Tamil Nadu 10th Standard Science Book Solution | Lesson 20 – Breeding And Biotechnology

Lesson 20. Breeding And Biotechnology

Breeding And Biotechnology - Book Back Answer

Lesson 20 > Breeding And Biotechnology

I. Choose the best answer

1. Which method of crop improvement can be practised by a farmer if he is inexperienced?

  1. clonal selection
  2. mass selection
  3. pureline selection
  4. hybridisation

Ans ; Mass selection

2. Pusa Komal is a disease resistant variety of __________.

  1. sugarcane
  2. rice
  3. cow pea

Ans ; Cow pea

3. Himgiri developed by hybridisation and selection for disease resistance against rust pathogens is a variety of __________.

  1. chilli
  2. maize
  3. sugarcane
  4. wheat

Ans ; Wheat

4. The miracle rice which saved millions of lives and celebrated its 50th birthday is __________.

  1. IR 8
  2. IR 24
  3. Atomita 2
  4. Ponni

Ans : (a) IR 8

5. Which of the following is used to produce products useful to humans by biotechnology techniques?

  1. enzyme from organism
  2. live organism
  3. vitamins
  4. both (a) and (b)

Ans : (d) both (a) and (b)

6. We can cut the DNA with the help of

  1. scissors
  2. restriction endonucleases
  3. knife
  4. RNAase

Ans ; Restriction endonucleases

7. rDNA is a

  1. vector DNA
  2. circular DNA
  3. recombinant of vector DNA and desired DNA
  4. satellite DNA

Ans ; Recombinant of vector DNA and desired DNA

8. DNA fingerprinting is based on the principle of identifying __________ sequences of DNA

  1. single stranded
  2. mutated
  3. polymorphic
  4. repititive

Ans ; Repititive

9. Organisms with modified endogenous gene or a foregin gene are also known as

  1. transgenic organsims
  2. genetically modified
  3. mutated
  4. both a and b

Ans ; Both a and b

10. In a hexaploid wheat ( 2n = 6 x = 42 ) the haploid (n) and the basic(x) number of chromosomes are

  1. n = 7 and x = 21
  2. n = 21 and x = 21
  3. n = 7 and x = 7
  4. n = 21 and x = 7

Ans ; n = 21 and x = 7

II. Fill in the blanks

1. Economically important crop plants with superior quality are raised by_________.

Ans ; Plant breding

2. A protein rich wheat variety is ________.

Ans ; Atlas 66

3. __________is the chemical used for doubling the chromosomes.

Ans ; Colchicine

4. The scientific process which produces crop plants enriched with desirable nutrients are called _____.

Ans ; Biofortification

5. Rice normally grows well in alluvial soil, but _________ is a rice variety produced by mutation breeding that grows well in saline soil.

Ans ; Atomita 2

6. __________ technique made it possible to genetically engineer living organism.

Ans ; Genetic Engineering

7. Restriction endonucleases cut the DNA molecule at specific positions known as __________.

Ans ; Restriction sites

8. Similar DNA fingerprinting is obtained for __________.

Ans ; Paternity testing

9. __________ cells are undifferentiated mass of cells.

Ans ; Stem

10. In gene cloning the DNA of interest is integrated in a __________.

Ans ; Vector DNA

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

1. Raphanobrassica is a tetraploid man–made genus produced by colchicine treatment. ( True )

2. The process of producing an organism with more than two sets of chromosome is called mutation. ( False )

  • The process of producing an organism with more than two sets of chromosome is called Polyploidy breeding.

3. A group of plants produced from a single plant through vegetative or asexual reproduction are called a pureline. ( False )

  • A group of plants produced from a single plant through vegetative or asexual reproduction are called Clones.

4. Iron fortified rice variety determines the protein quality of the cultivated plant. ( False )

  • Amino acid fortified rice variety determines the protein quality of the cultivated plant.

5. Golden rice is a hybrid. ( False )

  • Golden rice is a Genetically modified crop.

6. Bt gene from bacteria can kill insects. ( True )

7. In vitro fertilisation means the fertilisation done inside the body. ( False )

  • In vitro fertilisation means the fertilisation done outside the body.

8. DNA fingerprinting technique was developed by Alec Jeffrey. ( True )

9. Molecular scissors refers to DNA ligases. ( False )

  • Molecular scissors refers to Restriction Endonucleases.

