Stem Cells and Regeneration Practice Questions
40 free Stem Cells and Regeneration practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which type of stem cell has the potential to differentiate into all cell types of the body, including extraembryonic tissues like the placenta?
- A Pluripotent stem cells
- B Multipotent stem cells
- C Totipotent stem cells
- D Unipotent tissue-specific stem cells
Correct answer: Totipotent stem cells
Totipotent stem cells, such as the zygote and early blastomeres, have the highest level of potency. They can generate an entire organism along with the necessary supporting extraembryonic membranes.
The regenerative process in Planarians (flatworms) is primarily driven by a population of pluripotent adult stem cells known as:
- A Neoblasts (pluripotent stem cells)
- B Blastema progenitor cells
- C Satellite muscle stem cells
- D Mesenchymal stromal stem cells
Correct answer: Neoblasts (pluripotent stem cells)
Neoblasts are the only dividing cells in Planarians and are capable of differentiating into any cell type required to rebuild missing body parts. This makes them a classic model for studying extreme regeneration.
In the context of limb regeneration in salamanders (Urodeles), what is the mass of undifferentiated, proliferating cells that forms at the site of amputation?
- A Callus (cartilaginous repair tissue)
- B Blastema
- C Primitive streak
- D Apical ectodermal ridge
Correct answer: Blastema
A blastema is a pool of mesenchymal-like cells formed by the dedifferentiation of local tissues at the wound site. It serves as the progenitor source for the replacement of bones, muscles, and nerves in the regenerated limb.
Which type of regeneration is characterized by the remodeling of existing tissues into new structures without significant cell proliferation?
- A Epimorphosis
- B Compensatory hyperplasia
- C Morphallaxis
- D Metaplasia
Correct answer: Morphallaxis
Morphallaxis, famously observed in Hydra, involves the reorganization of existing cells into a smaller version of the organism. In contrast, epimorphosis relies heavily on new cell division and blastema formation.
Induced Pluripotent Stem Cells (iPSCs) are typically created by 'reprogramming' adult somatic cells with which set of transcription factors?
- A Hox, Pax, and Notch transcription factors
- B Oct4, Sox2, Klf4, and c-Myc
- C Bcl-2, Bax, and Caspases
- D MyoD, Myogenin, and Actin
Correct answer: Oct4, Sox2, Klf4, and c-Myc
Known as the Yamanaka factors, these four transcription factors are sufficient to revert a specialized adult cell back into a pluripotent state. This technology allows for the creation of patient-specific stem cells without using embryos.
Where is the 'stem cell niche' located in the mammalian small intestine for the continuous renewal of the epithelial lining?
- A The tips of the intestinal villi
- B The loose connective tissue of the lamina propria
- C The crypts of Lieberkühn
- D The lymphoid follicles of Peyer's patches
Correct answer: The crypts of Lieberkühn
The crypts of Lieberkühn house Lgr5+ intestinal stem cells at their base. These cells divide to produce transit-amplifying cells that migrate upward along the villus, differentiating as they go and replacing cells shed from the villus tips.
Regeneration of the mammalian liver after partial surgical removal is an example of:
- A Epimorphosis via blastema formation
- B Compensatory regeneration
- C Morphallaxis via cell remodeling
- D Autotomy followed by regrowth
Correct answer: Compensatory regeneration
In compensatory regeneration, the remaining hepatocytes re-enter the cell cycle to restore the original organ mass and function. Unlike limb regeneration, it does not involve a blastema or dedifferentiation of mature cells.
Which of the following describes 'unipotent' stem cells?
- A They can form any cell type in the body except placental cells
- B They can differentiate into only one specific cell type
- C They are found exclusively in the morula stage embryo
- D They have the capacity to form all three primary germ layers
Correct answer: They can differentiate into only one specific cell type
Unipotent stem cells, such as spermatogonial stem cells, retain the capacity for self-renewal but can generate only a single lineage of differentiated progeny. They are essential for the ongoing maintenance and repair of specific tissues.
