Q.1 Which of the following phases is NOT part of the mitotic cell cycle?
G1
S
M
Mitosis
Explanation - The mitotic cell cycle consists of G1, S, G2, and M phases. The term 'mitosis' refers to the process itself, not a distinct phase.
Correct answer is: Mitosis
Q.2 Which growth factor is primarily responsible for stimulating keratinocyte migration during wound healing?
Platelet-Derived Growth Factor (PDGF)
Epidermal Growth Factor (EGF)
Transforming Growth Factor-beta (TGF-β)
Fibroblast Growth Factor (FGF)
Explanation - EGF binds to its receptor on keratinocytes, promoting their proliferation and migration to cover the wound.
Correct answer is: Epidermal Growth Factor (EGF)
Q.3 What is the primary function of the extracellular matrix (ECM) in tissue regeneration?
Providing structural support only
Delivering electrical signals
Regulating cell adhesion, migration, and differentiation
Acting as a barrier against pathogens
Explanation - The ECM provides biochemical signals and structural cues that direct cellular behaviors essential for regeneration.
Correct answer is: Regulating cell adhesion, migration, and differentiation
Q.4 Which signaling pathway is most commonly associated with the maintenance of stem cell pluripotency?
Wnt/β-catenin
Notch
Hedgehog
JAK/STAT
Explanation - Wnt signaling stabilizes β‑catenin, which translocates to the nucleus to maintain stemness genes.
Correct answer is: Wnt/β-catenin
Q.5 In the context of angiogenesis, which molecule is released by hypoxic cells to stimulate new blood vessel formation?
Vascular Endothelial Growth Factor (VEGF)
Interleukin-6 (IL-6)
Tumor Necrosis Factor-alpha (TNF-α)
Matrix Metalloproteinase-9 (MMP-9)
Explanation - VEGF is up‑regulated under hypoxia and attracts endothelial cells to sprout new vessels.
Correct answer is: Vascular Endothelial Growth Factor (VEGF)
Q.6 Which of the following best describes apoptosis?
A form of necrotic cell death caused by infection
Programmed cell death involving caspase activation
Cell proliferation triggered by growth factors
Cellular autophagy that recycles organelles
Explanation - Apoptosis is a controlled process where caspases dismantle cellular components.
Correct answer is: Programmed cell death involving caspase activation
Q.7 Which cell surface receptor is primarily responsible for detecting mechanical stretch in muscle cells?
Integrin
Ionotropic glutamate receptor
GABA receptor
Toll-like receptor
Explanation - Integrins sense mechanical forces and transduce signals to the cytoskeleton, influencing gene expression.
Correct answer is: Integrin
Q.8 What is the role of matrix metalloproteinases (MMPs) during tissue remodeling?
They inhibit collagen synthesis
They degrade ECM components to allow cell migration
They act as cytokines to recruit immune cells
They are structural proteins that replace degraded collagen
Explanation - MMPs cleave ECM proteins, creating pathways for migrating cells during repair.
Correct answer is: They degrade ECM components to allow cell migration
Q.9 Which of the following is NOT a hallmark of cellular senescence?
Permanent cell cycle arrest
Increased secretion of pro-inflammatory factors
Elevated telomerase activity
Activation of DNA damage response pathways
Explanation - Senescent cells typically show reduced telomerase activity, leading to shortened telomeres.
Correct answer is: Elevated telomerase activity
Q.10 In regenerative medicine, what is the primary advantage of using induced pluripotent stem cells (iPSCs) over embryonic stem cells?
They can differentiate into all cell types
They do not require ethical approval
They are derived from the patient, reducing rejection risk
They grow faster in culture
Explanation - iPSCs originate from the patient’s own cells, providing a personalized cell source.
Correct answer is: They are derived from the patient, reducing rejection risk
Q.11 Which signaling cascade is triggered when the Notch receptor binds to its ligand on a neighboring cell?
Phosphatidylinositol 3‑kinase/Akt
MAPK/ERK
γ‑Secretase mediated cleavage leading to NICD translocation to nucleus
JAK/STAT
Explanation - Notch signaling involves proteolytic cleavage that releases the NICD, which enters the nucleus.
