Question

the importance of stem cells
national institutes of health
stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. in addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. when a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
stem cells are distinguished from other cell types by two important characteristics. first, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. second, under certain physiologic or experimental conditions, they can be induced to become tissue - or organ - specific cells with special functions. in some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues. in other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions
which statement refers to information that is explicitly mentioned in the passage?
a scientists working the field of stem cell development believe they have reached the end of mysteries regarding the inner workings of the stem cell
b some of the controversies surrounding the use of stem cells in laboratory research center around certain religious tenets of the various major religions.
c the stem cells that are used in laboratory research today all derive from embryonic stem cells developed from un - used in - vitro fertilization blastocysts.
d stem cells are unspecialized cells capable of renewing themselves through cell division and developing into various types of somatic cells, sometimes after long periods of inactivity.

Explanation:

• Option A: The passage doesn't say scientists believe they've reached the end of stem cell mysteries. Eliminate A.
• Option B: The passage has no mention of controversies related to religious tenets. Eliminate B.
• Option C: The passage doesn't state all lab - used stem cells come from embryonic stem cells of unused in - vitro fertilization blastocysts. Eliminate C.
• Option D: The passage says "Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue - or organ - specific cells with special functions." Option D's description about stem cells being unspecialized, renewing through cell division, and developing into various somatic cells (tissue - or organ - specific cells) sometimes after long inactivity matches the passage.

Answer:

D. Stem cells are unspecialized cells capable of renewing themselves through cell division and developing into various types of somatic cells, sometimes after long periods of inactivity