Q.1 Which of the following organelles is primarily responsible for producing ATP in eukaryotic cells?
Nucleus
Golgi apparatus
Mitochondrion
Endoplasmic reticulum
Explanation - Mitochondria contain the machinery for oxidative phosphorylation, generating ATP from ADP and inorganic phosphate.
Correct answer is: Mitochondrion
Q.2 What is the function of the ribosome in a cell?
Energy generation
Protein synthesis
DNA replication
Lipid synthesis
Explanation - Ribosomes read mRNA and catalyze peptide bond formation between amino acids to build proteins.
Correct answer is: Protein synthesis
Q.3 The lipid bilayer of the plasma membrane is composed mainly of which class of molecules?
Proteins
Carbohydrates
Phospholipids
Nucleic acids
Explanation - Phospholipids have hydrophilic heads and hydrophobic tails, forming the basic structure of cell membranes.
Correct answer is: Phospholipids
Q.4 Which cellular component stores genetic information in most eukaryotic cells?
Cytoplasm
Nucleolus
Nucleus
Mitochondria
Explanation - The nucleus houses chromosomal DNA and controls gene expression.
Correct answer is: Nucleus
Q.5 The process by which a cell divides into two genetically identical daughter cells is called?
Meiosis
Mitosis
Binary fission
Metamorphosis
Explanation - Mitosis is the division of somatic cells producing two identical cells; meiosis produces gametes.
Correct answer is: Mitosis
Q.6 Which organelle is responsible for modifying, sorting, and packaging proteins for secretion?
Ribosome
Golgi apparatus
Lysosome
Peroxisome
Explanation - The Golgi complex receives proteins from the ER, modifies them, and dispatches them to their destinations.
Correct answer is: Golgi apparatus
Q.7 What is the role of lysosomes in a cell?
Energy production
Protein synthesis
Enzymatic digestion of waste
Genetic replication
Explanation - Lysosomes contain hydrolytic enzymes that break down macromolecules and cellular debris.
Correct answer is: Enzymatic digestion of waste
Q.8 Which of the following best describes the cytoskeleton?
A network of filaments providing shape and motility
An organelle that stores DNA
A membrane-bound structure for protein synthesis
A pigment-containing organelle
Explanation - The cytoskeleton consists of microtubules, actin filaments, and intermediate filaments that maintain cell shape and facilitate movement.
Correct answer is: A network of filaments providing shape and motility
Q.9 Which molecule acts as the primary energy currency of the cell?
Glucose
ATP
DNA
RNA
Explanation - Adenosine triphosphate (ATP) stores and transfers energy for cellular processes.
Correct answer is: ATP
Q.10 Which of the following is a function of the endoplasmic reticulum?
Protein synthesis and folding
DNA replication
Protein packaging
Cell division
Explanation - The rough ER has ribosomes attached and synthesizes membrane-bound proteins; the smooth ER synthesizes lipids.
Correct answer is: Protein synthesis and folding
Q.11 The primary structure of a protein refers to its?
Amino acid sequence
3D shape
Subunit composition
Functional domains
Explanation - Primary structure is the linear order of amino acids in the polypeptide chain.
Correct answer is: Amino acid sequence
Q.12 Which organelle contains its own DNA and ribosomes?
Nucleus
Mitochondria
Golgi apparatus
Ribosome
Explanation - Mitochondria are semi-autonomous organelles with circular DNA and ribosomes for protein synthesis.
Correct answer is: Mitochondria
Q.13 Which process occurs in the cytoplasm of a cell to break down macromolecules?
Transcription
Translation
Lysosomal degradation
Replication
Explanation - Lysosomes fuse with vesicles containing waste material, using enzymes to hydrolyze macromolecules.
Correct answer is: Lysosomal degradation
Q.14 The plasma membrane's 'fluid mosaic' model implies that?
Proteins are fixed in place
Lipids and proteins can move laterally
Membrane is rigid
Only lipids can move
Explanation - The fluid mosaic model describes lateral mobility of lipids and proteins within the bilayer.
Correct answer is: Lipids and proteins can move laterally
Q.15 What is the primary function of the nucleolus within the nucleus?
DNA replication
Protein synthesis
RNA synthesis and ribosome assembly
Transport of molecules
Explanation - The nucleolus is the site of ribosomal RNA transcription and assembly of ribosomal subunits.
Correct answer is: RNA synthesis and ribosome assembly
Q.16 Which cellular component is involved in the synthesis of fatty acids?
Mitochondria
Endoplasmic reticulum (smooth)
Nucleus
Peroxisome
Explanation - The smooth ER is responsible for lipid synthesis, including fatty acids and cholesterol.
Correct answer is: Endoplasmic reticulum (smooth)
Q.17 In a typical eukaryotic cell, which structure contains the majority of the cell’s genetic material?
Mitochondria
Nucleus
Ribosome
Cytoplasm
Explanation - The nucleus houses chromosomes that contain the cell's DNA.
Correct answer is: Nucleus
Q.18 What type of bond joins amino acids together in a polypeptide chain?
Hydrogen bond
Ionic bond
Peptide bond
Disulfide bond
Explanation - Peptide bonds link the carboxyl group of one amino acid to the amino group of another.
Correct answer is: Peptide bond
Q.19 Which organelle is involved in detoxification processes in liver cells?
Peroxisomes
Mitochondria
Golgi apparatus
Ribosomes
Explanation - Peroxisomes contain enzymes that break down fatty acids and detoxify harmful substances.
Correct answer is: Peroxisomes
Q.20 The primary function of the rough endoplasmic reticulum is to?
Synthesize lipids
Transport vesicles
Translate mRNA and synthesize proteins
Degrade cellular waste
Explanation - RER has ribosomes on its surface, facilitating co-translational protein synthesis.
Correct answer is: Translate mRNA and synthesize proteins
Q.21 Which cellular structure is responsible for the synthesis of ATP during cellular respiration?
Nucleus
Mitochondria
Ribosome
Plasma membrane
Explanation - Mitochondria contain the electron transport chain and ATP synthase.
