Stem Cells and Regeneration Practice Questions
20 free Stem Cells and Regeneration practice questions for the USMLE Step 1. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following is a defining characteristic of a true stem cell?
- A Having a fixed, specialized function within a tissue
- B A complete inability to divide after birth
- C Self-renewal and differentiation into other cell types
- D Permanent residence in the G0 phase of the cell cycle
Correct answer: Self-renewal and differentiation into other cell types
Stem cells are undifferentiated cells that can self-renew (i.e. make more stem cells) and differentiate into specialized cell types — allowing tissue maintenance and repair.
Which term best describes stem cells that can give rise to all cell types of the adult body (but not extra-embryonic tissues)?
- A Totipotent
- B Pluripotent
- C Multipotent
- D Unipotent
Correct answer: Pluripotent
Pluripotent stem cells (such as embryonic stem cells) can differentiate into nearly all cell types of the body (but not extra-embryonic tissues like placenta), distinguishing them from totipotent cells.
Which type of stem cell is most important for ongoing tissue maintenance and repair in adult organisms?
- A Embryonic stem cell
- B Totipotent zygote
- C Adult (somatic) stem cell
- D Extra-embryonic stem cell
Correct answer: Adult (somatic) stem cell
Adult (somatic) stem cells reside in mature tissues and act as an internal repair system, replacing cells lost through normal wear, injury or disease — thus maintaining tissue homeostasis.
Which of the following best describes a multipotent stem cell?
- A It can generate all body cell types including extra-embryonic cells.
- B It differentiates into several related cell types within one lineage.
- C It can only produce one specific type of cell.
- D It has completely lost the ability to self-renew.
Correct answer: It differentiates into several related cell types within one lineage.
Multipotent stem cells can differentiate into several cell types within a related family (e.g. hematopoietic stem cells producing various blood cell types) — more restricted than pluripotent but still versatile.
Which of the following stem cell sources requires ethical considerations because they are derived from early embryos?
- A Adult bone marrow stem cells
- B Mesenchymal stem cells from fat tissue
- C Embryonic stem cells (ESCs)
- D Induced pluripotent stem cells (iPSCs)
Correct answer: Embryonic stem cells (ESCs)
Embryonic stem cells are derived from the inner cell mass of blastocysts (early embryos), raising ethical issues related to embryo use, unlike adult stem cells or iPSCs.
What is the main advantage of using Induced pluripotent stem cells (iPSCs) in regenerative medicine compared to embryonic stem cells?
- A They are totipotent rather than merely pluripotent.
- B They come from adult cells, avoiding ethical concerns.
- C They do not require specialized culture conditions.
- D They cannot differentiate, reducing risk of tumors.
Correct answer: They come from adult cells, avoiding ethical concerns.
iPSCs are generated by reprogramming adult somatic cells, avoiding use of embryos — thus bypassing many ethical issues associated with embryonic stem cells while retaining pluripotent properties.
Which of the following best describes the concept of a stem cell “niche”?
- A Any tissue where stem cells are actively dividing
- B A specialized microenvironment regulating stem cell fate
- C A laboratory dish used to culture stem cells in vitro
- D An organ composed entirely of undifferentiated stem cells
Correct answer: A specialized microenvironment regulating stem cell fate
A stem cell niche refers to the specialized microenvironment (extracellular matrix, supporting cells, signals) that maintains stem cells in an undifferentiated state or regulates their activation, self-renewal and differentiation.
Which of the following organs is well-known for containing adult stem cells that continuously regenerate tissue under normal physiologic conditions?
- A Brain cortex
- B Skeletal muscle (myofibers)
- C Bone marrow
- D Cardiac muscle
Correct answer: Bone marrow
Bone marrow contains hematopoietic stem cells, which continuously replenish blood and immune cells through self-renewal and differentiation — a classic example of adult stem cell mediated tissue regeneration.
Which of the following describes a major limitation of adult (somatic) stem cells compared to embryonic stem cells, in terms of potency?
- A Adult stem cells generally divide much more slowly than others
- B They are multipotent, not pluripotent, forming fewer cell types
- C Adult stem cells are entirely unable to self-renew
- D Adult stem cells always form tumors when transplanted
Correct answer: They are multipotent, not pluripotent, forming fewer cell types
Adult stem cells are typically multipotent (or unipotent), so they can generate only certain related cell types rather than all body cell types, limiting their differentiation potential compared to pluripotent embryonic stem cells.
Which of the following processes describes tissue regeneration by proliferation and differentiation of stem or progenitor cells after injury?
- A Fibrosis with scar formation
- B Stem cell–mediated regeneration
- C Apoptosis of damaged cells only
- D Transient inflammation without proliferation
Correct answer: Stem cell–mediated regeneration
Stem cell–mediated regeneration involves activation of stem or progenitor cells, which proliferate and differentiate to replace lost or damaged cells, restoring tissue structure and function.
Which statement best reflects why some tissues (e.g., brain, heart) have poor regenerative capacity despite the presence of stem cells in the body overall?