IV. Match the following

1. SonalikaPhaseolus mungo
2. IR 8Sugarcane
3. SaccharumSemi-dwarf wheat
4. Mung No. 1Ground nut
5. TMV – 2Semi-dwarf Rice
6. InsulinBacillus thuringienesis
7. Bt toxinBeta carotene
8. Golden ricefirst hormone produced using rDNA technique
Ans ; 1 – C, 2 – E, 3 – B, 4 – A, 5 – D, 6 – H, 7 – F, 8 – G

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

  1. Assertion is correct and reason is wrong
  2. Reason is correct and the assertion is wrong
  3. Both assertion and reason is correct
  4. Both assertion and reason is wrong

1. Assertion : Hybrid is superior than either of its parents.
Reason : Hybrid vigour is lost upon inbreeding.

  • Ans ; (c) Both assertion and reason is correct

2. Assertion : Colchicine reduces the chromosome number.
Reason : It promotes the movement of sister chromatids to the opposite poles.

  • Ans ; (b) Reason is correct and the assertion is wrong

3. Assertion : rDNA is superior over hybridisation techniques.
Reason : Desired genes are inserted without introducing the undesriable genes in target organisms.

  • Ans ; (c) Both assertion and reason is correct

VI Answer in a sentence

1. Give the name of wheat variety having higher dietary fibre and protein.

Atlas 66 is the wheat variety having higher dietary fibre and protein.

2. Semi-dwarf varieties were introduced in rice. This was made possible by the presence of dwarfing gene in rice. Name this dwarfing gene.

Name of the dwarfing gene is sd1.

3. Define genetic engineering.

Genetic engineering is the manipulation and transfer of genes from one organism to another organisms to create a new DNA called as recombinant DNA (rDNA). Genetic engineering is also called as recombinant DNA technology.

4. Name the types of stem cells.

  • Embryonic stem cells: They can be extracted and cultured from the early embryos.
  • Adult stem cells or somatic stem cells: They are found in the neonatal (new born) and adults.

5. What are transgenic organisms?

Plants or animals expressing a modified endogenous gene or a foreign gene are known as transgenic organisms.

6. State the importance of Biofortification .

Biofortification is used to develop the crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals.

VII. Short answers questions

1. Discuss the method of breeding for disease resistance.

Plant diseases are caused by pathogens like viruses, bacteria and fungi. This affects crop yield. Hence, it is important to develop disease resistant varieties of crops, that would increase the yield and reduce the use of fungicides and bactericides.

2. Name three improved characteristics of wheat that helped India to achieve high productivity.

  • Higher yield with better quality. eg: Protein Rich Atlas 66
  • Resistance to diseases. eg: Himgiri
  • Shorter duration / Semidwarf. eg: Sonalika and Kalyan Sona

3. Name two maize hybrids rich in amino acid lysine

Lysine (Amino acid ) rich maize hybrids are;

  • Protina,
  • Shakti and
  • Rathna

4. Distinguish between

  1. Somatic gene therapy and germ line gene therapy
  2.  Undifferentiated cells and differentiated cells

i) Differences between Somatic gene therapy and Germ line gene therapy.

Somatic Gene TherapyGermline Gene Therapy
1 It is the replacement of defective gene in somatic cell.It is the replacement of defective gene in germ cell (sperm and egg).
2 Correction of genetic defects is beneficial to patient. It may not be carried to next generation.It may not be carried to next generation and will be beneficial to next generation.

ii) Differences between Undifferentiated cells and Differentiated cells.

Undifferentiated cellsDifferentiated cells
1 They are unspecialized mass of cells. So these cells could still become any kind of cell that the body needs.They become specialized cells for doing certain jobs.
2 Example: Cells in early embryos are undifferentiated. The cells are multiplying, but they haven’t started become specific types of cells.Example: These cells become a liver cell, a blood cell, or a neuron, muscle cells, skin cells, etc.

5. State the applications of DNA fingerprinting technique.

Applications of DNA Fingerprinting

  • 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.
  • It also helps in the study of genetic diversity of population, evolution and speciation.

6. How are stem cells useful in regenerative process?

  • 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.

7. Differentiate between outbreeding and inbreeding.

1. It is the breeding of unrelated animals.It refers to the mating of closely related animals with the same breed.
2. The hybrids are stronger and vigorous than their parents.It helps in the accumulation of superior genes and elimination of genes which are undesirable.
3. Cross between two different species with desirable features of economic value are mated.

Male donkey + Female Horse = Mule.

Superior males and superior females of the same breed and identified and mated in pairs.

Bikaneri (Magra) ewes + Australian Marino

rams sheep = Hissardale Sheep.

VIII. Long answers questions

1. What are the effects of hybrid vigour in animals.

The superiority of the hybrid obtained by cross breeding is called as heterosis or hybrid vigour.

Effects of hybrid vigour in animal breeding

  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

Example 1: Cross breed of fowls:

White Leghorn X Plymouth Rock

Hybrid fowl – yield more eggs

Example 2: 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.

