MCQs on Human Cell Physiology
1. What is the basic structural unit of life?
- a) Atom
- b) Organ
- c) Cell
- d) Tissue
Answer: c) Cell
Explanation: The cell is the basic structural and functional unit of life. All organisms are made up of cells, and it performs essential life processes, such as metabolism, energy production, and reproduction.
2. Which organelle is responsible for protein synthesis in the cell?
- a) Mitochondrion
- b) Nucleus
- c) Ribosome
- d) Golgi apparatus
Answer: c) Ribosome
Explanation: Ribosomes are responsible for synthesizing proteins by translating messenger RNA (mRNA) into amino acid sequences, a process known as translation.
3. Which part of the cell controls the movement of substances in and out of the cell?
- a) Nucleus
- b) Plasma membrane
- c) Mitochondrion
- d) Endoplasmic reticulum
Answer: b) Plasma membrane
Explanation: The plasma membrane regulates the movement of substances in and out of the cell through mechanisms like passive diffusion, active transport, and endocytosis.
4. What is the function of mitochondria?
- a) Protein synthesis
- b) Energy production
- c) DNA replication
- d) Lipid metabolism
Answer: b) Energy production
Explanation: Mitochondria are known as the powerhouses of the cell. They generate energy in the form of ATP through cellular respiration, providing the necessary energy for cellular activities.
5. Which of the following structures is involved in cellular communication?
- a) Cytoplasm
- b) Nucleus
- c) Plasma membrane
- d) Lysosome
Answer: c) Plasma membrane
Explanation: The plasma membrane plays a crucial role in cellular communication. It contains receptors that bind with signaling molecules like hormones, triggering a response in the cell.
6. What type of cell division results in two identical daughter cells?
- a) Meiosis
- b) Binary fission
- c) Mitosis
- d) Amitosis
Answer: c) Mitosis
Explanation: Mitosis is the type of cell division where a parent cell divides to produce two genetically identical daughter cells, each having the same number of chromosomes as the parent cell.
7. Which organelle is involved in the synthesis of lipids and detoxification?
- a) Endoplasmic reticulum
- b) Golgi apparatus
- c) Mitochondria
- d) Lysosome
Answer: a) Endoplasmic reticulum
Explanation: The smooth endoplasmic reticulum (ER) synthesizes lipids and detoxifies harmful substances, while the rough ER is involved in protein synthesis.
8. Which process describes the movement of water across the cell membrane?
- a) Active transport
- b) Facilitated diffusion
- c) Osmosis
- d) Endocytosis
Answer: c) Osmosis
Explanation: Osmosis is the passive movement of water molecules from a region of low solute concentration to a region of high solute concentration through a semipermeable membrane.
9. What is the main function of lysosomes?
- a) Protein synthesis
- b) Energy production
- c) Digestion of cellular waste
- d) DNA replication
Answer: c) Digestion of cellular waste
Explanation: Lysosomes contain enzymes that break down waste materials, cellular debris, and foreign substances, recycling components within the cell.
10. What is the primary role of the Golgi apparatus?
- a) Lipid synthesis
- b) Protein modification and packaging
- c) DNA replication
- d) ATP production
Answer: b) Protein modification and packaging
Explanation: The Golgi apparatus modifies, sorts, and packages proteins and lipids from the endoplasmic reticulum for transport to their final destinations within or outside the cell.
11. Which structure in the cell contains genetic material?
- a) Plasma membrane
- b) Cytoplasm
- c) Nucleus
- d) Mitochondria
Answer: c) Nucleus
Explanation: The nucleus houses the cell's genetic material in the form of DNA, which controls cellular functions, including growth, metabolism, and reproduction.
12. Which of the following is the smallest unit of life that can carry out all necessary life functions?
- a) Organ
- b) Tissue
- c) Organism
- d) Cell
Answer: d) Cell
Explanation: A cell is the smallest unit of life capable of performing all essential functions such as metabolism, reproduction, and response to stimuli.
13. What does the term "cytoplasm" refer to?
- a) The part of the cell outside the membrane
- b) The liquid inside the nucleus
- c) The gel-like substance inside the cell membrane that holds organelles
- d) The outermost layer of the cell
Answer: c) The gel-like substance inside the cell membrane that holds organelles
Explanation: The cytoplasm consists of a jelly-like substance and organelles that are suspended in it. It is the site for most cellular activities, including metabolism.
