12th Bio - Botany - Book Back Answers - Chapter 4 - English Medium Guides

 

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Tamil Nadu Board 12th Standard Bio-Botany - Chapter 4: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Chapter 4 – Bio-Botany from the Tamil Nadu State Board 12th Standard Bio-Botany textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Bio-Botany Chapter 4 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 12 students! Prepare well and aim for top scores. Thank you!

Unit 4 - Principles and Processes of Biotechnology

I. Multiple Choice Questions

1. Restriction enzymes are 
a. Not always required in genetic engineering 
b. Essential tools in genetic engineering 
c. Nucleases that cleave DNA at specific sites 
d. both b and c 
Answer Key:
d. both b and c 

2. Plasmids are 
a. circular protein molecules 
b. required by bacteria 
c. tiny bacteria 
d. confer resistance to antibiotics
Answer Key:
d. confer resistance to antibiotics

3. EcoRI cleaves DNA at 
a. AGGGTT 
b. GTATATC 
c. GAATTC 
d. TATAGC 
Answer Key:
c. GAATTC 

4. Genetic engineering is 
a. making artificial genes. 
b. hybridization of DNA of one organism to that of the others. 
c. production of alcohol by using micro organisms. 
d. making artificial limbs, diagnostic instruments such as ECG, EEG etc., 
Answer Key:
b. hybridization of DNA of one organism to that of the others. 

5. Consider the following statements: 
I. Recombinant DNA technology is popularly known as genetic engineering is a stream of biotechnology which deals with the manipulation of genetic materials by man invitro 
II. pBR322 is the first artificial cloning vector developed in 1977 by Boliver and Rodriguez from E.coli plasmid 
III. Restriction enzymes belongs to a class of enzymes called nucleases. 
Choose the correct option regarding above statements 
a. I & II 
b. I & III 
c. II & III 
d. I,II & III
Answer Key:
d. I,II & III
 
6. The process of recombinant DNA technology has the following steps 
I. amplication of the gene 
II. Insertion of recombinant DNA into the host cells 
III. Cutting of DNA at specific location using restriction enzyme . 
IV. Isolation of genetic material (DNA) Pick out the correct sequence of step for recombinant DNA technology. 
a. II, III, IV, I 
b. IV, II, III, I 
c. I, II, III, IV 
d. IV, III, I, II 
Answer Key:
d. IV, III, I, II 

7. Which one of the following palindromic base sequence in DNA can be easily cut at about the middle by some particular restriction enzymes? 
a. 5 CGTTCG 3 3 ATCGTA 5
b. 5 GATATG 3 3 CTACTA 5 
c. 5 GAATTC 3 3 CTTAAG 5 
d. 5 CACGTA 3 3 CTCAGT 5 
Answer Key:
c. 5 GAATTC 3 3 CTTAAG 5 

8. pBR 322, BR stands for 
a. Plasmid Bacterial Recombination 
b. Plasmid Bacterial Replication 
c. Plasmid Boliver and Rodriguez 
d. Plasmid Baltimore and Rodriguez 
Answer Key:
c. Plasmid Boliver and Rodriguez 

9. Match the following: 

Column A	Column B
1 Exonuclease	a. add or remove phosphate
2 Endonuclease	b. binding the DNA fragments
3 Alkaline Phosphatase	c. cut the DNA at terminus
4 Ligase	d. cut the DNA at middle

1     2     3     4 
A)     a     b     c     d 
B)     c     d     b     a 
C)     a     c     b     d 
D)     c     d     a     b
Answer Key:
D)     c     d     a     b


10. In which techniques Ethidium Bromide is used? 
a. Southern Blotting techniques 
b. Western Blotting techniques 
c. Polymerase Chain Reaction 
d. Agrose Gel Electroporosis 
Answer Key:
d. Agrose Gel Electroporosis 

11. Assertion : Agrobacterium tumifaciens is popular in genetic engineering because this bacteriumis associated with the root nodules of all cereals and pulse crops 
Reason: A gene incorporated in the bacterial chromosomal genome gets atomatically transferred to the cross with which bacterium is associated. 
a) Both assertion and reason are true. But reason is correct explanation of assertion. 
b) Both assertion and reason are true. But reason is not correct explanation of assertion. 
c) Assertion is true, but reason is false. 
d) Assertion is false, but reason is true. 
e) Both assertion and reason are false.
Answer Key:
e) Both assertion and reason are false.

