Class 12 Biotechnology Sample Question Paper 2021 Solved

Class 12 Biotechnology Sample Paper 2021

Time: 3 Hours

Maximum Marks: 70

SECTION A

1. What is a shuttle vector? 1

Ans: Vectors used in eukaryotic cells which are constructed in such a way so that they can exist both in eukaryotic cells and E. coli.

2. Name the amino acids involved in the catalytic triad that regulates charge -relay system in the enzyme Chymotrypsin?

Ans: His-57, Asp-102 and Ser-195

3. Specify one advantage of developing vectors based on M13. 1

Ans: Genes cloned can be obtained in the form of single stranded DNA. Since genome is less than 10 kb in size, RF can be purified and manipulated exactly like a plasmid.

4. On which chromosome in humans, is the genetic defect for the Huntington disease located?

Ans: Chromosome 4

5. Name the red algae from which agar is obtained. 1

Ans: Gelidium amansii

6. What is RFLP? 1

Ans: Restriction Fragment Length Polymorphism

7. What are nutraceutical proteins? 1

Ans: The proteins that have both nutritional and pharmaceutical values.

8. What is the disadvantage of using primary animal culture as compared to secondary culture?

Ans: Primary culture is time consuming and requires the use of live animals or fresh tissue. There can also be considerable variation from one preparation to another, particularly, if prepared by different people.

9. Counting genes and predicting their presence have proved to be laden with inaccuracies. Give reasons.

Ans: Due to the existence of splice variants and overlapping genes.

10. Which technique is used to confirm the detection of Sickle cell anaemia? Who developed this technique?

Ans: Peptide mapping/ Protein fingerprinting, V.M. Ingram

11. (i) (A) – Native enzyme subtilisin is easily inactivated by bleach

(R)- Site-directed mutagenesis at codon position 222 to replace methionine with alanine is found best in terms of activity and stability

(a) Both (A) and (R) are true, and (R) is the correct explanation of (A)
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A)
(c) (A) is true, but (R) is false
(d) Both (A) and (R) are false

(ii) (A)- OKT-3 is used to prevent graft rejection following kidney transplantation

(R)- OKT-3 blocks immune cells which attack foreign grafts.

(a) Both (A) and (R) are true, and (R) is the correct explanation of (A)
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A)
(c) (A) is true, but (R) is false
(d) Both (A) and (R) are false

12. Composition of minerals like calcium and phosphorus in mg/ml is highest in

(a) Cow milk
(b) Buffalo milk
(c) Human milk
(d) Goat milk

13. RefSeq is a curated database of:

(a) mRNA and proteins
(b) DNA and proteins
(c) DNA and mRNA
(d) DNA and tRNA

14. During isolation of streptomycin, clear broth is-

(a) discarded
(b) subjected to liquid-liquid extraction chromatography
(c) subjected to ultrafiltration
(d) subjected to solubilization of proteins

15. Read the following and answer any four questions from 15 (i) to 15 (v)

Testing for COVID-19 using PCR

The objective of COVID-19 testing is to identify part of the coronavirus genome in the patient sample. As, there is insufficient viral RNA to detect directly in the patient sample, a process called reverse transcription polymerase chain reaction (RT-PCR) is used for amplification. Short single-stranded pieces of DNA called primers recognize unique RNA sequences within the viral genome. When a double-stranded DNA copy of the target region of the viral RNA is produced, it undergoes successive rounds of amplification during which the DNA undergoes denaturation. Two primers anneal to their target sequences, and then Taq polymerase extends a new strand. The number of copies of the target region of the viral genome doubles with each cycle. In practice, the virus is typically detected in 35 cycles of PCR, after which the number of DNA copies produced will be 235. PCR-based diagnosis is faster, safer, and more specific because it does not use live pathogens.

(i) The sequence of steps in PCR is-

(a) Denaturation, annealing, extension
(b)Annealing, denaturation, extension
(c) Extension, annealing, denaturation
(d)Denaturation, extension, annealing

(ii) A primer is-

(a) short ss piece of DNA
(b) short ds piece of DNA
(c) short ds piece of RNA
(d) Either (b) or (c)

(iii) After n cycles, the number of DNA copies produced are-

(a) n²
(b)2ⁿ
(c) nx2
(d)n÷2

(iv) Taq DNA polymerase synthesizes DNA at a temperature of around 70°C as it is-

(a) thermophilic
(b) thermostable
(c) thermoregulator
(d) thermolabile

(v) Culture-based approaches for detecting pathogens, as compared to PCR-based assays, are-

a) Faster, safer, but less specific
b) Slower but safer and more specific
c) Slower, less safe, and less specific
d) Slower, less safe, but more specific.