14. Which process involves the engulfing of solid particles by a cell?
- a) Exocytosis
- b) Phagocytosis
- c) Osmosis
- d) Diffusion
Answer: b) Phagocytosis
Explanation: Phagocytosis is a type of endocytosis where the cell engulfs large particles such as debris, pathogens, or dead cells, forming a vesicle that fuses with lysosomes for digestion.
15. What is the main function of the nuclear envelope?
- a) To store DNA
- b) To protect the nucleus
- c) To generate energy
- d) To synthesize proteins
Answer: b) To protect the nucleus
Explanation: The nuclear envelope is a double membrane that surrounds the nucleus, protecting the genetic material and regulating the passage of molecules in and out of the nucleus.
16. What is the role of ribosomal RNA (rRNA)?
- a) Helps synthesize proteins
- b) Carries genetic information
- c) Forms the structure of ribosomes
- d) Transports molecules
Answer: c) Forms the structure of ribosomes
Explanation: Ribosomal RNA (rRNA) is a structural component of ribosomes. It plays a crucial role in protein synthesis by facilitating the binding of mRNA and tRNA.
17. Which of the following processes uses energy to move substances against a concentration gradient?
- a) Diffusion
- b) Osmosis
- c) Active transport
- d) Facilitated diffusion
Answer: c) Active transport
Explanation: Active transport uses energy (ATP) to move molecules from areas of low concentration to areas of high concentration, against the concentration gradient.
18. Which type of cell communication involves a signal molecule traveling to distant target cells?
- a) Direct communication
- b) Paracrine signaling
- c) Autocrine signaling
- d) Endocrine signaling
Answer: d) Endocrine signaling
Explanation: In endocrine signaling, hormones are released into the bloodstream and travel to distant target cells to regulate various physiological processes.
19. What structure regulates the entry and exit of substances in the cell?
- a) Nucleus
- b) Plasma membrane
- c) Golgi apparatus
- d) Ribosomes
Answer: b) Plasma membrane
Explanation: The plasma membrane controls the passage of substances in and out of the cell through selective permeability, allowing some molecules to pass while blocking others.
20. Which of the following organelles is involved in the production of ATP?
- a) Lysosome
- b) Mitochondrion
- c) Ribosome
- d) Endoplasmic reticulum
Answer: b) Mitochondrion
Explanation: Mitochondria are the powerhouse of the cell, responsible for generating ATP, which is used as the primary energy source for cellular activities
21. Which of the following is responsible for the production of ATP during aerobic respiration?
- a) Ribosomes
- b) Mitochondria
- c) Nucleus
- d) Cytoplasm
Answer: b) Mitochondria
Explanation: Mitochondria produce ATP through oxidative phosphorylation during aerobic respiration, which occurs in the inner membrane of the mitochondria. This process requires oxygen and generates a large amount of energy.
22. Which of the following is the main structural component of the plasma membrane?
- a) Phospholipids
- b) Proteins
- c) Carbohydrates
- d) Nucleic acids
Answer: a) Phospholipids
Explanation: Phospholipids form the basic structure of the plasma membrane, creating a bilayer that provides selective permeability, while proteins embedded in the membrane assist in transport and signaling.
23. What is the main function of the cytoskeleton?
- a) Protein synthesis
- b) Maintaining cell shape and facilitating movement
- c) Storing genetic material
- d) Regulating transport in the cell
Answer: b) Maintaining cell shape and facilitating movement
Explanation: The cytoskeleton provides structural support to the cell, helping it maintain its shape and facilitating intracellular transport and cell movement.
24. What is the role of transport vesicles?
- a) Synthesize proteins
- b) Store energy
- c) Transport molecules between organelles
- d) Regulate gene expression
Answer: c) Transport molecules between organelles
Explanation: Transport vesicles carry proteins, lipids, and other molecules between different organelles, including the endoplasmic reticulum, Golgi apparatus, and plasma membrane.
25. In which cellular process does the cell divide its cytoplasm and organelles into two daughter cells?
- a) Mitosis
- b) Cytokinesis
- c) Meiosis
- d) Binary fission
Answer: b) Cytokinesis
Explanation: Cytokinesis is the process in which the cytoplasm and organelles are divided between two daughter cells following mitosis or meiosis, completing cell division.
26. Which of the following best describes the role of cholesterol in the plasma membrane?
- a) Provides energy
- b) Stabilizes membrane fluidity
- c) Forms a barrier against toxins
- d) Catalyzes reactions
Answer: b) Stabilizes membrane fluidity
Explanation: Cholesterol is an essential component of the plasma membrane. It helps maintain membrane fluidity, preventing the membrane from becoming too rigid or too fluid.
