1. Question 1 of 100

   Down syndrome is usually caused by

   A monosomy X B deletion of chromosome 5 C trisomy 21 due to nondisjunction D trisomy of the sex chromosomes
2. Question 2 of 100

   The oxygen released during photosynthesis comes from the

   A splitting (photolysis) of water B breakdown of CO₂ C breakdown of glucose D absorption of nitrogen
3. Question 3 of 100

   The light-dependent reactions of photosynthesis occur in the

   A stroma B cytoplasm C nucleolus D thylakoid membranes
4. Question 4 of 100

   The Calvin cycle uses ______ from the light reactions to produce sugars.

   A O₂ and water B DNA and RNA C ATP and NADPH D glucose and ADP
5. Question 5 of 100

   Cytokinesis in plant cells occurs by the formation of a

   A cell plate B cleavage furrow C contractile ring D spindle only
6. Question 6 of 100

   Rough endoplasmic reticulum appears rough because of

   A ribosomes attached to it B lipid droplets C chloroplasts D centrioles
7. Question 7 of 100

   Transcription is the synthesis of

   A protein from mRNA B DNA from DNA C lipids from sugar D mRNA from a DNA template
8. Question 8 of 100

   Mitochondria are unique because they

   A have two membranes and their own DNA B have no membrane C are found only in bacteria D contain chlorophyll
9. Question 9 of 100

   Mitochondrial DNA in humans is inherited

   A from the father only B equally from both parents C from neither parent D from the mother only
10. Question 10 of 100

    The process by which a cell engulfs large particles is

    A exocytosis B endocytosis C diffusion D osmosis
11. Question 11 of 100

    The cell cycle is regulated by

    A ribosomes and lysosomes B cyclins and cyclin-dependent kinases (CDKs) C chlorophyll and carotene D insulin and glucagon
12. Question 12 of 100

    Gap junctions in animal cells

    A seal cells to prevent leakage B anchor cells to the matrix only C allow small molecules and ions to pass between adjacent cells D are found in plant cell walls
13. Question 13 of 100

    A codon consists of

    A two nucleotides on DNA B one amino acid on tRNA C three nucleotides on mRNA coding for one amino acid D four bases on rRNA
14. Question 14 of 100

    Glycolysis occurs in the

    A mitochondrial matrix B nucleus C chloroplast stroma D cytoplasm
15. Question 15 of 100

    Chromosomes line up at the equator of the cell during

    A prophase B metaphase C anaphase D telophase
16. Question 16 of 100

    A fertilised egg (zygote) is described as totipotent because it

    A can form only blood cells B can give rise to all cell types of the organism and extra-embryonic tissues C cannot divide D is haploid
17. Question 17 of 100

    As a cell grows larger, its surface-area-to-volume ratio

    A increases B decreases C remains constant D becomes infinite
18. Question 18 of 100

    The cell theory was proposed by

    A Watson and Crick B Hooke and Darwin C Mendel and Morgan D Schleiden and Schwann
19. Question 19 of 100

    Meiosis produces

    A skin cells B identical somatic cells C gametes (sex cells) D red blood cells only
20. Question 20 of 100

    The basic structural and functional unit of life is the

    A tissue B organ C cell D molecule
21. Question 21 of 100

    The tumour suppressor protein p53 acts mainly by

    A halting the cell cycle for repair or triggering apoptosis B promoting uncontrolled division C making ATP D making lipids
22. Question 22 of 100

    Ribosomes of prokaryotic and eukaryotic cells are, respectively, of the type

    A 80S and 70S B 50S and 60S C 30S and 40S D 70S and 80S
23. Question 23 of 100

    The enzyme that fixes CO₂ in the Calvin cycle is

    A catalase B amylase C RuBisCO D DNA polymerase
24. Question 24 of 100

    The branch of biology that deals with the study of cells is called

    A histology B cytology C ecology D taxonomy
25. Question 25 of 100

    Proteins are synthesised at the

    A ribosomes B lysosomes C vacuoles D Golgi bodies
26. Question 26 of 100

    DNA replication occurs during the ______ phase of the cell cycle.

