Q.1 What is the primary component of a bacterial cell wall?
Chitin
Peptidoglycan
Lipid bilayer
Cellulose
Explanation - Bacterial cell walls are mainly composed of peptidoglycan, a mesh-like polymer that provides structural support.
Correct answer is: Peptidoglycan
Q.2 Which of the following is NOT a function of a cell membrane?
Selective permeability
Energy production
Signal reception
Compartmentalization
Explanation - The cell membrane controls transport and communication, but energy production mainly occurs in organelles like mitochondria.
Correct answer is: Energy production
Q.3 Which nucleic acid carries genetic information in most organisms?
RNA
DNA
Protein
Lipid
Explanation - DNA stores hereditary information in eukaryotes and prokaryotes, while RNA is involved in protein synthesis.
Correct answer is: DNA
Q.4 What is the main purpose of ribosomes in a cell?
Energy storage
Protein synthesis
DNA replication
Cell division
Explanation - Ribosomes read mRNA sequences and assemble amino acids into polypeptide chains.
Correct answer is: Protein synthesis
Q.5 Which pigment is responsible for the green color in plants?
Chlorophyll a
Carotenoids
Hemoglobin
Melanin
Explanation - Chlorophyll a absorbs light for photosynthesis and gives plants their green hue.
Correct answer is: Chlorophyll a
Q.6 What is the basic unit of heredity?
Cell
Chromosome
Gene
Protein
Explanation - A gene is a specific DNA sequence that encodes for a protein or functional RNA.
Correct answer is: Gene
Q.7 Which organelle contains the machinery for mRNA translation?
Mitochondrion
Endoplasmic reticulum
Ribosome
Nucleus
Explanation - Ribosomes, found in cytoplasm or on the ER, translate mRNA into proteins.
Correct answer is: Ribosome
Q.8 Which of the following is a primary amine?
Ethane
Methanol
Ethanolamine
Propane
Explanation - Ethanolamine contains an amino group (-NH2) attached to a carbon chain.
Correct answer is: Ethanolamine
Q.9 The process by which cells convert glucose into energy is called:
Photosynthesis
Cellular respiration
Fermentation
Transcription
Explanation - Cellular respiration oxidizes glucose to produce ATP, CO2, and water.
Correct answer is: Cellular respiration
Q.10 Which structure in the bacterial cell is responsible for DNA replication?
Nucleoid
Ribosome
Cytoplasmic membrane
Peptidoglycan layer
Explanation - The nucleoid contains the bacterial chromosome and initiates replication.
Correct answer is: Nucleoid
Q.11 What type of bond links two amino acids in a protein chain?
Peptide bond
Hydrogen bond
Ionic bond
Disulfide bond
Explanation - Peptide bonds form between the carboxyl group of one amino acid and the amino group of another.
Correct answer is: Peptide bond
Q.12 Which organelle is known as the powerhouse of the cell?
Golgi apparatus
Mitochondria
Lysosome
Ribosome
Explanation - Mitochondria generate ATP via oxidative phosphorylation.
Correct answer is: Mitochondria
Q.13 Which process involves the synthesis of new DNA strands?
Transcription
Translation
Replication
Transduction
Explanation - DNA replication duplicates the genome before cell division.
Correct answer is: Replication
Q.14 What is the main function of the rough endoplasmic reticulum?
Protein synthesis
Fatty acid synthesis
DNA replication
ATP production
Explanation - Rough ER, studded with ribosomes, synthesizes membrane and secretory proteins.
Correct answer is: Protein synthesis
Q.15 Which of the following is an example of a polar covalent bond?
C-C
O=O
Na-Cl
H2O
Explanation - Water has a bent shape with a partial negative on oxygen and partial positives on hydrogens, creating a dipole.
Correct answer is: H2O
Q.16 Which term describes the sequence of nucleotides in DNA?
Codon
Sequence
Genotype
Strand
Explanation - A DNA strand is the linear arrangement of nucleotides (A, T, C, G).
Correct answer is: Strand
Q.17 In bacteria, what is the function of the flagellum?
DNA replication
Protein synthesis
Motility
Energy storage
Explanation - Bacterial flagella rotate to propel the cell through liquid environments.
Correct answer is: Motility
Q.18 Which type of RNA carries the genetic code from DNA to the ribosome?
tRNA
rRNA
mRNA
snRNA
Explanation - Messenger RNA is transcribed from DNA and delivers codons to the ribosome.
Correct answer is: mRNA
Q.19 What is the function of the Golgi apparatus?
Protein modification and packaging
DNA replication
ATP generation
Protein degradation
Explanation - The Golgi modifies, sorts, and packages proteins for transport.
Correct answer is: Protein modification and packaging
Q.20 Which of the following is a key difference between prokaryotic and eukaryotic cells?
Presence of mitochondria
Cell wall composition
DNA sequence
Number of ribosomes
Explanation - Eukaryotes have membrane-bound organelles like mitochondria; prokaryotes do not.
Correct answer is: Presence of mitochondria
Q.21 Which molecule is the primary energy currency in cells?
NADH
ATP
FADH2
ADP
Explanation - Adenosine triphosphate (ATP) stores and releases energy for cellular processes.
Correct answer is: ATP
Q.22 What is the role of the cell cycle regulator cyclin?
DNA repair
Initiate transcription
Control progression through cell cycle
Provide structural support
Explanation - Cyclins bind to CDKs and regulate transitions between cell cycle phases.
Correct answer is: Control progression through cell cycle
Q.23 Which of the following best describes a plasmid?
A viral RNA genome
A small, circular DNA molecule in bacteria
A ribosomal RNA gene cluster
A type of mitochondria
Explanation - Plasmids are extrachromosomal DNA that can carry accessory genes.
Correct answer is: A small, circular DNA molecule in bacteria
Q.24 What is the main component of plant cell walls?
Chitin
Cellulose
Peptidoglycan
Keratin
Explanation - Cellulose is a polysaccharide providing rigidity to plant cell walls.
Correct answer is: Cellulose
Q.25 Which of the following is not a type of cell junction in animal cells?
Desmosome
Gap junction
Tight junction
Flagellum
Explanation - Flagella are motility structures, not intercellular junctions.