27. Which type of RNA carries genetic information from DNA to the ribosomes for protein synthesis?
- a) rRNA
- b) tRNA
- c) mRNA
- d) miRNA
Answer: c) mRNA
Explanation: Messenger RNA (mRNA) carries genetic information transcribed from DNA to the ribosomes, where it serves as a template for protein synthesis during translation.
28. What is the main function of the smooth endoplasmic reticulum (ER)?
- a) Protein synthesis
- b) Lipid synthesis and detoxification
- c) Transport of proteins
- d) DNA replication
Answer: b) Lipid synthesis and detoxification
Explanation: The smooth ER is involved in lipid synthesis, metabolism of carbohydrates, and detoxification of drugs and poisons. It lacks ribosomes on its surface.
29. What is the process by which cells ingest liquid from their environment?
- a) Phagocytosis
- b) Pinocytosis
- c) Endocytosis
- d) Exocytosis
Answer: b) Pinocytosis
Explanation: Pinocytosis is a form of endocytosis where cells take in extracellular fluid and its dissolved solutes through small vesicles, often referred to as "cell drinking."
30. Which of the following is NOT a function of the plasma membrane?
- a) Communication with other cells
- b) Maintaining cellular shape
- c) Synthesizing proteins
- d) Regulating molecule transport
Answer: c) Synthesizing proteins
Explanation: The plasma membrane functions in communication, maintaining cell shape, and regulating molecule transport, but protein synthesis occurs primarily in ribosomes, not the plasma membrane.
31. Which type of cell junction allows for direct communication between adjacent cells?
- a) Tight junctions
- b) Gap junctions
- c) Desmosomes
- d) Hemidesmosomes
Answer: b) Gap junctions
Explanation: Gap junctions are specialized structures that allow direct communication between adjacent cells by enabling the passage of ions and small molecules.
32. Which of the following processes involves the movement of solutes from a region of high concentration to low concentration?
- a) Active transport
- b) Osmosis
- c) Diffusion
- d) Phagocytosis
Answer: c) Diffusion
Explanation: Diffusion is the passive movement of solutes from a region of higher concentration to lower concentration. It does not require energy input.
33. What is the function of the nuclear pore complexes?
- a) Store genetic material
- b) Regulate the passage of molecules between the nucleus and cytoplasm
- c) Synthesize ribosomal RNA
- d) Facilitate DNA replication
Answer: b) Regulate the passage of molecules between the nucleus and cytoplasm
Explanation: Nuclear pore complexes are channels in the nuclear envelope that control the exchange of molecules, such as RNA and proteins, between the nucleus and the cytoplasm.
34. Which of the following best describes the role of glycoproteins in the plasma membrane?
- a) Catalyze chemical reactions
- b) Act as receptors and aid in cell recognition
- c) Transport molecules across the membrane
- d) Provide structural support
Answer: b) Act as receptors and aid in cell recognition
Explanation: Glycoproteins are proteins with carbohydrate chains attached to them. They play a key role in cell-cell recognition, signaling, and immune response.
35. Which organelle is responsible for the detoxification of harmful substances like alcohol and drugs?
- a) Mitochondrion
- b) Smooth ER
- c) Nucleus
- d) Lysosome
Answer: b) Smooth ER
Explanation: The smooth endoplasmic reticulum is involved in the detoxification of harmful substances, including drugs, alcohol, and metabolic waste products, by enzymatic modification.
36. What is the main function of the rough endoplasmic reticulum (ER)?
- a) Synthesis of lipids
- b) Protein synthesis and modification
- c) Detoxification of drugs
- d) Energy production
Answer: b) Protein synthesis and modification
Explanation: The rough ER, studded with ribosomes, synthesizes and modifies proteins that are either secreted or incorporated into the plasma membrane.
37. Which of the following is NOT a function of lysosomes?
- a) Digestion of cellular waste
- b) Recycling of cellular materials
- c) Protein synthesis
- d) Defense against pathogens
Answer: c) Protein synthesis
Explanation: Lysosomes are responsible for digesting waste materials, recycling components, and defending against pathogens, but they do not synthesize proteins.
38. What is the main purpose of cellular respiration?
- a) To create proteins
- b) To generate ATP for cellular energy
- c) To store genetic information
- d) To divide the cell into two daughter cells
Answer: b) To generate ATP for cellular energy
Explanation: Cellular respiration breaks down glucose and other molecules to produce ATP, which is the primary energy currency of the cell, used for various cellular processes.