Correct answer is: Mitochondria
Q.22 Which of the following best describes the function of the cytoplasmic ribosomes?
DNA replication
Protein synthesis
Energy storage
Signal transduction
Explanation - Cytoplasmic ribosomes translate mRNA into polypeptide chains.
Correct answer is: Protein synthesis
Q.23 Which organelle stores and secretes hormones?
Lysosome
Golgi apparatus
Endoplasmic reticulum
Chromoplast
Explanation - The Golgi modifies, sorts, and packages proteins and hormones for secretion.
Correct answer is: Golgi apparatus
Q.24 The process by which a cell’s plasma membrane engulfs a particle is called?
Pinocytosis
Phagocytosis
Exocytosis
Endocytosis
Explanation - Phagocytosis is the active ingestion of large particles, often used by immune cells.
Correct answer is: Phagocytosis
Q.25 Which of the following is NOT a component of the cell membrane?
Phospholipids
Proteins
Carbohydrates
Nucleic acids
Explanation - The membrane is composed of phospholipids, proteins, and carbohydrates; nucleic acids are not structural components.
Correct answer is: Nucleic acids
Q.26 In a eukaryotic cell, the nucleus is surrounded by a double membrane that contains what?
Mitochondria
Lysosomes
Nuclear pores
Microtubules
Explanation - Nuclear pores allow transport of molecules between the nucleus and cytoplasm.
Correct answer is: Nuclear pores
Q.27 Which organelle is the site of the citric acid cycle (Krebs cycle)?
Endoplasmic reticulum
Mitochondria
Golgi apparatus
Peroxisome
Explanation - The citric acid cycle occurs in the mitochondrial matrix.
Correct answer is: Mitochondria
Q.28 What is the main type of sugar found in the cell wall of bacteria?
Glucose
N-acetylglucosamine
Fructose
Mannose
Explanation - Bacterial cell walls contain peptidoglycan, composed of N-acetylglucosamine and N-acetylmuramic acid.
Correct answer is: N-acetylglucosamine
Q.29 Which of the following is a major function of peroxisomes?
Protein synthesis
DNA replication
Detoxification of hydrogen peroxide
Energy production
Explanation - Peroxisomes contain catalase, which breaks down hydrogen peroxide into water and oxygen.
Correct answer is: Detoxification of hydrogen peroxide
Q.30 What type of bond holds the two strands of DNA together?
Peptide bond
Ionic bond
Covalent bond
Hydrogen bond
Explanation - Hydrogen bonds form between complementary base pairs (A-T and G-C).
Correct answer is: Hydrogen bond
Q.31 Which organelle is responsible for the synthesis of ribosomal RNA?
Nucleolus
Ribosome
Mitochondria
Endoplasmic reticulum
Explanation - The nucleolus produces rRNA and assembles ribosomal subunits.
Correct answer is: Nucleolus
Q.32 Which structure in a cell provides a scaffold for cell division?
Centrosome
Cytoskeleton
Nucleus
Mitochondria
Explanation - The centrosome contains centrioles that help organize the mitotic spindle.
Correct answer is: Centrosome
Q.33 Which component of the cell is primarily involved in the synthesis of messenger RNA?
Ribosome
Nucleus
Endoplasmic reticulum
Golgi apparatus
Explanation - mRNA is transcribed from DNA by RNA polymerase in the nucleus.
Correct answer is: Nucleus
Q.34 What is the main function of the Golgi apparatus in plant cells?
Cell wall synthesis
Storage of starch
Protein modification and sorting
Photosynthesis
Explanation - The Golgi apparatus processes proteins and directs them to vacuoles, the cell wall, or secretion.
Correct answer is: Protein modification and sorting
Q.35 Which type of RNA carries amino acids to the ribosome during protein synthesis?
mRNA
tRNA
rRNA
siRNA
Explanation - Transfer RNA (tRNA) brings specific amino acids to the ribosome.
Correct answer is: tRNA
Q.36 Which of the following is a function of the smooth endoplasmic reticulum?
Protein synthesis
Lipid synthesis
DNA replication
mRNA splicing
Explanation - Smooth ER is involved in synthesizing lipids, steroid hormones, and detoxification.
Correct answer is: Lipid synthesis
Q.37 The enzyme responsible for replicating DNA during cell division is called?
DNA polymerase
RNA polymerase
Ligase
Helicase
Explanation - DNA polymerase adds nucleotides to the new DNA strand during replication.
Correct answer is: DNA polymerase
Q.38 Which organelle is known for producing reactive oxygen species as byproducts of respiration?
Mitochondria
Lysosome
Peroxisome
Golgi apparatus
Explanation - The electron transport chain in mitochondria can leak electrons, forming ROS.
Correct answer is: Mitochondria
Q.39 What is the primary structural component of the cell wall in Gram-positive bacteria?
Peptidoglycan
Lipid bilayer
Chitin
Murein
Explanation - Gram-positive bacteria have a thick peptidoglycan layer providing rigidity.
Correct answer is: Peptidoglycan
Q.40 The process of converting a protein into its functional 3D shape is called?
Transcription
Translation
Folding
Splicing
Explanation - Proteins fold into secondary, tertiary, and quaternary structures to become functional.
Correct answer is: Folding
Q.41 Which of these organelles contains enzymes for breaking down lysosomal substrates?
Peroxisome
Golgi apparatus
Lysosome
Ribosome
Explanation - Lysosomes house hydrolytic enzymes that digest biomolecules.
Correct answer is: Lysosome
Q.42 The nucleolus is involved in which of the following processes?
DNA replication
Protein folding
Ribosome assembly
Lipid synthesis
Explanation - The nucleolus synthesizes rRNA and assembles ribosomal subunits.
Correct answer is: Ribosome assembly
Q.43 Which organelle is the main site of photosynthesis in plant cells?
Mitochondria
Chloroplast
Ribosome
Golgi apparatus
Explanation - Chloroplasts contain chlorophyll and perform light-dependent reactions.
Correct answer is: Chloroplast
Q.44 Which of the following best describes the function of the cytoplasm?
