$$\text{Rate of stem cell division} = \text{Rate of cell loss by apoptosis or shedding}$$

$$\text{Number of stem cells} \leq \text{Niche capacity}$$

Question 1

Which of the following best describes the role of stem cells in tissue homeostasis, as illustrated by the analogy of a river system?

Accepted Answer

Stem cells provide a constant supply of new cells, similar to rain supplying water to a river.

Question 2

In the gut epithelium, what is the primary function of Paneth cells?

Accepted Answer

They secrete antimicrobial molecules and support stem cells.

Question 3

Which equation best represents the balance required for tissue homeostasis in a renewing tissue?

Accepted Answer

$$	ext{Rate of stem cell division} = 	ext{Rate of cell loss by apoptosis or shedding}$$

Question 4

Which of the following is a key feature of asymmetric stem cell division?

Accepted Answer

One daughter cell self-renews while the other differentiates.

Question 5

A patient receives a bone marrow transplant after irradiation. Which process allows the transplanted stem cells to restore blood cell production?

Accepted Answer

Self-renewal and differentiation of hematopoietic stem cells.

Question 6

Which of the following statements about the stem cell niche is correct?

Accepted Answer

The niche provides signals that maintain stem cell identity.

Question 7

Which cell type in the gut epithelium is responsible for rapid division and acts as a transit-amplifying cell?

Accepted Answer

Progenitor cell

Question 8

Which of the following best describes the potency of embryonic stem cells?

Accepted Answer

Totipotent

Question 9

A researcher uses OKSM factors to reprogram fibroblasts. What is the expected outcome?

Accepted Answer

The fibroblasts are converted into induced pluripotent stem cells (iPS cells).

Question 10

Which of the following is a limitation of tissue regeneration in mammals?

Accepted Answer

Some tissues, such as the auditory epithelium, lack stem cells and cannot regenerate.

Question 11

Which process is illustrated by the migration of epithelial cells from the crypt to the villus tip in the gut?

Accepted Answer

Cell turnover and renewal

Question 12

Which of the following equations best describes the relationship between stem cell number and niche size?

Accepted Answer

$$	ext{Number of stem cells} \leq 	ext{Niche capacity}$$

Question 13

Which of the following best explains why hematopoietic stem cell transplantation can cure certain blood disorders?

Accepted Answer

Transplanted stem cells can self-renew and differentiate into all blood cell types.

Question 14

Which of the following is a real-world application of induced pluripotent stem (iPS) cell technology?

Accepted Answer

Generation of patient-specific cells for disease modeling and drug screening.

Question 15

Which of the following best describes the difference between symmetric and asymmetric stem cell division?

Accepted Answer

Symmetric division produces two identical daughter cells, while asymmetric division produces one stem cell and one differentiated cell.

Question 16

A mutation causes loss of function in the Sox2 gene during iPS cell generation. What is the most likely outcome?

Accepted Answer

Failure to upregulate embryonic stem cell genes, blocking iPS cell formation.

Question 17

Which of the following best explains why the auditory epithelium does not regenerate after injury?

Accepted Answer

It lacks resident stem cells capable of regeneration.

Question 18

Which of the following is a critical function of the stem cell niche in the bone marrow?

Accepted Answer

Providing signals that maintain hematopoietic stem cell self-renewal.

Question 19

Which of the following best describes the fate of a transit-amplifying cell in the epidermis?

Accepted Answer

It divides a limited number of times before differentiating.

Question 20

Which of the following is a key step in the generation of a chimeric mouse using embryonic stem cells?

Accepted Answer

Injection of ES cells into the inner cell mass of a host blastocyst.

Stem Cells in Tissue Homeostasis and Regeneration: Study Notes

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