NBME 29 Exam Questions and
Answer 100% PASS
1
Exam Section 1: Item 1 of 50
National Board of Medical Examiners'
Comprehensive Basic Science Self-Assessment
1. Patients with prolonged starvation or untreated type 1 diabetes mellitus overproduce
ketone bodies. Which of the following is a common factor that is responsible for ketosis in
patients with
these two conditions?
A) Depletion of pentose phosphate pathway intermediates
B) Increased availability of acetyl COA
C) Inhibition of fatty acid oxidation
D) Inhibition of gluconeogenesis
E) Inhibition of glycogenolysis—ANSWER-B.
,Increased availability of acetyl CoA is common to states of starvation and untreated type 1
diabetes mellitus. In starvation, glycogen stores are gradually depleted. The body then relies
on the
breakdown of fat through oxidation of fatty acids to provide energy. Fatty acid oxidation
occurs in the mitochondria of the cell. In each cycle of oxidation, two-carbon fragments are
cleaved to form
acetyl CoA, which leaves the mitochondria via the carnitine shuttle. In addition to a molecule
of acetyl CoA which then enters the citric acid cycle, a molecule of NADH is produced in each
cycle.
Ketogenesis occurs in starvation via two-carbon fragments, with formation of ketoacids such
as acetoacetyl CoA and B-hydroxybutyrate. The ability to generate energy from adipose
during a
period of starvation is critical to maintaining the function of vital organs, such as the brain. In
untreated type 1 diabetes mellitus, there is an absolute deficiency of insulin, which renders
many
cells incapable of shuttling glucose into the cell for use in cellular respiration. While there
are several glucose transporters that do not require insulin for glucose entry, GLUT4 is
commonly
expressed in many cell types and requires insulin to function. Patients with untreated type 1
diabetes mellitus will have serum glucose concentrations in the high-normal to high range as
a result
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Brittie Donald
,of ongoing gluconeogenesis and glycogenolysis, but insulin deficiency prevents entry of
circulating glucose into cells through glucose transport proteins, effectively resulting in a
state of
starvation. This results in ketogenesis and accounts for the presence of ketone bodies in the
blood and urine of patients with starvation or untreated type 1 diabetes mellitus.
Incorrect Answers: A, C, D, and E.
Depletion of pentose phosphate pathway intermediates (Choice A) is not correct. This
pathway is active in many tissues including the liver, adrenal cortex, and in erythrocytes. It
produces
NADPH, ribose-5-phosphate, and erythrose-4-phosphate from glucose. Decreased activity of
this pathway would not lead to generation of ketones.
Inhibition of fatty acid oxidation (Choice C) is not correct. Fatty acid oxidation is increased
during states of starvation or untreated type 1 diabetes mellitus.
Inhibition of gluconeogenesis (Choice D) and inhibition of glycogenolysis (Choice E) are not
features of starvation or untreated type 1 diabetes mellitus. In fact, these processes are
accelerated in
both states, although in starvation, this is caused by a deficiency of glucose. In untreated
type 1 diabetes mellitus, these pathways are upregulated as a result of insulin deficiency,
perceived by
the cell as a hypoglycemic state.
, Educational Objective: Both starvation and untreated type 1 diabetes mellitus result in an
increased rate of fatty acid oxidation, which generates acetyl CoA to be used in the citric acid
cycle and
NADH. Concomitant ketogenesis results in the formation of ketone bodies that can be
detected in serum and urine.
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2
Exam Section 1: Item 2 of 50
National Board of Medical Examiners'
Comprehensive Basic Science Self-Assessment
2. A 65-year-old man comes to the emergency department because of a 1-week history of
blood in his sputum. A mass is found on a radiograph. Bronchoscopy is planned. In order to
pass the
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Brittie Donald
Answer 100% PASS
1
Exam Section 1: Item 1 of 50
National Board of Medical Examiners'
Comprehensive Basic Science Self-Assessment
1. Patients with prolonged starvation or untreated type 1 diabetes mellitus overproduce
ketone bodies. Which of the following is a common factor that is responsible for ketosis in
patients with
these two conditions?
A) Depletion of pentose phosphate pathway intermediates
B) Increased availability of acetyl COA
C) Inhibition of fatty acid oxidation
D) Inhibition of gluconeogenesis
E) Inhibition of glycogenolysis—ANSWER-B.
,Increased availability of acetyl CoA is common to states of starvation and untreated type 1
diabetes mellitus. In starvation, glycogen stores are gradually depleted. The body then relies
on the
breakdown of fat through oxidation of fatty acids to provide energy. Fatty acid oxidation
occurs in the mitochondria of the cell. In each cycle of oxidation, two-carbon fragments are
cleaved to form
acetyl CoA, which leaves the mitochondria via the carnitine shuttle. In addition to a molecule
of acetyl CoA which then enters the citric acid cycle, a molecule of NADH is produced in each
cycle.
Ketogenesis occurs in starvation via two-carbon fragments, with formation of ketoacids such
as acetoacetyl CoA and B-hydroxybutyrate. The ability to generate energy from adipose
during a
period of starvation is critical to maintaining the function of vital organs, such as the brain. In
untreated type 1 diabetes mellitus, there is an absolute deficiency of insulin, which renders
many
cells incapable of shuttling glucose into the cell for use in cellular respiration. While there
are several glucose transporters that do not require insulin for glucose entry, GLUT4 is
commonly
expressed in many cell types and requires insulin to function. Patients with untreated type 1
diabetes mellitus will have serum glucose concentrations in the high-normal to high range as
a result
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Brittie Donald
,of ongoing gluconeogenesis and glycogenolysis, but insulin deficiency prevents entry of
circulating glucose into cells through glucose transport proteins, effectively resulting in a
state of
starvation. This results in ketogenesis and accounts for the presence of ketone bodies in the
blood and urine of patients with starvation or untreated type 1 diabetes mellitus.
Incorrect Answers: A, C, D, and E.
Depletion of pentose phosphate pathway intermediates (Choice A) is not correct. This
pathway is active in many tissues including the liver, adrenal cortex, and in erythrocytes. It
produces
NADPH, ribose-5-phosphate, and erythrose-4-phosphate from glucose. Decreased activity of
this pathway would not lead to generation of ketones.
Inhibition of fatty acid oxidation (Choice C) is not correct. Fatty acid oxidation is increased
during states of starvation or untreated type 1 diabetes mellitus.
Inhibition of gluconeogenesis (Choice D) and inhibition of glycogenolysis (Choice E) are not
features of starvation or untreated type 1 diabetes mellitus. In fact, these processes are
accelerated in
both states, although in starvation, this is caused by a deficiency of glucose. In untreated
type 1 diabetes mellitus, these pathways are upregulated as a result of insulin deficiency,
perceived by
the cell as a hypoglycemic state.
, Educational Objective: Both starvation and untreated type 1 diabetes mellitus result in an
increased rate of fatty acid oxidation, which generates acetyl CoA to be used in the citric acid
cycle and
NADH. Concomitant ketogenesis results in the formation of ketone bodies that can be
detected in serum and urine.
%3D
Next
Score Report
Lab Values
Calculator
Help
Pause
2
Exam Section 1: Item 2 of 50
National Board of Medical Examiners'
Comprehensive Basic Science Self-Assessment
2. A 65-year-old man comes to the emergency department because of a 1-week history of
blood in his sputum. A mass is found on a radiograph. Bronchoscopy is planned. In order to
pass the
© 2026 Copyright. All Rights Reserved. This document is
protected by copyright law, Copyrighted By Brittie Donald