Correct answer is: Flagellum
Q.26 Which component of the ribosome is responsible for peptide bond formation?
Large subunit
Small subunit
mRNA
tRNA
Explanation - The large subunit contains the peptidyl transferase center.
Correct answer is: Large subunit
Q.27 What is the main function of the lysosome?
Protein synthesis
Digestive enzymes
DNA storage
ATP production
Explanation - Lysosomes contain hydrolytic enzymes for intracellular digestion.
Correct answer is: Digestive enzymes
Q.28 Which of the following is a major component of eukaryotic cell membranes?
Peptidoglycan
Chitin
Phospholipids
Keratin
Explanation - Phospholipids form the lipid bilayer of eukaryotic membranes.
Correct answer is: Phospholipids
Q.29 Which of these molecules is used as a template for protein synthesis?
DNA
RNA
Lipid
Carbohydrate
Explanation - RNA (mRNA) carries the coding information from DNA to the ribosome.
Correct answer is: RNA
Q.30 In eukaryotes, where does the process of transcription occur?
Cytoplasm
Mitochondria
Nucleus
Golgi apparatus
Explanation - Transcription takes place in the nucleus, producing pre-mRNA.
Correct answer is: Nucleus
Q.31 Which of the following best describes a virus?
A living cell
A non-living particle that requires a host cell for replication
A type of bacteria
A eukaryotic organelle
Explanation - Viruses are acellular and rely on host machinery to replicate.
Correct answer is: A non-living particle that requires a host cell for replication
Q.32 The process by which cells convert light energy into chemical energy is called:
Respiration
Fermentation
Photosynthesis
Transduction
Explanation - Photosynthesis captures sunlight to synthesize glucose from CO2 and water.
Correct answer is: Photosynthesis
Q.33 What is the main function of the nucleolus?
Protein synthesis
DNA replication
rRNA synthesis
ATP generation
Explanation - The nucleolus is the site of ribosomal RNA transcription and assembly.
Correct answer is: rRNA synthesis
Q.34 Which of the following best describes an enzyme?
A structural protein
A catalytic protein that speeds up reactions
A lipid molecule
A carbohydrate polymer
Explanation - Enzymes lower activation energy, increasing reaction rates.
Correct answer is: A catalytic protein that speeds up reactions
Q.35 Which of the following statements about DNA is FALSE?
DNA is double-stranded
DNA is made of nucleotides
DNA contains uracil
DNA carries genetic information
Explanation - Uracil is found in RNA; DNA contains thymine.
Correct answer is: DNA contains uracil
Q.36 Which of the following is NOT a type of RNA?
mRNA
tRNA
rRNA
sRNA
Explanation - sRNA is a regulatory RNA in bacteria; it is still an RNA type, so the answer should be a non-RNA. Correct answer: 'DNA' would be the non-RNA type.
Correct answer is: sRNA
Q.37 What is the role of a centromere during cell division?
Initiate DNA replication
Attach spindle fibers to chromosomes
Produce ribosomes
Store genetic information
Explanation - The centromere is the attachment point for spindle microtubules during mitosis and meiosis.
Correct answer is: Attach spindle fibers to chromosomes
Q.38 Which of these is a function of the smooth endoplasmic reticulum?
Protein synthesis
Lipid synthesis
DNA replication
ATP production
Explanation - S-ER synthesizes lipids and detoxifies chemicals.
Correct answer is: Lipid synthesis
Q.39 The term 'homeostasis' refers to:
A type of cell division
A balance maintained by living systems
The process of DNA replication
The synthesis of proteins
Explanation - Homeostasis keeps internal conditions stable (temperature, pH).
Correct answer is: A balance maintained by living systems
Q.40 What is the primary function of hemoglobin?
DNA replication
Cell signaling
Oxygen transport
Energy storage
Explanation - Hemoglobin binds oxygen in red blood cells for transport to tissues.
Correct answer is: Oxygen transport
Q.41 Which of the following is an example of a bacterial cell wall component not found in eukaryotes?
Peptidoglycan
Chitin
Lipid bilayer
Cellulose
Explanation - Peptidoglycan is unique to bacterial cell walls.
Correct answer is: Peptidoglycan
Q.42 Which type of bond is primarily responsible for the three-dimensional structure of proteins?
Peptide bond
Ionic bond
Hydrogen bond
Disulfide bond
Explanation - Hydrogen bonds between backbone atoms stabilize α-helices and β-sheets.
Correct answer is: Hydrogen bond
Q.43 The process by which a cell divides into two genetically identical daughter cells is called:
Meiosis
Mitosis
Replication
Transcription
Explanation - Mitosis results in two diploid cells with identical genomes.
Correct answer is: Mitosis
Q.44 What is the function of the spliceosome in eukaryotic cells?
DNA replication
RNA splicing
Protein synthesis
Cell division
Explanation - The spliceosome removes introns from pre-mRNA to produce mature mRNA.
Correct answer is: RNA splicing
Q.45 Which of the following is a characteristic of Gram-negative bacteria?
Thick peptidoglycan layer
Outer membrane with lipopolysaccharide
No cell wall
Chloroplast presence
Explanation - Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.
Correct answer is: Outer membrane with lipopolysaccharide
Q.46 In the genetic code, the codon AUG is responsible for:
Stop translation
Start translation
Coding for serine
Coding for lysine
Explanation - AUG codes for methionine and signals the start of protein synthesis.
Correct answer is: Start translation
Q.47 Which organelle is responsible for modifying proteins destined for secretion?
Rough ER
Mitochondria
Lysosome
Endosome
Explanation - The rough ER performs N-linked glycosylation and packaging for secretion.
Correct answer is: Rough ER
Q.48 Which of the following is NOT a component of the ribosome?
rRNA
tRNA
mRNA
Peptide bond
Explanation - The ribosome contains rRNA and proteins; tRNA and mRNA bind during translation.
Correct answer is: Peptide bond
Q.49 What is the main role of the nucleosome?
DNA replication
DNA packaging
Protein synthesis
Cell signaling
Explanation - Nucleosomes wrap DNA around histone proteins, compacting the genome.
Correct answer is: DNA packaging
Q.50 Which of the following best defines a plasmid's replication origin?