16. Read the following and answer any four questions from 16 (i) to 16 (v)

Tissue Culture in Rose Propagation

In January 2014, an experiment was conducted to explore the intricacies of in vitro propagation of Rosa hybrida from explants. The purpose was to determine the proper basal medium and growth regulators for these tissue culture techniques. Plant hormones play a pivotal role in the growth and differentiation of cultured cells and tissues. An acidic pH is also very important. There are several types of media, like MS, LS, B5, and Nitsch’s medium, and the choice of media is dictated by the plant species, variety, or plant part. However, the most extensively used nutrient medium is MS medium, which was developed by Murashige and Skoog in 1962. Rosa hybrida L. species are propagated around the world, using seed propagation, micropropagation, stem cuttings, budding, grafting, and even tissue culture. To increase the productivity of roses, somatic hybridization is also thought of.

(i) To enhance productivity through micropropagation, which medium is generally used.

(a) MS medium
(b) LS
(c) B5
(d) Nitsch’s medium

(ii) An optimum pH is very important in plant cell tissue culture. It is usually:

(a) 8.7
(b) 7.7
(c) 9.7
(d) 5.7

(iii) In order to enhance the productivity of rose plants, which of the following could be an effective strategy?

(a) Somatic hybridization
(b) Generation of haploids
(c) Embryo rescue
(d) Generation of triploids

(iv) Which technique is not included in vegetative propagation?

(a) Layering propagation
(b) Transgenic
(c) Budding
(d) Grafting

(v) The term explant used in the passage is …

(a) any part of the plant
(b) only shoot
(c) only root
(d) only leaf

SECTION B

17. A given protein with a molecular weight of 20,000 daltons containing 5,4,3,2, and charges is subjected to mass spectrometry. Find the sequence of protein ions detected by the mass spectrometer.

Ans: m/z= M+ nH + /n

m/z=20,005/5=4001

m/z=20,004/4= 5001

m/z=20,003/3=6668

m/z=20,002/2=10,001

m/z=20,001/1=20,001

Sequence—It detects protein ions at m/z=4001, 5001, 6668, 10001 and 20,001respectively

Thalassemic patients produce excess alpha or beta subunits of haemoglobin, leading to impaired oxygen-binding capacity by their erythrocytes. How can the subunit produced in excess be determined?

Ans: Normal and thalassemic erythrocytes were obtained and their lysates analysed. Protein fingerprinting/2-D gel electrophoresis/MALDI-TOF/SDS-PAGE can identify if the α or β chain is absent.

18 Which information can be retrieved from the following databases?

i) EMBL

ii) PDB

Ans: (i) Nucleotide Sequence

(ii) Three-dimensional structure of proteins

19 Name any two diseases showing gene polymorphism with complex inheritance.

Ans: Two diseases showing gene polymorphism with complex inheritance

• Common late-onset Alzheimer’s disease

• Migraine

(a) Which database was created to manage the redundancy in EST data?

(b) What is the role of the curator in bioinformatics?

Ans: a) Unigene

b) The curator reviews and checks newly submitted data to ensure that biological features are adequately described and the conceptual translations of any coding regions obey known rules.

20 Name any two medical conditions for which stem cells can be used. 2

Ans: Leukemia (Cancerous blood cells), Heart disease, Heart attack (cardiac tissue damage). Paralysis (spinal cord injury), Alzheimer’s, Parkinson’s, Huntington’s (dead brain cells), and Burns (damaged skin cells)

21 Differentiate between somaclones and gametoclones. Who proposed the term somaclones?

Ans: While somaclones are plant variants obtained from tissue cultures of somatic tissues, gametoclones are plant variants with gametophytic origin obtained from tissue such as pollen or egg cells.

