12th Class Biology Chapter 20 MCQs with Answers

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Welcome to the 12th Class Biology Chapter 20 MCQs Online Test. We are presenting you with top MCQ questions from the 12th Class Biology Chapter  Chromosome.

We want to tell you that you can find all the 12th Class Biology Chapter 20 MCQs online tests on our website. These online tests are great for learning and as well as for scoring maximum marks in your Intermediate Exams. We are making these Class 12 Biology MCQs online tests for those who want full marks in their exams. Attempt all these Grade 12 Biology Online Multiple Choice Questions MCQs before going for the exam and it will be beneficial for you! These online tests contain all the important multiple choice questions in the important topics of the FSC Part 2 Biology Chapter 20 Chromosome.

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1 12th Class Biology Chapter 20 MCQs with Answers
1.1 MCQs Class 12 Biology with Answers
1.2 What are Chromosome And DNA?
1.3 Related posts:

12th Class Biology Chapter 20 MCQs with Answers

Youth For Pakistan has provided an excellent opportunity for the students of the 12th class to prepare their Biology Chapter 20 Chromosome online with MCQs test.

This is a free platform for students to prepare for Biology Exams for Class 12 to get the best accomplishments in annual exams. 12th class Students can analyze themself by attempting this online test system as many times as they want until they find themself fully prepared.

MCQs Class 12 Biology with Answers

The purpose of these online MCQs tests is to help you evaluate your 12th Class Biology Chapter 20 MCQs. These Multiple Choice Questions (MCQs) will prepare you for your academic success in the 12th Class Exams. 12th Class Biology Chapters include Ch#15 Homeostasis, Ch#16 Support and Movement, Ch#17 Coordination and Control, Ch#18 Reproduction, Ch#19 Growth and Development, Ch#20 Chromosome and DNA, Ch#21 Cell Cycle, Ch#22 Variation and Genetics, Ch#23 Biotechnology, Ch#24 Evolution, Ch#25 Ecosystem, Ch#26 Some major Ecosystems and Ch#27 Man and his Environment. 

What are Chromosome And DNA?

Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.

12th Class Biology Chapter 20 Chromosome And DNA

1. Chromosomes were first observed by choose which one is correct:

  1. W.S. Sutton
  2. Robert Brown
  3. Walther Fleming
  4. Strasberger

2. Walther Fleming discovered chromosomes in larva of choose which one is correct:

  1. Frog
  2. Sea urchin
  3. Star fish
  4. Salamander

3. The number of chromosomes in some ferns is choose which one is correct:

  1. 32
  2. 500
  3. 400
  4. 0

4. Number of chromosomes in Sugar cane is choose which one is correct:

  1. 48
  2. 100
  3. 80
  4. 40

5. Number of chromosomes in mouse is choose which one is correct:

  1. 45
  2. 35
  3. 40
  4. 30

6. The karyotypes of a chromosomes are choose which one is correct:

  1. Size
  2. Number
  3. Position of centromere
  4. All of the above

7. The chromosome in which centromere is present near the centre of chromatids is choose which one is correct:

  1. Acrocentric
  2. Telocentric
  3. Sub metacentric
  4. Metacentric

8. The chromosome with centromere near the end of chromatids is choose which one is correct:

  1. Acrocentric
  2. Telocentric
  3. Sub metacentric
  4. Metacentric

9. The amount of DNA in chromosomes is choose which one is correct:

  1. 20%
  2. 40%
  3. 60%
  4. 80%

10. A typical chromosome contain nucleotide about choose which one is correct:

  1. 100 million
  2. 120 million
  3. 140 million
  4. 160 million

11. The bead like structure present in the chromosome is choose which one is correct:

  1. Histone
  2. Nucleosome
  3. Nucleolus
  4. None of the above

12. Number of histone protein molecules in single nucleosomes are choose which one is correct:

  1. 6
  2. 8
  3. 9
  4. 10

13. The structure formed by super coiling of DNA is choose which one is correct:

  1. Nucleosome
  2. Chromatin
  3. Chromosome
  4. All of the above

14. The highly condensed portion of chromatin is called choose which one is correct:

  1. Euchromatin
  2. Heterochromatin
  3. Both (A) and (B)
  4. None of the above

15. The part of chromosome whose genes are expressed is called choose which one is correct:

  1. Euchromatin
  2. Heterochromatin
  3. Both (A) and (B)
  4. None of the above

16. “The central role of chromosome in heredity” was suggested by choose which one is correct:

  1. Walter Sutton
  2. Walther Fleming
  3. Mendel
  • Karl Correns

17. Chromosomal theory of heredity was proposed by choose which one is correct:

  1. Walter Sutton
  2. Karl Correns
  3. Mendel
  4. Walther Fleming

18. The strong evidence in support of chromosomal theory of inheritance was given by choose which one is correct:

  1. Walter Sutton
  2. T.H Morgan
  3. Mendel
  4. Karl Correns

19. Experiments on mice were performed by choose which one is correct:

  1. Wlater Sutton
  2. Oswald Avery
  3. Fred Griffith
  4. Karl Correns

20. Transforming principle was formulated by choose which one is correct:

  1. Oswald Avery
  2. Fred Griffith
  3. Karl Correns
  4. Walter Sutton

21. The transforming activity is destroyed due to choose which one is correct:

  1. Protein
  2. DNA
  3. Carbohydrates
  4. Lipids

22. Experiments on bacteriophage were performed by choose which one is correct:

  1. Walter Sutton
  2. Hershy and Chase
  3. Fred Griffith
  4. Karl Correns

23. In the next generation of phage virus, the virus found radioactive were with choose which one is correct:

  1. S34
  2. S35
  3. P31
  4. P32

24. DNA was discovered in 1869 by choose which one is correct:

  1. Walter Sutton
  2. Rosalind Franklin
  3. F. Miescher
  4. Karl Correns

25. Basic structure of nucleic acid was determined by choose which one is correct:

  1. P.A. Levene
  2. Walther Fleming
  3. F. Miescher
  4. Watson and Crick

26. X-ray diffraction technique was used by choose which one is correct:

  1. Walter Sutton
  2. Rosalin Franklin
  3. F. Miescher
  4. Karl Correns

27. Double helical structure of DNA was proposed by choose which one is correct:

  1. P.A. Levene
  2. Walther Fleming
  3. F. Miescher
  4. Watson and Crick

28. The diameter of DNA molecule is choose which one is correct:

  1. 2 nm
  2. 3 nm
  3. 4 nm
  4. 4 nm

29. Number of hydrogen bonds formed between Guanine and Cytosine are choose which one is correct:

  1. 1
  2. 2
  3. 3
  4. 4

30. Number of hydrogen bonds formed between Adenine and Thymine are choose which one is correct:

  1. 1
  2. 2
  3. 3
  4. 4

31. The base pair stack is apart choose which one is correct:

  1. 0.24 nm
  2. 0.34 nm
  3. 0.35 nm
  4. 0.36 nm

32. The model of DNA replication in which one strand is conserved and other is synthesized is choose which one is correct:

  1. Conservative
  2. Semi-conservative
  3. Dispersive
  4. None of the above

33. In semi-conservative model the strands are separated and act as choose which one is correct:

  1. Enzyme
  2. Tool
  3. Model
  4. Finger prints

34. The model in which both strands are preserved is choose which one is correct:

  1. Conservative
  2. Semi-conservative
  3. Dispersive
  4. None of the above

35. The model in which both strands break is choose which one is correct:

  1. Dispersive
  2. Conservative
  3. Semi-conservative
  4. None of the above

36. The semi conservative model of DNA was proved by choose which one is correct:

  1. P.A. Levene
  2. Meselson – Stahl
  3. F. Miescher
  4. Watson and Crick

37. Meselson and Stahl used radioactive isotope of choose which one is correct:

  1. Carbon
  2. Phosporus
  3. Sulphur
  4. Nitrogen

38. The enzyme which attaches the fragments of DNA is choose which one is correct:

  1. DNA polymerase I
  2. Primase
  3. Ligase
  4. DNA polymerase II

39. The true replicating enzyme is choose which one is correct:

  1. DNA polymerase III
  2. Ligase
  3. Primase
  4. DNA polymerase II

40. The enzyme which plays a supporting role in DNA replication is choose which one is correct:

  • DNA polymerase I
  • Pirmase
  • Ligase
  • DNA polymerase II

41. The DNA polymerase adds how many nucleotides to the end?

  1. 2
  2. 3
  3. 4
  4. 5

42. The strand which elongate towards replication fork is choose which one is correct:

  1. Leading strand
  2. Lagging strand
  3. Both (A) and (B)
  4. None of the above

43. The length of Okazaki fragments is choose which one is correct:

  1. 100-200 nucleotide
  2. 200-300 nucleotide
  3. 300-400 nucleotide
  4. 400-500 nucleotide