    A G₁ B M C G₂ D S
27. Question 27 of 100

    The folds of the inner mitochondrial membrane are called

    A grana B cristae C thylakoids D cisternae
28. Question 28 of 100

    The Krebs cycle takes place in the

    A cytoplasm B nucleus C mitochondrial matrix D Golgi body
29. Question 29 of 100

    The endosymbiotic theory, proposed by Lynn Margulis, suggests that

    A the nucleus came from a virus B mitochondria and chloroplasts arose from engulfed prokaryotes C ribosomes came from the Golgi body D cells arose from cork
30. Question 30 of 100

    Chemiosmosis refers to

    A movement of water through aquaporins B movement of Na⁺ via pumps C ATP synthesis driven by the flow of protons through ATP synthase D breakdown of glucose in cytoplasm
31. Question 31 of 100

    The jelly-like fluid inside a cell, excluding the nucleus, is the

    A cytoplasm B cell wall C vacuole D ribosome
32. Question 32 of 100

    The sodium–potassium pump moves, per ATP,

    A 3 K⁺ out and 2 Na⁺ in B 3 Na⁺ out and 2 K⁺ into the cell C 2 Na⁺ out and 3 K⁺ in D 1 Na⁺ out and 1 K⁺ in
33. Question 33 of 100

    The cell membrane is mainly composed of

    A cellulose and lignin B phospholipids and proteins C starch and glycogen D DNA and RNA
34. Question 34 of 100

    The organelle that packages and secretes substances from the cell is the

    A mitochondrion B chloroplast C nucleus D Golgi apparatus
35. Question 35 of 100

    Photosynthesis takes place in the

    A mitochondria B ribosomes C chloroplasts D lysosomes
36. Question 36 of 100

    Prokaryotic cells differ from eukaryotic cells in that they

    A lack DNA B lack ribosomes C lack cell membrane D lack a membrane-bound nucleus
37. Question 37 of 100

    The resolving power (resolution limit) of a light microscope is about

    A 0.2 μm B 0.2 nm C 2 mm D 20 μm
38. Question 38 of 100

    The nucleolus is mainly involved in making

    A ATP B ribosomal RNA and ribosome subunits C lysosomal enzymes D chlorophyll
39. Question 39 of 100

    Enzymes are

    A carbohydrates that store energy B biological catalysts, mostly proteins C lipids that form membranes D nucleic acids only
40. Question 40 of 100

    The network of membranes that helps in transport of materials within a cell is the

    A cell wall B nucleolus C centriole D endoplasmic reticulum
41. Question 41 of 100

    In DNA, adenine always pairs with

    A thymine B guanine C cytosine D uracil
42. Question 42 of 100

    Genes are located on

    A chromosomes B ribosomes C lysosomes D vacuoles
43. Question 43 of 100

    The control centre of the cell is the

    A vacuole B lysosome C nucleus D cell wall
44. Question 44 of 100

    During meiosis I, the chromosomes that separate are

    A sister chromatids B non-homologous chromosomes only C centrioles D homologous chromosomes
45. Question 45 of 100

    Plasmolysis occurs when a plant cell is placed in a

    A hypotonic solution B isotonic solution C hypertonic solution D distilled water
46. Question 46 of 100

    Apoptosis is

    A death due to injury B programmed cell death carried out through caspase enzymes C uncontrolled growth of cells D division of bacteria
47. Question 47 of 100

    Which of the following is absent in animal cells?

    A Cell wall B Nucleus C Cell membrane D Mitochondria
48. Question 48 of 100

    A scanning electron microscope (SEM) is mainly used to

    A view internal structures in thin sections only B view living cells C measure DNA length D view three-dimensional surface details of specimens
49. Question 49 of 100

    There are ______ codons in the genetic code, of which 61 code for amino acids.