Larkin and Scowcroft (1981) proposed the term ‘somaclones’

22 The laboratory scale design cannot be scaled up to industrial scale directly. Write any two points that need to be considered while going for industrial scale

production.

Ans: Bulk purchase of chemicals and other raw materials would bring down costs.

The labour cost decreases sharply with increase in production.

23 a) Animal cells in a culture medium were placed in a regular incubator used for growing bacterial cells. Do you expect the animal cells to grow in it?

b) What are Interferons?

Ans: a) No, animal cells need a CO2 incubator.

b) Interferons are proteins secreted by virally infected cells and interfere with viral propagation.

24 How does the metagenomics approach help to identify novel genes present in the environment? Explain the process.

Ans: The Metagenomics approach has been developed to identify and select microbial genes synthesizing novel molecules. This approach utilizes the large number of microbial genomes present in an environmental niche (eg. in soil, in water such as the ocean or in the human gut). These genomes are contributed by both the culturable and the nonculturable varieties of microbes and together constitute the metagenome.

25 Specify two advantages of animal cell culture. 2

Ans: Advantages :

Homogeneous genetic population//Controlled physico-chemical environment/ Easy to add genes (Transfection) // regulate protein levels (RNAi). Available in adequate numbers to do chemical study//Easy production of biopharmaceuticals. //No ethical clearance required. //Cost-effective screening assays.

SECTION C

26 Which functional property of whey protein is exploited in the following food systems:

(i) Eggless cakes; (ii) Soups; (iii) Coffee whiteners

Also, state their mode of action.

Ans:

Food Systems	Functional Property	Mode of Action
(i) Eggless cakes	Whipping/foaming	Forms a stable film
(ii) Soups	Viscosity	Thickening/water binding
(iii) Coffee whiteners	Emulsification	Formation and stabilisation of fat emulsions.

27 Listed below are four different single strands of DNA. Which of these would you expect to be cleaved by a restriction endonuclease? Give reason.

(a) ACTCCAGAATTCACTCCG
(b) ACTCCACTCCCGACTCCG
(c) GCCTCATTCGAAGCCTGA
(d) GAGCGGTTTATCTGAGCAG

Ans: Restriction endonuclease cleaves,

(a) ACTCCAGAATTCACTCCG

Restriction enzymes recognize palindromic sequences.

Students of Class XII visited Microbial Type Culture Collection, Chandigarh, and observed microbial cultures of Providencia stuartii, Streptomyces albus, and Haemophilus aegyptus. Name the restriction enzymes obtained from them, and also specify their restriction sites.

Ans:

28 With the help of a diagram, show the cultivation of adult stem cells from bone marrow and their differentiation into specialized cells. Name two scientists who established the field of stem cell research

Ans: Cultivation of adult stem cells from bone marrow and their differentiation into specialized cells.

Ernest McCulloch and James Till

29. Considering the impact of Biotechnology in our lives, write any three applications of plant genetic engineering.

Ans:

Production of healthy oils with altered fatty acid profiles.
Modification of starch properties for specific uses.
Favourable change of grain storage products and their chemical composition to improve the processing of bread making with wheat flour, malting of barley, and brewing of beer.
Removal of undesirable toxic compounds in certain plants.
Development of blue roses/ blue coloured cotton, which is otherwise not possible by conventional plant breeding because of the absence of blue pigment in roses/ cotton
Development of tearless onions, caffeine-free coffee, and low-nicotine tobacco. (Any three)

30 What kinds of analysis can be undertaken using various bioinformatics tools? State any three.

Ans: Processing raw information:

The experimentally determined sequence (raw information) is processed using bioinformatics tools into genes, the proteins encoded, and their function, the regulatory sequences, and inferring phylogenetic relationships.
Genes: Gene prediction can be done by using computer programs like GeneMark for bacterial genomes and GENSCAN for eukaryotes.
Proteins: Protein sequences can be inferred from the predicted genes by using simple computer programs.
Regulatory sequences: Regulatory sequences can also be identified and analysed by using bioinformatics tools.
Inferring phylogenetic relationships: Information regarding the relationships between organisms can be obtained by aligning multiple sequences, calculating evolutionary distance, and constructing phylogenetic trees.
Making a Discovery: Using the bioinformatics tools and databases, the functions of unknown genes can be predicted. (Any three )

SECTION D

31 What are BCAA? Name any two BCAA. State any two functions of BCAA. Also, explain Biological Value.

Ans: BCAA are branched-chain amino acids.