Stores genetic material
Hosts cellular organelles
Contains plasma membrane
Synthesizes proteins only
Explanation - The cytoplasm is the matrix that houses organelles and supports cellular functions.
Correct answer is: Hosts cellular organelles
Q.45 Which of the following is NOT a function of the mitochondria?
ATP production
Apoptosis signaling
DNA replication
Fatty acid oxidation
Explanation - Mitochondria participate in apoptosis via cytochrome c release but do not directly signal apoptosis.
Correct answer is: Apoptosis signaling
Q.46 Which of the following components of a cell are involved in the transport of vesicles?
Microfilaments
Microtubules
Intermediate filaments
Actin
Explanation - Microtubules serve as tracks for vesicle movement via motor proteins.
Correct answer is: Microtubules
Q.47 Which structure is responsible for storing genetic information in the form of chromatin?
Nucleus
Mitochondria
Cytoplasm
Golgi apparatus
Explanation - Chromatin fibers are packed within the nucleus.
Correct answer is: Nucleus
Q.48 The process by which mRNA is transported out of the nucleus is called?
Transcription
Translation
Export
Splicing
Explanation - mRNA is packaged and exported through nuclear pores to the cytoplasm.
Correct answer is: Export
Q.49 Which organelle is involved in the breakdown of fatty acids during beta-oxidation?
Lysosome
Peroxisome
Mitochondria
Endoplasmic reticulum
Explanation - Peroxisomes carry out beta-oxidation of very-long-chain fatty acids.
Correct answer is: Peroxisome
Q.50 What is the primary role of the cytoskeleton's intermediate filaments?
Cell motility
Maintaining cell shape and mechanical stability
Energy production
Protein synthesis
Explanation - Intermediate filaments provide structural support and resilience.
Correct answer is: Maintaining cell shape and mechanical stability
Q.51 Which of the following statements about ribosomes is FALSE?
They are made of rRNA and proteins
They are found only in eukaryotic cells
They catalyze peptide bond formation
They translate mRNA into protein
Explanation - Ribosomes are present in both prokaryotes and eukaryotes.
Correct answer is: They are found only in eukaryotic cells
Q.52 Which of these processes is performed by the endoplasmic reticulum?
DNA replication
Protein synthesis
Energy production
Cell division
Explanation - The rough ER synthesizes membrane and secretory proteins.
Correct answer is: Protein synthesis
Q.53 The main structural component of the cytoskeleton that forms microtubules is made of?
Actin
Tubulin
Intermediate filament proteins
Spectrin
Explanation - Microtubules are polymers of α- and β-tubulin heterodimers.
Correct answer is: Tubulin
Q.54 Which of the following is a typical function of lysosomes?
DNA replication
Protein synthesis
Autophagy and degradation of macromolecules
Energy storage
Explanation - Lysosomes digest cellular waste via hydrolytic enzymes.
Correct answer is: Autophagy and degradation of macromolecules
Q.55 The enzyme catalase is found in which organelle?
Peroxisome
Mitochondrion
Ribosome
Golgi apparatus
Explanation - Catalase converts hydrogen peroxide into water and oxygen, preventing oxidative damage.
Correct answer is: Peroxisome
Q.56 Which cellular structure is involved in the packaging of DNA into nucleosomes?
Nucleolus
Nucleus
Chromosome
Lysosome
Explanation - Chromatin fibers coil around histones to form nucleosomes, constituting chromosomes.
Correct answer is: Chromosome
Q.57 The primary function of the plasma membrane is to?
Generate ATP
Provide structural support
Control passage of molecules into and out of the cell
Store genetic material
Explanation - The membrane acts as a selective barrier regulating transport.
Correct answer is: Control passage of molecules into and out of the cell
Q.58 Which component of a cell is responsible for the synthesis of fatty acids and steroid hormones?
Endoplasmic reticulum (smooth)
Endoplasmic reticulum (rough)
Golgi apparatus
Mitochondria
Explanation - The smooth ER synthesizes lipids, steroids, and detoxifies xenobiotics.
Correct answer is: Endoplasmic reticulum (smooth)
Q.59 In eukaryotic cells, which organelle contains its own DNA and ribosomes, indicating a possible origin from an endosymbiont?
Mitochondria
Golgi apparatus
Lysosome
Ribosome
Explanation - Mitochondria have circular DNA and 70S ribosomes, supporting the endosymbiotic theory.
Correct answer is: Mitochondria
Q.60 The structure that transports proteins from the endoplasmic reticulum to the Golgi apparatus is?
Transport vesicle
Cytoskeleton
Microtubule
Actin filament
Explanation - Transport vesicles bud off from the ER and fuse with the Golgi to deliver cargo.
Correct answer is: Transport vesicle
Q.61 Which of the following is a primary function of the smooth endoplasmic reticulum?
Protein synthesis
DNA replication
Lipid synthesis
ATP production
Explanation - The smooth ER produces lipids and steroid hormones.
Correct answer is: Lipid synthesis
Q.62 The main protein-coding unit in a cell is the?
Chromosome
Nucleosome
Gene
Promoter
Explanation - Genes are DNA segments that encode proteins.
Correct answer is: Gene
Q.63 Which organelle is responsible for the majority of protein modification via glycosylation?
Golgi apparatus
Ribosome
Endoplasmic reticulum
Lysosome
Explanation - The Golgi further glycosylates proteins and sorts them for transport.
Correct answer is: Golgi apparatus
Q.64 The enzyme that ligates nicks in DNA during replication is?
DNA polymerase
Ligase
Topoisomerase
Helicase
Explanation - DNA ligase joins Okazaki fragments by forming phosphodiester bonds.
Correct answer is: Ligase
Q.65 Which cellular component is most directly involved in the regulation of cell volume?
Plasma membrane
Cytoskeleton
Lysosome
Nucleus
Explanation - The membrane regulates ion and water permeability, controlling cell volume.
Correct answer is: Plasma membrane
Q.66 Which of these organelles is NOT found in prokaryotic cells?
Nucleus
Ribosome
Mitochondria
Lysosome
Explanation - Prokaryotes lack a true nucleus; their DNA is in the nucleoid.