- A Their resident stem cells are totipotent rather than multipotent
- B Their niche does not support effective stem cell activation
- C They lack the blood supply necessary for proper stem cell function
- D They undergo continuous inflammation preventing regeneration
Correct answer: Their niche does not support effective stem cell activation
Poor regenerative capacity in certain tissues often reflects the absence of a supportive niche or insufficient activation of resident stem cells, limiting their ability to replace lost cells effectively. Stem cell presence alone does not guarantee regeneration.
Which type of potency refers to the ability to differentiate into a single cell type only?
- A Multipotent
- B Pluripotent
- C Unipotent
- D Totipotent
Correct answer: Unipotent
Unipotent stem cells are capable of self-renewal but can differentiate into only one cell type. They are more restricted than multipotent or pluripotent cells.
Which of the following best describes a risk associated with uncontrolled use of pluripotent stem cells in regenerative therapy?
- A They may differentiate into unrelated cell lineages far too quickly
- B They may permanently lose their ability to divide
- C They may form tumors like teratomas from uncontrolled proliferation
- D They can only ever produce blood cells
Correct answer: They may form tumors like teratomas from uncontrolled proliferation
Because pluripotent stem cells can differentiate into many cell types and proliferate extensively, if not properly regulated they may form teratomas or other tumors — a recognized risk in regenerative medicine.
In the context of regeneration, what is the meaning of the term “plasticity” with respect to adult stem cells?
- A Permanent quiescence of all resident stem cells
- B Complete inability of adult stem cells to differentiate at all
- C Gaining broader differentiation potential in some conditions
- D A fixed output of only one specific cell type
Correct answer: Gaining broader differentiation potential in some conditions
Plasticity refers to the capacity of some adult stem cells to widen their differentiation potential (beyond their usual lineage) under certain environmental or experimental conditions, which may aid in tissue repair.
Which of the following is true about symmetric vs. asymmetric division of stem cells in a tissue niche?
- A Asymmetric division produces two identical stem cells every time
- B Symmetric division always immediately leads to differentiation
- C Asymmetric division yields one stem and one differentiated cell
- D Symmetric division is never observed in any adult tissue
Correct answer: Asymmetric division yields one stem and one differentiated cell
In asymmetric division, a stem cell divides to produce one daughter that remains a stem cell and one that differentiates — allowing continual maintenance of the stem cell pool while generating specialized daughter cells. This balances self-renewal and tissue regeneration.
Which class of stem cells would be most suitable for generating all different cell types of a human organ in vitro (assuming appropriate conditions)?
- A Adult tissue-specific unipotent stem cells
- B Multipotent mesenchymal stem cells
- C Pluripotent embryonic stem cells or iPSCs
- D Tissue-committed progenitor cells
Correct answer: Pluripotent embryonic stem cells or iPSCs
Pluripotent stem cells (embryonic stem cells or iPSCs) have the broadest differentiation potential, making them suitable for generating all or most cell types of a given organ under proper culture and differentiation conditions.
Which of the following scenarios exemplifies regeneration by stem cell activation rather than repair by scar (fibrosis)?
- A Formation of granulation tissue and collagen deposition after myocardial infarction
- B Renewal of intestinal epithelium via intestinal stem cells after mucosal injury
- C Formation of nonfunctional fibrous tissue replacing lost tissue in severe liver damage
- D Permanent scar formation in skeletal muscle after trauma
Correct answer: Renewal of intestinal epithelium via intestinal stem cells after mucosal injury
The intestinal epithelium regenerates via activation of resident intestinal stem cells to replace damaged mucosal cells, restoring normal structure and function — a true regenerative process rather than fibrotic scar formation. Adult stem cells in tissues with high turnover mediate this.
Which of the following correctly ranks stem cell potency from most to least potent?
- A Unipotent > Multipotent > Pluripotent > Totipotent
- B Totipotent > Pluripotent > Multipotent > Unipotent
- C Multipotent > Totipotent > Pluripotent > Unipotent
- D Pluripotent > Totipotent > Multipotent > Unipotent
Correct answer: Totipotent > Pluripotent > Multipotent > Unipotent
Totipotent cells (e.g. zygote) can form all cell types including extra-embryonic tissues; pluripotent cells can form nearly all body cell types; multipotent cells generate a restricted lineage; unipotent cells only one cell type — so potency decreases in that order.
Which of the following is a key challenge in using stem cells for regenerative therapies in clinical practice?
- A Lack of ability to differentiate into specialized cells
- B Achieving proper differentiation without tumor formation
- C Stem cells are unable to proliferate in vitro
- D Stem cells only exist during embryonic development
Correct answer: Achieving proper differentiation without tumor formation
A critical challenge is to control stem cell differentiation precisely to yield desired cell types and avoid risks such as teratoma or other unintended growth, which can complicate therapeutic applications.
Which statement best describes why some tissues heal primarily by fibrosis rather than regeneration despite the presence of stem or progenitor cells?
- A Stem cells in those tissues are always inactive
- B Niche signals may favor fibroblast scarring over regeneration
- C Scar tissue is often more functional than regenerated tissue
- D Stem cells transform directly into fibroblasts upon injury
Correct answer: Niche signals may favor fibroblast scarring over regeneration
Even with stem/progenitor cells, if the microenvironment or signals after injury do not favor regeneration, the repair process may default to fibroblast proliferation and deposition of extracellular matrix — resulting in fibrosis rather than true tissue regeneration.