39. What is the structure of DNA in eukaryotic cells?
- a) Circular
- b) Linear and found in the nucleus
- c) Linear and found in the cytoplasm
- d) Circular and found in the mitochondria
Answer: b) Linear and found in the nucleus
Explanation: DNA in eukaryotic cells is linear and located in the nucleus, whereas in prokaryotes, it is typically circular and found in the cytoplasm.
40. Which type of transport mechanism does NOT require energy?
- a) Active transport
- b) Diffusion
- c) Endocytosis
- d) Exocytosis
Answer: b) Diffusion
Explanation: Diffusion is a passive process that occurs without the expenditure of energy, as molecules move from areas of higher to lower concentration.
41. Which of the following is responsible for carrying amino acids to the ribosomes during protein synthesis?
- a) mRNA
- b) tRNA
- c) rRNA
- d) miRNA
Answer: b) tRNA
Explanation: Transfer RNA (tRNA) carries amino acids to the ribosome, where it helps assemble the amino acids into proteins according to the sequence specified by mRNA.
42. What is the function of the centrosome?
- a) Control gene expression
- b) Organize microtubules for cell division
- c) Transport proteins
- d) Synthesize lipids
Answer: b) Organize microtubules for cell division
Explanation: The centrosome organizes microtubules that form the spindle apparatus during mitosis and meiosis, aiding in chromosome movement and cell division.
43. Which organelle is responsible for the synthesis of ribosomal RNA (rRNA)?
- a) Nucleus
- b) Ribosome
- c) Golgi apparatus
- d) Nucleolus
Answer: d) Nucleolus
Explanation: The nucleolus, located within the nucleus, is responsible for synthesizing ribosomal RNA (rRNA) and assembling ribosomal subunits.
44. What is the primary function of the Golgi apparatus?
- a) Protein synthesis
- b) Lipid synthesis
- c) Modifying, sorting, and packaging proteins
- d) Cellular respiration
Answer: c) Modifying, sorting, and packaging proteins
Explanation: The Golgi apparatus modifies proteins produced by the rough ER, sorts them based on their destinations, and packages them into vesicles for transport.
45. What does the term "homeostasis" refer to in cell physiology?
- a) The process of DNA replication
- b) The movement of substances into and out of the cell
- c) The maintenance of a stable internal environment
- d) The production of energy
Answer: c) The maintenance of a stable internal environment
Explanation: Homeostasis is the process by which cells, tissues, and organs maintain a stable internal environment, such as temperature and pH, to support life processes.
46. Which of the following cellular components is involved in the modification of proteins and lipids?
- a) Ribosomes
- b) Golgi apparatus
- c) Lysosomes
- d) Smooth ER
Answer: b) Golgi apparatus
Explanation: The Golgi apparatus modifies proteins and lipids received from the ER, sorts them, and packages them into vesicles for secretion or delivery to other parts of the cell.
47. What is the major role of the nuclear matrix?
- a) Control gene expression
- b) Provide structural support to the nucleus
- c) Synthesize ribosomal RNA
- d) Carry out DNA replication
Answer: b) Provide structural support to the nucleus
Explanation: The nuclear matrix provides structural support to the nucleus and organizes chromatin, playing a role in gene expression and DNA replication.
48. Which of the following is NOT part of the cell cycle?
- a) G1 phase
- b) M phase
- c) Cytokinesis
- d) Endocytosis
Answer: d) Endocytosis
Explanation: Endocytosis is a process where the cell engulfs external substances. The cell cycle consists of interphase (G1, S, G2) and M phase, followed by cytokinesis.
49. In which stage of mitosis do the chromosomes align at the cell’s equator?
- a) Prophase
- b) Metaphase
- c) Anaphase
- d) Telophase
Answer: b) Metaphase
Explanation: During metaphase, chromosomes align at the cell’s equator, preparing to be separated into two daughter cells during anaphase.
50. What is the function of the mitochondrion's inner membrane?
- a) Contains enzymes for protein synthesis
- b) Facilitates ATP production via the electron transport chain
- c) Modifies proteins before they are sent to the Golgi apparatus
- d) Controls the movement of ions in and out of the mitochondrion
Answer: b) Facilitates ATP production via the electron transport chain
Explanation: The inner mitochondrial membrane contains the electron transport chain, which generates ATP through oxidative phosphorylation by transferring electrons and pumping protons.
51. Which of the following structures is responsible for modifying, sorting, and packaging proteins into vesicles?
- a) Nucleus
- b) Endoplasmic reticulum
- c) Golgi apparatus
- d) Lysosome
Answer: c) Golgi apparatus
Explanation: The Golgi apparatus receives proteins from the rough endoplasmic reticulum, modifies them, sorts them based on their destination, and packages them into vesicles.