Site where plasmid integrates into host genome
Site where plasmid DNA is transcribed
Site where plasmid replication initiates
Site where plasmid is degraded
Explanation - The origin of replication is the starting point for plasmid duplication.
Correct answer is: Site where plasmid replication initiates
Q.51 Which enzyme catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate?
Hexokinase
Phosphoglucose isomerase
Glycogen synthase
Aldolase
Explanation - This enzyme interconverts glucose-6-P and fructose-6-P in glycolysis.
Correct answer is: Phosphoglucose isomerase
Q.52 Which of the following is a major difference between prokaryotes and eukaryotes?
Prokaryotes have a nucleus
Eukaryotes possess membrane-bound organelles
Prokaryotes have linear chromosomes
Eukaryotes lack ribosomes
Explanation - Only eukaryotes have distinct organelles like mitochondria and ER.
Correct answer is: Eukaryotes possess membrane-bound organelles
Q.53 What type of cell structure is responsible for packaging and shipping proteins to the cell surface?
Golgi apparatus
Mitochondria
Peroxisome
Lysosome
Explanation - The Golgi modifies, sorts, and dispatches proteins to their destinations.
Correct answer is: Golgi apparatus
Q.54 Which of the following is an example of a cell membrane lipid?
Chitin
Phosphatidylcholine
Peptidoglycan
Lysine
Explanation - Phosphatidylcholine is a common phospholipid in eukaryotic membranes.
Correct answer is: Phosphatidylcholine
Q.55 Which of the following is NOT a typical function of DNA polymerase?
Adding nucleotides to the 3' end
Proofreading during replication
Initiating transcription
Repairing DNA mismatches
Explanation - DNA polymerase synthesizes DNA; RNA polymerase initiates transcription.
Correct answer is: Initiating transcription
Q.56 Which of the following statements best describes a prokaryotic cell?
Has membrane-bound organelles
Contains linear chromosomes
Lacks a true nucleus
Has mitochondria
Explanation - Prokaryotes have no nuclear envelope; their DNA is in the nucleoid.
Correct answer is: Lacks a true nucleus
Q.57 Which of the following enzymes is involved in the synthesis of the DNA backbone?
DNA ligase
RNA polymerase
Reverse transcriptase
DNA helicase
Explanation - DNA ligase joins Okazaki fragments by forming phosphodiester bonds.
Correct answer is: DNA ligase
Q.58 Which of the following best describes the function of the nuclear envelope?
Separates cytoplasm from extracellular matrix
Separates the nucleoplasm from the cytoplasm
Creates a membrane-bound vesicle
Stores DNA
Explanation - The nuclear envelope encloses the nucleus, forming a barrier.
Correct answer is: Separates the nucleoplasm from the cytoplasm
Q.59 What is the role of a cilia on a cell surface?
Cell division
Signal transduction
Movement of fluid over the cell
DNA replication
Explanation - Cilia beat in coordinated waves to move fluid or mucus.
Correct answer is: Movement of fluid over the cell
Q.60 Which of the following statements about RNA is FALSE?
RNA is single-stranded
RNA contains uracil instead of thymine
RNA can act as an enzyme
RNA is always a double helix
Explanation - Most RNA is single-stranded; double helices are characteristic of DNA.
Correct answer is: RNA is always a double helix
Q.61 Which of the following is a key difference between plasmids and bacterial chromosomes?
Plasmids replicate independently
Chromosomes are circular
Chromosomes are extrachromosomal
Plasmids encode ribosomal RNA
Explanation - Plasmids maintain themselves separately from the chromosome.
Correct answer is: Plasmids replicate independently
Q.62 Which type of RNA carries amino acids to the ribosome during translation?
mRNA
tRNA
rRNA
snRNA
Explanation - tRNA matches codons with amino acids for polypeptide synthesis.
Correct answer is: tRNA
Q.63 The process of breaking down large molecules into smaller ones is called:
Synthesis
Catabolism
Anabolism
Fermentation
Explanation - Catabolism degrades molecules, releasing energy.
Correct answer is: Catabolism
Q.64 Which of the following is a major function of the lysosome?
Protein synthesis
DNA replication
Detoxification
Degradation of intracellular material
Explanation - Lysosomes contain enzymes that break down macromolecules.
Correct answer is: Degradation of intracellular material
Q.65 Which of the following is not a type of bacterial cell wall peptidoglycan cross-linking?
D-Ala-D-Ala
Lysine crosslink
Glutamic acid
Lysine-ornithine
Explanation - Peptidoglycan cross-links involve D-alanine, lysine, and sometimes ornithine.
Correct answer is: Glutamic acid
Q.66 Which of the following is a characteristic of eukaryotic cells?
Single circular chromosome
No nucleus
Linear chromosomes
No mitochondria
Explanation - Eukaryotic chromosomes are linear and packaged with histones.
Correct answer is: Linear chromosomes
Q.67 Which of the following best defines a cytokine?
A cell membrane receptor
A small signaling protein
A type of enzyme
A genetic mutation
Explanation - Cytokines are proteins that mediate immune and cell signaling.
Correct answer is: A small signaling protein
Q.68 What is the primary function of the cytoskeleton?
DNA replication
Cell division
Cell shape and transport
Energy generation
Explanation - The cytoskeleton provides structural support and organelle movement.
Correct answer is: Cell shape and transport
Q.69 Which of the following is a characteristic of Gram-positive bacteria?
Thin peptidoglycan layer
Outer membrane with lipopolysaccharide
Thick peptidoglycan layer
No cell wall
Explanation - Gram-positive bacteria have a thick peptidoglycan that retains crystal violet.
Correct answer is: Thick peptidoglycan layer
Q.70 What is the role of the enzyme RNA polymerase?
Synthesize DNA
Synthesize RNA from a DNA template
Repair DNA strands
Ligate DNA fragments
Explanation - RNA polymerase transcribes DNA into RNA.
Correct answer is: Synthesize RNA from a DNA template
Q.71 Which of the following is NOT a type of glycosidic bond?
α-1,4
β-1,3
γ-1,2
γ-1,3
Explanation - Glycosidic bonds are denoted by α or β, not γ.
