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cycle and this leads to development of tumours., tumour r, A Cancer. Growth and division of normal cells are regulated by control mechanisms. These control mechanisms, ault in fixed life span for cells and for the organisms. One such control mechanism is contact inhibition. As a, Tedr of multiplication, the cells become crowded and come in contact with one another. This surface contact, hecks movement and division of cells. Therefore, the genes which control these processes are turned off., Vertebrate cells grown in a culture adhere to the bottom as they need a support, divide, and keep' in contact with, e another and spread as a monolayer. Cell to cell contact inhibits their growth., Cancer is a disease of cells wherein the control mechanism that normally restrict cell proliferation does not, nerate. In other words, in the case of cancer cells, the mechanism of contact inhibition does not function. The, ells continue to divide, forming a tissue mass called tumour. The cancer cells may invade other tissues and, cause tumours in them also,, Cancer is caused, not only by viruses, but also by other mutagens such as radiation and chemicals. All these, factors are called carcinogens. They alter (activate) the protooncogenes. Altered protooncogenes are called, oncogenes. Alteration may involve breaking into fragments, amplification or shifting to a new chromosomal, location. Intact genes control normal growth and development of cells. Alteration in genes leads to the formation, of abnormal proteins, change in gene environment, suspension of the mechanism that controls cell division,, which cause uncontrolled cell division and growth, and this is cancer., The cancer cells show three main characteristics -, (0 They have lost normal control mechanisms for division and growth., (i) Therefore, they undergo indefinite division and growth, forming tumours (cancer)., (üi) They may break off from the tumour tissue and invade normal tissues away from the original site, and cause, transformation in the new tissues. This is known as metastasis., PRACTICE QUESTIONS, L., Multiple Choice Questions, (a) Reverse transcriptase, 1. The two polynucleotide chains in DNA are, (a) Discontinuous, (b) Antiparallel, (b) DNA polymerase, (c) RNA polymerase, (DPMT 2007), (d) Ligase, 4. tRNA consisting of three unpaired bases, constitute, (c) Semiconservative, (d) Parallel, (AIPMT 2007), 2. During transcription, RNA polymerase, holoenzyme binds to a gene promoter and, assumes a saddle-like structure. What is its, DNA- binding sequence, (а) Codon, (b) Anticodon, (c) Clover-leaf model (d) Acceptor loop, (Odisha JEE 2007), (b) CACC, (d) TTAA, (a) AATT, 5. The codon AUG is, (c) TATA, (a) Ochre, (b) Amber, (AIPMT 2007), (c) Initiation codon, (d) Termination codon, 3. Central dogma of genetic information is, modified by the discovery of, (Jammu and Kashmir PMT 2007), ANSWERS, 2. (c), 3. (а), 4. (b), 5. (c), 1. (b)
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Pradeep's ATEXT BOOK OF BIOLOGY (XI), I1/196, 13. Which one of the following pairs of codons te, 6. During the replication of DNA, the synthesis of, DNA as lagging strand takes place in segments,, ad these segments are called, (a) Double helix segments, (b) Satellite segments (c) Kornberg segments, (d) Okazaki segments, correctly matched with their function or th, signal for the particular amino acid ?, (a) AUG, ACG-Start/methionine, (b) UUA, UCA Leucine, (c) GUU, GCU - Alanine, (d) UAG, UGA - Stop, 14. The term genome