Science
Questions 1-11 are based on the following passage.
Adapted from “A Molecular Model of Blood Cell Renewal.” ©2004 by the Public Library of Science.
1 The main purpose of the passage is to
A) contradict a widely held belief about hematopoietic stem cells.
B) discuss the social implications of human stem cell research.
C) describe the results of a study concerning hematopoietic stem cells.
D) Explain the process by which human stem cells differentiate into specific tissues.
2 It can reasonably be inferred from the passage that, prior to Goodell’s study, research concerning stem cells had
A) resulted in a comprehensive list of those genes involved in stem cell renewal and differentiation.
B) failed to identify any genes that were expressed exclusively in stem cells.
C) elucidated a number of regulatory mechanisms underlying gene expression in stem cells.
D) isolated a few genes that were expressed exclusively in stem cells but had not identified how they worked.
3 Which choice best summarizes the results of Goodell’s study concerning hematopoietic stem cell renewal?
A) Hematopoietic stem cells can differentiate into either red blood cells or white blood cells.
B) The process of stem cell renewal can be subdivided into the stages of quiescence, activation, and proliferation.
C) Hematopoietic stem cells differentiate in a fashion similar to fetal mouse stem cells.
D) Different sets of genes are expressed in hematopoietic stem cells based on the stage of stem cell renewal.
4 As used in line 12, “mature” most nearly means
A) developed.
B) mellow.
C) thorough
D) experienced
5 Which choice best summarizes the results of Goodell’s study concerning hematopoietic stem cell renewal?
A) Hematopoietic stem cells can differentiate into either red blood cells or white blood cells.
B) The process of stem cell renewal can be subdivided into the stages of quiescence, activation, and proliferation.
C) Hematopoietic stem cells differentiate in a fashion similar to fetal mouse stem cells.
D) Different sets of genes are expressed in hematopoietic stem cells based on the stage of stem cell renewal.
6 Which choice provides the best evidence for the answer to the previous question?
A) lines 16-17 (“Adult...rare”)
B) lines 34-36 (“HSCs...infection”)
C) lines 47-52 (“They...states”)
D) lines 57-60 (“Functional...groupings”)
7 As used in line 26, “obscure” most nearly means
A) unclear
B) complicated
C) ambiguous
D) secluded
8 Which choice best represents the author’s perspective on stem cell research?
A) Stem cell research has the potential to substantially improve scientists’ ability to repair damaged tissues in the body.
B) While stem cell research can improve our understanding of human development, it requires advanced training and education.
C) It is worthwhile to pursue stem cell research using fetal mouse stem cells but not human stem cells.
D) Stem cell research has the potential to substantially improve doctors’ ability to diagnose and treat diseases.
9 The main purpose of the figure is to
A) suggest that both human and mouse embryonic stem cells spend most of their rime in the quiescent phase of stem cell renewal.
B) show that the timelines of stem cell renewal in human and mouse embryonic stem cells are identical.
C) illustrate the different timelines by which human and mouse embryonic stem cells renew and differentiate.
D) highlight how mouse stem cells differentiate into various tissues of the body.
10 How does the figure support the author’s description of the stem cell renewal process in the final paragraph of the passage?
A) It establishes that stem cells go through a short period of quiescence before returning to a prolonged state of proliferation.
B) It indicates that the stem cell renewal process occurs rapidly before birth but then slows down considerably after birth.
C) It shows how stem cells go through a phase of rapid proliferation before returning to a state of quiescence.
D) It clarifies how stem cells could be used to help repair damaged tissues in various clinical situations.
11 According to the figure, at 15.5 days of embryonic development a mouse’s hematopoietic stem cells are in the
A) specification phase.
B) emergence phase.
C) maturation phase.
D) expansion phase.