Correct answer is: Nucleus
Q.67 Which of the following best describes the function of the nucleolus?
DNA replication
RNA splicing
Ribosome assembly
Protein folding
Explanation - The nucleolus produces rRNA and assembles ribosomal subunits.
Correct answer is: Ribosome assembly
Q.68 The cell cycle is divided into phases that include G1, S, G2, and M. Which phase involves DNA synthesis?
G1
S
G2
M
Explanation - The S (synthesis) phase is when DNA replication occurs.
Correct answer is: S
Q.69 Which of the following is a major function of the cytoskeleton?
Protein synthesis
Energy storage
Maintaining cell shape and intracellular transport
DNA replication
Explanation - The cytoskeleton provides structural support and tracks for organelle movement.
Correct answer is: Maintaining cell shape and intracellular transport
Q.70 The transport of molecules across the plasma membrane via protein channels is called?
Active transport
Facilitated diffusion
Osmosis
Pinocytosis
Explanation - Facilitated diffusion uses channel proteins to move solutes down a concentration gradient.
Correct answer is: Facilitated diffusion
Q.71 Which structure contains the enzymes necessary for the breakdown of cellular waste?
Peroxisome
Lysosome
Golgi apparatus
Mitochondria
Explanation - Lysosomes house hydrolytic enzymes that digest waste materials.
Correct answer is: Lysosome
Q.72 Which organelle contains a double membrane and is involved in the production of ATP?
Nucleus
Mitochondrion
Endoplasmic reticulum
Golgi apparatus
Explanation - Mitochondria have an outer and inner membrane; the inner folds form cristae for ATP production.
Correct answer is: Mitochondrion
Q.73 The process by which a cell engulfs large particles is called?
Pinocytosis
Phagocytosis
Endocytosis
Exocytosis
Explanation - Phagocytosis is the active ingestion of large particles, often performed by immune cells.
Correct answer is: Phagocytosis
Q.74 Which of the following is NOT a component of the cell wall in plant cells?
Cellulose
Chitin
Lignin
Pectin
Explanation - Chitin is a cell wall component in fungi and insects, not plants.
Correct answer is: Chitin
Q.75 Which of the following organelles is responsible for the synthesis of steroid hormones in animal cells?
Ribosome
Smooth endoplasmic reticulum
Mitochondrion
Golgi apparatus
Explanation - The smooth ER synthesizes steroid hormones from cholesterol.
Correct answer is: Smooth endoplasmic reticulum
Q.76 Which component of a ribosome is responsible for catalyzing peptide bond formation?
Large subunit
Small subunit
tRNA
mRNA
Explanation - The large ribosomal subunit contains peptidyl transferase activity.
Correct answer is: Large subunit
Q.77 What is the primary function of the cell's mitochondria?
Protein synthesis
DNA replication
ATP production
Lipid storage
Explanation - Mitochondria generate ATP through oxidative phosphorylation.
Correct answer is: ATP production
Q.78 Which of the following is a major component of the cytoskeleton?
Microfilaments
Centrosome
Vacuole
Ribosome
Explanation - Microfilaments are actin-based structures that maintain cell shape and facilitate movement.
Correct answer is: Microfilaments
Q.79 Which of the following is not typically found in the cell membrane?
Phospholipids
Proteins
Carbohydrate chains
Nucleic acids
Explanation - The cell membrane is composed of phospholipids, proteins, and carbohydrates; nucleic acids are not part of it.
Correct answer is: Nucleic acids
Q.80 Which organelle is responsible for the synthesis of ribosomal RNA?
Nucleolus
Golgi apparatus
Mitochondria
Endoplasmic reticulum
Explanation - The nucleolus is the site of rRNA synthesis and ribosome assembly.
Correct answer is: Nucleolus
Q.81 In eukaryotic cells, the mitochondria are thought to have originated from?
Viruses
Bacteria
Archaea
Protozoa
Explanation - The endosymbiotic theory suggests mitochondria evolved from free-living bacteria.
Correct answer is: Bacteria
Q.82 The main function of the endoplasmic reticulum is?
DNA replication
Protein synthesis
Energy production
Storage of lipids
Explanation - The rough ER is responsible for synthesizing membrane and secretory proteins.
Correct answer is: Protein synthesis
Q.83 Which of the following structures is a major site for lipid synthesis in the cell?
Mitochondrion
Golgi apparatus
Smooth endoplasmic reticulum
Nucleus
Explanation - The smooth ER synthesizes fatty acids and cholesterol.
Correct answer is: Smooth endoplasmic reticulum
Q.84 Which organelle contains its own DNA and ribosomes, suggesting a history of endosymbiosis?
Mitochondria
Ribosome
Nucleus
Golgi apparatus
Explanation - Mitochondria have circular DNA and ribosomes similar to bacteria.
Correct answer is: Mitochondria
Q.85 Which of the following organelles is primarily involved in the processing and sorting of proteins for secretion?
Golgi apparatus
Endoplasmic reticulum
Mitochondrion
Lysosome
Explanation - The Golgi apparatus modifies, sorts, and packages proteins and lipids for transport.
Correct answer is: Golgi apparatus
Q.86 Which structure in a plant cell is involved in photosynthesis?
Mitochondria
Chloroplast
Ribosome
Golgi apparatus
Explanation - Chloroplasts contain chlorophyll and perform light-dependent reactions of photosynthesis.
Correct answer is: Chloroplast
Q.87 The cell's central storage organelle for starch in plant cells is known as the?
Vacuole
Chloroplast
Mitochondrion
Endoplasmic reticulum
Explanation - Large central vacuoles store nutrients like starch in plant cells.
Correct answer is: Vacuole
Q.88 What type of bond joins amino acids in a polypeptide chain?
Peptide bond
Ionic bond
Disulfide bond
Hydrogen bond
Explanation - A peptide bond links the carboxyl group of one amino acid to the amino group of the next.
Correct answer is: Peptide bond
Q.89 Which organelle is responsible for producing ribosomal proteins and rRNA?
Nucleolus
Golgi apparatus
Ribosome
Mitochondria
Explanation - The nucleolus synthesizes rRNA and assembles ribosomal subunits.
