51. Lysozyme in the phage tail:
Answer: B. digests a portion of the host cell wall
Biology Class 11 Unit 5: Acellular Life MCQs
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52. Tail fibres and tail pins of bacteriophage help in:
Answer: B. adsorption (attachment)
53. The first step in the infection process of a phage is:
Answer: C. adsorption
54. Contraction of the sheath pushes the core tube through the bacterial envelope. This step is:
Answer: B. penetration
55. Only the viral nucleic acid is injected in the host. The protein coat:
Answer: B. remains outside the bacterium
56. A phage which immediately lyses its host cell after multiplication is:
Answer: C. virulent (lytic)
57. The disintegration of host DNA in the lytic cycle is done by:
Answer: C. virally encoded DNase
58. Viral DNA is not digested by the DNase because it:
Answer: C. has undergone certain chemical modification
59. The correct order in lytic cycle is:
Answer: B. adsorption, penetration, synthesis, assembly (maturation), lysis
60. In the lytic cycle, about how many phage particles are produced in 20 to 25 minutes?
Answer: C. 200
61. Packaging of nucleic acid into the phage head is called:
Answer: B. maturation
62. Phages which can either multiply via lytic cycle or enter a dormant state are:
Answer: B. temperate (lysogenic) phages
63. Integrated phage DNA in the bacterial chromosome is called:
Answer: B. prophage
64. Bacteria harbouring a prophage are called:
Answer: B. lysogenic bacteria
65. Termination of lysogenic state by adverse conditions is called:
Answer: C. induction
66. Which of these favour induction of the lysogenic phage?
Answer: B. UV radiation, desiccation or mutagenic chemicals
67. Change in properties of a bacterium due to prophage genes is called:
Answer: C. lysogenic (phage) conversion
68. Clostridium botulinum toxins are partly encoded by:
Answer: B. prophage genomes
69. Bacteriophage DNA is used in genetic engineering as a:
Answer: C. vector
70. Phage therapy is the application of phages to:
Answer: B. kill pathogenic bacteria without harming normal flora
71. HIV was identified in 1984 by the research teams from Pasteur Institute in France and:
Answer: B. National Institute of Health, USA
72. The virus was named HIV in:
Answer: B. 1986
73. HIV is a:
Answer: B. retrovirus
74. The outer glycoprotein of HIV needed to attach to the host cell is:
Answer: B. gp120
75. The transmembrane glycoprotein critical for cell fusion in HIV is:
Answer: B. gp41
76. The shape of the HIV capsid is:
Answer: C. somewhat conical
77. The HIV core contains:
Answer: B. two single stranded RNA molecules and enzymes
78. The enzyme of HIV that converts viral RNA to viral DNA is:
Answer: C. reverse transcriptase
79. The enzyme that incorporates viral DNA into host DNA is:
Answer: B. integrase
80. The enzyme that cuts large viral proteins into smaller units is:
Answer: C. protease
81. HIV attacks specific host cells called:
Answer: B. CD4 cells
82. Which cells are CD4 cells?
Answer: B. Helper T cells, macrophages and certain brain cells
83. The first step in the HIV life cycle is:
Answer: C. attachment of gp120 to CD4 receptor
84. HIV enters the host cell by:
Answer: B. fusion and endocytosis
85. Removal of the protective coat inside the host cell is called:
Answer: B. uncoating
86. The DNA made from HIV RNA by reverse transcriptase is called:
Answer: B. complementary DNA (cDNA)
87. After reverse transcription the viral RNA is broken down by:
Answer: C. ribonuclease
88. The integrated viral DNA in host DNA is called:
Answer: B. provirus
89. Viral mRNA is transcribed from provirus by:
Answer: B. host cell RNA polymerase
90. New HIV virions are released from the host cell by:
Answer: B. budding
91. HIV got its name Human Immunodeficiency Virus because it destroys:
Answer: B. helper T cells which regulate the immune system
92. Helper T cells:
Answer: B. activate B cells and cytotoxic T cells
93. AIDS stands for:
Answer: B. Acquired Immuno-Deficiency Syndrome
94. The three stages of HIV infection are:
Answer: B. asymptomatic carrier, AIDS Related Complex, full blown AIDS
95. In the asymptomatic carrier stage the person:
Answer: B. shows antibodies positive but few symptoms for nine months or more
96. Opportunistic diseases of AIDS are caused due to:
Answer: B. weak defence from loss of T cells
97. HIV itself:
Answer: C. only destroys T cells, and the patient dies from opportunistic diseases
98. ART stands for:
Answer: B. Antiretroviral Therapy
99. Antiretroviral therapy:
Answer: B. controls the virus so the patient lives longer and risk of transmission falls
100. AIDS is NOT transmitted by:
Answer: C. mosquito bites, toilets or door knobs
About Biology Class 11 Unit 5 MCQs (Federal Board)
These 170 Biology MCQs cover Class 11 Unit 5: Acellular Life of the Federal Board (FBISE) HSSC-I (1st Year / Class 11) syllabus. They are SLO-based MCQs as per the new pattern for FBISE exams. Each question has four options and the correct answer is shown, so you can practise for the annual examination and find the topics you still need to revise. The questions are split over 4 pages of 50. Use the Print button to save this chapter as a PDF.