BIOD 121 Module 4 Exam | Portage Learning
Nutrition Test Bank 2026
1. A 45-year-old male with a history of type 2 diabetes and hypertension presents with fatigue and
muscle cramps. His serum potassium is 3.2 mEq/L, and he is on hydrochlorothiazide. Which of the
following mechanisms best explains the hypokalemia?
A. Increased renal potassium reabsorption due to aldosterone suppression
B. Enhanced sodium-potassium ATPase activity in skeletal muscle
C. Increased distal tubular potassium secretion secondary to increased sodium delivery
D. Reduced dietary potassium intake combined with gastrointestinal losses
Answer: C
Rationale: Thiazide diuretics increase sodium delivery to the distal tubule, which stimulates potassium
secretion via the sodium-potassium exchange mechanism. Aldosterone is not suppressed; it may be
stimulated. The other options do not directly explain the effect of thiazides.
2. In a randomized controlled trial, participants consuming a diet with a glycemic index of 55
showed a 15% lower incidence of type 2 diabetes over 10 years compared to those consuming a diet
with glycemic index 70. Which physiological mechanism most likely mediates this protective effect?
A. Increased postprandial insulin secretion leading to improved beta-cell function
B. Reduced postprandial glucose excursions and lower insulin demand
C. Enhanced glucagon-like peptide-1 secretion from the distal ileum
D. Decreased hepatic glucose output due to improved insulin sensitivity
Answer: B
Rationale: Low glycemic index diets result in slower glucose absorption, reducing postprandial spikes
and insulin demand. This reduces beta-cell stress and insulin resistance over time. Option A is incorrect
because high insulin secretion is not beneficial; option C is not the primary mechanism; option D is a
downstream effect but not the direct mechanism.
3. Which of the following best explains why vitamin B12 deficiency can lead to megaloblastic
anemia while folate deficiency causes a similar macrocytic anemia, but only B12 deficiency results
in neurological symptoms?
A. Folate is involved in DNA synthesis, while B12 is only involved in myelin production
B. B12 is required for the conversion of methylmalonyl-CoA to succinyl-CoA, which is critical for fatty acid
metabolism in neurons
C. Folate can cross the blood-brain barrier, but B12 cannot
D. B12 deficiency impairs the folate cycle, leading to homocysteine accumulation, which is neurotoxic
Answer: B
Rationale: Vitamin B12 is a cofactor for methionine synthase (involved in folate metabolism) and
methylmalonyl-CoA mutase. The latter is essential for myelin synthesis; its impairment leads to
neurological damage. Folate deficiency does not affect this pathway. Option D is partially true but not
Page 1
,the primary reason for neurological symptoms.
4. A study reports a Pearson correlation coefficient of -0.72 between dietary fiber intake and serum
LDL cholesterol levels (p < 0.001). Which of the following conclusions is most appropriate?
A. High fiber intake causes a decrease in LDL cholesterol
B. Approximately 52% of the variability in LDL cholesterol is explained by fiber intake
C. For every gram increase in fiber, LDL decreases by 0.72 mg/dL
D. The relationship is nonlinear and requires log transformation
Answer: B
Rationale: The coefficient of determination (r²) is 0.52, meaning 52% of the variance in LDL is explained
by fiber intake. Correlation does not imply causation (A). Option C would require a regression
coefficient, not correlation. Option D is not indicated by the data.
5. A patient with chronic kidney disease (stage 4) has a serum phosphorus of 6.5 mg/dL and
calcium of 9.2 mg/dL. Which dietary intervention is most appropriate to manage
hyperphosphatemia while avoiding calcium overload?
A. Increase dairy intake to bind phosphorus in the gut
B. Prescribe calcium carbonate with meals to bind phosphorus
C. Recommend sevelamer carbonate as a phosphate binder
D. Restrict dietary protein intake to 0.6 g/kg/day without binders
Answer: C
Rationale: Sevelamer is a non-calcium-based phosphate binder, preferred in CKD to avoid calcium
overload and vascular calcification. Calcium-based binders (B) can exacerbate hypercalcemia. Dairy is
high in phosphorus (A). Protein restriction alone is insufficient (D).