Correct answer is: Nucleolus
Q.90 Which of the following statements about the cytoskeleton is TRUE?
It is composed of only actin filaments
It provides structural support and facilitates intracellular transport
It is found only in prokaryotic cells
It is primarily involved in DNA replication
Explanation - The cytoskeleton includes microtubules, actin filaments, and intermediate filaments for structure and transport.
Correct answer is: It provides structural support and facilitates intracellular transport
Q.91 Which organelle is the main site of ATP production?
Mitochondrion
Peroxisome
Golgi apparatus
Endoplasmic reticulum
Explanation - Mitochondria house the electron transport chain and ATP synthase.
Correct answer is: Mitochondrion
Q.92 In the cell, which structure contains enzymes for hydrolyzing proteins?
Lysosome
Ribosome
Vacuole
Peroxisome
Explanation - Lysosomes contain proteases that break down proteins.
Correct answer is: Lysosome
Q.93 Which of the following is a function of the plasma membrane?
DNA replication
Protein synthesis
Selective barrier for transport
Energy storage
Explanation - The plasma membrane regulates entry and exit of substances.
Correct answer is: Selective barrier for transport
Q.94 The enzyme that attaches a phosphate group to ADP to form ATP is?
ATP synthase
ATPase
Kinase
Ligase
Explanation - ATP synthase catalyzes the phosphorylation of ADP to ATP during oxidative phosphorylation.
Correct answer is: ATP synthase
Q.95 Which organelle is responsible for the synthesis of most proteins that are secreted outside the cell?
Endoplasmic reticulum (rough)
Peroxisome
Lysosome
Golgi apparatus
Explanation - The rough ER synthesizes proteins destined for secretion or membrane insertion.
Correct answer is: Endoplasmic reticulum (rough)
Q.96 The smooth endoplasmic reticulum is especially abundant in cells that need to produce large amounts of?
Proteins
Lipids
Carbohydrates
Nucleic acids
Explanation - The smooth ER specializes in lipid and steroid hormone synthesis.
Correct answer is: Lipids
Q.97 Which organelle has a double membrane and houses the machinery for oxidative phosphorylation?
Ribosome
Mitochondrion
Golgi apparatus
Endoplasmic reticulum
Explanation - The inner mitochondrial membrane contains the electron transport chain.
Correct answer is: Mitochondrion
Q.98 Which of the following is NOT a type of RNA?
mRNA
tRNA
rRNA
dRNA
Explanation - dRNA is not a recognized type of RNA; the known types are mRNA, tRNA, rRNA, and others like miRNA.
Correct answer is: dRNA
Q.99 What is the major function of the nucleus?
Protein synthesis
Energy production
Gene expression regulation
Detoxification
Explanation - The nucleus houses DNA and controls transcription of genes.
Correct answer is: Gene expression regulation
Q.100 Which of the following is a primary function of the cell membrane?
Synthesize proteins
Regulate transport of molecules
Store genetic information
Produce ATP
Explanation - The plasma membrane controls the passage of substances into and out of the cell.
Correct answer is: Regulate transport of molecules
Q.101 The cytoplasm contains which of the following?
DNA
Organelle membranes
All of the above
None of the above
Explanation - The cytoplasm houses organelles, cytosol, and various molecules.
Correct answer is: All of the above
Q.102 Which organelle is often called the 'factory of the cell'?
Golgi apparatus
Endoplasmic reticulum
Mitochondria
Ribosome
Explanation - Ribosomes are the sites of protein synthesis.
Correct answer is: Ribosome
Q.103 Which of the following structures is involved in the detoxification of harmful substances?
Peroxisome
Ribosome
Lysosome
Golgi apparatus
Explanation - Peroxisomes contain enzymes that break down toxic molecules.
Correct answer is: Peroxisome
Q.104 Which organelle is responsible for the transport of proteins to lysosomes?
Golgi apparatus
Ribosome
Endoplasmic reticulum
Mitochondrion
Explanation - The Golgi modifies and tags proteins for lysosomal delivery.
Correct answer is: Golgi apparatus
Q.105 Which of the following is a characteristic of prokaryotic cells?
Presence of membrane-bound organelles
Large size
Lack of nucleus
Multiple mitochondria
Explanation - Prokaryotes do not have a true nucleus; their DNA is in the nucleoid region.
Correct answer is: Lack of nucleus
Q.106 Which organelle is involved in the synthesis of steroid hormones?
Smooth endoplasmic reticulum
Ribosome
Peroxisome
Vacuole
Explanation - The smooth ER synthesizes lipids and steroid hormones.
Correct answer is: Smooth endoplasmic reticulum
Q.107 Which organelle stores DNA that is transcribed into RNA?
Nucleus
Golgi apparatus
Endoplasmic reticulum
Mitochondria
Explanation - The nucleus contains chromatin, which is transcribed into mRNA.
Correct answer is: Nucleus
Q.108 Which organelle has a network of tubules and is involved in protein folding?
Golgi apparatus
Endoplasmic reticulum
Ribosome
Lysosome
Explanation - The ER contains a network of tubules for protein folding and transport.
Correct answer is: Endoplasmic reticulum
Q.109 What type of bond holds the two strands of DNA together?
Peptide bond
Covalent bond
Hydrogen bond
Ionic bond
Explanation - Complementary bases are linked by hydrogen bonds in the DNA double helix.
Correct answer is: Hydrogen bond
Q.110 Which organelle is primarily responsible for the modification and sorting of proteins before secretion?
Golgi apparatus
Endoplasmic reticulum
Mitochondrion
Ribosome
Explanation - The Golgi modifies, sorts, and packages proteins for transport.
Correct answer is: Golgi apparatus
Q.111 Which of the following is a function of the lysosome?
Protein synthesis
DNA replication
Enzymatic breakdown of waste
ATP production
Explanation - Lysosomes contain hydrolytic enzymes that digest cellular waste.
Correct answer is: Enzymatic breakdown of waste
Q.112 Which of the following is not found in the cytoplasm?
