NEET Bioology Previous Papers Chapterwise

21. DNA or RNA segment tagged with a radioactive molecule is called [NEET 2010]
(a) Vector (b) Probe
(c) Clone (d) Plasmid
Ans: (b) DNA or RNA segment tagged with a radioactive molecule is called Probe. They are used to detect the presence of complementary sequences in nucleic acid samples. Probes are used for identification and isolation of DNA and RNA.
22. Restriction endonucleases are enzymes which [NEET 2010]
(a) make cuts at specific positions within the DNA molecule
(b) recognize a specific nucleotide sequence for binding of DNA ligase
(c) restrict the action of the enzyme DNA polymerase
(d) remove nucleotides from the ends of the DNA molecule
Ans: (a) Restriction endonucleases are enzymes that makes cuts at specific positions within the DNA molecule. They acts as molecular scissors. They recognise specific base sequence at palindrome sites in DNA duplex and cut its strands.
23. Stirred tank bioreactors have been designed for [NEET 2010]
(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
Ans: (d) A stirred-tank bioreactor is a cylindrical or curved base to facilitate the mixing of the reaction content. It has been designed for availability of oxygen throughout the process.
24. Polyethylene glycol method is used for [NEET 2009]
(a) biodiesel production
(b) seedless fruit production
(c) energy production from sewage
(d) gene transfer without a vector
Ans: (d) Direct gene transfer is the transfer of naked DNA into plant cells but the presence of rigid plant cell wall acts as a barrier to uptake. Therefore protoplasts are the favoured target for direct gene transfer. Polyethylene glycol mediated DNA uptake is a direct gene transfer method that utilizes the interaction between polyethylene glycol, naked DNA, salts and the protoplast membrane to effect transport of the DNA into the cytoplasm.
25. Which one of the following is commonly used in transfer of foreign DNA into crop plants?
(a) Meloidogyne incognita [NEET 2009]
(b) Agrobacterium tumefaciens
(c) Penicillium expansum
(d) Trichoderma harzianum
Ans: (b) Agrobacterium tumefaciens is the causal agent of crown gall disease (the formation of tumours) in over 140 species of dicot. This disease caused by a DNA plasmid (Ti plasmid) carried by bacterium and transferred to the plant cells. Ti plasmid has widely used in plant engineering as a vector in order to inject gene in host plant to form transgenic plant.
26. The linking of antibiotic resistance gene with the plasmid vector became possible with
(a) DNA ligase [NEET 2008]
(b) Endonucleases
(c) DNA polymerase
(d) Exonucleases
Ans: (a) The linking of antibiotic resistance gene with the plasmid vector became possible with DNA ligase. DNA ligase is an enzyme that is able to join together two portions of DNA and therefore plays an important role in DNA repair. DNA ligase is also used in recombinant DNA technology as it ensures that the foreign DNA is bound to the plasmid into which it is incorporated.
27. Gel electrophoresis is used for [NEET 2008]
(a) cutting of DNA into fragments
(b) separation of DNA fragments according to their size
(c) construction of recombinant DNA by joining with cloning vectors
(d) isolation of DNA molecule
Ans: (b) Gel electrophoresis is a technique to separation of DNA fragments according to their size. DNA is negatively charged so in gel tank when electricity is passed, DNA move towards positive electrode.
28. What is antisense technology? [NEET 2008]
(a) A cell displaying a foreign antigen used for synthesis of antigens
(b) Production of somaclonal variants in tissue cultures
(c) When a piece of RNA that is complementary in sequence is used to stop expression of a specific gene
(d) RNA polymerase producing DNA
Ans: (c) An RNA molecule whose base sequence is complementary to that of the RNA transcript of a gene, i.e. the sense RNA, such as a messenger RNA (mRNA). Hence, an antisense RNA can undergo base pairing with its complementary mRNA sequence. This blocks gene expression, either by preventing access for ribosome to translate the mRNA or by triggering degradation of the double stranded RNA by ribonuclease enzymes. Antisense RNA and DNA both have therapeutic potential for modifying the activity of disease causing genes.
29. Chromosomes in a bacterial cell can be 1 – 3 in number and [NEET 2003]
(a) can be circular as well as linear within the same cell
(b) are always circular
(c) are always linear
(d) can be either circular or linear, but never both within the same cell
Ans: (b) Prokaryotes (bacteria) have only circular chromosomes.