    A 20 B 64 C 16 D 61
50. Question 50 of 100

    The plant cell wall is mainly made of

    A protein B chitin C phospholipid D cellulose
51. Question 51 of 100

    Centrioles, which help to form the spindle, are found in

    A animal cells B bacterial cells only C all plant cells D red blood cells
52. Question 52 of 100

    Diffusion is the movement of molecules from

    A lower to higher concentration B a region of higher concentration to lower concentration C one cell to another only D solid to liquid only
53. Question 53 of 100

    Cells are studied with the help of a

    A microscope B telescope C stethoscope D barometer
54. Question 54 of 100

    The energy currency of the cell is

    A DNA B RNA C ATP D glucose
55. Question 55 of 100

    Active transport

    A moves substances against their concentration gradient using ATP B moves substances down the gradient without energy C is the same as osmosis D occurs only in plants
56. Question 56 of 100

    The cell membrane is described as selectively permeable because it

    A allows everything to pass B allows nothing to pass C allows only certain substances to pass through D is made of cellulose
57. Question 57 of 100

    DNA stands for

    A dinucleic acid B deoxyribose nitrogen acid C deoxyribonucleic acid D double nucleic acid
58. Question 58 of 100

    The cell was first observed by

    A Charles Darwin B Gregor Mendel C Robert Hooke D Louis Pasteur
59. Question 59 of 100

    The final electron acceptor in the mitochondrial electron transport chain is

    A NAD⁺ B oxygen C carbon dioxide D water
60. Question 60 of 100

    The Calvin cycle occurs in the

    A thylakoid lumen B mitochondrial matrix C stroma of the chloroplast D nucleus
61. Question 61 of 100

    The powerhouse of the cell is the

    A nucleus B mitochondrion C ribosome D Golgi apparatus
62. Question 62 of 100

    The Golgi apparatus adds carbohydrate groups to proteins, a process called

    A transcription B phosphorylation only C translation D glycosylation
63. Question 63 of 100

    Facilitated diffusion requires

    A ATP but no proteins B neither proteins nor ATP C only lipids D carrier or channel proteins but no ATP
64. Question 64 of 100

    Anaerobic respiration in yeast produces

    A lactic acid only B water and CO₂ only C glucose and oxygen D ethanol and carbon dioxide
65. Question 65 of 100

    Cancer is caused by

    A absence of cell division B excess apoptosis C uncontrolled cell division D too much oxygen
66. Question 66 of 100

    The longest cell in the human body is the

    A red blood cell B skin cell C nerve cell (neuron) D white blood cell
67. Question 67 of 100

    When a plant cell is placed in a hypotonic solution, it

    A becomes plasmolysed B shrinks and dies instantly C bursts due to lack of a cell wall D becomes turgid
68. Question 68 of 100

    Which of the following is a unicellular organism?

    A Amoeba B Hydra C Earthworm D Mango tree
69. Question 69 of 100

    Stem cells are

    A fully specialised nerve cells B dead plant cells C undifferentiated cells able to divide and become specialised cells D red blood cells
70. Question 70 of 100

    A competitive inhibitor

    A binds elsewhere and changes shape of the enzyme B permanently destroys the substrate C binds to the active site and competes with the substrate D increases enzyme activity
71. Question 71 of 100

    Mitosis produces

    A four different cells B gametes only C a single large cell D two genetically identical daughter cells
72. Question 72 of 100

    During cell division, chromatin condenses into visible

    A ribosomes B mitochondria C centrioles D chromosomes
73. Question 73 of 100

    In meiosis, the chromosome number is

    A doubled B halved, from diploid to haploid C unchanged D tripled
74. Question 74 of 100

    In enzyme kinetics, Kₘ is the

    A substrate concentration at which the reaction rate is half of Vmax B maximum rate of the reaction C temperature of denaturation D enzyme concentration at half rate
75. Question 75 of 100

    Okazaki fragments are formed on the

    A leading strand B mRNA C lagging strand during DNA replication D tRNA
76. Question 76 of 100