denotes, (a) Haploid set of chromosomes, (b) Bivalent, (d) Diploid chromosomal set (Odisha JEE 2009, 15. The number of stop codons which do not code, for any amino acid is, (a) 1, (c) 3, (AIPMT 2008), (Jammu & Kashmir PMT 2007), 7. Meselson and Stahl experiment proved, (c) Monovalent, (a) DNA is genetic material, (b) Central dogma, (c) Transformation, (d) Semi conservative DNA replication, (b) 2, (d) 4, (AMU Medical 2009), (e) Transduction, 8. The haploid content of human DNA is, ft (a) 3.3 x 10° bp, b (c) 4-6 x 106 bp, (e) 1-65 x 10° bp, 9. The distance between the genes a, b, c, d in, mapping units are, a -d = 3-5; b-c = 1; a-b 6;, C-d 1-5; a-c = 5, Find out the sequence of arrangement of these, (Kerala PMT 2008), d(b) 3-3 x 10° Kbp, (d) 48502 bp, 16. DNA sequences that code for protein are known, as, (a) Intron, (c) Control regions, (b) Exons, (d) Intervening sequences, (Kerala PMT 2008), (WB JEE 2009), 17. During replication of DNA, Okazaki fragments, are formed in the direction of, (b) 5"→ 3', (d) 3' → 3', (a) 3' 5', (c) 5' → 5', genes, (WB JEE 2009), (a) acdb, (b) abcd, 18. MRNA directs the building of proteins through, (c) adbc, (d) acbd, a sequence of, (а) Еxons, (e) adcb, (Kerala PMT 2008), (b) Introns, 10. The basis of DNA fingerprinting is, (a) The double helix, (b) Errors in base sequence, (c) Сodons, (d) Anticodons, (DPMT 2009), 19. The antiparallel nature of DNA refers to, (a) Its charged phosphate group, (b) The formation of hydrogen bonds between bases, from opposite strands, (c) The opposite direction of the two strands, (d) The pairing of bases on one strand with bases, on the other strand., 20. What is not true for genetic code ?, (a) It is nearly universal, (b) It is degenerate, (d) A codon in MRNA is read in a non-contiguous, fashion, (c) Polymorphism in sequence, (d) DNA replication, (e) DNA coiling, 11. Which of the following be named for DNA, produced from RNA ?, (Kerala PMT 2008), (a) A-DNA, (DPMT 2009), (b) B-DNA, (to (c) C-DNA, (d) Z-DNA, (WB JEE 2008), 12. In the DNA molecule, (c) It is unambiguous, (a) The proportion of adenine in relation to thymine, varies with the organism, (AIPMT 2009), 21. Removal of introns and joining the exons in a, defined order in a transcription unit is called, (a) Tailing, (c) Capping, (te (b) There are two strands which run antiparallel-, one in 5' 3' direction and other in 3'- 5', (c) The total amount of purine nucleotides and, pyrimidine nucleotide is not always equal, (d) There are two strands which run parallel in the, 5 3' direction., (b) Transformation, (d) Splicing, (AIPMT 2009), 22. Whose experiments cracked the DNA and, discovered unequivocally that a genetic code B, a 'triplet' ?, (AIPMT 2008), ANSWERS, 7. (d), 6. (d), 16. (b), 8. (a), 9. (e), 10. (c), 11. (c), 20. (d) 21. (d), 17. (b), 18. (c), 12. (b), 13. (d), 14. (a), 15. (c), 19. (c)
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MOLECULAR BASIS OF INHERITANCE, 23. The human chromosomes with the highest and, that interact with RNA polymerase and affect, (statements is correct about regulatory protein ?, 22. (b) 23. (c) 24. (d) 25. (b) 26. (b), 29. Regulatory proteins are the accessory proteins, I1/197, (a) Hershey and Chase, (b) Nirenberg and Mathaei, (c) Morgan and Sturtevant, (d) Beadle and Tatum, (c) They interact with RNA polymerase but do not, affect the expression, (d) They can act both as activators and as repressors, (AIPMT 2009), (NCERT Exemplar), 30. Which was the last human chromosome to be, completely sequenced :, (a) Chromosome 1, (c) Chromosome 21, least