Correct answer is: γ‑Secretase mediated cleavage leading to NICD translocation to nucleus
Q.12 Which of the following molecules is a key regulator of the G1/S checkpoint in the cell cycle?
Cyclin B1
Cyclin D1
Cyclin A
Cyclin E
Explanation - Cyclin D1 partners with CDK4/6 to phosphorylate Rb, promoting entry into S phase.
Correct answer is: Cyclin D1
Q.13 During which phase of the cell cycle does DNA replication occur?
G1
S
G2
M
Explanation - The S (synthesis) phase is dedicated to DNA replication.
Correct answer is: S
Q.14 Which cytokine is known to inhibit osteoclast differentiation during bone remodeling?
RANKL
M-CSF
Osteoprotegerin (OPG)
TNF-α
Explanation - OPG acts as a decoy receptor for RANKL, preventing osteoclast activation.
Correct answer is: Osteoprotegerin (OPG)
Q.15 What is the main function of autophagy in cellular stress responses?
To trigger apoptosis
To degrade and recycle damaged organelles
To initiate DNA replication
To stimulate angiogenesis
Explanation - Autophagy sequesters damaged components into autophagosomes for lysosomal degradation.
Correct answer is: To degrade and recycle damaged organelles
Q.16 Which of the following is a hallmark of epithelial to mesenchymal transition (EMT) during wound healing?
Upregulation of E‑cadherin
Downregulation of N‑cadherin
Acquisition of migratory phenotype
Decreased cell–cell adhesion
Explanation - EMT involves loss of epithelial markers and gain of mesenchymal traits, enabling migration.
Correct answer is: Acquisition of migratory phenotype
Q.17 Which of the following best describes the role of hypoxia-inducible factor 1-alpha (HIF‑1α) in tissue repair?
Promotes apoptosis of damaged cells
Stabilizes under hypoxia to activate VEGF expression
Inhibits angiogenesis
Acts as a scaffold for collagen deposition
Explanation - Under low oxygen, HIF‑1α triggers VEGF transcription, aiding new vessel formation.
Correct answer is: Stabilizes under hypoxia to activate VEGF expression
Q.18 Which molecule is primarily responsible for maintaining the stemness of neural stem cells in the subventricular zone?
BMP-2
Shh
Notch
Ephrin-A5
Explanation - Notch signaling keeps neural progenitors undifferentiated within the niche.
Correct answer is: Notch
Q.19 What is the function of integrins in the context of stem cell niche signaling?
They act as ion channels
They transduce ECM mechanical signals into intracellular pathways
They synthesize extracellular matrix components
They inhibit cell division
Explanation - Integrins connect the ECM to the cytoskeleton, translating mechanical cues to biochemical signals.
Correct answer is: They transduce ECM mechanical signals into intracellular pathways
Q.20 Which of the following is NOT a typical feature of fibroblast activation during tissue repair?
Increased collagen synthesis
Expression of alpha-smooth muscle actin (α‑SMA)
Secretion of growth factors
Loss of proliferative capacity
Explanation - Activated fibroblasts (myofibroblasts) are highly proliferative and produce ECM proteins.
Correct answer is: Loss of proliferative capacity
Q.21 Which signaling pathway is primarily involved in the response to mechanical stretch in cardiac myocytes?
RhoA/ROCK
JAK/STAT
PI3K/Akt
Notch
Explanation - Mechanical stretch activates RhoA/ROCK, influencing cytoskeletal remodeling.
Correct answer is: RhoA/ROCK
Q.22 During angiogenesis, which cell type forms the lumen of a new capillary?
Pericytes
Endothelial cells
Smooth muscle cells
Fibroblasts
Explanation - Endothelial cells proliferate and align to create the lumen of nascent vessels.
Correct answer is: Endothelial cells
Q.23 Which enzyme is responsible for removing damaged mitochondria during mitophagy?
LC3
PINK1
Cathepsin D
Beclin‑1
Explanation - PINK1 recruits Parkin to damaged mitochondria, marking them for autophagic degradation.
Correct answer is: PINK1
Q.24 Which of the following molecules is NOT typically found in the basal lamina of epithelial tissues?
Collagen IV
Laminin
Fibronectin
Perlecan
Explanation - Fibronectin is more abundant in interstitial ECM, not the basal lamina.