In Hydra, the gradient of which signaling molecule is primarily responsible for establishing the 'head' organizer at the apical end?
- A BMP signaling
- B Wnt signaling
- C Hedgehog signaling
- D Notch signaling
Correct answer: Wnt signaling
Wnt signaling establishes the head organizer in Hydra, with the highest pathway activity at the hypostome. This morphogen gradient controls axial patterning and is a deeply conserved regulator across the animal kingdom.
Which type of adult stem cells are found in the bone marrow and can differentiate into osteoblasts, chondrocytes, and adipocytes?
- A Hematopoietic stem cells
- B Mesenchymal stem cells
- C Neural crest cells
- D Satellite cells
Correct answer: Mesenchymal stem cells
Mesenchymal stem cells (MSCs) are multipotent stromal cells that can differentiate into various mesodermal lineages. They are distinct from hematopoietic stem cells, which produce blood and immune cells.
What happens during the 'dedifferentiation' phase of epimorphic limb regeneration?
- A Cells migrate to the wound surface and are eliminated by programmed apoptosis
- B Specialized cells such as muscle fibers lose their differentiated state to become proliferative progenitor cells
- C The animal undergoes a full molt that initiates replacement limb tissue
- D The remaining skeletal elements elongate by endochondral bone growth to fill the gap
Correct answer: Specialized cells such as muscle fibers lose their differentiated state to become proliferative progenitor cells
Dedifferentiation involves mature, specialized cells reverting to a simpler progenitor state to form the blastema. This restores a pool of proliferative cells that can subsequently re-differentiate into the various tissues of the regenerated limb.
The 'Stem Cell Niche' refers to:
- A The physical location where stem cells are isolated and maintained in a laboratory culture dish
- B The specific microenvironment that regulates stem cell self-renewal and differentiation
- C The cellular process by which a normal stem cell acquires mutations and transforms into a cancer cell
- D The total population of all stem cells distributed throughout the tissues of an adult organism
Correct answer: The specific microenvironment that regulates stem cell self-renewal and differentiation
The stem cell niche consists of neighboring support cells, extracellular matrix components, and paracrine signaling molecules that collectively maintain stem cell quiescence or controlled proliferation. When stem cells leave the niche, they typically begin differentiating.
Which signaling pathway is most famously associated with maintaining the 'stemness' of hematopoietic stem cells and intestinal stem cells?
- A Notch signaling
- B Glycolysis pathway
- C Krebs cycle
- D Apoptotic pathway
Correct answer: Notch signaling
The Notch signaling pathway involves contact-dependent communication between cells. It is critical for binary fate decisions and helps prevent premature differentiation in various adult stem cell populations.
Why are human embryonic stem cells (hESCs) considered 'pluripotent' rather than 'totipotent'?
- A They can only form neural and glial cells of the nervous tissue lineage
- B They cannot give rise to extraembryonic tissues like the trophoblast
- C They are derived from multipotent adult stem cells in the bone marrow
- D They lose the ability to proliferate or be maintained in a laboratory culture
Correct answer: They cannot give rise to extraembryonic tissues like the trophoblast
hESCs are derived from the inner cell mass of the blastocyst. Although they can generate all three germ layers and therefore any somatic cell type, they have lost the ability to form extraembryonic structures such as the placenta, which is the hallmark of totipotency.
In amphibians, what is the 'Apical Epithelial Cap' (AEC)?
- A The outer protective membrane that encases and shields the amphibian egg
- B A thickened epidermal layer at the wound site that is essential for blastema formation and limb regeneration
- C The photoreceptor organ in the tadpole head that senses environmental light levels
- D The embryonic tail-forming structure that secretes signaling molecules during axial patterning
Correct answer: A thickened epidermal layer at the wound site that is essential for blastema formation and limb regeneration
The Apical Epithelial Cap (AEC) forms rapidly after amputation and secretes fibroblast growth factors (FGFs) that sustain the underlying mesenchymal cells in a proliferative, undifferentiated state. Removal of the AEC prevents blastema formation and halts regeneration.