Mitochondria
Ribosomes
Nucleus
Endoplasmic reticulum
Explanation - The nucleus is a membrane-bound organelle located in the cytoplasm, but not part of the cytosol.
Correct answer is: Nucleus
Q.113 Which structure in a plant cell is the site of photosynthesis?
Chloroplast
Mitochondrion
Ribosome
Vacuole
Explanation - Chloroplasts contain chlorophyll and carry out photosynthesis.
Correct answer is: Chloroplast
Q.114 What is the main function of the ribosomal RNA (rRNA) in a cell?
Carry genetic information
Catalyze peptide bond formation
Store genetic material
Transport proteins
Explanation - rRNA forms the catalytic core of the ribosome and facilitates protein synthesis.
Correct answer is: Catalyze peptide bond formation
Q.115 Which organelle is involved in the detoxification of hydrogen peroxide?
Mitochondrion
Peroxisome
Golgi apparatus
Ribosome
Explanation - Peroxisomes contain catalase to break down hydrogen peroxide.
Correct answer is: Peroxisome
Q.116 The cell membrane is composed of which of the following molecules?
Phospholipids, proteins, carbohydrates
DNA, RNA, proteins
Carbohydrates, nucleic acids
Lipids only
Explanation - The membrane is a phospholipid bilayer embedded with proteins and carbohydrates.
Correct answer is: Phospholipids, proteins, carbohydrates
Q.117 Which organelle is the primary site for the synthesis of proteins that are destined for secretion?
Golgi apparatus
Ribosome
Rough endoplasmic reticulum
Peroxisome
Explanation - Rough ER synthesizes proteins that will be secreted or integrated into membranes.
Correct answer is: Rough endoplasmic reticulum
Q.118 Which of the following is a characteristic of a eukaryotic cell?
Lack of membrane-bound organelles
Presence of a nucleus
Single circular chromosome
No cytoplasm
Explanation - Eukaryotic cells contain a membrane-bound nucleus and other organelles.
Correct answer is: Presence of a nucleus
Q.119 Which of the following organelles is involved in the synthesis of ribosomal subunits?
Mitochondrion
Golgi apparatus
Nucleolus
Ribosome
Explanation - The nucleolus produces rRNA and assembles ribosomal subunits.
Correct answer is: Nucleolus
Q.120 The main function of the cytoskeleton is to?
Store genetic material
Maintain cell shape and provide support
Synthesize proteins
Generate ATP
Explanation - The cytoskeleton provides structural integrity and facilitates movement.
Correct answer is: Maintain cell shape and provide support
Q.121 The process of mRNA leaving the nucleus and entering the cytoplasm is called?
Transcription
Translation
Export
Splicing
Explanation - mRNA is exported through nuclear pores to the cytoplasm for translation.
Correct answer is: Export
Q.122 Which organelle is responsible for the breakdown of fatty acids?
Lysosome
Peroxisome
Golgi apparatus
Ribosome
Explanation - Peroxisomes carry out beta-oxidation of long-chain fatty acids.
Correct answer is: Peroxisome
Q.123 What type of membrane transport uses energy to move molecules against a gradient?
Passive diffusion
Facilitated diffusion
Active transport
Osmosis
Explanation - Active transport requires ATP to move molecules against their concentration gradient.
Correct answer is: Active transport
Q.124 Which organelle contains the machinery for translating mRNA into proteins?
Nucleus
Ribosome
Golgi apparatus
Endoplasmic reticulum
Explanation - Ribosomes read mRNA and catalyze peptide bond formation.
Correct answer is: Ribosome
Q.125 Which of the following is a primary component of the cytoskeleton?
Microfilaments
Mitochondria
Chloroplast
Ribosome
Explanation - Microfilaments (actin) are part of the cytoskeletal network.
Correct answer is: Microfilaments
Q.126 Which organelle is known for its role in the degradation of cellular waste materials?
Mitochondria
Lysosome
Peroxisome
Golgi apparatus
Explanation - Lysosomes contain hydrolytic enzymes that digest waste.
Correct answer is: Lysosome
Q.127 Which organelle is involved in the transport of proteins and lipids through the cell?
Endoplasmic reticulum
Ribosome
Vacuole
Lysosome
Explanation - The ER serves as a network for protein and lipid synthesis and transport.
Correct answer is: Endoplasmic reticulum
Q.128 Which of the following is NOT a function of the cell membrane?
Regulating cell entry and exit of materials
Providing structural support
Facilitating signal transduction
Storing genetic information
Explanation - Genetic information is stored in the nucleus, not the membrane.
Correct answer is: Storing genetic information
Q.129 Which organelle is responsible for the synthesis of most proteins that are secreted by the cell?
Ribosome
Golgi apparatus
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
Explanation - Rough ER is where secretory proteins are synthesized.
Correct answer is: Rough endoplasmic reticulum
Q.130 The process of translating mRNA into a polypeptide chain occurs in the?
Nucleus
Ribosome
Mitochondrion
Endoplasmic reticulum
Explanation - Ribosomes carry out translation, synthesizing proteins from mRNA.
Correct answer is: Ribosome
Q.131 Which of the following is an example of a protein that functions in the cytoskeleton?
Actin
Tubulin
Spectrin
All of the above
Explanation - Actin, tubulin, and spectrin are cytoskeletal proteins.
Correct answer is: All of the above
Q.132 Which organelle stores and releases calcium ions in a cell?
Ribosome
Golgi apparatus
Endoplasmic reticulum
Mitochondrion
Explanation - The ER serves as a calcium ion reservoir, releasing Ca2+ during signaling.
Correct answer is: Endoplasmic reticulum
Q.133 The main site of protein synthesis is the?
Golgi apparatus
Nucleus
Ribosome
Rough endoplasmic reticulum
Explanation - Ribosomes are the molecular machines that synthesize proteins.
Correct answer is: Ribosome
Q.134 Which of the following structures is involved in the synthesis and modification of lipids?
Mitochondrion
Golgi apparatus
Endoplasmic reticulum
Ribosome
Explanation - The smooth ER synthesizes lipids.