number of genes in them are respectively :, (a) Chromosome 21 and Y, (b) Chromosome 1 and X, (c) Chromosome 1 and Y, GD Chromosome X and Y (NCERT Exemplar), 24. Who amongst the following scientists had no, contribution in the development of the double, helix model for the structure of DNA ?, (a) Rosalind Franklin (b) Maurice Wilkins, (b) Chromosome 11, (d) Chromosome X, (NCERT Exemplar), 31. Which of the following are the functions of, RNA ?, (a) It is a carrier of genetic information from DNA, to ribosomes synthesising polypeptides., (b) It carries amino acids to ribosomes., (c) It is a constituent component of ribosomes., (d) All of the above., 32. While analysing the DNA of an organism a total, number of 5386 nucleotides were found out of, which the proportion of different bases were :, Adenine = 29%, Guanine = 17%, Cytosine, 32%, Thymine 17%. Considering the, Chargaffs rule it can be concluded that :, (a) it is a double stranded circular DNA, (d) Meselson and Stahl, (NCERT Exemplar), AMR (c) Erwin Chargaff, (NCERT Exemplar), 25. DNA is a polymer of nucleotides which are linked, to each other by 3'-5' phosphodiester bond. To, prevent polymerisation of nucleotides, which of, the following modifications would you choose ?, (a) Replace purine with pyrimidines, (b) Remove/Replace 3' OH group in deoxyribose, (c) Remove/Replace 2' OH group with some other, group in deoxyribose, (d) Both 'B' and 'C', 26. Discontinuous synthesis of DNA occurs in one, strand, because :, (a) DNA molecule being synthesised is very long, (0 (b) DNA dependent, (b) It is single stranded DNA, (c) It is a double stranded linear DNA, (d) No conclusion can be drawn, (NCERT Exemplar), (NCERT Exemplar), 33. In some viruses, DNA is synthesised by using, RNA as template. Such a DNA is called :, (b) B-DNA, (d) r DNA, (NCERT Exemplar), polymerase catalyses, (a) A-DNA, polymerisation only in one direction (5' 3'), (c) it is a more efficient process, (c) c DNA, 34. If Meselson and Stahl's experiment is continued, for four generations in bacteria, the ratio of 15, 15 : 15/14: 14 N/14, containing DNA in the, (d) DNA ligase has to have a role, (NCERT Exemplar), 27. Which of the following steps in transcription is, catalysed by RNA polymerase ?, (a) Initiation, (c) Termination, es, fourth generation would be:, (a) 1:1:0, (c) 0:1:3, (b) 1:4:0, (d) 0:1:7, (b) Elongation, (d) All of the above, (NCERT Exemplar), es, (NCERT Exemplar), 20. Control of gene expression takes place at the level, of :, 35. If the sequence of nitrogen base of the coding, strand of DNA in a transcription unit is :, 5'-ATGAATG-3',, (a) DNA-replication, (c) Translation, (b) Transcription, (d) None of the above, (NCERT Exemplar), the sequence of bases in its RNA transcript, would be :, (a) 5'- AUGA AUG-3', us, 9), ro (b) 5' - UACUUAC-3', (c) 5'- CAUUCAU-3', ft al, (d) 5'- GUAAGUA-3' (NCERT Exemplar), us role in transcription. Which of the following, 36. The RNA polymerase holoenzyme transcribes :, (a) the promoter, structural gene and the terminator, region, nd, is, (a) They only increase expression, (6) They only decrease expression, ANSWERS, 28. (b), 29. (d) 30. (a), 27. (b), 31. (d) 32. (b), 34. (d) 35. (a), 33. (c)