Correct answer is: Fibronectin
Q.25 Which of these processes is directly responsible for removing apoptotic cells without triggering inflammation?
Necrosis
Phagocytosis by macrophages
Autophagy
Extracellular matrix remodeling
Explanation - Macrophages clear apoptotic bodies in an anti‑inflammatory manner.
Correct answer is: Phagocytosis by macrophages
Q.26 What is the primary role of TGF‑β in fibroblast‑mediated scar formation?
Inhibits collagen deposition
Stimulates collagen synthesis and fibroblast differentiation
Induces fibroblast apoptosis
Blocks angiogenesis
Explanation - TGF‑β promotes myofibroblast differentiation and ECM production, leading to scar tissue.
Correct answer is: Stimulates collagen synthesis and fibroblast differentiation
Q.27 Which of the following best describes the 'Yin-Yang' role of macrophages in tissue repair?
M1 macrophages only promote inflammation while M2 macrophages only repair
M1 macrophages are involved in early inflammation, M2 macrophages in resolution and remodeling
Both M1 and M2 macrophages have the same function
Macrophages do not play a role in tissue regeneration
Explanation - M1 macrophages clear debris and pathogens; M2 macrophages secrete anti-inflammatory cytokines and promote healing.
Correct answer is: M1 macrophages are involved in early inflammation, M2 macrophages in resolution and remodeling
Q.28 Which of the following is a direct consequence of up‑regulated MMP activity during inflammation?
Stabilization of the basement membrane
Enhanced barrier function
Degradation of ECM facilitating cell migration
Inhibition of angiogenesis
Explanation - MMPs break down ECM barriers, allowing immune cells and progenitors to infiltrate damaged tissue.
Correct answer is: Degradation of ECM facilitating cell migration
Q.29 What is the primary function of the 'crosstalk' between Notch and Wnt signaling pathways during stem cell differentiation?
To inhibit both pathways simultaneously
To synergistically regulate cell fate decisions
To promote apoptosis of differentiated cells
To silence gene expression globally
Explanation - Notch and Wnt pathways interact to fine‑tune differentiation outcomes.
Correct answer is: To synergistically regulate cell fate decisions
Q.30 Which of these molecules is most commonly used as a marker for proliferating cells during histological analysis?
Ki‑67
CD34
S100
α‑SMA
Explanation - Ki‑67 is expressed during all active phases of the cell cycle but not in quiescent cells.
Correct answer is: Ki‑67
Q.31 Which of the following is NOT a direct target of the transcription factor Sox9 during chondrogenesis?
Aggrecan
Collagen type II
Runx2
Sox5
Explanation - Runx2 is more involved in osteogenesis; Sox9 regulates cartilage-specific genes like aggrecan and collagen II.
Correct answer is: Runx2
Q.32 During the repair of a bone fracture, which cell type first colonizes the fracture site to produce callus?
Chondrocytes
Osteoclasts
Mesenchymal stem cells (MSCs)
Endothelial cells
Explanation - MSCs migrate to the fracture site and differentiate into chondroblasts and osteoblasts forming a cartilaginous callus.
Correct answer is: Mesenchymal stem cells (MSCs)
Q.33 Which of the following best describes the role of the Rho‑A kinase pathway in cytoskeletal dynamics during cell migration?
Promotes actin polymerization at the leading edge
Increases microtubule stability
Stimulates focal adhesion turnover
Suppresses myosin II contractility
Explanation - Rho‑A kinase phosphorylates downstream targets that facilitate actin assembly and contractility.
Correct answer is: Promotes actin polymerization at the leading edge
Q.34 Which of the following cytokines is known to induce a fibrotic response when overexpressed?
Interferon-gamma (IFN‑γ)
IL‑10
TGF‑β
IL‑4
Explanation - TGF‑β drives fibroblast activation and excessive ECM deposition leading to fibrosis.
Correct answer is: TGF‑β
Q.35 Which of the following is an effect of increased shear stress on vascular endothelial cells?
Induction of apoptosis
Upregulation of eNOS expression
Downregulation of cell adhesion molecules
Inhibition of nitric oxide production
Explanation - Shear stress stimulates eNOS, enhancing NO production and promoting vasodilation.
Correct answer is: Upregulation of eNOS expression
Q.36 What is the primary function of the protein osteopontin in bone remodeling?