Correct answer is: Endoplasmic reticulum
Q.135 Which of the following is not a type of RNA?
mRNA
tRNA
rRNA
dRNA
Explanation - dRNA is not recognized; the known types are mRNA, tRNA, rRNA, etc.
Correct answer is: dRNA
Q.136 The nucleolus is located in the nucleus and is involved in?
DNA replication
mRNA splicing
Ribosome assembly
Protein transport
Explanation - The nucleolus synthesizes rRNA and assembles ribosomal subunits.
Correct answer is: Ribosome assembly
Q.137 Which organelle has the ability to produce energy in the form of ATP through oxidative phosphorylation?
Peroxisome
Endoplasmic reticulum
Mitochondrion
Golgi apparatus
Explanation - Mitochondria generate ATP via the electron transport chain and ATP synthase.
Correct answer is: Mitochondrion
Q.138 The main function of the Golgi apparatus is to?
Store genetic material
Produce ATP
Modify, sort, and package proteins
Synthesize ribosomal RNA
Explanation - The Golgi modifies proteins, sorts them, and directs them to destinations.
Correct answer is: Modify, sort, and package proteins
Q.139 Which of the following is the largest organelle in a eukaryotic cell?
Mitochondrion
Nucleus
Ribosome
Lysosome
Explanation - The nucleus is typically the largest organelle, housing the cell’s DNA.
Correct answer is: Nucleus
Q.140 Which organelle is involved in the detoxification of hydrogen peroxide?
Golgi apparatus
Mitochondrion
Peroxisome
Ribosome
Explanation - Peroxisomes contain catalase to break down hydrogen peroxide.
Correct answer is: Peroxisome
Q.141 Which organelle is the site of ATP production?
Ribosome
Mitochondrion
Golgi apparatus
Peroxisome
Explanation - Mitochondria generate ATP via cellular respiration.
Correct answer is: Mitochondrion
Q.142 The cell membrane is composed of which of the following molecules?
Phospholipids
Proteins
Carbohydrates
All of the above
Explanation - The plasma membrane is a phospholipid bilayer embedded with proteins and carbohydrates.
Correct answer is: All of the above
Q.143 The process of a cell engulfing a particle is called?
Phagocytosis
Pinocytosis
Endocytosis
Exocytosis
Explanation - Phagocytosis is the active ingestion of large particles.
Correct answer is: Phagocytosis
Q.144 Which organelle is involved in the synthesis of proteins that are destined for the lysosome?
Golgi apparatus
Ribosome
Endoplasmic reticulum
Mitochondrion
Explanation - The Golgi tags proteins with mannose-6-phosphate for lysosomal delivery.
Correct answer is: Golgi apparatus
Q.145 Which of the following is not a characteristic of eukaryotic cells?
Presence of a nucleus
Presence of membrane-bound organelles
Single circular chromosome
Complex cytoskeletal structures
Explanation - Eukaryotic cells have multiple linear chromosomes within a nucleus.
Correct answer is: Single circular chromosome
Q.146 Which organelle is the site of ribosomal assembly and rRNA synthesis?
Ribosome
Golgi apparatus
Nucleolus
Endoplasmic reticulum
Explanation - The nucleolus is the site of rRNA transcription and ribosome subunit assembly.
Correct answer is: Nucleolus
Q.147 Which organelle is involved in the synthesis of cholesterol and steroid hormones?
Peroxisome
Endoplasmic reticulum (smooth)
Golgi apparatus
Mitochondrion
Explanation - The smooth ER synthesizes sterols and steroid hormones from cholesterol.
Correct answer is: Endoplasmic reticulum (smooth)
Q.148 The main function of the cytoskeleton is to?
Store genetic material
Maintain cell shape and facilitate intracellular transport
Synthesize proteins
Generate ATP
Explanation - The cytoskeleton provides structural support and serves as tracks for organelle movement.
Correct answer is: Maintain cell shape and facilitate intracellular transport
Q.149 The function of the nuclear pore complex is to?
Export RNA from the nucleus
Import proteins into the nucleus
Both A and B
Neither A nor B
Explanation - Nuclear pores mediate transport of RNA out and proteins into the nucleus.
Correct answer is: Both A and B
Q.150 The process of cellular respiration occurs mainly in which organelle?
Ribosome
Golgi apparatus
Mitochondrion
Endoplasmic reticulum
Explanation - Mitochondria carry out glycolysis, the citric acid cycle, and oxidative phosphorylation.
Correct answer is: Mitochondrion
Q.151 Which structure in a cell is responsible for the synthesis of ribosomes?
Nucleus
Nucleolus
Ribosome
Endoplasmic reticulum
Explanation - Ribosomes are assembled in the nucleolus from rRNA and proteins.
Correct answer is: Nucleolus
Q.152 Which organelle is involved in the degradation of cellular components in the lysosome?
Mitochondrion
Golgi apparatus
Peroxisome
Lysosome
Explanation - Lysosomes contain digestive enzymes that degrade macromolecules.
Correct answer is: Lysosome
Q.153 What is the main component of the cell’s cytoskeleton?
Microfilaments, microtubules, and intermediate filaments
Ribosomes
Mitochondria
Chloroplasts
Explanation - The cytoskeleton is composed of three types of filamentous structures.
Correct answer is: Microfilaments, microtubules, and intermediate filaments
Q.154 Which organelle is responsible for producing the building blocks of the cell membrane?
Peroxisome
Endoplasmic reticulum
Golgi apparatus
Mitochondrion
Explanation - The ER synthesizes phospholipids and cholesterol for the plasma membrane.
Correct answer is: Endoplasmic reticulum
Q.155 The structure that provides a scaffold for protein synthesis and assembly is the?
Ribosome
Golgi apparatus
Lysosome
Peroxisome
Explanation - Ribosomes are the cellular machines that synthesize proteins.
Correct answer is: Ribosome
Q.156 Which of the following is a function of the endoplasmic reticulum?
Protein synthesis
DNA replication
Energy production
Storing genetic material
Explanation - The rough ER is involved in synthesizing membrane and secretory proteins.