12. Which one of the following is not correct statement. 
a) Ti plasmid causes the bunchy top disease 
b) Multiple cloning site is known as Polylinker 
c) Non viral method transfection of Nucleic acid in cell 
d) Polylactic acid is a kind of biodegradable and bioactive thermoplastic. 
Answer Key:
a) Ti plasmid causes the bunchy top disease 

13. An analysis of chromosomal DNA using the southern hybridisation technique does not use 
a) Electrophoresis 
b) Blotting 
c) Autoradiography 
d) Polymerase Chain Reaction 
Answer Key:
d) Polymerase Chain Reaction 

14. An antibiotic gene in a vector usually helps in the selection of 
a) Competent cells 
b) Transformed cells 
c) Recombinant cells 
d) None of the above 
Answer Key:
b) Transformed cells 

15. Some of the characteristics of Bt cotton are 
a) Long fibre and resistant to aphids 
b) Medium yield, long fibre and resistant to beetle pests 
c) high yield and production of toxic protein crystals which kill dipteran pests. 
d) High yield and resistant to ball worms
Answer Key:
d) High yield and resistant to ball worms

II. Short Answer Questions

1.How do you use the biotechnology in modern practice?

• The use of the biotechnology In modern practice are
• Fermentation for production of acids, enzymes, alcohols, antibiotics, fine chemicals, vitamins and toxins
• Biomass for bulk production of single cell protein, alcohol, and blofuel
• Enzymes as biosensors, in processing Industry
• Biofuels for production of hydrogen, alcohol, methane
• Microbial inoculants as biofertiliser, and nitrogen fixers
• Plant and animal cell culture for production of secondary metabolites, monoclonal antibodies
• Recombinant DNA technology for production of fine chemicals, enzymes, vaccines, growthhormones, antibiotics and interferon
• Process engineering-tools of biotechnology is used for effluent treatment, water recycling.

 
2. What are the materials used to grow microorganism like Spirulina?

• Spirulina can be grown easily on materials like waste water from potato processing plants, straw, molasses, animal manure and even sewage.

 
3. You are working in a biotechnology lab with a becterium namely E.coli, How will you cut the nucleotide sequence? explain it.

• Eco R1 is restriction enzymes isolated from E.coli bacterium.
• The enzyme recognise and cuts specific DNA sequence.
• Some cleave both strands of DNA through the centre resulting in blunt or flush end. These are known as symmetric cuts.
• Some enzymes cut in a way producing protruding and recessed ends known as sticky or cohesive end. Such cut are called staggered or asymmetric cuts

 
4. What are the enzymes you can used to cut terminal end and internal phospho di ester band of nucleotide sequence?

• Exonucleases: It remove nucleotides one at a time from the end of a DNA molecule. 
• Ex: Bal 31, Exonuclease III. 
• Endonucleases: It break the internal Phosphodiester bonds within a DNA molecule. 
• Ex: Hind ll, EcoRI, Pvul, BamHI, Taql

 
5. Name the chemicals used in gene transfer.

• Polyethylene glycol (PEG) and Dextran sulphate are the chemicals used in gene transfer.

 
6. What do you know about the word pBR332?

• pBR332 plasmid is a reconstructed plasmid.
• it is most widely used as cloning vector.
• It contains 4361 base pairs.

 

• In pBR, p for plasmid, Band R for scientist Boliver and Rodriguez.322 is the number of plasmid developed from their laboratory.
• It contains ampR and tetR two different antibiotic resistance genes.
• It is a recognition sites for several restriction enzymes (Hind III, EcoRl, BamH l, Sal l, Pvu ll, Pst l, Cla l),
• ori and antibiotic resistance genes.
• Rop codes for the proteins involved in the replication of the plasmid.