2. Describe mutation breeding with an example.

Mutation is defined as the sudden heritable change in the nucleotide sequence of DNA in an organism. It is a process by which genetic variations are created which in turn brings about changes in the organism. The organism which undergoes mutation is called a mutant. The factors which induce mutations are known as mutagens or mutagenic agents. Mutagens are of two types namely physical mutagens and chemical mutagens.

a) Physical mutagens :

Radiations like X-rays, α, β and γ-rays, UV rays, temperature etc. which induce mutations are called physical mutagens

b) Chemical mutagens :

Chemical substances that induce mutations are called chemical mutagens.

e.g. Mustard gas and nitrous acid. The utilisation of induced mutation in crop improvement is called mutation breeding.

Achievements of mutation breeding : Some achievements of mutation breeding are

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

3. Biofortification may help in removing hidden hunger. How?
Hidden hunger (Micronutrient deficiencies) may occur when one or more vitamins and minerals important for human health are consistently inadequate in a person’s diet. Diets based mostly on staple crops, such as maize, wheat and rice, which provide large amounts of energy but relatively low amounts of essential bioavailable vitamins and minerals, frequently result in hidden hunger.

Biofortification may help in removing hidden hunger.

  1. Biofortification is the scientific process of developing crop plants enriched with high levels of desirable nutrients like vitamins, proteins and minerals.
  2. Biofortification is a complementary intervention to supplementation and fortification.
  3. Biofortified staple foods can help close the intake gap of targeted micronutrient deficiencies in most other cases and increase the daily intake of micronutrients throughout a person’s life cycle.
  4. Some examples of crop varieties developed as a result of biofortifi cation 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 fortifi ed rice variety.
    4. Vitamin A enriched carrots, pumpkin and spinach.

4. With a neat labelled diagram explain the techniques involved in gene cloning.

The carbon copy of an individual is oft en called a clone. However, more appropriately, a clone means to make a genetically exact copy of an organism.

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.

A brief outline of 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 bacterial host cell (Transformation)
  • Selection and multiplication of recombinant host cell to get a clone v. Expression of cloned gene in host cell.

5. Discuss the importance of biotechnology in the field of medicine.

Using genetic engineering techniques medicinally important valuable proteins or polypeptides that form the potential pharmaceutical products for treatment of various diseases have been developed on a commercial scale.

Pharmaceutical products developed by rDNA technique :

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

IX Higher Order Thinking Skills (HOTS)

1. A breeder wishes to incorporate desirable characters into the crop plants. Prepare a list of characters he will incorporate.

The desirable characters into the crop plants :

  1. Higher yield.
  2. Resistance to diseases.
  3. Insects/Pests Resistance.
  4. Drought resistant.
  5. Shorter duration.
  6. Frtilizer responsive.
  7. The nutritional quality with respect to its
    • Protein content and quality of protein,
    • Oil content and
    • Mineral content.

2. Organic farming is better than Green Revolution. Give reasons.

i) When we hear about organic farming we think of clean, unadulterated food, while when people hear about the green revolution labs with genetically mutated seeds and plants come to mind.

ii) The basic idea of the green revolution is to improve the yield of crops by using:

  • Chemical fertilizers,
  • Pesticides and
  • Genetically altered seeds/plants.

iii) Pesticides are not only bad for plants, but also for humans. If we spray too many pesticides on our plants they too, like the chemical fertilizers, get washed into the local water sources and can be consumed if the spraying happened close to the harvest of the crops.

iv) Because of tremendous benefits on environmental, social and health front, organic agriculture seems to be emerging as an alternative to ‘green revolution technology’.

3. Polyploids are characterised by gigantism. Justify your answer.

An organism having more than two sets of chromosomes is called polyploidy.

Quantitative changes in the mass of chromosomes and genes must have played a very important part in the development of plants towards greater variability including the size of the organisms and with it more appropriate adaptations to the demands of their environment. Mostly gigantism is usual consequence in plants. It seems as though doubling the number of chromosomes will increase the size of the organism also.

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?

  • P = Beta Carotene Gene
  • Q = Plasmid of vector
  • R = Transgenic Organism

ii. State the importance of ‘R’ in India.

The importance of ‘R’ (Transgenic Organism) in India : The transgenic plants are much stable, with improved nutritional quality, resistant to diseases and tolerant to various environment conditions.Similarly transgenic animals are used to produce proteins of medicinal importance at low cost and improve livestock quality. In India, transgenic organism provide an opportunity to increase food and feed production efficiently by generating plants with higher yields and greater nutritional benefits in reasonably short times.


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