Which of these is a significant ethical advantage of using iPSCs compared to ESCs?
- A iPSCs can be expanded in culture more easily and in far greater quantities than ESCs
- B iPSCs do not require the destruction of a human embryo to derive
- C iPSCs accumulate no somatic mutations and maintain perfect genomic stability
- D iPSCs are restricted to experimental animal models and cannot be used in humans
Correct answer: iPSCs do not require the destruction of a human embryo to derive
Because iPSCs are generated by reprogramming adult somatic cells such as skin fibroblasts or blood cells, their derivation avoids the ethical controversy surrounding the use and destruction of human blastocysts. They additionally offer the advantage of being immunologically matched to the donor.
Satellite cells are the resident stem cells of which tissue?
- A Skeletal muscle
- B Cardiac muscle
- C Peripheral nervous tissue
- D Hepatic liver tissue
Correct answer: Skeletal muscle
Satellite cells reside between the sarcolemma and basal lamina of skeletal muscle fibers. Upon injury or exercise-induced damage, they activate, proliferate, and fuse to repair damaged fibers or form new ones, driving skeletal muscle regeneration.
The ability of an organism to regrow a lost tail, such as in many lizards, is often achieved through a process called:
- A Autotomy followed by regeneration
- B Metamorphosis from larval to adult form
- C Parthenogenetic development from unfertilized eggs
- D Binary fission producing two identical offspring
Correct answer: Autotomy followed by regeneration
Autotomy is the voluntary shedding of a body part, typically to escape a predator. After autotomy, specialized tissues at the stump initiate a regenerative program; however, the regrown lizard tail typically contains cartilage rather than true vertebrae.
Which animal is used as a model to study 'lens regeneration', where the iris cells dedifferentiate and transform into a new lens?
- A Laboratory mouse
- B Common fruit fly
- C Red-spotted newt
- D Nematode roundworm
Correct answer: Red-spotted newt
Newts (and some other salamanders) exhibit Wolffian regeneration. After lens removal, pigmented epithelial cells of the dorsal iris lose their pigment, proliferate, and transdifferentiate into a new functional crystalline lens.
As an animal ages, the regenerative capacity typically declines. This is often attributed to:
- A An increase in the number of active stem cells in most tissues
- B Enhanced and more efficient DNA repair mechanisms in aged cells
- C Stem cell exhaustion and accumulating cellular senescence
- D Decreased inflammatory signaling that normally drives repair
Correct answer: Stem cell exhaustion and accumulating cellular senescence
Aging is associated with progressive depletion of functional stem cell pools and the accumulation of senescent cells that no longer divide. Alterations in the niche microenvironment further impair the ability of remaining stem cells to support tissue repair.
Which of the following describes 'Totipotency' in the context of animal development?
- A The ability to form all embryonic and extra-embryonic cell types
- B The ability to form any cell type of the adult body only
- C The ability to form multiple related cell lineages like blood cells
- D The ability to produce only one specific cell type
Correct answer: The ability to form all embryonic and extra-embryonic cell types
Totipotent cells, such as the zygote and early blastomeres, have the highest differentiation potential. They can give rise to an entire organism, including the placenta and umbilical cord tissues.
In Planarian regeneration, which signaling pathway is primarily responsible for establishing the anterior-posterior (A-P) polarity?
- A Wnt/Beta-catenin signaling
- B Notch signaling
- C Hedgehog/Patched signaling
- D Insulin signaling
Correct answer: Wnt/Beta-catenin signaling
Wnt signaling acts as a molecular switch in planarians. High Wnt activity at the posterior end promotes tail formation, while inhibition of Wnt at the anterior end allows for head regeneration.
Which type of regeneration is characterized by the dedifferentiation of adult cells into a proliferative mass called a blastema?
- A Epimorphosis
- B Morphallaxis
- C Compensatory hyperplasia
- D Stem cell-mediated regeneration
Correct answer: Epimorphosis
Epimorphosis, seen in salamander limb regeneration, involves the formation of a blastema. This structure consists of undifferentiated cells that eventually redifferentiate to replace the missing complex structures.