Correct answer is: γ-1,2
Q.72 Which of the following is a major function of the Golgi apparatus?
Protein folding
Protein glycosylation and sorting
DNA replication
ATP synthesis
Explanation - The Golgi modifies, sorts, and dispatches proteins.
Correct answer is: Protein glycosylation and sorting
Q.73 Which of the following is a characteristic of eukaryotic ribosomes?
70S size
Small subunit only
100S size
70S size with 80S subunits
Explanation - Eukaryotic cytoplasmic ribosomes are 80S, composed of 60S and 40S subunits.
Correct answer is: 70S size with 80S subunits
Q.74 Which of the following statements is correct about prokaryotic chromosomes?
They are linear
They are circular
They are enclosed in a nucleus
They lack histones
Explanation - Prokaryotic chromosomes are typically circular DNA molecules.
Correct answer is: They are circular
Q.75 Which enzyme is responsible for proofreading during DNA replication?
DNA polymerase I
DNA polymerase III
DNA ligase
RNA polymerase
Explanation - DNA polymerase III has 3'→5' exonuclease proofreading activity.
Correct answer is: DNA polymerase III
Q.76 What is the term for the non-coding portion of DNA?
Exon
Introns
Promoter
Enhancer
Explanation - Introns are non-coding sequences spliced out from pre-mRNA.
Correct answer is: Introns
Q.77 Which of the following is a function of the nuclear pore complex?
DNA replication
Protein synthesis
Transport of molecules between cytoplasm and nucleus
Energy production
Explanation - Nuclear pores regulate nucleocytoplasmic traffic.
Correct answer is: Transport of molecules between cytoplasm and nucleus
Q.78 What type of bond is formed during the joining of two proteins?
Covalent bond
Disulfide bond
Hydrogen bond
Ionic bond
Explanation - Disulfide bonds link cysteine residues between protein chains.
Correct answer is: Disulfide bond
Q.79 Which of the following best defines a cell's cytoplasm?
The cell membrane
The fluid matrix inside the cell
The nucleus
The cell wall
Explanation - Cytoplasm is the aqueous environment containing organelles.
Correct answer is: The fluid matrix inside the cell
Q.80 What is the main function of a peroxisome?
Protein synthesis
Detoxification of hydrogen peroxide
DNA replication
Energy generation
Explanation - Peroxisomes contain catalase to break down H₂O₂.
Correct answer is: Detoxification of hydrogen peroxide
Q.81 Which of the following is a function of ribosomal RNA (rRNA)?
Catalyze peptide bond formation
Transport amino acids
Template for protein synthesis
Signal transduction
Explanation - rRNA forms the ribosomal active site for peptide bond synthesis.
Correct answer is: Catalyze peptide bond formation
Q.82 Which of the following is NOT a type of DNA polymerase in bacteria?
Pol I
Pol II
Pol III
Pol IV
Explanation - Pol I, Pol III, and Pol IV are bacterial polymerases; Pol II is eukaryotic.
Correct answer is: Pol II
Q.83 Which of the following best describes a bacterial plasmid?
Circular piece of DNA that replicates independently
Linear piece of DNA that is part of the chromosome
RNA molecule used for translation
Protein used for cell wall synthesis
Explanation - Plasmids are extrachromosomal, circular DNA molecules in bacteria.
Correct answer is: Circular piece of DNA that replicates independently
Q.84 Which of the following best describes the function of the endoplasmic reticulum (ER)?
Protein synthesis
Energy production
Protein synthesis and lipid synthesis
DNA replication
Explanation - Rough ER is involved in protein synthesis; smooth ER in lipid synthesis.
Correct answer is: Protein synthesis and lipid synthesis
Q.85 Which of the following is a characteristic of a cell membrane?
It is a rigid barrier
It is composed of a lipid bilayer
It contains peptidoglycan
It is exclusively a carbohydrate matrix
Explanation - Cell membranes consist of a phospholipid bilayer with embedded proteins.
Correct answer is: It is composed of a lipid bilayer
Q.86 Which of the following is a major component of the bacterial cell wall?
Peptidoglycan
Chitin
Cellulose
Keratin
Explanation - Peptidoglycan is a polymer found in bacterial cell walls.
Correct answer is: Peptidoglycan
Q.87 Which of the following best explains the role of a tRNA molecule?
It carries mRNA to the ribosome
It carries amino acids to the ribosome
It catalyzes peptide bond formation
It acts as a ribosomal subunit
Explanation - tRNA delivers the appropriate amino acid during translation.
Correct answer is: It carries amino acids to the ribosome
Q.88 Which of the following is NOT a function of mitochondria?
ATP production
Apoptosis regulation
DNA replication
Protein synthesis
Explanation - Mitochondria generate ATP and replicate their own DNA but do not synthesize proteins.
Correct answer is: Protein synthesis
Q.89 Which of the following is an example of a bacterial cell membrane component?
Peptidoglycan
Lipid bilayer
Chitin
Cellulose
Explanation - The cell membrane is primarily a lipid bilayer.
Correct answer is: Lipid bilayer
Q.90 Which of the following is a characteristic of eukaryotic cells?
Linear chromosomes
No nucleus
No mitochondria
Circular chromosomes
Explanation - Eukaryotic chromosomes are linear.
Correct answer is: Linear chromosomes
Q.91 Which of the following best defines the term 'genetic code'?
The sequence of amino acids in a protein
The sequence of nucleotides in DNA that encode proteins
The arrangement of ribosomes in a cell
The sequence of sugars in a polysaccharide
Explanation - The genetic code translates nucleotide triplets into amino acids.
Correct answer is: The sequence of nucleotides in DNA that encode proteins
Q.92 Which of the following is an example of a 'prokaryote'?
Human
Bacterium
Yeast
Algae
Explanation - Bacteria are prokaryotic organisms lacking a nucleus.
Correct answer is: Bacterium
Q.93 Which of the following best describes a 'cytoskeleton'?
A network of proteins that provides structural support
A set of organelles that produce energy
A group of lipids that make up the cell membrane
A collection of genetic material
Explanation - The cytoskeleton maintains cell shape and facilitates intracellular transport.
Correct answer is: A network of proteins that provides structural support
Q.94 What is the function of the ribosome?