52. What process does the cell use to engulf large particles or microorganisms?
- a) Phagocytosis
- b) Pinocytosis
- c) Endocytosis
- d) Exocytosis
Answer: a) Phagocytosis
Explanation: Phagocytosis is a type of endocytosis where the cell engulfs large particles or microorganisms, forming a phagosome that later fuses with a lysosome for digestion.
53. What is the role of tRNA in protein synthesis?
- a) Carry genetic information from DNA to ribosomes
- b) Translate mRNA into an amino acid sequence
- c) Form the structure of the ribosome
- d) Synthesize proteins from amino acids
Answer: b) Translate mRNA into an amino acid sequence
Explanation: Transfer RNA (tRNA) reads the codons on mRNA and carries the appropriate amino acid to the ribosome to build proteins during translation.
54. Which of the following best describes the role of the plasma membrane?
- a) Provides structural support to the cell
- b) Controls the movement of molecules in and out of the cell
- c) Stores genetic information
- d) Produces proteins
Answer: b) Controls the movement of molecules in and out of the cell
Explanation: The plasma membrane regulates the entry and exit of substances, allowing cells to maintain homeostasis and respond to environmental changes.
55. What is the function of microvilli in the cell?
- a) Protein synthesis
- b) Increase surface area for absorption
- c) Cellular communication
- d) Transport of molecules across the membrane
Answer: b) Increase surface area for absorption
Explanation: Microvilli are small finger-like projections on the surface of cells that increase the surface area for absorption, especially in the intestines.
56. What is the primary purpose of the cell’s endoplasmic reticulum (ER)?
- a) Store cellular energy
- b) Transport lipids and proteins
- c) Protect the nucleus
- d) Synthesize ribosomal RNA
Answer: b) Transport lipids and proteins
Explanation: The endoplasmic reticulum (ER) is responsible for synthesizing lipids and proteins, with the rough ER involved in protein synthesis and the smooth ER in lipid metabolism.
57. Which of the following occurs during the G1 phase of the cell cycle?
- a) DNA is replicated
- b) The cell grows and performs normal functions
- c) The cell divides into two daughter cells
- d) The mitotic spindle forms
Answer: b) The cell grows and performs normal functions
Explanation: During the G1 phase, the cell grows, carries out its regular functions, and prepares for DNA replication in the S phase.
58. Which of the following best describes the function of the nucleolus?
- a) Stores DNA
- b) Synthesizes ribosomal RNA (rRNA)
- c) Modifies proteins
- d) Directs protein synthesis
Answer: b) Synthesizes ribosomal RNA (rRNA)
Explanation: The nucleolus is responsible for synthesizing ribosomal RNA (rRNA) and assembling ribosomal subunits, which are then transported to the cytoplasm for protein synthesis.
59. What is the term for the process by which a cell actively transports substances out of the cell?
- a) Exocytosis
- b) Phagocytosis
- c) Endocytosis
- d) Osmosis
Answer: a) Exocytosis
Explanation: Exocytosis is the process by which cells expel substances such as waste or secretory products by merging vesicles with the plasma membrane.
60. Which of the following is a component of the cell membrane that helps in maintaining fluidity?
- a) Phospholipids
- b) Carbohydrates
- c) Cholesterol
- d) Proteins
Answer: c) Cholesterol
Explanation: Cholesterol molecules are embedded within the lipid bilayer of the plasma membrane and help regulate membrane fluidity, preventing it from becoming too rigid or too fluid.
61. What structure in the cell regulates the movement of molecules in and out of the cell?
- a) Mitochondria
- b) Plasma membrane
- c) Nucleus
- d) Lysosomes
Answer: b) Plasma membrane
Explanation: The plasma membrane regulates the movement of substances into and out of the cell, maintaining homeostasis and protecting the cell from harmful substances.
62. What is the function of ribosomes in a cell?
- a) Synthesize proteins
- b) Store genetic material
- c) Produce energy
- d) Transport proteins
Answer: a) Synthesize proteins
Explanation: Ribosomes are responsible for protein synthesis in the cell, either floating freely in the cytoplasm or attached to the rough endoplasmic reticulum.
63. What is the function of lysosomes in a cell?
- a) Synthesize proteins
- b) Digest unwanted particles or microbes
- c) Produce ATP
- d) Transport lipids
Answer: b) Digest unwanted particles or microbes
Explanation: Lysosomes contain enzymes that break down waste materials, cellular debris, and foreign particles, such as bacteria, within the cell.