7. Mention the application of Biotechnology.

• Biotechnology is one of the most important applied interdisciplinary sciences of the 21st century.
• It is the trusted area that enables us to find the beneficial way of life.
• It has wide applications in various sectors ilke agriculture, medicine, environment and commercial industries.
• This science has an invaluable outcome like transgenic varietles of plants e.g. Bt-cotton, rice, tomato, tobacco, cauliflower, potato and banana.
• The development of transgenics as pesticide, stress and disease resistant varieties of agricultural crops is the outcome of biotechnology.
• The synthesis of human Insulin and blood protein in E.coli
• Vaccines, enzymes, antibiotics, dairy products and beverages are the products of biotech industries.
• Biochip based biological computer is one of the successes of biotechnology.
• Genetic engineering involves genetic manipulation, tissue culture involves aseptic cultivation of totipotent plant cell into plant clones under controlled atmospheric conditions.
• Single cell protein from Spirulina is utilized in food industries.
• Production of secondary metabolites, biofertilizers, biopesticides and enzymes.
• Biomass energy, biofuel, Bioremediation, phytoremediation for environmental biotechnology.

 
8. What are restriction enzyme. Mention their type with role in Biotechnology.

• A restriction enzyme is an enzyme that cleaves DNA into fragments at or near specific recognition sites. Restriction enzyme also called restriction endonuclease. Based on their mode of action restriction enzymes are classified into.
• a.Exonucleases:
• It removes nucleotides one at a time from the end of a DNA molecule. 
• Ex: Bal 31, Exonuclease III.
• b. Endonucleases:
• It breaks the internal Phosphodiester bonds within a DNA molecule. 
• Ex: Hind II, EcoRI, Pvul, BamHI, Taqi.
• Restriction endonuclease: Molecular scissors
• The restriction enzymes are called as molecular scissors.
• These act as foundation of recombinant DNA technology.
• There are three main classes of restriction endonuclease: Type l, Type ll and Type III, which differ slightly by their
• mode of action,
• Only type II enzyme is preferred for use in recombinant DNA technology.
• They recognise and cut DNA within a specific sequence typically consisting of 4-8 bp.
• The restriction enzyme Hind II always cut DNA molecules at a point of recognising a specific sequence of six base pairs.
• This sequence is known as recognition sequence,
• Today more than 900 restriction enzymes have been isolated from over 230 strains of bacteria with different recognition sequences.
• This sequence is referred to as a restriction site and is generally-palindromic which means that the sequence in both DNA strands at this site read same in 5'-3'direction and in the 3'-5' direction
• Example: MALAYALAM:
• This phrase is read the same in either of the directions.
• Some cleave both strands of DNA through the centre resulting in blunt or flush end.
• These are known as symmetric cuts.
• Some enzymes cut in a way producing protruding and recessed ends known as sticky or cohesive end.
• Such cut are called staggered or asymmetric cuts.

 
9. Is their any possibilities to transfer a suitable desirable gene to host plant without vector? Justify your answer.

• Yes. In the direct gene transfer methods, the foreign gene of interest is delivered into the host plant without the help of a vector.
• The following are some of the common methods are
• a. Chemical mediated gene transfer:
• Certain chemicals like polyethylene glycol (PEG) and dextran sulphate induce DNA uptake into plant protoplasts.
• b. Microinjection:
• The DNA is directly injected into the nucleus using fine tipped glass needle or micro pipette to transform plant celis.
• c. Electroporation Methods of Gene Transfer:
• A pulse of nigh voltage is applied to protoplasts, cells or tissues which makes transient pores in the plasma membrane through which uptake of foreign DNA occurs.
• d. Liposome mediated method of Gene Transfer:
• Liposomes the artificial phospholipid vesicles are useful in gene transfer.
• The gene or DNA is transferred from liposome into vacuole of plant cells.
• It is carried out by encapsulated DNA into the vacuole.
• Liposome and tonoplast of vacuole fusion resulted in gene transfer
• This process is called lipofection.
• e.Biolistics:
• The foreign DNA is coated onto the surface of minute gold or tungsten particles (1-3 µm) and bombarded onto the target tissue or cells using a particle gun (also called as gene gun/micro projectile gun/shotgun).
• Then the bombarded cells or tissues are cultured on selected medium to regenerate plants from the transformed cells.