6. A 30-year-old female with a BMI of 17.5 and amenorrhea is diagnosed with anorexia nervosa.
Which of the following laboratory findings is most consistent with her condition?
A. Elevated serum leptin and low ghrelin
B. Low serum leptin and elevated ghrelin
C. Elevated serum cortisol and low growth hormone
D. Low serum cortisol and elevated growth hormone
Answer: B
Rationale: In anorexia, adipose tissue is depleted, so leptin levels are low. Ghrelin, the hunger hormone,
is elevated due to chronic energy deficit. Cortisol may be elevated (C) due to stress, but growth hormone
is typically elevated, not low. Option A is opposite.
7. A researcher conducts a 24-hour dietary recall and calculates the probability of inadequacy for
iron using the Estimated Average Requirement (EAR) cut-point method. Which assumption is
critical for the validity of this method?
A. The nutrient intake distribution is symmetric and the requirement distribution is normal
B. Intake and requirement are correlated within individuals
C. The variability of intake is greater than the variability of requirement
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,D. The nutrient has a high prevalence of inadequacy in the population
Answer: A
Rationale: The EAR cut-point method assumes that the distribution of intakes and requirements are
independent and normally distributed. It also assumes that the variance of intake is greater than the
variance of requirement, but the key assumption is normality and independence. Option B is incorrect
because correlation would bias the estimate.
8. Which of the following metabolic adaptations occurs during prolonged fasting (72 hours) that
distinguishes it from short-term starvation (24 hours)?
A. Increased muscle protein breakdown to provide gluconeogenic substrates
B. Increased ketone body production to supply energy to the brain
C. Depletion of liver glycogen stores leading to increased glucose production from glycerol
D. Increased insulin secretion to promote glucose uptake by peripheral tissues
Answer: B
Rationale: After 72 hours, ketogenesis is significantly upregulated, and the brain adapts to use ketones
for energy, reducing glucose demand. Option A occurs but is not unique to prolonged fasting; it also
occurs in short-term starvation. Option C occurs earlier. Option D is incorrect; insulin decreases.
9. A clinical trial investigates the effect of a Mediterranean diet supplemented with extra-virgin
olive oil (EVOO) on cardiovascular events. The hazard ratio for the primary endpoint is 0.70 (95%
CI 0.55-0.89) compared to a low-fat diet. Which interpretation is correct?
A. The Mediterranean diet with EVOO reduces the risk of cardiovascular events by 30% over the study period
B. The Mediterranean diet with EVOO reduces the hazard of cardiovascular events by 30% at any given time
point
C. The Mediterranean diet with EVOO increases the risk of cardiovascular events by 30%
D. The hazard ratio indicates a non-significant reduction because the confidence interval includes 1.0
Answer: B
Rationale: A hazard ratio of 0.70 means that at any given time, the instantaneous risk of the event is 30%
lower in the intervention group. Option A is a common misinterpretation; hazard ratio is not cumulative
risk. The CI does not include 1.0, so it is significant (D).
10. A patient with short bowel syndrome has an intact colon and is receiving parenteral nutrition.
Which dietary modification is most likely to reduce parenteral nutrition dependence?
A. High simple carbohydrate diet to increase caloric absorption
B. High fiber diet with soluble fiber to slow transit and enhance colonic fermentation
C. Low-fat diet to reduce steatorrhea
D. High protein diet to promote intestinal adaptation
Answer: B
Rationale: Soluble fiber is fermented in the colon to short-chain fatty acids, which are absorbed and
provide additional energy. This can reduce reliance on parenteral nutrition. Simple carbohydrates (A)
may worsen osmotic diarrhea. Low-fat diet (C) reduces calories and essential fatty acids. Protein (D) is
important but not the most effective for reducing PN dependence in this scenario.
Page 3
, 11. In a clinical trial, participants with metabolic syndrome are randomly assigned to either a
high-fiber diet (30 g/day) or a standard diet (<15 g/day). After 12 weeks, the high-fiber group
shows a significant reduction in serum C-reactive protein (CRP) levels compared to controls.