Correct answer is: Protein synthesis
Q.157 The mitochondria’s inner membrane folds are called what?
Cristae
Ribs
Spines
Fibers
Explanation - Cristae increase the surface area for oxidative phosphorylation.
Correct answer is: Cristae
Q.158 The primary function of the cell wall in plant cells is to?
Store genetic information
Maintain shape and protect against osmotic lysis
Store energy
Transport water
Explanation - The cell wall provides structural support and prevents the cell from bursting.
Correct answer is: Maintain shape and protect against osmotic lysis
Q.159 Which organelle is responsible for packaging proteins for secretion?
Golgi apparatus
Endoplasmic reticulum
Ribosome
Lysosome
Explanation - The Golgi modifies, sorts, and dispatches proteins to their destinations.
Correct answer is: Golgi apparatus
Q.160 What is the main structural component of the cell membrane’s interior?
Phospholipid tails
Carbohydrate chains
Protein cores
Nucleic acids
Explanation - Phospholipid tails form the hydrophobic interior of the bilayer.
Correct answer is: Phospholipid tails
Q.161 Which organelle is responsible for the synthesis of proteins that are destined for the lysosome?
Ribosome
Golgi apparatus
Endoplasmic reticulum
Peroxisome
Explanation - Golgi tags proteins with mannose-6-phosphate for lysosomal delivery.
Correct answer is: Golgi apparatus
Q.162 What is the primary role of the mitochondria’s outer membrane?
To provide a barrier for ATP synthesis
To control the import and export of proteins and metabolites
To contain the electron transport chain
To synthesize ribosomal RNA
Explanation - The outer membrane contains porin proteins that allow passage of small molecules.
Correct answer is: To control the import and export of proteins and metabolites
Q.163 Which organelle is involved in the synthesis of ribosomal subunits?
Ribosome
Golgi apparatus
Nucleolus
Mitochondrion
Explanation - The nucleolus is the site of rRNA transcription and ribosome assembly.
Correct answer is: Nucleolus
Q.164 Which structure in a cell is the site of ATP synthesis during aerobic respiration?
Mitochondrion
Golgi apparatus
Peroxisome
Endoplasmic reticulum
Explanation - The mitochondrial inner membrane hosts oxidative phosphorylation.
Correct answer is: Mitochondrion
Q.165 Which organelle is known for its role in the detoxification of hydrogen peroxide?
Mitochondrion
Peroxisome
Golgi apparatus
Ribosome
Explanation - Catalase in peroxisomes breaks down hydrogen peroxide.
Correct answer is: Peroxisome
Q.166 Which organelle contains the genetic material that encodes mitochondrial proteins?
Nucleus
Mitochondria
Ribosome
Endoplasmic reticulum
Explanation - Mitochondria have their own circular DNA encoding some mitochondrial proteins.
Correct answer is: Mitochondria
Q.167 Which of the following structures is a major site for the synthesis of ribosomal proteins?
Ribosome
Nucleus
Endoplasmic reticulum
Mitochondrion
Explanation - Ribosomes synthesize proteins from mRNA; ribosomal proteins are part of ribosomal structure.
Correct answer is: Ribosome
Q.168 What is the primary function of the cell membrane?
Transport molecules
Energy production
Genetic storage
Protein synthesis
Explanation - The plasma membrane selectively allows transport of substances in and out of the cell.
Correct answer is: Transport molecules
Q.169 Which organelle is involved in the synthesis of proteins that are destined for secretion?
Rough endoplasmic reticulum
Golgi apparatus
Smooth endoplasmic reticulum
Peroxisome
Explanation - Rough ER synthesizes secretory proteins on its ribosome-coated surface.
Correct answer is: Rough endoplasmic reticulum
Q.170 Which organelle is the site of ATP production?
Ribosome
Golgi apparatus
Mitochondrion
Endoplasmic reticulum
Explanation - ATP is produced in the mitochondrial matrix and inner membrane.
Correct answer is: Mitochondrion
Q.171 Which organelle is involved in the detoxification of hydrogen peroxide?
Golgi apparatus
Peroxisome
Ribosome
Mitochondrion
Explanation - Peroxisomes contain catalase to break down H₂O₂.
Correct answer is: Peroxisome
Q.172 Which organelle is responsible for the synthesis of ribosomes?
Nucleolus
Ribosome
Golgi apparatus
Endoplasmic reticulum
Explanation - The nucleolus assembles ribosomal subunits from rRNA and proteins.
Correct answer is: Nucleolus
Q.173 Which organelle is known for its role in the detoxification of hydrogen peroxide?
Mitochondrion
Peroxisome
Golgi apparatus
Ribosome
Explanation - Catalase in peroxisomes degrades hydrogen peroxide to water and oxygen.
Correct answer is: Peroxisome
Q.174 Which organelle is involved in the synthesis of proteins that are destined for secretion?
Golgi apparatus
Endoplasmic reticulum (rough)
Mitochondrion
Peroxisome
Explanation - Rough ER synthesizes proteins that will be secreted or integrated into membranes.
Correct answer is: Endoplasmic reticulum (rough)
Q.175 Which organelle is primarily responsible for the production of ATP?
Ribosome
Golgi apparatus
Mitochondrion
Endoplasmic reticulum
Explanation - Mitochondria generate ATP via oxidative phosphorylation.
Correct answer is: Mitochondrion
Q.176 The cell membrane is composed of which of the following molecules?
Phospholipids
Proteins
Carbohydrates
All of the above
Explanation - The plasma membrane is a phospholipid bilayer with embedded proteins and carbohydrates.
Correct answer is: All of the above
Q.177 The process of protein synthesis occurs in which organelle?
Mitochondrion
Golgi apparatus
Ribosome
Endoplasmic reticulum
Explanation - Ribosomes read mRNA and synthesize polypeptides.
Correct answer is: Ribosome
Q.178 The cytoskeleton is composed of?
Microfilaments, microtubules, intermediate filaments
Microtubules only
Actin only
Microfilaments only
Explanation - The cytoskeleton consists of three classes of filamentous proteins.
Correct answer is: Microfilaments, microtubules, intermediate filaments