30. In bacteria, plasmid is [NEET 2002]
(a) extra – chromosomal material
(b) main DNA
(c) non-functional DNA
(d) repetitive gene
Ans: (a) Plasmid is attached to mesosome in bacteria.
31. Introduction of food plants developed by genetic engineering is not desirable because [NEET 2002]
(a) economy of developing countries may suffer
(b) these products are less tasty as compared to the already existing products
(c) this method is costly
(d) there is danger of entry of viruses and toxins with introduced crop
Ans: (d) Plants developed by genetic engineering are called transgenic plants or genetically modified crops from which genetically modified food is produced. For their production micro-organisms (bacteria, virus) are used. So, by consuming them there is a danger of entry of viruses and toxins causing differ types of allergies and other health hazards to human beings.
32. Two bacteria found to be very useful in genetic engineering experiments are [NEET 1998]
(a) Escherichia and Agrobacterium
(b) Nitrobacter and Azotobacter
(c) Rhizobium and Diplococcus
(d) Nitrosomonas and Klebsiella
Ans: (a) Escherichia and Agrobacterium are both used as vectors in genetic engineering. Nitrobact converts nitrites to nitrates. is a free living nitrogen fixing bacteria. Nitrosomonas converts ammonia to nitrite. Rhizobium is a symbiotic nitrogen fixing bacteria living in the root nodules of leguminous plants. Diplococcus pneumoniae causes pneumonia.
33. The plasmids pesent in the bacterial cells are [NEET 1997]
(a) circular double helical DNA molecules
(b) circular double helical RNA molecules
(c) linear double helical DNA molecules
(d) linear double helical RNA molecules.
Ans: (a) Plasmids are the extrachromosomal DNA.
34. The process of separation and purification of expressed protein before marketing is called:
(a) Downstream processing [NEET 2017]
(b) Bioprocessing
(c) Postproduction processing
(d) Upstream processing
Ans: (a) The various stages of processing that occur after the completion of fermentation or biosynthetic stage which include separation and purification of product called downstream processing.
35. In vitro clonal propagation in plants is characterized by: [NEET 2014]
(a) PCR and RAPD
(b) Northern blotting
(c) Electrophoresis and HPLC
(d) Microscopy
Ans: (a) Now a days PCR and RAPD technique are used for the characterisation of in vitro clonal propagation in plants.
36. Commonly used vectors for human genome sequencing are: [NEET 2014]
(a) T-DNA
(b) BAC and YAC
(c) Expression Vectors
(d) kT/A Cloning Vectors
Ans: (b) Human genome sequencing is a process that determines the complete DNA sequence of an organism’s genome at a single time. This requires sequencing all of an organism’s chromosomal DNA as well as DNA contained in the mitochondria and, for plants, in the chloroplast. Commonly used vectors for human genome sequencing are BAC (Bacterial artificial chromosomes) and YAC (Yeast artificial chromosomes).
37. DNA fragments generated by the restriction endonucleases in a chemical reaction can be separated by : [NEET NEET 2013]
(a) Polymerase chain reaction
(b) Electrophoresis
(c) Restriction mapping
(d) Centrifugation
Ans: (b) DNA fragments generated by restriction endonucleases in a chemical reaction can be separated by gel electrophoresis. Since DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium/matrix. The DNA fragments separate according to their size through sieving effect provided by matrix.
38. PCR and Restriction Fragment Length Polymorphism are the methods for : [NEET 2012]
(a) Study of enzymes
(b) Genetic transformation
(c) DNA sequencing
(d) Genetic Fingerprinting
Ans: (d)
39. Which one is a true statement regarding DNA polymerase used in PCR [NEET 2012]
(a) It is used to ligate introduced DNA in recipient cell
(b) It serves as a selectable marker
(c) It is isolated from a virus
(d) It remains active at high temperature
Ans: (d) The name of this DNA polymerase is Taq polymerase extracted from a thermophilic bacteria. It is a relatively thaermostable enzyme which is used in PCR during denaturation, which requires high temperature.
40. For transformation, micro-particles coated with DNA to be bombarded with gene gun are made up of : [NEET 2012]
(a) Silver or Platinum
(b) Platinum or Zinc
(c) Silicon or Platinum
(d) Gold or Tungsten
Ans: (d) For gene transfer into the host cell without using vector microparticles made of Tungsten and Gold coated with foreign DNA are bombarded into target cells at a very high velocity.