Inhibits osteoblast differentiation
Acts as a scaffold for mineral deposition
Promotes osteoclast adhesion and activity
Blocks RANKL signaling
Explanation - Osteopontin is a glycoprotein that facilitates osteoclast attachment to the bone matrix.
Correct answer is: Promotes osteoclast adhesion and activity
Q.37 Which of these molecules directly binds to DNA to activate the transcription of genes involved in cell cycle progression?
Cyclin‑dependent kinase
Transcription factor E2F
Growth factor receptor
Protein kinase C
Explanation - E2F binds to promoter regions of genes essential for S phase entry.
Correct answer is: Transcription factor E2F
Q.38 Which of the following is NOT a characteristic of the 'mesenchymal stem cell niche' in bone marrow?
High oxygen tension
Presence of osteoblastic cells
Expression of CXCL12
Low levels of inflammatory cytokines
Explanation - The niche is hypoxic, which helps maintain stemness.
Correct answer is: High oxygen tension
Q.39 Which of the following best describes the 'metabolic reprogramming' observed in proliferating cells?
Switch from oxidative phosphorylation to glycolysis
Increased reliance on fatty acid oxidation
Reduced glucose uptake
Enhanced mitochondrial biogenesis
Explanation - The Warburg effect describes increased glycolysis even in oxygenated conditions during proliferation.
Correct answer is: Switch from oxidative phosphorylation to glycolysis
Q.40 What is the primary role of the protein SIRT1 in cellular senescence?
Promotes DNA replication
Activates telomerase
Deacetylates p53 to modulate cell cycle arrest
Stabilizes ribosomal RNA
Explanation - SIRT1 deacetylates p53, influencing the senescence pathway.
Correct answer is: Deacetylates p53 to modulate cell cycle arrest
Q.41 Which of the following is a key outcome of Wnt/β‑catenin signaling in hair follicle stem cells?
Induction of apoptosis
Promotion of hair growth
Inhibition of cell proliferation
Differentiation into adipocytes
Explanation - Wnt signaling activates hair follicle stem cells, driving hair regeneration.
Correct answer is: Promotion of hair growth
Q.42 During the process of myogenesis, which transcription factor is essential for the fusion of myoblasts into multinucleated myotubes?
Myf5
MyoD
Myogenin
Myozenin
Explanation - Myogenin drives terminal differentiation and fusion of muscle progenitors.
Correct answer is: Myogenin
Q.43 What is the role of the protein p53 in the DNA damage response?
It repairs double‑strand breaks directly
It signals for cell cycle arrest or apoptosis
It acts as a DNA polymerase
It stabilizes ribosomal RNA
Explanation - p53 activates genes that halt the cell cycle or trigger programmed cell death when DNA damage is detected.
Correct answer is: It signals for cell cycle arrest or apoptosis
Q.44 Which of the following best describes the 'matrix‑bound growth factor' concept?
Growth factors are stored in the ECM and released upon degradation
Growth factors are only found in the cytoplasm
Growth factors degrade the ECM
Growth factors are secreted directly into the bloodstream
Explanation - Binding to ECM components keeps growth factors in a reservoir, released when ECM is remodeled.
Correct answer is: Growth factors are stored in the ECM and released upon degradation
Q.45 Which of the following pathways is primarily responsible for regulating the synthesis of extracellular matrix proteins in fibroblasts?
mTOR
NF‑κB
TGF‑β/SMAD
JAK/STAT
Explanation - TGF‑β binds SMADs to upregulate ECM gene expression in fibroblasts.
Correct answer is: TGF‑β/SMAD
Q.46 In the context of neural regeneration, which of the following molecules is known to inhibit axon regeneration?
Netrin‑1
Nogo‑66
BDNF
Neurotrophin‑3
Explanation - Nogo‑66, expressed in oligodendrocytes, prevents axonal growth after CNS injury.
Correct answer is: Nogo‑66
Q.47 Which of the following is a hallmark of the G2/M checkpoint?
Detection of DNA strand breaks
Verification of complete DNA replication
Activation of telomerase
Induction of autophagy
Explanation - The G2/M checkpoint ensures that replication is finished before mitosis.