44. Okazaki fragment is a choose which one is correct:

  1. RNA
  2. DNA
  3. Protein
  4. Enzyme

45. Okazaki fragments are synthesize by choose which one is correct:

  1. DNA polymerase I
  2. Pirmase
  3. Ligase
  4. DNA polymerase III

46. The disease alkaptonuria was studied by choose which one is correct:

  1. Beadle and Tatum
  2. Meselson – Stahl
  3. Garrod and Bateson
  4. Watson and Crick

47. Experiments on Neurosopora were performed by choose which one is correct:

  1. Beadle and Tatum
  2. Meselson – Stahl
  3. Garrod and Bateson
  4. Watson and Crick

48. Match homogenetisic acid with one of the followings choose which one is correct:

  1. Hemophilia
  2. Anemia
  3. Alkaptonuria
  4. Tay Sach’s disease

49. Which of the followings is absent in minimal medium?

  1. Sugar
  2. Ammonia
  3. Enzymes
  4. Vitamins

50. Minimal medium was prepared by choose which one is correct:

  1. Beadle and Tatum
  2. Meselson – Stahl
  3. Garrod and Bateson
  4. Watson and Crick

51. One gene encodes for one choose which one is correct:

  1. Enzyme
  2. Protein
  3. Polypeptide
  4. Polysaccharide

52. Sequence of amino acids in insulin molecules were determined by choose which one is correct:

  1. Vernon Ingram
  2. Sanger
  3. P.A. Levene
  4. F. Miescher

53. Sickle cell anemia was discovered by choose which one is correct:

  1. Vernon Ingram
  2. Sanger
  3. P.A. Levene
  4. F. Miescher

54. Sickle cell anemia is caused due to change of glutamic acid to choose which one is correct:

  1. Histidine
  2. Leucine
  3. Valine
  4. Proline

55. Central dogma is composed of choose which one is correct:

  1. Protein
  2. DNA
  3. mRNA
  4. All of the above

56. The synthesis of protein is called choose which one is correct:

  1. Replication
  2. Transcription
  3. Translation
  4. None of the above

57. The synthesis of RNA from DNA is choose which one is correct:

  1. Transcription
  2. Replication
  3. Translation
  4. None of the above

58. Anticodons are present on choose which one is correct:

  1. mRNA
  2. rRNA
  3. tRNA
  4. None of the above

59. Codes are present on choose which one is correct:

  1. mRNA
  2. rRNA
  3. tRNA
  4. None of the above

60. The strand which is transcribed during transcription is choose which one is correct:

  1. Leading strand
  2. Antisense strand
  3. Sense strand
  4. Lagging strand

61. Coding strand is choose which one is correct:

  1. Leading strand
  2. Antisense strand
  3. Sense strand
  4. Lagging strand

62. mRNA is synthesized by choose which one is correct:

  1. RNA Polymerase I
  2. RNA Polymerase II
  3. RNA Polymerase III
  4. None of the above

63. tRNA is synthesized by choose which one is correct:

  1. RNA Polymerase I
  2. RNA Polymerase II
  3. RNA Polymerase III
  4. None of the above

64. Transcription starts at choose which one is correct:

  1. Operator
  2. Promoter
  3. Enhancer
  4. None of the above

65. The binding site is choose which one is correct:

  1. TTGGC
  2. TTGACA
  3. TTGCAA
  4. TTGAAC

66. RNA polymerase has subunit choose which one is correct:

  1. Alpha factor
  2. Sigma factor
  3. Beta factor
  4. Gama factor

67. Which of the followings is a stop signal for transcription?

  1. CA
  2. GA
  3. GC
  4. A

68. Cap in mRNA is choose which one is correct:

  1. Poly A
  2. Poly C
  3. Methyl GTP
  4. Methyl ATP

69. Tail of mRNA is choose which one is correct:

  1. Poly A
  2. Poly C
  3. Methyl GTP
  4. Methyl ATP

70. Genetic code is combination of choose which one is correct:

  1. Two nucleotides
  2. Three nucleotides
  3. Four nucleotides
  4. All of the above

71. Total number of genetic codes is choose which one is correct:

  1. 43
  2. 60
  3. 64
  4. 68

72. Which of these initiation codes?

  1. AUU
  2. AUG
  3. UGA
  4. UCC

73. Which of the following is not termination or non-sense code?

  1. UAA
  2. UAG
  3. UCC
  4. UGA

74. Which of the following is mismatched for genetic code?

  1. Crick
  2. Watson
  3. Nirenberg
  4. Philip Leader

75. The code of arginine is choose which one is correct:

  1. CAU
  2. CCU
  3. CGU
  4. CAA

76. The genetic code for alanine is choose which one is correct:

  1. GUU
  2. GUA
  3. GUC
  4. GU

77. Genetic code for phenylalanine is choose which one is correct:

  1. CCC
  2. UUU
  3. AAA
  4. GGG

78. Genetic code for glycine is choose which one is correct:

  1. UUU
  2. GCU
  3. GCA
  4. GGG

79. The site of ribosome where peptide bond is formed is choose which one is correct:

  1. A site
  2. P site
  3. E site
  4. None of the above

80. Empty tRNA is present in choose which one is correct:

  1. A site
  2. P site
  3. E site
  4. None of the above

81. First amino acid in the synthesis of protein is choose which one is correct:

  1. Glycine
  2. Methionine
  3. Alanine
  4. Phenylalanine

82. The binding of tRNA to ribosomal unit is controlled by choose which one is correct:

  1. tRNA synthase
  2. Initiation factor
  3. Elongation factor
  4. Termination factor