64. Which process allows substances to move across the cell membrane without energy expenditure?
- a) Active transport
- b) Passive transport
- c) Endocytosis
- d) Exocytosis
Answer: b) Passive transport
Explanation: Passive transport is the movement of substances across the cell membrane without the use of energy, driven by concentration gradients (e.g., diffusion and osmosis).
65. Which type of RNA carries genetic information from DNA to ribosomes for protein synthesis?
- a) mRNA
- b) tRNA
- c) rRNA
- d) miRNA
Answer: a) mRNA
Explanation: Messenger RNA (mRNA) carries the genetic code from the DNA in the nucleus to the ribosomes, where it is translated into a specific protein.
66. What is the function of the smooth endoplasmic reticulum (ER)?
- a) Synthesize proteins
- b) Synthesize lipids and detoxify substances
- c) Modify proteins
- d) Package proteins for secretion
Answer: b) Synthesize lipids and detoxify substances
Explanation: The smooth ER is involved in lipid synthesis, carbohydrate metabolism, and detoxification of drugs and poisons, unlike the rough ER, which is involved in protein synthesis.
67. What process involves the movement of water across a semi-permeable membrane?
- a) Diffusion
- b) Osmosis
- c) Active transport
- d) Facilitated diffusion
Answer: b) Osmosis
Explanation: Osmosis is the passive movement of water molecules from an area of low solute concentration to an area of high solute concentration across a semi-permeable membrane.
68. Which of the following cell organelles is responsible for ATP production?
- a) Mitochondria
- b) Lysosomes
- c) Golgi apparatus
- d) Endoplasmic reticulum
Answer: a) Mitochondria
Explanation: Mitochondria are the powerhouses of the cell, generating ATP through cellular respiration, which provides energy for various cellular functions.
69. What is the primary function of the cytoskeleton in a cell?
- a) Transport proteins
- b) Maintain cell shape and provide mechanical support
- c) Synthesize proteins
- d) Produce energy
Answer: b) Maintain cell shape and provide mechanical support
Explanation: The cytoskeleton provides structural support, maintains cell shape, and facilitates movement within the cell and during cell division.
70. Which of the following is a feature of prokaryotic cells?
- a) Presence of a nucleus
- b) Presence of mitochondria
- c) Absence of a nucleus
- d) Presence of membrane-bound organelles
Answer: c) Absence of a nucleus
Explanation: Prokaryotic cells, such as bacteria, do not have a nucleus or other membrane-bound organelles, unlike eukaryotic cells, which have a defined nucleus.
71. Which of the following best describes the function of the nuclear envelope?
- a) Controls the movement of substances in and out of the nucleus
- b) Synthesizes ribosomal RNA
- c) Stores genetic information
- d) Transports proteins within the cell
Answer: a) Controls the movement of substances in and out of the nucleus
Explanation: The nuclear envelope is a double membrane that surrounds the nucleus and controls the exchange of materials, such as RNA and proteins, between the nucleus and cytoplasm.
72. What does the term "fluid mosaic model" refer to in cell biology?
- a) Structure of the Golgi apparatus
- b) Structure of the plasma membrane
- c) Arrangement of mitochondria
- d) Function of ribosomes
Answer: b) Structure of the plasma membrane
Explanation: The fluid mosaic model describes the plasma membrane's structure, consisting of a phospholipid bilayer with embedded proteins that can move fluidly within the membrane.
73. Which part of the cell is responsible for assembling ribosomal subunits?
- a) Cytoplasm
- b) Nucleus
- c) Nucleolus
- d) Endoplasmic reticulum
Answer: c) Nucleolus
Explanation: The nucleolus, located inside the nucleus, is responsible for the synthesis of ribosomal RNA (rRNA) and assembling ribosomal subunits that will function in protein synthesis.
74. What is the role of chaperone proteins in cells?
- a) Facilitate protein folding
- b) Store genetic information
- c) Synthesize proteins
- d) Transport proteins across membranes
Answer: a) Facilitate protein folding
Explanation: Chaperone proteins assist in the proper folding of newly synthesized proteins and prevent misfolding that could lead to diseases such as cystic fibrosis.
75. In what phase of mitosis does the nuclear envelope break down?
- a) Prophase
- b) Metaphase
- c) Anaphase
- d) Telophase
Answer: a) Prophase
Explanation: During prophase, the nuclear envelope begins to break down, allowing the mitotic spindle to interact with the chromosomes for further separation during mitosis.