Correct answer is: Verification of complete DNA replication
Q.48 Which molecule is a primary mediator of the inflammatory response during the early stages of wound healing?
Interleukin‑4 (IL‑4)
Interferon‑γ (IFN‑γ)
Tumor Necrosis Factor-alpha (TNF‑α)
Transforming Growth Factor-beta (TGF‑β)
Explanation - TNF‑α is released by macrophages and activates endothelial cells during inflammation.
Correct answer is: Tumor Necrosis Factor-alpha (TNF‑α)
Q.49 Which of the following is a major function of the protein fibronectin in tissue repair?
It inhibits fibroblast proliferation
It binds to integrins to facilitate cell migration
It is a secreted hormone
It acts as a transcription factor
Explanation - Fibronectin provides adhesion sites for cells during migration to the wound site.
Correct answer is: It binds to integrins to facilitate cell migration
Q.50 Which of these processes is primarily driven by the PI3K/Akt pathway in cell survival?
Activation of caspase cascade
Inhibition of mTOR signaling
Promotion of protein synthesis via mTOR
Induction of autophagy
Explanation - PI3K/Akt activates mTOR, which promotes protein synthesis and cell growth.
Correct answer is: Promotion of protein synthesis via mTOR
Q.51 What is the main role of the protein connexin in cell–cell communication?
Forming gap junctions to allow small molecules to pass
Acting as a hormone
Transporting ions across the plasma membrane
Serving as a scaffold for cytoskeletal proteins
Explanation - Connexins assemble into channels that permit ionic and metabolic coupling between cells.
Correct answer is: Forming gap junctions to allow small molecules to pass
Q.52 Which of the following best describes the effect of mechanical tension on fibroblast differentiation?
It inhibits myofibroblast formation
It promotes fibroblast proliferation only
It drives fibroblasts towards a myofibroblast phenotype
It has no effect
Explanation - Mechanical tension activates signaling that induces α‑SMA expression, forming contractile myofibroblasts.
Correct answer is: It drives fibroblasts towards a myofibroblast phenotype
Q.53 In the context of cartilage repair, which enzyme is primarily responsible for matrix breakdown?
Collagenase
Matrix metalloproteinase‑13 (MMP‑13)
Alkaline phosphatase
Sulfatase
Explanation - MMP‑13 specifically degrades type II collagen in cartilage.
Correct answer is: Matrix metalloproteinase‑13 (MMP‑13)
Q.54 Which of the following molecules is a hallmark of the hypoxic response in ischemic tissue?
HIF‑1α
p53
NF‑κB
STAT3
Explanation - HIF‑1α is stabilized under low oxygen, inducing genes like VEGF for angiogenesis.
Correct answer is: HIF‑1α
Q.55 Which of the following best describes the role of microRNAs in tissue regeneration?
They encode structural proteins
They are transcription factors
They post‑transcriptionally regulate gene expression
They directly stimulate cell division
Explanation - microRNAs bind mRNA to inhibit translation or promote degradation.
Correct answer is: They post‑transcriptionally regulate gene expression
Q.56 During the formation of a blood clot, which of these proteins is responsible for stabilizing the fibrin mesh?
Factor VII
Factor XII
Platelet factor 4
Factor XIIIa
Explanation - Factor XIIIa cross‑links fibrin strands, providing clot stability.
Correct answer is: Factor XIIIa
Q.57 Which of the following signaling molecules is involved in the regulation of the epithelial barrier during wound healing?
EGF
TNF‑α
IL‑1β
IL‑10
Explanation - EGF promotes epithelial proliferation and closure of the wound.
Correct answer is: EGF
Q.58 What is the main effect of the protein Tiam1 in cell migration?
Activation of RhoA
Activation of Rac1
Inhibition of Cdc42
Stabilization of microtubules
Explanation - Tiam1 is a guanine nucleotide exchange factor that activates Rac1 to promote lamellipodia formation.
Correct answer is: Activation of Rac1
Q.59 Which of the following is a characteristic of the ‘stem cell niche’ in the intestinal crypt?
High oxygen levels
Presence of Paneth cells secreting Wnt
High levels of IL‑4
Low proliferation rate
Explanation - Paneth cells provide Wnt signals that maintain intestinal stem cell self‑renewal.