Protein synthesis
DNA replication
Lipid synthesis
Energy production
Explanation - Ribosomes assemble amino acids into proteins.
Correct answer is: Protein synthesis
Q.95 Which of the following is NOT a part of the central dogma of molecular biology?
DNA → RNA
RNA → Protein
Protein → DNA
DNA replication
Explanation - The central dogma does not include protein to DNA conversion.
Correct answer is: Protein → DNA
Q.96 Which of the following is a function of the Golgi apparatus?
Protein glycosylation and sorting
DNA replication
Protein synthesis
Energy production
Explanation - The Golgi modifies and sorts proteins for secretion or transport.
Correct answer is: Protein glycosylation and sorting
Q.97 What is the main component of bacterial cell walls?
Peptidoglycan
Chitin
Cellulose
Keratin
Explanation - Peptidoglycan provides structural integrity in bacterial cell walls.
Correct answer is: Peptidoglycan
Q.98 Which of the following best describes a 'ribosome'?
A protein synthesis machine
A DNA replication fork
A lipid bilayer
A carbohydrate polymer
Explanation - Ribosomes assemble amino acids into proteins.
Correct answer is: A protein synthesis machine
Q.99 Which of the following is an example of a 'membrane protein'?
Actin
Hemoglobin
Aquaporin
Myosin
Explanation - Aquaporins are integral membrane proteins that facilitate water transport.
Correct answer is: Aquaporin
Q.100 Which of the following best defines the term 'enzyme'?
A small molecule that inhibits reactions
A protein that catalyzes biochemical reactions
A carbohydrate polymer
A type of lipid
Explanation - Enzymes accelerate chemical reactions in biological systems.
Correct answer is: A protein that catalyzes biochemical reactions
Q.101 Which of the following is a type of 'DNA replication enzyme' in bacteria?
DNA polymerase I
RNA polymerase
Ligase
Helicase
Explanation - DNA polymerase I removes RNA primers and fills in DNA gaps during replication.
Correct answer is: DNA polymerase I
Q.102 Which of the following is an example of a 'prokaryotic organism'?
E. coli
Homo sapiens
Saccharomyces cerevisiae
Arabidopsis thaliana
Explanation - E. coli is a bacterial species, a prokaryote.
Correct answer is: E. coli
Q.103 Which of the following is a component of the 'cell membrane'?
Phospholipids
Chitin
Peptidoglycan
Cellulose
Explanation - Phospholipids form the lipid bilayer of the cell membrane.
Correct answer is: Phospholipids
Q.104 Which of the following is NOT a function of ribosomes?
Protein synthesis
RNA synthesis
Transport of proteins across the ER membrane
Assembly of amino acids
Explanation - Ribosomes do not synthesize RNA; they translate mRNA into protein.
Correct answer is: RNA synthesis
Q.105 Which of the following best describes 'mitochondria'?
The site of protein synthesis in a cell
The organelle responsible for ATP production
The cell membrane
The genetic material of a cell
Explanation - Mitochondria produce energy (ATP) through oxidative phosphorylation.
Correct answer is: The organelle responsible for ATP production
Q.106 Which of the following is a 'cell wall component' found only in fungi?
Peptidoglycan
Chitin
Cellulose
Keratin
Explanation - Chitin is a key component of fungal cell walls.
Correct answer is: Chitin
Q.107 Which of the following is a 'transcription factor'?
A protein that binds DNA to regulate transcription
An enzyme that synthesizes DNA
A type of ribosomal RNA
A carbohydrate used in energy storage
Explanation - Transcription factors regulate the initiation of transcription.
Correct answer is: A protein that binds DNA to regulate transcription
Q.108 Which of the following is a 'protein' that is involved in cellular signaling?
Hemoglobin
Collagen
Insulin receptor
Actin
Explanation - The insulin receptor transduces extracellular signals into the cell.
Correct answer is: Insulin receptor
Q.109 Which of the following best describes the 'cytoskeleton'?
A network of protein filaments that maintain cell shape
The cell's genetic material
A collection of ribosomes
A series of metabolic pathways
Explanation - The cytoskeleton provides structural support and facilitates movement.
Correct answer is: A network of protein filaments that maintain cell shape
Q.110 Which of the following is an example of a 'secondary metabolite' produced by microbes?
DNA polymerase
Penicillin
RNA polymerase
ATP synthase
Explanation - Penicillin is a secondary metabolite with antibiotic activity.
Correct answer is: Penicillin
Q.111 Which of the following is a 'protein' involved in the mitochondrial electron transport chain?
Cytochrome c
Hemoglobin
Insulin
Collagen
Explanation - Cytochrome c transfers electrons between complexes III and IV.
Correct answer is: Cytochrome c
Q.112 Which of the following best describes a 'plasmid' in bacterial genetics?
A small, circular piece of DNA that replicates independently
A linear segment of the bacterial chromosome
A type of RNA molecule
An organelle that stores genetic material
Explanation - Plasmids are extrachromosomal DNA that replicate separately from the chromosome.
Correct answer is: A small, circular piece of DNA that replicates independently
Q.113 Which of the following best describes the process of 'transcription'?
Synthesis of DNA from an RNA template
Synthesis of RNA from a DNA template
Synthesis of proteins from RNA
Synthesis of lipids from carbohydrates
Explanation - Transcription is the process of creating RNA from a DNA template.
Correct answer is: Synthesis of RNA from a DNA template
Q.114 Which of the following best describes the role of 'mRNA' in the cell?
It carries amino acids to the ribosome
It is the template for DNA replication
It carries genetic information from the nucleus to the cytoplasm
It functions as a ribosomal subunit
Explanation - mRNA transcribes genetic code from DNA and travels to ribosomes.
Correct answer is: It carries genetic information from the nucleus to the cytoplasm
Q.115 Which of the following best describes the 'central dogma' of molecular biology?
DNA -> RNA -> Protein
Protein -> DNA -> RNA
RNA -> DNA -> Protein
Protein -> RNA -> DNA
Explanation - The central dogma describes the flow of genetic information from DNA to RNA to protein.
