BIO 117 – EXAM 3 | 412 2026 EXAM REVIEW
SOLVED QUESTIONS AND CORRECT
ANSWERS GRADED A+
◉ _____ is responsible for forming the three distinct layers during
gastrulation.
Answer: Cell movement (differential expansion)
◉ The predominant mechanism driving cellular differentiation is the
difference in gene _____.
Answer: expression
◉ Programmed cell death, apoptosis, plays a major role in all of the
following developmental situations except: _____.
Answer: growth of nerves and blood vessels into a body segment
◉ Which observation shows that cellular differentiation does not
involve changes in the genetic makeup of cells?
Answer: A single root cell from an adult carrot can grow into an
entire carrot plant.
◉ Differential gene expression and apoptosis are key processes in
development because they _____.
, Answer: offer an explanation as to how transcription controls
development and how loss of specific cells can facilitate formation of
mature organs
◉ How does the Bicoid protein provide positional information along
the anterior-posterior axis of the fly embryo?
Answer: It is present at high concentration at the anterior end and
low concentration at the posterior end.
◉ What is the regulatory gene cascade triggered by Bicoid that leads
to the differentiation of segments along the anterior-posterior axis
of the fly embryo?
Answer: segmentation genes→Hox genes→effector genes
◉ The anterior-posterior axis of most animals is determined by _____.
Answer: regulatory gene expression in a concentration gradient
from the anterior to the posterior end
◉ The order of Hox genes on the Drosophila chromosome has been
found to be conserved in other animals. Moreover, these genes have
been shown to be duplicated and changed in different organisms
that have different form. This indicates _____.
Answer: evolutionary changes in developmental pathways are
genetically based
SOLVED QUESTIONS AND CORRECT
ANSWERS GRADED A+
◉ _____ is responsible for forming the three distinct layers during
gastrulation.
Answer: Cell movement (differential expansion)
◉ The predominant mechanism driving cellular differentiation is the
difference in gene _____.
Answer: expression
◉ Programmed cell death, apoptosis, plays a major role in all of the
following developmental situations except: _____.
Answer: growth of nerves and blood vessels into a body segment
◉ Which observation shows that cellular differentiation does not
involve changes in the genetic makeup of cells?
Answer: A single root cell from an adult carrot can grow into an
entire carrot plant.
◉ Differential gene expression and apoptosis are key processes in
development because they _____.
, Answer: offer an explanation as to how transcription controls
development and how loss of specific cells can facilitate formation of
mature organs
◉ How does the Bicoid protein provide positional information along
the anterior-posterior axis of the fly embryo?
Answer: It is present at high concentration at the anterior end and
low concentration at the posterior end.
◉ What is the regulatory gene cascade triggered by Bicoid that leads
to the differentiation of segments along the anterior-posterior axis
of the fly embryo?
Answer: segmentation genes→Hox genes→effector genes
◉ The anterior-posterior axis of most animals is determined by _____.
Answer: regulatory gene expression in a concentration gradient
from the anterior to the posterior end
◉ The order of Hox genes on the Drosophila chromosome has been
found to be conserved in other animals. Moreover, these genes have
been shown to be duplicated and changed in different organisms
that have different form. This indicates _____.
Answer: evolutionary changes in developmental pathways are
genetically based