76. What is the function of the extracellular matrix (ECM)?
- a) Transports molecules across the cell membrane
- b) Provides structural support to tissues
- c) Synthesizes proteins
- d) Modifies and sorts proteins
Answer: b) Provides structural support to tissues
Explanation: The extracellular matrix (ECM) is a network of proteins and polysaccharides outside the cell that provides structural and biochemical support to tissues and regulates cell behavior.
77. Which of the following is a characteristic of all living cells?
- a) Ability to perform photosynthesis
- b) Ability to synthesize proteins
- c) Presence of mitochondria
- d) Presence of a cell wall
Answer: b) Ability to synthesize proteins
Explanation: All living cells have the ability to synthesize proteins, which are essential for cell structure, function, and metabolism.
78. What is the primary role of the rough endoplasmic reticulum?
- a) Synthesize lipids
- b) Synthesize proteins
- c) Detoxify harmful substances
- d) Synthesize ribosomal RNA
Answer: b) Synthesize proteins
Explanation: The rough endoplasmic reticulum (rough ER) is studded with ribosomes, which are responsible for synthesizing proteins that are either secreted, incorporated into the cell membrane, or sent to the lysosome.
79. What happens during anaphase of mitosis?
- a) Chromosomes align at the equator
- b) Chromosomes are pulled apart toward opposite poles
- c) The nuclear envelope reforms
- d) The cell splits into two daughter cells
Answer: b) Chromosomes are pulled apart toward opposite poles
Explanation: During anaphase, the sister chromatids of each chromosome are separated and pulled toward opposite poles of the cell.
80. What is the role of the vesicle in endocytosis?
- a) Modify proteins
- b) Store waste materials
- c) Transport substances into the cell
- d) Produce ATP
Answer: c) Transport substances into the cell
Explanation: In endocytosis, the cell membrane engulfs extracellular substances, forming a vesicle that transports the materials into the cell for processing or digestion.
81. What is the function of the Golgi apparatus in the cell?
- a) Synthesize lipids
- b) Modify, package, and transport proteins
- c) Synthesize ATP
- d) Produce ribosomal RNA
Answer: b) Modify, package, and transport proteins
Explanation: The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids into vesicles for transport to their final destinations inside or outside the cell.
82. What structure is involved in protein synthesis within the cell?
- a) Mitochondria
- b) Golgi apparatus
- c) Ribosomes
- d) Endoplasmic reticulum
Answer: c) Ribosomes
Explanation: Ribosomes are the molecular machines responsible for translating messenger RNA (mRNA) into protein sequences during protein synthesis, either in the cytoplasm or attached to the rough endoplasmic reticulum.
83. What is the role of the sodium-potassium pump?
- a) Transport oxygen across the membrane
- b) Maintain the resting membrane potential
- c) Facilitate glucose absorption
- d) Synthesize proteins
Answer: b) Maintain the resting membrane potential
Explanation: The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, which is essential for maintaining the resting membrane potential and proper cellular function.
84. In which stage of the cell cycle does DNA replication occur?
- a) G1 phase
- b) S phase
- c) G2 phase
- d) M phase
Answer: b) S phase
Explanation: DNA replication occurs during the S phase of the cell cycle. This phase ensures that each daughter cell receives an identical copy of the genetic material during cell division.
85. What structure helps in the movement of chromosomes during cell division?
- a) Cytoskeleton
- b) Golgi apparatus
- c) Nucleolus
- d) Mitotic spindle
Answer: d) Mitotic spindle
Explanation: The mitotic spindle is a structure made of microtubules that helps in the movement and separation of chromosomes during mitosis and meiosis.
86. What is the main function of the centrosome in a cell?
- a) Protein synthesis
- b) DNA replication
- c) Organize microtubules for cell division
- d) Transport substances within the cell
Answer: c) Organize microtubules for cell division
Explanation: The centrosome organizes the microtubules of the cell, which play a crucial role in the formation of the mitotic spindle during cell division.
87. Which of the following is true regarding the function of mitochondria?
- a) Synthesize proteins
- b) Produce ATP through cellular respiration
- c) Store genetic material
- d) Detoxify harmful substances
Answer: b) Produce ATP through cellular respiration
Explanation: Mitochondria are the powerhouses of the cell, where ATP (the energy currency of the cell) is produced via aerobic respiration. They are essential for energy production and metabolism.
88. What is the function of peroxisomes?
- a) Protein synthesis
- b) Break down fatty acids and detoxify harmful substances
- c) Store calcium ions
- d) Manufacture ribosomal RNA
Answer: b) Break down fatty acids and detoxify harmful substances
Explanation: Peroxisomes contain enzymes that break down fatty acids and detoxify harmful substances, such as hydrogen peroxide, into less harmful molecules like water and oxygen.
