CBSE Class 12 Biology Biotechnology Principles and Processes diagrams based questions

CBSE Class 12 Biology Biotechnology Principles and Processes diagrams based questions. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

Important Questions for NCERT Class 12 Biology Biotechnology: Principles and Processes

Ques. Recombinant DNA is achieved by cleaving the pro-DNAs by
(a) ligase
(b) restriction endonuclease
(c) primase
(d) exonucleases. 

Answer: B

Ques. Two bacteria found to be very useful in genetic engineering experiments are
(a) Nitrobacter and Azotobacter
(b) Rhizobium and Diplococcus
(c) Nitrosomonas and Klebsiella
(d) Escherichia and Agrobacterium. 

Answer: D

Ques. Restriction endonucleases are
(a) used for in vitro DNA synthesis
(b) used in genetic engineering
(c) synthesized by bacteria
(d) present in mammalian cells for degradation of DNA. 

Answer: B

Ques. The restriction enzymes are used in genetic engineering, because
(a) they can cut DNA at specific base sequence
(b) they are nucleases that cut DNA at variable sites
(c) they can degrade harmful proteins
(d) they can join different DNA fragments.

DIAGRAM BASED QUESTIONS IN BIOLOGY FOR CLASS XII
11. BIOTECHNOLOGY: PRINCIPLES AND PROCESSES

11.1 a) Label A and B
b) When such process/ event is required?

[Figure: Diagram titled DNA at the top showing a DNA duplex with its sequence of base pairs. An arrow labelled A points down from the duplex to two DNA fragments. The left fragment has a short single-stranded overhang, and the right fragment has a complementary overhang. An arrow labelled B links the two overhangs, which join to form one continuous DNA molecule]

Answer:
a) A is a restriction enzyme (restriction endonuclease) that cuts the DNA at specific palindromic sites, producing fragments with sticky ends. B is DNA ligase, which joins the complementary sticky ends of the two fragments.
b) This process is required in recombinant DNA technology, when a desired gene is to be cut out of one DNA and joined into a vector (plasmid) for cloning.

Teacher's Note:
a) Restriction enzymes act like molecular scissors, and ligase acts like molecular glue.
b) Sticky ends are complementary, so fragments from the same enzyme can pair up.

11.2 The diagram shows a setup for electrophoresis.
a) Why is it needed in experiments in Molecular Genetics or Biotechnology?
b) Write the principle behind working of this apparatus.

[Figure: Electrophoresis apparatus showing a power supply at the top. Wires connect it to two electrodes at each end of a gel tank. The electrode marked positive (+) is at the end where the direction of electrophoresis is shown, and the negative electrode (-) is at the other end. The gel tank is filled with buffer solution and the arrow shows the direction of movement of the samples towards the positive electrode]

Answer:
a) Electrophoresis is needed to separate DNA (or RNA and protein) fragments according to their size, so that they can be analysed, identified and compared.
b) DNA carries a negative charge because of its phosphate groups. When an electric field is applied, the DNA fragments move through the agarose gel towards the positive electrode. Smaller fragments move faster and farther than larger fragments.

Teacher's Note:
a) Fragments are separated by size, not by sequence, on the gel.
b) The movement is towards the anode (positive electrode), which is the most common exam trap.
c) The gel acts as a sieve, so the smaller the fragment, the faster it moves.

11.3 This is a diagram of a plasmid.
a) Name the RE required to cut a tetR gene.
b) What will happen if a foreign gene is inserted into the tetR locus?

[Figure: Circular map of plasmid pBR322 (4,361 bp) with an origin of replication (ori) marked. Labelled restriction sites are EcoRI, BamHI, SalI, PvuI and PstI. The region marked Ampicillin resistance (amp R) lies between PvuI and PstI, and the region marked Tetracycline resistance (tet R) lies between BamHI and SalI]

Answer:
a) BamHI is the restriction enzyme that cuts within the tetR gene.
b) The tetR gene gets inactivated (insertional inactivation). The bacterium loses resistance to tetracycline, but it remains resistant to ampicillin, so recombinants can be identified by their inability to grow on tetracycline medium.

Teacher's Note:
a) Read the map clockwise to find which sites lie inside the tetracycline resistance region.
b) Loss of one antibiotic resistance is the key clue to a successful insertion.
c) Ampicillin resistance stays intact, which is why it is used as a second marker.