    Bacteria reproduce asexually by

    A meiosis B budding only C pollination D binary fission
77. Question 77 of 100

    The normal number of chromosomes in a human body cell is

    A 23 B 46 C 48 D 44
78. Question 78 of 100

    Red blood cells transport oxygen with the help of

    A chlorophyll B insulin C keratin D haemoglobin
79. Question 79 of 100

    Bacteria are

    A prokaryotic organisms B eukaryotic organisms C multicellular plants D viruses
80. Question 80 of 100

    The green pigment in plants is

    A chlorophyll B haemoglobin C melanin D carotene
81. Question 81 of 100

    The large central sac that stores water and dissolved substances in plant cells is the

    A vacuole B ribosome C centriole D nucleolus
82. Question 82 of 100

    Telomeres are

    A repetitive DNA sequences at chromosome ends that protect them B the centre of chromosomes C sites of protein synthesis D proteins in ribosomes
83. Question 83 of 100

    DNA replication is described as semi-conservative because

    A both strands are new B each new DNA molecule has one old and one new strand C both strands are old D it occurs only in half of the cells
84. Question 84 of 100

    Crossing over occurs in

    A prophase I of meiosis B metaphase of mitosis C anaphase II D telophase of mitosis
85. Question 85 of 100

    RNA differs from DNA because RNA has

    A thymine instead of uracil B uracil instead of thymine C deoxyribose sugar D a double helix always
86. Question 86 of 100

    Chloroplasts are found in

    A animal cells only B plant cells C bacteria only D red blood cells
87. Question 87 of 100

    Most ATP in aerobic respiration is produced by

    A glycolysis in the cytoplasm B fermentation C oxidative phosphorylation in the inner mitochondrial membrane D the Calvin cycle
88. Question 88 of 100

    Peroxisomes contain the enzyme catalase which

    A breaks down hydrogen peroxide into water and oxygen B makes ATP C replicates DNA D makes ribosomes
89. Question 89 of 100

    The anticodon is found on

    A mRNA B rRNA C tRNA D DNA
90. Question 90 of 100

    Osmosis is the movement of

    A solutes only B proteins only C gases only D water through a semi-permeable membrane
91. Question 91 of 100

    Lysosomes are called suicide bags because they

    A produce ATP B store water C make proteins D contain digestive enzymes that can destroy the cell
92. Question 92 of 100

    A cell drawn 5 mm long under a magnification of ×500 has an actual length of

    A 2.5 mm B 10 μm C 100 μm D 1 μm
93. Question 93 of 100

    A group of similar cells performing a particular function is called a

    A tissue B organ C organelle D organ system
94. Question 94 of 100

    Gram-positive bacteria retain the crystal violet stain because they have

    A no cell wall B a thick peptidoglycan cell wall C an outer lipid membrane D a nucleus
95. Question 95 of 100

    In differential centrifugation of a cell homogenate, the first fraction to settle at low speed is the

    A ribosomes B mitochondria C microsomes D nuclei
96. Question 96 of 100

    A cubical cell has a side of 2 μm. Its surface area to volume ratio is

    A 6 μm⁻¹ B 3 μm⁻¹ C 1.5 μm⁻¹ D 12 μm⁻¹
97. Question 97 of 100

    Most enzymes are denatured at

    A 0 °C permanently B neutral pH only C low substrate concentration D high temperature
98. Question 98 of 100

    The largest single cell is the

    A red blood cell B human egg C egg of an ostrich D amoeba
99. Question 99 of 100

    The correct order of mitosis is

    A prophase → metaphase → anaphase → telophase B metaphase → prophase → telophase → anaphase C anaphase → prophase → metaphase → telophase D telophase → anaphase → metaphase → prophase
100. Question 100 of 100

     The fluid mosaic model of the cell membrane was proposed by

     A Singer and Nicolson B Watson and Crick C Hooke and Leeuwenhoek D Schleiden and Schwann

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