 
10. How will you identify a vectors?

• Vectors are able to replicate autonomously to produce multiple copies of them along with their DNA insert in the host cell.
• It should be small in size and of low molecular weight, less than 10 kb (kilo base pair) in size, so that entry/transfer into host cell is easy.
• Vector must contain an origin of replication so that it can independently replicate within the hast.
• It should contain a suitable marker such as antibiotic resistance, to permit its detection in transformed host cell.
• Vector should have unique target sites for integration with DNA insert
• It should have the ability to Integrate with DNA insert it carries into the genome of the host cell.
• Most of the commonly used cloning vectors have more than one restriction site.
• These are Multiple Cloning Site (MCS) or polylinker
• Presence of MCS facilitates the use of restriction enzyme of choice

   

11. Compare the various types of Blotting techniques.
The compare of the various types of Blotting techniques are 

	Southern blotting	Northern blotting	Western blotting
Name	Southern name of the inventor	Northern a misnomer	Western a misnomer
Separation of	DNA	RNA	Proteins
Denaturation	Needed	Not needed	Needed
Membrance	Nitrocellulose	Amino benzyloxymethyl	Nitrocellulose
Hybridisaiton	DNA+DNA	RNA+DNA	Protein-antibody
Visualising	Autoradiogram	Autoradiogram	Dark room

 
12. Write the advantages of herbicide tolerant crops.

• The advantages of herbicide tolerant crops are
• Weed control improves higher crop yields
• Reduces spray of herbicide
• Reduces competition between crop plant and weed
• Use of low toxicity compounds which do not remain active in the soil
• The ability to conserve soil structure and microbes

 
13. Write the advantages and disadvantages of Bt cotton.

• The advantages of Bt cotton are
• Yield of catton is increased due to effective control of bollworms.
• Reduction in insecticide use in the cultivation of Bt cottor
• Potential reduction in the cost of cultivation,
• The disadvantages of Bt cotton are
• Cost of at cotton seed is high.
• Effectiveness up to 120 days after that efficiency is reduced Ineffective against sucking pests like Jassids, aphids and whitefly.
• Affects pollinating insects and thus yield.

 
14. What is bioremediation? give some examples.

• The use of microorganisms or plants to clean up environmental pollution is called bioremediation.
• It is used in wastewater, industrial waste and solid waste.
• It is applied to the removal of oil, petrochemical residues, pesticides or heavy metals from soil or ground water.
• It is a cheaper, eco-friendly and remove contaminants more effectively.
• Some examples of bioremediation technologies are:
• Phytoremediation use of plants for remediation.
• Mycoremediation use of fungi for remediation.
• Bioventing increases the oxygen or air flow to accelerate the degradation of environmental pollutants.
• Bioleaching use of microorganisms in solution to recover metal pollutants from contaminated sites.
• Bioaugmentation the addition of selected microbes to speed up degradation process,
• Composting-the solid waste is composted by the use of microbes into manure .It acts as a nutrient for plant growth.
• Rhizofiltration- the uptake of metals by rhizosphere
• microorganisms.
• Rhizostimulation - the stimulation of plant growth by the rhizosphere by providing better growth condition or reduction in toxic materials.

 
15.Write the benefits&risk of Genetically Modified Foods.

• Benefits
• High yield without pest
• 70% reduction of pesticide usage
• Reduce soil pollution problem.
• Conserve microbial population in soil

• Risk
• Affect liver, kidney function and cancer
• Hormonal imbalance and physical disorder
• Sudden hypersensitive reaction and allergies.
• Adverse effect in immune system because of bacterial protein.
• Loss of viability of seeds show in terminator seed technology of GM crops.

 

III. Long Answer Questions

12th bio botany

IV. Exercise

12thbio botany