11.4 a) Name the enzymes used to isolate DNA by breaking the cells of fungus, plant and bacteria.
b) How is DNA isolated in the laboratory?

[Figure: Photograph of a test tube containing a white, thread-like mass of DNA that has been spooled onto the tip of a glass rod. A hand holds the tube]

Answer:
a) Chitinase is used for fungal cells, cellulase is used for plant cells, and lysozyme is used for bacterial cells.
b) 1. The cells are broken open (lysed) using the enzymes and a detergent.
2. Proteins are removed by protease, and RNA is removed by RNase.
3. Chilled ethanol is poured in, and the DNA comes out of the solution as a white, thread-like precipitate.
4. The precipitated DNA is collected on a glass rod.

Teacher's Note:
a) Fungal cell walls are made of chitin, so chitinase is the right enzyme.
b) Plant cell walls contain cellulose, which is why cellulase is needed.
c) Cold ethanol is added slowly so that the DNA precipitates cleanly without mixing with the solution.

Ques. Match the organism with its use in biotechnology.
(A) Bacillus (i) Cloning vector thuringiensis
(B) Thermus (ii) Construction of first aquaticus rDNA molecule
(C) Agrobacterium (iii) DNA polymerase tumefaciens
(D) Salmonella (iv) Cry proteins typhimurium
Select the correct option from the following.
    (A) (B) (C) (D)
(a) (ii) (iv) (iii) (i)
(b) (iv) (iii) (i) (ii)
(c) (iii) (ii) (iv) (i)
(d) (iii) (iv) (i) (ii) 

Answer: B

Ques. DNA precipitation out of a mixture of biomolecules can be achieved by treatment with
(a) chilled chloroform
(b) isopropanol
(c) chilled ethanol
(d) methanol at room temperature. 

Answer: C

Ques. Which one of the following equipments is essentially required for growing microbes on a large scale, for industrial production of enzymes?
(a) Bioreactor (b) BOD incubator
(c) Sludge digester (d) Industrial oven

Ques. The correct order of steps in Polymerase Chain Reaction (PCR) is
(a) extension, denaturation, annealing
(b) annealing, extension, denaturation
(c) denaturation, extension, annealing
(d) denaturation, annealing, extension.

Answer: D

Ques. The process of separation and purification of expressed protein before marketing is called
(a) downstream processing
(b) bioprocessing
(c) postproduction processing
(d) upstream processing. 

Ques. Stirred-tank bioreactors have been designed for
(a) purification of product
(b) addition of preservatives to the product
(c) availability of oxygen throughout the process
(d) ensuring anaerobic conditions in the culture

Answer: C

Ques. Which of the following is not a component of downstream processing?
(a) Separation (b) Purification
(c) Preservation (d) Expression

Answer: D

Ques. The Taq polymerase enzyme is obtained from
(a) Bacillus subtilis
(b) Pseudomonas putida
(c) Thermus aquaticus
(d) Thiobacillus ferroxidans. 

Answer: C

Ques. An analysis of chromosomal DNA using the Southern hybridization technique does not use
(a) electrophoresis (b) blotting
(c) autoradiography (d) PCR. 

Answer: D

Ques. In vitro clonal propagation in plants is characterized by
(a) PCR and RAPD
(b) Northern blotting
(c) electrophoresis and HPLC
(d) microscopy. 

Ques. Which of the following is not correctly matched for the organism and its cell wall degrading enzyme?
(a) Algae – Methylase
(b) Fungi – Chitinase
(c) Bacteria – Lysozyme
(d) Plant cells – Cellulase 

Ques. During the process of isolation of DNA, chilled ethanol is added to
(a) precipitate DNA
(b) break open the cell to release DNA
(c) facilitate action of restriction enzymes
(d) remove proteins such as histones.

Ques. PCR and restriction fragment length polymorphism are the methods for
(a) study of enzymes
(b) genetic transformation
(c) DNA sequencing
(d) genetic fingerprinting. 

Answer: D

Ques. Which one is a true statement regarding DNA polymerase used in PCR?
(a) It is used to ligate introduced DNA in recipient cells.
(b) It serves as a selectable marker.
(c) It is isolated from a virus.
(d) It remains active at high temperature.

Answer: D

Ques. Stirred-tank bioreactors have been designed for
(a) addition of preservatives to the product
(b) purification of the product
(c) ensuring anaerobic conditions in the culture vessel
(d) availability of oxygen throughout the process.

Answer: D