Correct answer is: Presence of Paneth cells secreting Wnt
Q.60 Which of the following best describes the role of the protein caspase‑3?
Promotes DNA replication
Induces apoptosis by cleaving cellular substrates
Stimulates angiogenesis
Inhibits cell migration
Explanation - Caspase‑3 is an executioner caspase that dismantles the cell during apoptosis.
Correct answer is: Induces apoptosis by cleaving cellular substrates
Q.61 Which of the following molecules is primarily responsible for the early stages of bone mineralization?
Osteocalcin
Osteopontin
Type I collagen
Fibronectin
Explanation - Osteocalcin binds hydroxyapatite and helps nucleate mineral deposition.
Correct answer is: Osteocalcin
Q.62 What is the primary effect of the protein NF‑κB in inflammation?
Suppresses cytokine production
Promotes transcription of pro‑inflammatory genes
Induces apoptosis in immune cells
Inhibits angiogenesis
Explanation - NF‑κB drives expression of cytokines like TNF‑α, IL‑1β, and others.
Correct answer is: Promotes transcription of pro‑inflammatory genes
Q.63 Which of the following is a hallmark of the G1 checkpoint?
Detection of DNA damage before replication
Verification of complete DNA replication
Ensuring correct spindle attachment
Activation of cytokine production
Explanation - The G1 checkpoint evaluates DNA integrity prior to S phase entry.
Correct answer is: Detection of DNA damage before replication
Q.64 Which of the following best describes the role of fibroblast growth factor (FGF) during limb regeneration?
Inhibits angiogenesis
Stimulates proliferation of mesenchymal cells
Promotes apoptosis of chondrocytes
Blocks nerve growth
Explanation - FGF promotes growth of progenitor cells necessary for regrowth of limb tissues.
Correct answer is: Stimulates proliferation of mesenchymal cells
Q.65 Which of the following signaling molecules is directly involved in the differentiation of mesenchymal stem cells into adipocytes?
PDGF
BMP‑2
PPARγ
VEGF
Explanation - PPARγ is a master transcription factor for adipogenic differentiation.
Correct answer is: PPARγ
Q.66 What is the primary role of the protein 'E-cadherin' in epithelial tissues?
Facilitates cell‑cell adhesion
Inhibits cell migration
Promotes ECM degradation
Acts as a growth factor
Explanation - E‑cadherin mediates strong adhesion between epithelial cells, maintaining tissue integrity.
Correct answer is: Facilitates cell‑cell adhesion
Q.67 Which of the following is an effect of the protein RANKL in bone remodeling?
Inhibition of osteoclast differentiation
Stimulation of osteoblast activity
Promotion of osteoclast precursor recruitment
Degradation of collagen type I
Explanation - RANKL binds RANK on osteoclast precursors, driving their differentiation.
Correct answer is: Promotion of osteoclast precursor recruitment
Q.68 Which of the following molecules is a direct regulator of mitochondrial biogenesis in proliferating cells?
PGC‑1α
mTOR
AKT
JAK
Explanation - PGC‑1α co‑activates transcription factors that drive mitochondrial DNA replication.
Correct answer is: PGC‑1α
Q.69 What is the role of the protein 'Sox9' in skeletal development?
It induces chondrocyte differentiation
It promotes osteoclastogenesis
It inhibits collagen deposition
It stimulates vascular smooth muscle contraction
Explanation - Sox9 is essential for chondrogenesis, controlling cartilage matrix production.
Correct answer is: It induces chondrocyte differentiation
Q.70 Which of the following is NOT a characteristic of the fibroblast activation protein (FAP) expressed during wound healing?
High expression in activated myofibroblasts
Degrades ECM components
Functions as a serine protease
Is essential for apoptosis of fibroblasts
Explanation - FAP mainly remodels ECM and promotes proliferation, not apoptosis.
Correct answer is: Is essential for apoptosis of fibroblasts
Q.71 Which of the following molecules is known to activate the MAPK/ERK pathway in response to growth factors?
EGF
TNF‑α
IL‑6
IL‑10
Explanation - EGF binds EGFR, leading to Ras‑Raf‑MEK‑ERK signaling.
Correct answer is: EGF
Q.72 During embryonic development, which of the following signals is crucial for establishing the dorsal-ventral axis?