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(c) Cysteine is coded by UGU and UGC, (d) tyrosine is coded by UAU and UAC codons, 46. In genetic fingerprinting, 'the probe' refers, (c) a radio-actively labelled single stranded DNA, b(d) a radioactively labelled single stranded RNA, 45. Which one of these statements is not corre, (a) a radioactively labelled double stranded RNA, 54. Which one of the following have dual function, (b) a radioactively labelled double stranded DNA, UGY (XI, Pradeep's A TEXT, MOLE, during protein synthesis., (a) UAA codon codes for lysine, (b) UGG codon codes for tryptophan, 1/198, (b) the promoter, (c) the structural gene and the terminator regions, (d) the structural gene only. (NCERT Exemplar), 37. If the base sequence of a codon in mRNA is 5-, AUG-3', the sequence of tRNA pairing with it, must be :, 55. A, codone, ylotaly, (K-CET 201, (b) 5'- CAU - 3', (d) 5'- GUA 3', (NCERT Exemplar), 56., (a) 5' - UAC - 3', (c) 5'- AUG -3', molecule, 38. The amino acid attaches to the tRNA at its:, (a) 5' - end, (c) Anti codon site, (b) 3' - end, (d) DHU loop, (NCERT Exemplar), dab molecule, 57., molecule, 39. To initiate translation, the mRNA first binds to :, (a) The smaller ribosomal sub-unit,, (K-CET 2010, lama molecule., 47. In a DNA molecule distance between twe, is, 58. 1, In (b) The larger ribosomal sub-unit, lo (c) The whole ribosome, V (d) No such specificity exists., (b) 0-2 nm/2 Å, (d) 0-34 nm/3-4 Å, diier, (a) 2 nm/20 Ă, (c) 3-4 nm/34 A, (NCERT Exemplar), (WB JEE 2011, 40. In E.coli, the lac operon gets switched on when :, (a) lactose is present and it binds to the repressor, (b) repressor binds to operator, (c) RNA polymerase binds to the operator, 59., 48. Purine possess nitrogen at, (a) 1, 2, 4, 6 position (b) 1, 3, 5, 7 position, (c) 1, 3, 7, 9 positions (d) 1, 2, 6 and 8th positin, 49. Which one is diaminodicarboxylic amino acid!, (a) Cystine, (d) lactose is present and it binds to RNA, polymerase, (NCERT Exemplar), (b) Lysine, (d) Aspartic acid, (WB JEE 2010, 60., 41. The one aspect which is not a salient feature of, genetic code is its being, (a) specific, (c) ambiguous, u (c) Cysteine, (b) degenerate, (d) universal20), 10., 50. Transposons are:, (a) house keeping genes, (b) jumping genes, (selg (d) stationary genes, 51. How many effective codons are there for th, synthesis of twenty amino acids ?, (a) 64, (AIPMT 2010), 61., 42. The 3' to 5' phosphodiester linkages of a, polynucleotide chain join, (a) one DNA strand with other DNA strand, (c) transporting genes, (WB JEE 2010, (b) one nucleoside with other nucleoside, (c) one nucleotide with other nucleotide, (b) 32, 62., (d) one nitrogenous base with pentose sugar., (c) 60, (d) 61, (WB JEE 2010, 52. Which of the following is structural sub-unit, DNA, (3100, (AIPMT Mains 2010), 43. The lac oparon consists of, (a) four regulatory genes only, (b) one regulatory and 3 structural genes, (c) two regulatory genes and 2 structural genes, (d) three regulatory genes and three structural genes., (a) Protein, (b) Carbohydrate, (d) Nucleotides, (WB JEE 20, (c) RNA, 53. In lac operon i gene codes for :, (a) inducer of lac operon, (b) repressor of lac operon, (c) hydrolysis of disaccharide, (d) permease, 63., (AIPMT Mains 2010), 44. DNA gyrase, the enzyme that participates in the, process of DNA replication is a type of, (a) DNA-ligase, (c) DNA-topoisomerase, (d) Reverse transcriptase, ANSWERS, (b) DNA-polymerase, (AMU 2010, It codes for methionine and acts as, codon, initia, (К-СЕТ 2010), 63., 36. (c) 37. (b) 38. (b) 39. (a), 46. (c) 47. (d), 40. (a), 50. (b), 48. (c) 49. (a), 42. (c), 51. (d) 52. (d), 41. (c), 53. (b)