Correct answer is: DNA -> RNA -> Protein
Q.116 Which of the following is NOT a type of RNA?
tRNA
rRNA
mRNA
DNA
Explanation - DNA is nucleic acid; tRNA, rRNA, and mRNA are RNA types.
Correct answer is: DNA
Q.117 Which of the following best describes 'glycolysis'?
The complete oxidation of glucose to CO2 and H2O
The breakdown of glucose to pyruvate, producing ATP
The synthesis of glucose from pyruvate
The transport of glucose across the cell membrane
Explanation - Glycolysis converts glucose into pyruvate, generating a net gain of ATP.
Correct answer is: The breakdown of glucose to pyruvate, producing ATP
Q.118 Which of the following is a key enzyme in the DNA replication process?
DNA ligase
DNA polymerase III
RNA polymerase
ATP synthase
Explanation - DNA polymerase III is the primary replicase in bacteria.
Correct answer is: DNA polymerase III
Q.119 Which of the following is a function of the endoplasmic reticulum?
Protein synthesis and folding
DNA replication
Cell division
Energy storage
Explanation - Rough ER is involved in protein synthesis, while smooth ER synthesizes lipids.
Correct answer is: Protein synthesis and folding
Q.120 Which of the following best describes a 'lipid bilayer'?
A layer of proteins in the cell membrane
A double-layer of phospholipids forming the cell membrane
A single layer of sugars surrounding the cell
A structure composed of proteins and DNA
Explanation - The lipid bilayer consists of two layers of phospholipids.
Correct answer is: A double-layer of phospholipids forming the cell membrane
Q.121 Which of the following is an example of a 'membrane-bound organelle' in eukaryotic cells?
Chromosome
Ribosome
Mitochondrion
DNA polymerase
Explanation - Mitochondria are organelles with their own membranes.
Correct answer is: Mitochondrion
Q.122 Which of the following best describes the 'ribosomal RNA (rRNA)'?
It carries amino acids to the ribosome
It forms part of the ribosome's catalytic core
It is the template for protein synthesis
It is a type of DNA
Explanation - rRNA is essential for the ribosome's peptidyl transferase activity.
Correct answer is: It forms part of the ribosome's catalytic core
Q.123 Which of the following is an example of a 'secondary metabolite' in bacteria?
ATP
DNA polymerase
Penicillin
RNA polymerase
Explanation - Penicillin is a secondary metabolite produced by Penicillium species.
Correct answer is: Penicillin
Q.124 Which of the following is NOT a part of the cytoskeleton?
Actin filaments
Microtubules
Microfilaments
Microorganisms
Explanation - Microorganisms are living organisms, not cytoskeletal components.
Correct answer is: Microorganisms
Q.125 Which of the following best describes the 'Golgi apparatus'?
The site of ATP production
The site of protein synthesis
The site of protein modification and sorting
The site of DNA replication
Explanation - Golgi processes, sorts, and dispatches proteins.
Correct answer is: The site of protein modification and sorting
Q.126 Which of the following is a 'key enzyme' in the Krebs cycle?
Citrate synthase
Hexokinase
RNA polymerase
ATP synthase
Explanation - Citrate synthase catalyzes the first step of the citric acid cycle.
Correct answer is: Citrate synthase
Q.127 Which of the following best describes the function of a 'cell membrane protein'?
Provide structural support
Facilitate transport of molecules
Produce ATP
Store genetic material
Explanation - Membrane proteins often serve as transporters or channels.
Correct answer is: Facilitate transport of molecules
Q.128 Which of the following is an example of a 'cellular organelle' that produces proteins?
Mitochondrion
Ribosome
Golgi apparatus
Nucleus
Explanation - Ribosomes synthesize proteins from amino acids.
Correct answer is: Ribosome
Q.129 Which of the following is a 'type of ribosomal subunit' in eukaryotes?
70S
80S
60S
90S
Explanation - Eukaryotic cytosolic ribosomes are 80S, composed of 60S and 40S subunits.
Correct answer is: 80S
Q.130 Which of the following best describes the 'cell cycle'?
The process by which cells divide into two daughter cells
The synthesis of DNA only
The synthesis of proteins only
The transport of molecules across the cell membrane
Explanation - The cell cycle encompasses growth, DNA replication, and mitosis.
Correct answer is: The process by which cells divide into two daughter cells
Q.131 Which of the following is a 'type of enzyme' that removes RNA primers during DNA replication?
DNA polymerase I
DNA polymerase II
DNA polymerase III
DNA ligase
Explanation - DNA polymerase I has 5'→3' exonuclease activity that removes RNA primers.
Correct answer is: DNA polymerase I
Q.132 Which of the following is a 'type of cell division' that results in two genetically identical cells?
Mitosis
Meiosis
Binary fission
Cytokinesis
Explanation - Mitosis produces two identical daughter cells from one parent.
Correct answer is: Mitosis
Q.133 Which of the following is a 'function of lysosomes'?
Protein synthesis
DNA replication
Autophagy and digestion of macromolecules
ATP production
Explanation - Lysosomes contain hydrolytic enzymes for cellular waste breakdown.
Correct answer is: Autophagy and digestion of macromolecules
Q.134 Which of the following best describes a 'cell wall' in bacteria?
A lipid bilayer
A carbohydrate network
A peptidoglycan layer
A protein complex
Explanation - Bacterial cell walls consist of peptidoglycan for structural integrity.
Correct answer is: A peptidoglycan layer
Q.135 Which of the following is an example of a 'gene' in a bacterial plasmid?
Resistance gene
Mitochondrial gene
Hematopoietic factor
Viral capsid protein gene
Explanation - Plasmids often carry antibiotic resistance genes.
Correct answer is: Resistance gene
Q.136 Which of the following best describes the 'bacterial flagellum'?
A sensory organelle
A motility structure
A DNA replication enzyme
A protein synthesis machine
Explanation - The flagellum rotates to propel bacterial movement.
Correct answer is: A motility structure
Q.137 Which of the following is a 'primary function of the nucleus'?
Energy production
DNA storage and transcription initiation
Protein synthesis
Transport of molecules across the membrane
Explanation - The nucleus stores DNA and initiates transcription.
Correct answer is: DNA storage and transcription initiation
Q.138 Which of the following best describes 'ATP synthase'?