The 'Yamanaka Factors' used to create induced Pluripotent Stem Cells (iPSCs) include which of the following sets?
- A Oct4, Sox2, Klf4, and c-Myc
- B Nanog, Oct4, Wnt, and Notch
- C HoxA1, HoxB1, Pax6, and Shh
- D MyoD, GATA4, Brachyury, and Tbx5
Correct answer: Oct4, Sox2, Klf4, and c-Myc
Shinya Yamanaka identified four specific transcription factors (Oct4, Sox2, Klf4, and c-Myc) that can reprogram adult somatic cells back into a pluripotent state similar to embryonic stem cells.
In the mammalian intestinal niche, which cells provide the essential Wnt signals to maintain the Lgr5+ stem cells at the crypt base?
- A Paneth cells
- B Goblet cells
- C Enterocytes
- D M cells
Correct answer: Paneth cells
Paneth cells reside adjacent to the Lgr5+ intestinal stem cells in the crypts of Lieberkühn. They secrete Wnt, EGF, and Notch ligands that are strictly required to maintain the stem cell population.
Regeneration in Hydra, where the organism reshapes its existing body parts into a smaller version of itself without significant new growth, is termed:
- A Epimorphosis
- B Autotomy
- C Morphallaxis
- D Neoteny
Correct answer: Morphallaxis
Morphallaxis involves the reorganization of existing tissues. In Hydra, if the body is cut, the remaining cells rearrange themselves to form a complete, though smaller, individual through transdifferentiation.
Which of the following stem cells are considered 'multipotent'?
- A Zygote
- B Embryonic stem cells (ESCs)
- C Hematopoietic stem cells (HSCs)
- D Spermatogonial stem cells (unipotent)
Correct answer: Hematopoietic stem cells (HSCs)
Multipotent stem cells can differentiate into multiple cell types within a specific lineage. HSCs can give rise to all types of blood cells (RBCs, WBCs, platelets) but cannot form nerve or muscle cells.
What is the primary role of 'Satellite cells' found beneath the basal lamina of mature muscle fibers?
- A To provide electrical insulation to the fiber
- B To act as unipotent stem cells for muscle repair and growth
- C To secrete calcium ions from the sarcoplasmic reticulum during contraction
- D To phagocytose cellular debris
Correct answer: To act as unipotent stem cells for muscle repair and growth
Satellite cells are quiescent muscle stem cells. Upon injury or exercise-induced stress, they become activated, proliferate, and fuse to form new myofibers or repair existing ones.
During salamander limb regeneration, the 'Apical Epithelial Cap' (AEC) is essential because it secretes:
- A Fibroblast Growth Factors (FGFs)
- B Melanin
- C Collagen, a structural matrix protein
- D Keratin
Correct answer: Fibroblast Growth Factors (FGFs)
The AEC is a thickened layer of epidermis that covers the wound. It produces FGFs (like FGF8) which keep the underlying blastema cells in a proliferative, undifferentiated state.
Which animal model is famous for its 'Wolffian lens regeneration', where the lens is replaced by cells from the dorsal iris?
- A Zebrafish
- B Adult newt
- C Xenopus
- D Drosophila
Correct answer: Adult newt
Newts exhibit a remarkable form of transdifferentiation called Wolffian regeneration. If the lens is removed, pigmented epithelial cells of the dorsal iris dedifferentiate and then redifferentiate into a new lens.
The ability of a differentiated cell to revert to a less specialized, proliferative state is known as:
- A Transdifferentiation
- B Dedifferentiation
- C Apoptosis
- D Senescence
Correct answer: Dedifferentiation
Dedifferentiation is a key step in epimorphic regeneration. Mature cells at the wound site lose their specialized features and regain the ability to divide, contributing to the formation of the blastema.
Which of the following is an example of 'compensatory regeneration' in mammals?