Which of the following mechanisms most likely explains the observed anti-inflammatory effect of
dietary fiber?
A. Direct inhibition of cyclooxygenase-2 (COX-2) by short-chain fatty acids (SCFAs) in adipocytes
B. Reduction of intestinal permeability and subsequent decrease in lipopolysaccharide (LPS) translocation,
attenuating Toll-like receptor 4 (TLR4) signaling
C. Increased renal excretion of pro-inflammatory cytokines due to enhanced glomerular filtration rate
D. Competitive antagonism of interleukin-6 (IL-6) receptors by butyrate at the hepatocyte membrane
Answer: B
Rationale: Dietary fiber is fermented by gut microbiota to produce SCFAs, which strengthen gut barrier
function, reducing LPS translocation. Lower systemic LPS reduces TLR4 activation and downstream
inflammation. Direct COX-2 inhibition (A) is not a primary mechanism; SCFAs act via
G-protein-coupled receptors and histone deacetylase inhibition. Renal excretion (C) and IL-6 receptor
antagonism (D) are not established effects of dietary fiber.
12. A researcher is investigating the bioavailability of a novel iron-fortified food product. She
administers the product to a group of non-anemic, iron-replete volunteers and measures serum
iron levels over 8 hours. The area under the curve (AUC) for iron absorption is significantly lower
than that of a reference dose of ferrous sulfate. Which factor is most likely responsible for the
reduced iron absorption from the fortified food?
A. The food contains high levels of ascorbic acid, which chelates iron and prevents mucosal uptake
B. The iron in the food is predominantly in the ferric (Fe3+) form and is complexed with phytates present in the
food matrix
C. The food has a high pH (>8) that promotes the conversion of ferrous iron to insoluble ferric hydroxide
D. The iron is encapsulated in a lipid matrix that requires bile salt emulsification before release in the duodenum
Answer: B
Rationale: Phytates, common in plant-based foods, strongly chelate ferric iron (Fe3+), forming insoluble
complexes that reduce absorption. Ferrous sulfate provides Fe2+, which is more bioavailable. Ascorbic
acid enhances iron absorption, not reduces it (A). High pH can reduce solubility, but typical food pH is
not >8 (C). Lipid encapsulation might delay release but is not the most likely factor in a standard food
matrix (D).
13. A 45-year-old individual with a family history of type 2 diabetes undergoes an oral glucose
tolerance test (OGTT). Fasting plasma glucose is 108 mg/dL, and 2-hour plasma glucose is 155
mg/dL. Hemoglobin A1c is 6.2%. According to the American Diabetes Association criteria, which
of the following best categorizes this individual's glycemic status?
A. Normal glucose tolerance
B. Impaired fasting glucose (IFG) only
C. Impaired glucose tolerance (IGT) only
D. Both IFG and IGT (prediabetes)
Answer: D
Page 4
Nutrition Test Bank 2026
1. A 45-year-old male with a history of type 2 diabetes and hypertension presents with fatigue and
muscle cramps. His serum potassium is 3.2 mEq/L, and he is on hydrochlorothiazide. Which of the
following mechanisms best explains the hypokalemia?
A. Increased renal potassium reabsorption due to aldosterone suppression
B. Enhanced sodium-potassium ATPase activity in skeletal muscle
C. Increased distal tubular potassium secretion secondary to increased sodium delivery
D. Reduced dietary potassium intake combined with gastrointestinal losses
Answer: C
Rationale: Thiazide diuretics increase sodium delivery to the distal tubule, which stimulates potassium
secretion via the sodium-potassium exchange mechanism. Aldosterone is not suppressed; it may be
stimulated. The other options do not directly explain the effect of thiazides.
2. In a randomized controlled trial, participants consuming a diet with a glycemic index of 55
showed a 15% lower incidence of type 2 diabetes over 10 years compared to those consuming a diet
with glycemic index 70. Which physiological mechanism most likely mediates this protective effect?