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$6. Which of the following sequences will be, middle by some particular restriction enzyme., 63. Which one of the following palindromic base, xI), (b) AUC, (d) ACA, 11/199, (a) AUG, (e) ACU, t A typical nucleosome contains, () 100 bp of DNA helix, () 200 bp of DNA helix, (e) 300 bp of DNA helix, () 400 bp of DNA helix, (d) 5' GAATTC 3; CTTAAG 5 (AIPMP 2010), 64. Given below is a sample of a portion of DNA, strand giving the base sequence on the opposite, strands. What is so special shown in it ?, 5' GAATTC 3', rrect, (AMU 2010), Iliw, (C10 3' *CTTAAG, AR (a) replication completed, ones, Dns, (AMU 2010), 2010), (b) deletion mutation, produced as a result of transcription of the DNA, sequence- CGATTACAG, (a) GCUAAUGUC, (e) GCTAATGTC, rs to, (c) start codon at the 5'end, RNA, (b) CGUAAUCUG, (d) palindromic sequence of base pairs, (d) GCUAATCTG, (AIPMT 2011), 65. The unequivocal proof of DNA as the genetic, Leomaterial came from the studies on a, DNA, (AMU 2010), s7. RNA polymerase II is responsible for, transcription of, DNA, (a) bacterium, (b) fungus, (d) bacterial virus, (AIPMT Mains 2011), (c) viroid, (a) rRNA, (c) tRNA, 58. Nitrogenous bases present in DNA, (a) Adenine Guanine Cytosine, Thiamine, (b) Adenine Guanine Cytosine Uracil, (C) Adenine Thiamine Uracil, (d) Guanine and Uracil, 59. A nucleoside differs from a nucleotide in not, having, (a) sugar, (c) Nitrogen base, RNA, 2010), (b) hnRNA, (d) SNRNA (AMU 2010), 66. In history of biology, human genome project led, to the development of, (a) biotechnology, (c) bioinformatics, bases, (b) biomonitoring, (d) biosystematics, (AIPMT Mains 2011), Care(AFMC 2010), 67. Which one of the following is not a part of a, transcription unit in DNA ?, aldeaa) The inducer, 2010), (b) A terminator, (b) glucose, (d) Phosphate group, (c) A promoter, (d) The structural gene, osition, (AIPMT Prelim 2012), 68. Removal of RNA polymerase III from, nucleoplasm will affect the synthesis of:, (a) tRNA, acid ?, (DUMET 2010), 60. If the total amount of adenine and thiamine in a, double stranded DNA is 45%, the amount of, guanine in this DNA will be, (a) 22-5%, (b) hn RNA, (d) r RNA, (AIPMT Prelim 2012), TE (6), (c) m RNA, 2010), (b) 27-5%, (d) 55% (DUMET 2010), (c) 45%, 61. Okazaki is known for his contribution to the, understanding of, (a) transcription, (c) DNA replication, 69. PCR and Restriction Fragment Length, Polymorphism are the methods for:, (a) Study of enzymes (b) Genetic transformation, (c) DNA sequencing, iw a, es, 2010), (d) Genetic fingerprinting, (b) translation, (d) mutation, or the, (AIPMT Prelim 2012), 70. Ribosomal RNA is actively synthesized in, (a) Lysosomes, (c) Nucleoplasm, (DUMET 2010), 02. Restriction endonucleases are enzymes which, (a) Remove nucleotides from ends of DNA molecule, (6) make cuts at specific positions within the DNA, molecule, (b) Nucleolus, (d) Ribosomes, (AIPMT Prelim 2012), 2010), anit of, 71. Removal of introns and joining of exons in, defined order during transcription is called:, (a) Looping, (c) Slicing, a, (c) recognise a specific nucleotide sequence for, binding of DNA ligase, (a) restrict the action of enzyme DNA polymerase., (b) Inducing, (d) Splicing, (AIPMT Prelim 2012), 2010), (AIPMT 2010), 72. If one strand of DNA has the nitrogenous base, the, sequence as ATCTG, what would, complementary RNA strand sequence, (b) UAGAC, (d) ATCGU, sequences in DNA can be easily cut at about the, (a) 5' CACGTA 3'; 3' CTCAGT 5', (6) 5' CGTTCG 3' : 3' ATGGTA 5, (c) 5' GATATC 3': 3' CTACTA 5, (a) TTAGU, (c) AACTG, 2010), ction ?, itiator, (AIPMT Prelim 2012), ANSWERS, 60. (c), 70. (b), 62. (b), 72. (b), 58. (a), 59. (d), 61. (c), 54. (a) 55. (b) 56. (a), 64. (d) 65. (d), 57. (b), 67. (a), 63. (d), 68. (a) 69. (d), 71. (d), 66. (c), (a)