- A Regrowth of a lost finger
- B Repair of the spinal cord
- C Regeneration of the liver
- D Renewal of the lens of the eye
Correct answer: Regeneration of the liver
In compensatory regeneration, differentiated cells (hepatocytes) divide to recover the original mass and function of the organ without first reverting to a stem cell or blastema state.
Mesenchymal Stem Cells (MSCs) are characterized by their ability to differentiate into which three lineages?
- A Neurons, Glia, and Microglia
- B Osteoblasts, Chondrocytes, and Adipocytes
- C Erythrocytes, Lymphocytes, and Myelocytes
- D Hepatocytes, Enterocytes, and Pancreatic cells
Correct answer: Osteoblasts, Chondrocytes, and Adipocytes
MSCs are multipotent stromal cells that can differentiate into various mesodermal tissues, specifically bone (osteoblasts), cartilage (chondrocytes), and fat (adipocytes).
In the zebrafish heart, regeneration after injury occurs primarily through:
- A Activation of a resident heart stem cell niche in the epicardium
- B Dedifferentiation and proliferation of cardiomyocytes
- C Morphallactic remodeling of the atrium
- D Recruitment of bone marrow cells to the heart
Correct answer: Dedifferentiation and proliferation of cardiomyocytes
Zebrafish can fully regenerate their heart. Unlike mammals, zebrafish cardiomyocytes can temporarily lose their contractile structure, re-enter the cell cycle, and proliferate to replace lost tissue.
What defines a 'Stem Cell Niche'?
- A The specific set of genes within a stem cell
- B A microenvironment that regulates stem cell fate
- C The geometric shape of a stem cell colony in a petri dish
- D The waste products produced by proliferating cells
Correct answer: A microenvironment that regulates stem cell fate
The niche provides the physical and chemical signals (cell-cell contacts, secreted factors, extracellular matrix) necessary to prevent stem cells from differentiating prematurely or depleting the pool.
Which transcription factor is often called the 'master regulator' of pluripotency and is expressed in the inner cell mass of the blastocyst?
- A MyoD
- B Pax6
- C Snail
- D Oct4
Correct answer: Oct4
Oct4 (Octamer-binding transcription factor 4) is essential for maintaining the undifferentiated state and pluripotency of embryonic stem cells. Loss of Oct4 leads to immediate differentiation into trophectoderm.
The process where one differentiated cell type transforms directly into another differentiated cell type without a proliferative intermediate is called:
- A Reversible metaplasia
- B Compensatory hypertrophy
- C Dysplasia
- D Transdifferentiation
Correct answer: Transdifferentiation
Transdifferentiation (or metaplasia in pathology) is the direct conversion of one cell lineage to another. An example is the conversion of iris cells to lens cells in newts.
In the hematopoietic niche of the bone marrow, which cells are responsible for anchoring HSCs and maintaining their quiescence?
- A Osteoblasts
- B Osteoclasts
- C Red blood cells
- D T-lymphocytes
Correct answer: Osteoblasts
Osteoblasts on the inner surface of the bone (endosteum) interact with HSCs through molecules like N-cadherin and Tie2 to maintain the stem cells in a dormant (quiescent) state until they are needed.
What is the primary limitation of adult (somatic) stem cells compared to embryonic stem cells?
- A They are more likely to form tumors (teratomas)
- B They are easier to harvest in large quantities
- C They do not contain the full genome of the organism
- D They have a restricted differentiation potential
Correct answer: They have a restricted differentiation potential
Adult stem cells are typically multipotent or unipotent, meaning they can only form a limited range of cell types related to their tissue of origin, whereas ESCs are pluripotent and can form any body cell.
The 'Hayflick Limit' refers to which phenomenon that affects regenerative capacity?
- A The maximum speed at which a blastema can grow
- B The depth of a wound that can successfully heal
- C The temperature threshold for regeneration in reptiles
- D The limited number of times a cell population divides
Correct answer: The limited number of times a cell population divides
The Hayflick Limit is the number of times a cell population will divide before cell division stops, often due to telomere shortening. This contributes to the decline in stem cell function during aging.