83. Which of the followings helps the tRNA to attach on exposed mRNA code at A site choose which one is correct:

  1. tRNA synthase
  2. Initiation factor
  3. Elongation factor
  4. Termination factor

84. The movement of ribosome to next code is controlled by choose which one is correct:

  1. Termination factor
  2. Elongation factor
  3. Initiation factor
  4. tRNA synthase

85. The ribosome moves in a direction of mRNA choose which one is correct:

  1. 3
  2. 4
  3. 5
  4. 6

86. The termination codes are recognized by choose which one is correct:

  1. Termination factor
  2. Elongation factor
  3. Initiation factor
  4. Releasing factor

87. If the DNA of an human adult is lined up end to end, it will stretch nearly choose which one is correct:

  1. 50 billion km
  2. 100 billion km
  3. 200 billion km
  4. 300 billion km

88. The substitution of one or more bases of DNA is called choose which one is correct:

  1. Insertion
  2. Point mutation
  3. Deletion
  4. Transposition

89. The addition of one or a few bases is choose which one is correct:

  1. Insertion
  2. Point mutation
  3. Deletion
  4. Transposition

90. Change in gene position is choose which one is correct:

  1. Insertion
  2. Point mutation
  3. Deletion
  4. Transposition

91. The change of chromosomal number is choose which one is correct:

  1. Deletion
  2. Point mutation
  3. Insertion
  4. Aberration

92. Which of the following is not mutagen?

  1. Chemicals
  2. Radiations
  3. Water
  4. None of the above

93. Sickle anemia is a choose which one is correct:

  1. Insertion
  2. Point mutation
  3. Deletion
  4. Transposition

94. The disease which causes mental retardation is choose which one is correct:

  1. Sickle cell anemia
  2. Diabetes
  3. Phenylketouria
  4. None of the above

95. Chromosomal theory of inheritance suggests that choose which one is correct:

  1. Genes are present on DNA
  2. Genes are present on chromatids
  3. Genes are present on chromosomes
  4. All of the above

96. The objection on chromosomal theory of inheritance was choose which one is correct:

  1. There are more chromosomes but less gene
  2. There are more gene but less chromosomes
  3. Each chromosome carry only one gene
  4. None of the above

97. The strange result of T.H. Morgan was choose which one is correct:

  1. All the male were red eyed
  2. All the female were white eyed
  3. Neither of female white eyed
  4. All of the above

98. Which of the following is incorrect observation of experiments by Avery and coworkers?

  1. Transforming activity continues after destruction of protein
  2. Transforming activity continues after destruction of lipids
  3. Transforming activity continues after destruction of DNA
  4. Transforming activity continues after destruction of carbohydrates

99. Which is incorrect about Watson and Crick model?

  1. DNA is double helix
  2. Base paring is purine and pyrimidine
  3. DNA is composed of parallel strands
  4. Base pair are plainer

100. The semi conservative model is choose which one is correct:

  1. Both strands are synthesized
  2. None of the strands is synthesized
  3. Only one strand is synthesized
  4. None of the above

101. Meselson and Stahl found that the DNA collected immediately after transfer was dense because choose which one is correct:

  1. Both strands contain N14
  2. Both strands contain N15
  3. One strand is N14 and other N15
  4. All of the above

102. Okazaki fragments are formed in lagging strand because choose which one is correct:

  1. Lagging strand does not allow continuous replication
  2. Lagging strand is 3 to 5 direction
  3. Lagging strand is 5 to 3 direction
  4. Lagging strand is placed near to leading strand

103. Which of the following does not come within central dogma?

  1. Synthesis of DNA
  2. Synthesis of mRNA
  3. Synthesis of protein
  4. All of the above

104. The opposite strand is called coding strand or sense strand in transcription because choose which one is correct:

  1. It has opposite codes of template strand
  2. It has similar codes as of template strand
  3. Its codes are similar to mRNA codes
  4. Its codes are opposite to mRNA codes
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