Wnt
BMP
Notch
Hedgehog
Explanation - BMP gradients specify dorsal‑ventral patterning during gastrulation.
Correct answer is: BMP
Q.73 Which of the following best describes the role of the protein 'YAP/TAZ' in mechanotransduction?
They inhibit actin polymerization
They are transcription co‑activators modulated by mechanical cues
They degrade ECM components
They function as ion channels
Explanation - YAP/TAZ translocate to the nucleus in response to mechanical signals to regulate gene expression.
Correct answer is: They are transcription co‑activators modulated by mechanical cues
Q.74 Which of the following is a key difference between the inflammatory and regenerative phases of wound healing?
Inflammation involves fibroblast proliferation
Regeneration involves removal of debris
Inflammation includes infiltration by neutrophils and macrophages
Regeneration is characterized by scar formation
Explanation - The inflammatory phase is dominated by immune cell infiltration, while the regenerative phase involves tissue rebuilding.
Correct answer is: Inflammation includes infiltration by neutrophils and macrophages
Q.75 Which of the following molecules is a hallmark of the epithelial-mesenchymal transition (EMT) in cancer metastasis?
E‑cadherin upregulation
N‑cadherin upregulation
MMP‑9 downregulation
Decreased integrin expression
Explanation - EMT involves loss of E‑cadherin and gain of N‑cadherin, facilitating cell migration.
Correct answer is: N‑cadherin upregulation
Q.76 What is the primary function of the protein 'Hsp90' in stressed cells?
Acts as a transcription factor
Stabilizes client proteins during folding
Degrades damaged DNA
Inhibits apoptosis
Explanation - Hsp90 is a molecular chaperone that assists protein folding under stress.
Correct answer is: Stabilizes client proteins during folding
Q.77 Which of the following is an effect of the 'Wnt/β‑catenin' pathway in osteoblast differentiation?
It inhibits bone formation
It promotes osteoblast proliferation and differentiation
It stimulates osteoclast activity
It has no role in bone biology
Explanation - Wnt signaling activates β‑catenin to upregulate osteogenic genes.
Correct answer is: It promotes osteoblast proliferation and differentiation
Q.78 Which of the following molecules is a key regulator of the transition from inflammation to repair in a wound?
IL‑1β
IL‑10
TNF‑α
IFN‑γ
Explanation - IL‑10 is anti‑inflammatory, helping to resolve inflammation and initiate repair.
Correct answer is: IL‑10
Q.79 Which of the following is a characteristic of the 'G0' phase in the cell cycle?
Cell division is actively occurring
Cell is quiescent and not actively cycling
DNA replication occurs
Chromosomes are condensed
Explanation - G0 is a resting phase where cells are temporarily out of the cell cycle.
Correct answer is: Cell is quiescent and not actively cycling
Q.80 During the differentiation of a skeletal muscle cell, which protein is critical for the formation of the contractile apparatus?
Troponin
Collagen I
Fibronectin
Hemoglobin
Explanation - Troponin, along with tropomyosin, regulates actin–myosin interactions in muscle contraction.
Correct answer is: Troponin
Q.81 Which of the following molecules is directly involved in the formation of a basement membrane in epithelial tissues?
Collagen I
Laminin
Fibronectin
Desmin
Explanation - Laminin is a major structural glycoprotein of the basement membrane.
Correct answer is: Laminin
Q.82 Which of the following best describes the role of the protein 'p21' in the cell cycle?
Activates cyclin‑dependent kinases
Inhibits cyclin‑dependent kinases to enforce cell cycle arrest
Promotes DNA replication
Degrades cell surface receptors
Explanation - p21 is a CDK inhibitor that halts cell cycle progression in response to stress.
Correct answer is: Inhibits cyclin‑dependent kinases to enforce cell cycle arrest
Q.83 What is the primary function of 'matrix metalloproteinase‑2 (MMP‑2)' during tissue remodeling?
Degrades laminin and type IV collagen
Synthesizes collagen fibers
Promotes fibroblast proliferation
Inhibits angiogenesis
Explanation - MMP‑2 cleaves basement membrane components, allowing cell migration.
Correct answer is: Degrades laminin and type IV collagen
Q.84 Which of the following is a direct downstream target of the TGF‑β/SMAD pathway that promotes extracellular matrix production?