89. What is the function of the smooth endoplasmic reticulum in muscle cells?
- a) Synthesize proteins
- b) Store and release calcium ions for muscle contraction
- c) Synthesize lipids
- d) Digest proteins
Answer: b) Store and release calcium ions for muscle contraction
Explanation: In muscle cells, the smooth ER, known as the sarcoplasmic reticulum, stores and releases calcium ions that are critical for muscle contraction.
90. Which of the following structures is responsible for maintaining the cell's shape?
- a) Nucleus
- b) Cytoskeleton
- c) Plasma membrane
- d) Ribosomes
Answer: b) Cytoskeleton
Explanation: The cytoskeleton is a network of protein filaments and tubules that provide structural support, maintain the shape of the cell, and enable cellular movement.
91. What is the primary function of the plasma membrane?
- a) Protect the cell from mechanical damage
- b) Regulate the movement of substances into and out of the cell
- c) Store energy
- d) Synthesizes proteins
Answer: b) Regulate the movement of substances into and out of the cell
Explanation: The plasma membrane is selectively permeable, allowing the cell to control the substances that enter and exit, maintaining homeostasis and protecting the cell.
92. What type of transport does not require energy from ATP?
- a) Facilitated diffusion
- b) Active transport
- c) Endocytosis
- d) Exocytosis
Answer: a) Facilitated diffusion
Explanation: Facilitated diffusion is a passive transport mechanism that allows molecules to move across the cell membrane with the help of transport proteins, without the need for energy.
93. Which of the following cell types lack a nucleus?
- a) Red blood cells
- b) Muscle cells
- c) Neurons
- d) Epithelial cells
Answer: a) Red blood cells
Explanation: Mature red blood cells (erythrocytes) lack a nucleus, which allows for more space to carry hemoglobin and transport oxygen throughout the body.
94. What is the function of aquaporins in a cell?
- a) Facilitate the transport of water across the membrane
- b) Facilitate protein synthesis
- c) Transport sodium ions
- d) Break down glucose
Answer: a) Facilitate the transport of water across the membrane
Explanation: Aquaporins are specialized membrane proteins that facilitate the rapid movement of water molecules across the cell membrane, aiding in osmosis.
95. Which structure plays a key role in the production of energy (ATP) in a cell?
- a) Ribosomes
- b) Mitochondria
- c) Golgi apparatus
- d) Nucleolus
Answer: b) Mitochondria
Explanation: Mitochondria are the cell's energy producers. They generate ATP through the process of cellular respiration, providing energy for cellular activities.
96. What is the function of the nucleolus?
- a) Synthesizes ribosomal RNA
- b) Replicates DNA
- c) Modifies proteins
- d) Synthesizes ATP
Answer: a) Synthesizes ribosomal RNA
Explanation: The nucleolus is responsible for synthesizing ribosomal RNA (rRNA) and assembling ribosomes, which are essential for protein synthesis.
97. Which of the following processes requires energy input from ATP?
- a) Osmosis
- b) Active transport
- c) Facilitated diffusion
- d) Simple diffusion
Answer: b) Active transport
Explanation: Active transport requires energy from ATP to move substances against their concentration gradient, from areas of low concentration to areas of high concentration.
98. Which cellular organelle is involved in the synthesis of lipids and detoxification of chemicals?
- a) Rough endoplasmic reticulum
- b) Mitochondria
- c) Smooth endoplasmic reticulum
- d) Lysosomes
Answer: c) Smooth endoplasmic reticulum
Explanation: The smooth ER is involved in the synthesis of lipids and plays a major role in detoxifying harmful substances in the liver and other cells.
99. Which of the following occurs during cytokinesis?
- a) DNA replication
- b) Chromosome separation
- c) Cytoplasm divides, resulting in two daughter cells
- d) Nuclear envelope breaks down
Answer: c) Cytoplasm divides, resulting in two daughter cells
Explanation: Cytokinesis is the final step of cell division, where the cytoplasm divides and forms two genetically identical daughter cells.
100. Which of the following cell structures is involved in intracellular digestion?
- a) Ribosomes
- b) Lysosomes
- c) Mitochondria
- d) Golgi apparatus
Answer: b) Lysosomes
Explanation: Lysosomes contain enzymes that break down waste materials, cellular debris, and foreign particles like bacteria. They play an essential role in intracellular digestion.
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