BCAA: ile, leu,val, lys, trp (Any two)

They-

• are essential for the biosynthesis of muscle protein
• help in increasing the bioavailability of highly complex carbohydrates
• Reduce muscle breakdown and act as an energy source before and after exercise. Hence, while maintaining exercise performance and delaying exhaustion, BCAAs are very important for muscle growth. (Any 2 points)

Biological value- It measures the amount of protein nitrogen that is retained by the body from a given amount of protein nitrogen that has been consumed.

Explain any five protein-based products.

Ans:

(i) Blood products and vaccines, e.g., Factor IX for treating hemophilia
(ii) Therapeutic antibodies and enzymes, e.g., Monoclonal antibodies OKT3 for preventing graftness.
(iii) Therapeutic hormones and growth factors, e.g., Insulin to treat diabetes.
(iv) Regulatory factors, e.g., Interferons for antiviral properties.
(v) Analytical applications, e.g,. Horse radish peroxidase for ELISA.
(vi) Industrial enzymes, e.g., Papain for meat tenderization.
(vii) Functional non-catalytic protein,s e.g., Kappa casein for milk protein stabilization.
(viii) Nutraceutical proteins eg, Infant food formulation to provide adequate nutrition for infants.
These products are of commercial value to the Biotechnology industry. (Any 5)

32 Explain the method for the selection of recombinants that makes use of insertional inactivation, with the help of suitable diagram.

Ans: Principle of Insertional Inactivation- When cloned DNA is inserted into a gene, it inactivates its functioning. Sequence/ insert cloned into vectors within genes of antibiotic resistance, leading to loss of function.

Steps

1. Host cells (E. coli cells) with recombinant pBR322 plasmid are first plated on solid media (agarose containing) with the antibiotic ampicillin (assume that the insert has been ligated within the tetracycline resistance gene). Colonies from every single cell plate having the plasmid will develop overnight
2. A Petri plate containing solid media with the antibiotic tetracycline is kept carefully under aseptic conditions(Laminar flow hood)
3. A circular piece of velvet or velvet paper is aligned and pressed onto the colony containing ampicillin plate (master plate). With the same alignment, it is pressed onto the tetracycline plate. Overnight, only colonies not containing the insert will grow, while due to insertional inactivation, no colonies will grow that have the insert. The colonies that have the insert can easily be scored off by comparing the two plates.

Explain various steps involved in a recombinant DNA technology experiment. Name any two molecular biologists who helped to create the first r-DNA molecule.

Ans: Steps involved:

1. Isolation of a DNA fragment containing a gene of interest that needs to be cloned (called as insert).
2. Generation of a recombinant DNA (rDNA) molecule by insertion of the DNA fragment into a carrier DNA molecule called a vector (e.g., plasmid) that can self-replicate within a host cell.
3. Transfer of the rDNA into an E. coli host cell (process called transformation).
4. Selection of only those host cells carrying the rDNA and allowing them to multiply, thereby multiplying the rDNA molecules. Paul Berg, Herbert Boyer, Annie Chang, and Stanley Cohen. (Any two)

33 Write the steps involved in microbial strain isolation. How can the presence of a particular strain be confirmed?

Ans:

a) The sample containing the microbes (e.g., soil) is put in a nutritive medium and allowed to grow in shake cultures. The growth conditions (e.g., temperature, nutrients) in the medium are provided, and these favour the growth of microbes of our interest.
b) Screening is done using a method where the organism will show its desired properties. For example, if we are looking for a microorganism that produces an antibiotic, we may detect it by growing the culture on an agar plate in the presence of that bacterium against which antimicrobial activity is desired. Immunological methods are also available in which the microbes producing products are detected using specific antibodies. Use of probes, which enable the detection of organisms capable of producing specific products.

Differentiate between Fed Batch and Continuous microbial culture, along with well-defined graphs for them.

Ans:

Fed Batch Culture	Continuous Microbial Culture
Nutrients added without removal of culture	Nutrients added with the removal of culture
Volume increases	Volume constant
Used for high cell density	Used for Biomass or metabolite production