MMP‑9
Collagen type I gene
VEGF
IL‑6
Explanation - SMAD complexes activate collagen gene transcription during ECM synthesis.
Correct answer is: Collagen type I gene
Q.85 In the process of angiogenesis, what is the role of the protein 'VEGF‑A'?
Inhibits endothelial cell proliferation
Promotes endothelial cell migration and proliferation
Stimulates fibroblast apoptosis
Encodes a structural protein of the basement membrane
Explanation - VEGF‑A is a key growth factor that drives new blood vessel formation.
Correct answer is: Promotes endothelial cell migration and proliferation
Q.86 Which of the following best describes the function of the 'RhoA/ROCK' pathway in cell motility?
Promotes microtubule destabilization
Stimulates actomyosin contractility and focal adhesion formation
Inhibits actin polymerization
Activates DNA replication
Explanation - RhoA/ROCK increases contractility, aiding cell migration.
Correct answer is: Stimulates actomyosin contractility and focal adhesion formation
Q.87 Which of the following molecules is involved in the maintenance of quiescent hematopoietic stem cells in the bone marrow niche?
SDF‑1 (CXCL12)
VEGF
TGF‑β
Epidermal growth factor
Explanation - SDF‑1 binds CXCR4 on HSCs, promoting quiescence and retention in the niche.
Correct answer is: SDF‑1 (CXCL12)
Q.88 Which of the following best explains how mechanical forces influence stem cell fate during regeneration?
They alter the chemical composition of the ECM
They activate mechanosensitive ion channels that trigger signaling pathways
They inhibit cell proliferation
They have no effect on stem cells
Explanation - Mechanical cues are sensed via ion channels and integrins, influencing gene expression.
Correct answer is: They activate mechanosensitive ion channels that trigger signaling pathways
Q.89 Which of the following molecules is a key regulator of autophagosome formation?
LC3
p53
EGFR
MMP‑9
Explanation - LC3 associates with autophagosome membranes, marking autophagosome formation.
Correct answer is: LC3
Q.90 Which of the following is NOT typically a function of myofibroblasts during wound healing?
Secrete collagen
Generate contractile force via α‑SMA
Produce matrix metalloproteinases to remodel ECM
Serve as antigen-presenting cells
Explanation - Myofibroblasts mainly produce ECM and contractile force; they are not antigen-presenting cells.
Correct answer is: Serve as antigen-presenting cells
Q.91 Which of the following pathways is most closely associated with the maintenance of cellular quiescence in stem cells?
Notch
Wnt
Hedgehog
JAK/STAT
Explanation - Notch signaling often keeps stem cells in a quiescent, undifferentiated state.
Correct answer is: Notch
Q.92 During the late stages of bone healing, which cells are primarily responsible for bone remodeling?
Osteoclasts
Fibroblasts
Chondrocytes
Myofibroblasts
Explanation - Osteoclasts resorb old bone to allow new bone deposition by osteoblasts.
Correct answer is: Osteoclasts
Q.93 Which of the following best describes the role of the protein 'Snail' in epithelial-mesenchymal transition (EMT)?
It promotes the expression of E‑cadherin
It represses E‑cadherin expression to facilitate EMT
It stimulates fibroblast apoptosis
It acts as a growth factor
Explanation - Snail is a transcription factor that downregulates E‑cadherin, enabling cells to become migratory.
Correct answer is: It represses E‑cadherin expression to facilitate EMT
Q.94 Which of the following molecules is a key mediator of the inflammatory response in the skin during the early wound healing phase?
IL‑10
IL‑6
TNF‑α
TGF‑β
Explanation - TNF‑α is produced by macrophages and neutrophils to amplify the inflammatory response.
Correct answer is: TNF‑α
Q.95 Which of the following best explains the term 'cellular senescence' in the context of tissue regeneration?
Cells continue to proliferate without limit
Cells enter a permanent growth arrest while remaining metabolically active
Cells undergo rapid apoptosis
Cells differentiate into another cell type
Explanation - Senescent cells stop dividing but continue to secrete inflammatory cytokines and ECM proteins.
Correct answer is: Cells enter a permanent growth arrest while remaining metabolically active