic DNA. The remaining 1 % DNA sequence differs from one individual to another. This 1 % DNA sequence is present as a small stretch of repeated sequences which is called as satellite DNA. The number of copies of the repeat sequence also called VNTRs differs from one individual to another and results in variation in the size of the DNA segment.

As shown in the illustration, the sequence AGCT is repeated six times in the first person, five times in the second person and seven times in the third person. Because of this, the DNA segment of the third person will be larger in size followed by a DNA segment of first – person and then the second person. Thus it is clear that satellite DNA brings about variation within the population. Variation in the DNA banding pattern reveals differences among the individuals.

Question 4.
Write a detailed account of stem cells, types of stem cells and stem cell therapy?
Answer:
Our body is composed of over 200 specialised cell types, that can carry out specific functions, eg. Neurons or nerve cell that can transmit signals or heart cells which contract to pump blood or pancreatic cells to secrete insulin. These specialised cells are called differentiated cells. These specialised cells are called as differentiated cells. In contrast to differentiated cells, stem cells are the undifferentiated or unspecialised mass of cells. The stem cells are the cells of variable potency.
The two important properties of stem cells are:

• its ability to divide and give rise to more stem cells by self-renewal,
• its ability to give rise to specialised cells with specific functions by the process of differentiation.

Types of stem cells:

1. Embryonic stem cells: These cells are extracted and cultured from the early embryos. These cells are derived from the inner cell mass of the blastocyst. These cells can be developed into any cell in the body.
2. Adult stem cell or somatic stem cell: They are found in the neonatal (newborn) and adults. They have the ability to divide and give rise to specific cell types. The sources of adult stem cells are amniotic fluid, umbilical cord and bone marrow.
3. Stem – cell therapy: Sometimes cells, tissues and organs in the body may be permanently damaged or lost due to genetic condition or disease or injury. In such situations, stem cells are used for the treatment of diseases, which is called stem cell therapy. In treating neurodegenerative disorders like Parkinson’s disease and Alzheimer’s disease neuronal stem cells can be used to replace the damaged or lost neurons.

Question 5.
(a) Explain genetically modified organisms |GMOs|.
(b) With the help of a tabular column tabulate the genetically modified plants and animals, with the objectives, gene inserted and achievement.
Answer:
(a) Genetic modification is the alteration or manipulation of genes in the organisms using rDNA techniques in order to produce the desired characteristics. The DNA fragment inserted is called transgene. Plants or animals expressing a modified endogenous gene or a foreign gene are also known as transgenic organisms.

The transgenic plants are much stable, with improved nutritional quality, resistant to diseases and tolerant to various environmental conditions. Similarly, transgenic animals are used to produce proteins of medicinal importance at low cost and improve livestock quality.

(b) Genetically modified plants and animals:
1. Genetically Modified Plants:

Objective	Gene Inserted	Achievement
Improved nutritional quality in Rice	Beta carotene gene (In humans, Beta carotene is required for the synthesis of Vitamin A)	Golden Rice (Genetically modified rice can produce beta carotene, that can prevent Vitamin A deficiency)
Increased crop production	Bt gene from bacteria Bacillus thuringiensis. (Bt gene produces a protein that is toxic to insects)	Insect resistant plants (These plants can produce the toxin protein that kills the insects which attack them)

2. Genetically Modified Animals:

Objective	Gene inserted	Achievement
The improved wool quality and production	Genes for synthesis of amino acid, cysteine	Transgenic sheep (gene expressed)
Increased growth in fishes	Salmon or Rainbow trout or Tilapia growth hormone gene	Transgenic fish (gene expressed)

VII. Higher Order Thinking Skills (HOTS) Questions

Question 1.
Name the Indian scientist who is known for his leading role in India’s green revolution.
Answer:
Dr M. S. Swaminathan.

Question 2.
The application of biotechnology ‘A’ to treat a person born with a hereditary disease.
(a) What does ‘A’ mean?
(b) Mention its types.
Answer:
(a) Gene therapy refers to the replacement of defective gene.
(b) The two type of gene therapy are Somatic and Germline.

Question 3.
Write the crossbreeds of the following:
(a) Crossbreed of fowls
(b) Crossbreed of cows
Answer:
(a) A crossbreed of fowls:

• White Leghorn × Plymouth Rock
  ↓
  Hybrid fowl – yield more eggs

(b) A crossbreed of cows:

• Brown Swiss × Sahiwal
  ↓
  Karan Swiss [yield 2 – 3 times more milk than indigenous cows]

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