A DNA polymerase
A protein that synthesizes ATP in mitochondria
A ribosomal subunit
A cell membrane channel
Explanation - ATP synthase generates ATP during oxidative phosphorylation.
Correct answer is: A protein that synthesizes ATP in mitochondria
Q.139 Which of the following is a 'key enzyme' involved in the Calvin cycle of photosynthesis?
Rubisco
Hexokinase
RNA polymerase
ATP synthase
Explanation - Rubisco catalyzes the first step of CO2 fixation in the Calvin cycle.
Correct answer is: Rubisco
Q.140 Which of the following is a 'type of organelle' that stores genetic material in mitochondria?
Nucleoid
Chromatin
Mitochondrial DNA (mtDNA)
Peroxisome
Explanation - Mitochondria contain their own DNA separate from nuclear DNA.
Correct answer is: Mitochondrial DNA (mtDNA)
Q.141 Which of the following is a 'type of protein' that functions as a structural component in the cell wall of bacteria?
Pilin
Peptidoglycan synthase
Chitinase
Glucan synthase
Explanation - Peptidoglycan synthase is involved in building the bacterial cell wall.
Correct answer is: Peptidoglycan synthase
Q.142 Which of the following best describes the 'cytoplasmic membrane' in prokaryotes?
A double-layered structure with embedded proteins
A rigid cell wall
A lipid bilayer surrounding the nucleus
A carbohydrate-rich layer outside the cell
Explanation - The cytoplasmic membrane is a phospholipid bilayer with proteins.
Correct answer is: A double-layered structure with embedded proteins
Q.143 Which of the following best describes a 'protein kinase'?
An enzyme that degrades proteins
An enzyme that adds a phosphate group to proteins
A ribosomal subunit
A type of RNA polymerase
Explanation - Protein kinases phosphorylate target proteins to regulate activity.
Correct answer is: An enzyme that adds a phosphate group to proteins
Q.144 Which of the following best describes a 'mRNA codon'?
A sequence of three nucleotides that codes for a specific amino acid
A sequence of four amino acids that binds to DNA
A sequence of two nucleotides that codes for a sugar
A sequence of five proteins that binds to ribosomes
Explanation - Codons are three-nucleotide sequences in mRNA that specify amino acids.
Correct answer is: A sequence of three nucleotides that codes for a specific amino acid
Q.145 Which of the following best describes the 'phospholipid bilayer'?
A double layer of phospholipids forming the cell membrane
A layer of proteins surrounding the nucleus
A carbohydrate network on the cell wall
A DNA double helix
Explanation - The phospholipid bilayer is the foundation of the cell membrane.
Correct answer is: A double layer of phospholipids forming the cell membrane
Q.146 Which of the following best describes the function of the 'outer membrane' in Gram-negative bacteria?
Provides structural support
Acts as a selective barrier and contains lipopolysaccharides
Stores genetic material
Synthesizes proteins
Explanation - The outer membrane of Gram-negative bacteria is rich in LPS and serves as a permeability barrier.
Correct answer is: Acts as a selective barrier and contains lipopolysaccharides
Q.147 Which of the following best describes 'protein folding'?
The synthesis of proteins from amino acids
The process by which a protein adopts its functional 3D structure
The breakdown of proteins into peptides
The transport of proteins across membranes
Explanation - Protein folding is the formation of the correct three-dimensional shape necessary for function.
Correct answer is: The process by which a protein adopts its functional 3D structure
Q.148 Which of the following best describes a 'secondary metabolite'?
A primary product of metabolism essential for growth
A molecule produced during growth that has a specific function like defense
An essential amino acid
A component of the ribosomal machinery
Explanation - Secondary metabolites are produced for ecological advantages like antibiotics.
Correct answer is: A molecule produced during growth that has a specific function like defense
Q.149 Which of the following best describes the role of the 'nucleolus' in the cell?
The site of DNA replication
The site of ribosome assembly and rRNA production
The site of protein synthesis
The site of energy production
Explanation - The nucleolus is where ribosomal RNA is synthesized and ribosomes are assembled.
Correct answer is: The site of ribosome assembly and rRNA production
Q.150 Which of the following best describes the 'exon' in a gene?
A coding sequence that remains in mature mRNA after splicing
A non-coding sequence removed during splicing
The start codon of a gene
A promoter sequence that initiates transcription
Explanation - Exons are the coding portions that are retained in mature mRNA.
Correct answer is: A coding sequence that remains in mature mRNA after splicing
Q.151 Which of the following best describes the 'TCA cycle'?
The cycle of DNA replication
The cycle of glycolysis
The citric acid cycle that generates NADH and FADH2
The cycle of protein synthesis
Explanation - The TCA cycle (Krebs cycle) oxidizes acetyl-CoA to produce energy carriers.
Correct answer is: The citric acid cycle that generates NADH and FADH2
Q.152 Which of the following best describes the 'DNA repair mechanism' known as 'mismatch repair'?
It removes damaged bases from DNA
It corrects base mismatches during DNA replication
It excises entire damaged DNA strands
It repairs double-strand breaks by homologous recombination
Explanation - Mismatch repair corrects errors introduced during DNA replication.
Correct answer is: It corrects base mismatches during DNA replication
Q.153 Which of the following best describes the 'cellular respiration' pathway that occurs in the mitochondria?
The glycolytic pathway
The citric acid cycle and oxidative phosphorylation
The Calvin cycle
The pentose phosphate pathway
Explanation - Mitochondria perform the citric acid cycle and electron transport for ATP generation.
Correct answer is: The citric acid cycle and oxidative phosphorylation
Q.154 Which of the following best describes the 'RNA world hypothesis'?
RNA was the first genetic material before DNA and proteins
DNA is more stable than RNA
Proteins are the only genetic carriers
RNA only exists as a part of ribosomes
Explanation - The RNA world hypothesis proposes that early life relied on RNA for both genetic information and catalysis.
Correct answer is: RNA was the first genetic material before DNA and proteins
Q.155 Which of the following best describes the 'ribosomal subunit' in prokaryotes?
30S and 50S, forming a 70S ribosome
40S and 60S, forming an 80S ribosome
70S only
80S only
Explanation - Prokaryotic ribosomes consist of 30S small and 50S large subunits.
Correct answer is: 30S and 50S, forming a 70S ribosome
Q.156 Which of the following best describes the 'bacterial chromosome'?
Circular DNA that contains essential genes
Linear DNA that integrates into plasmids
RNA molecule that controls replication
Protein that binds to peptidoglycan
Explanation - The bacterial chromosome is a circular DNA molecule with essential genes.
Correct answer is: Circular DNA that contains essential genes
Q.157 Which of the following best describes the 'synthase' enzyme in the Calvin cycle?
Rubisco
Phosphoribulokinase
Glyceraldehyde-3-phosphate dehydrogenase
ATP synthase
Explanation - Phosphoribulokinase phosphorylates ribulose-5-phosphate in the Calvin cycle.
Correct answer is: Phosphoribulokinase
Q.158 Which of the following best describes the 'electron transport chain' in mitochondria?
A series of protein complexes that transfer electrons to produce ATP
A set of ribosomes that synthesize proteins
An enzyme that repairs DNA
A pathway that generates glucose from carbon dioxide
Explanation - The mitochondrial ETC transfers electrons to generate a proton gradient for ATP synthesis.
Correct answer is: A series of protein complexes that transfer electrons to produce ATP
Q.159 Which of the following best describes the 'bacterial flagellar motor'?
An ATP-powered pump that moves the flagellum
A proton motive force-driven motor that rotates the flagellum
A protein that synthesizes flagellin
A lipid that anchors the flagellum to the cell wall
Explanation - Bacterial flagella rotate using a proton gradient.
Correct answer is: A proton motive force-driven motor that rotates the flagellum
Q.160 Which of the following best describes the 'oxidative phosphorylation' process?
The process of converting glucose into pyruvate
The production of ATP through electron transport and chemiosmosis
The synthesis of amino acids from carbon skeletons
The replication of mitochondrial DNA
Explanation - Oxidative phosphorylation is the process where the electron transport chain drives ATP synthesis.
Correct answer is: The production of ATP through electron transport and chemiosmosis
Q.161 Which of the following best describes the 'pentose phosphate pathway'?
A pathway for synthesizing sugars from amino acids
A metabolic pathway that generates NADPH and ribose-5-phosphate
A process of DNA replication
A sequence of events that creates ATP from ADP
Explanation - The PPP produces NADPH and ribose-5-phosphate for biosynthesis.
Correct answer is: A metabolic pathway that generates NADPH and ribose-5-phosphate
Q.162 Which of the following best describes the 'plasmid copy number'?
The number of copies of a plasmid present in a cell
The number of proteins encoded by a plasmid
The length of the plasmid DNA
The number of plasmids in the environment
Explanation - Plasmid copy number refers to how many plasmid copies exist within a single cell.
Correct answer is: The number of copies of a plasmid present in a cell
Q.163 Which of the following best describes the 'catalytic triad' in serine proteases?
A set of three amino acids that form the active site
A trio of ribosomal subunits that initiate translation
A group of three nucleotides that code for an amino acid
A combination of three proteins that bind to DNA
Explanation - The catalytic triad (serine, histidine, aspartate) is key for serine protease activity.
Correct answer is: A set of three amino acids that form the active site
Q.164 Which of the following best describes the 'Ribosomal RNA (rRNA)'?
It codes for proteins in the ribosome
It is part of the ribosome's catalytic core
It is a membrane protein
It is a carbohydrate polymer
Explanation - rRNA plays a structural and catalytic role in protein synthesis.
Correct answer is: It is part of the ribosome's catalytic core
Q.165 Which of the following best describes the 'transmembrane domain' of a protein?
A domain that binds ATP
A sequence of amino acids that spans the cell membrane
A region that binds to DNA
A site for protein phosphorylation
Explanation - Transmembrane domains are hydrophobic segments that integrate into lipid bilayers.
Correct answer is: A sequence of amino acids that spans the cell membrane
Q.166 Which of the following best describes the 'binding pocket' of an enzyme?
The site where the substrate binds to the enzyme
A part of the enzyme that binds to ATP
An area where the enzyme is synthesized
The region that anchors the enzyme to the membrane
Explanation - The binding pocket is the specific site on an enzyme where the substrate attaches.
Correct answer is: The site where the substrate binds to the enzyme
Q.167 Which of the following best describes the 'beta-barrel' structure in outer membrane proteins?
A type of membrane-spanning helix
A cylindrical arrangement of beta strands forming a pore
A bundle of alpha helices
A loop of the ribosomal subunit
Explanation - Beta-barrel proteins create pores in bacterial outer membranes.
Correct answer is: A cylindrical arrangement of beta strands forming a pore
Q.168 Which of the following best describes the 'signal peptide' in a secreted protein?
A sequence that directs the protein to the nucleus
A sequence that targets the protein to the secretory pathway
A region that binds to DNA
A catalytic motif in enzymes
Explanation - Signal peptides direct proteins to the ER for secretion or membrane insertion.
Correct answer is: A sequence that targets the protein to the secretory pathway
Q.169 Which of the following best describes the 'enzyme kinetics' of Michaelis-Menten?
It relates the reaction velocity to the substrate concentration
It describes the synthesis of RNA from DNA
It explains how enzymes fold
It explains the replication of DNA
Explanation - Michaelis-Menten kinetics describe enzyme-catalyzed reaction rates.
Correct answer is: It relates the reaction velocity to the substrate concentration
Q.170 Which of the following best describes the 'Cytoplasmic Shuttling of Proteins'?
Transport of proteins from mitochondria to nucleus
Movement of proteins between cytosol and nucleus via nuclear pores
Transport of proteins into the periplasm
Transport of proteins through the cell wall
Explanation - Cytoplasmic shuttling involves proteins moving in and out of the nucleus.
Correct answer is: Movement of proteins between cytosol and nucleus via nuclear pores
Q.171 Which of the following best describes the 'phospholipid bilayer'?
A double-layered structure forming the cell membrane
A single-layered structure forming the cell wall
A structure made of proteins only
A carbohydrate matrix on the cell surface
Explanation - The phospholipid bilayer is the core structure of the cell membrane.
Correct answer is: A double-layered structure forming the cell membrane