A. Increased postprandial insulin secretion leading to improved beta-cell function
B. Reduced postprandial glucose excursions and lower insulin demand
C. Enhanced glucagon-like peptide-1 secretion from the distal ileum
D. Decreased hepatic glucose output due to improved insulin sensitivity
Answer: B
Rationale: Low glycemic index diets result in slower glucose absorption, reducing postprandial spikes
and insulin demand. This reduces beta-cell stress and insulin resistance over time. Option A is incorrect
because high insulin secretion is not beneficial; option C is not the primary mechanism; option D is a
downstream effect but not the direct mechanism.
3. Which of the following best explains why vitamin B12 deficiency can lead to megaloblastic
anemia while folate deficiency causes a similar macrocytic anemia, but only B12 deficiency results
in neurological symptoms?
A. Folate is involved in DNA synthesis, while B12 is only involved in myelin production
B. B12 is required for the conversion of methylmalonyl-CoA to succinyl-CoA, which is critical for fatty acid
metabolism in neurons
C. Folate can cross the blood-brain barrier, but B12 cannot
D. B12 deficiency impairs the folate cycle, leading to homocysteine accumulation, which is neurotoxic
Answer: B
Rationale: Vitamin B12 is a cofactor for methionine synthase (involved in folate metabolism) and
methylmalonyl-CoA mutase. The latter is essential for myelin synthesis; its impairment leads to
neurological damage. Folate deficiency does not affect this pathway. Option D is partially true but not
Page 1
,the primary reason for neurological symptoms.
4. A study reports a Pearson correlation coefficient of -0.72 between dietary fiber intake and serum
LDL cholesterol levels (p < 0.001). Which of the following conclusions is most appropriate?
A. High fiber intake causes a decrease in LDL cholesterol
B. Approximately 52% of the variability in LDL cholesterol is explained by fiber intake
C. For every gram increase in fiber, LDL decreases by 0.72 mg/dL
D. The relationship is nonlinear and requires log transformation
Answer: B
Rationale: The coefficient of determination (r²) is 0.52, meaning 52% of the variance in LDL is explained
by fiber intake. Correlation does not imply causation (A). Option C would require a regression
coefficient, not correlation. Option D is not indicated by the data.
5. A patient with chronic kidney disease (stage 4) has a serum phosphorus of 6.5 mg/dL and
calcium of 9.2 mg/dL. Which dietary intervention is most appropriate to manage
hyperphosphatemia while avoiding calcium overload?
A. Increase dairy intake to bind phosphorus in the gut
B. Prescribe calcium carbonate with meals to bind phosphorus
C. Recommend sevelamer carbonate as a phosphate binder
D. Restrict dietary protein intake to 0.6 g/kg/day without binders
Answer: C
Rationale: Sevelamer is a non-calcium-based phosphate binder, preferred in CKD to avoid calcium
overload and vascular calcification. Calcium-based binders (B) can exacerbate hypercalcemia. Dairy is
high in phosphorus (A). Protein restriction alone is insufficient (D).
6. A 30-year-old female with a BMI of 17.5 and amenorrhea is diagnosed with anorexia nervosa.
Which of the following laboratory findings is most consistent with her condition?
A. Elevated serum leptin and low ghrelin
B. Low serum leptin and elevated ghrelin
C. Elevated serum cortisol and low growth hormone
D. Low serum cortisol and elevated growth hormone
Answer: B
Rationale: In anorexia, adipose tissue is depleted, so leptin levels are low. Ghrelin, the hunger hormone,
is elevated due to chronic energy deficit. Cortisol may be elevated (C) due to stress, but growth hormone
is typically elevated, not low. Option A is opposite.
7. A researcher conducts a 24-hour dietary recall and calculates the probability of inadequacy for
iron using the Estimated Average Requirement (EAR) cut-point method. Which assumption is
critical for the validity of this method?
A. The nutrient intake distribution is symmetric and the requirement distribution is normal
B. Intake and requirement are correlated within individuals
C. The variability of intake is greater than the variability of requirement
Page 2
,D. The nutrient has a high prevalence of inadequacy in the population
Answer: A
Rationale: The EAR cut-point method assumes that the distribution of intakes and requirements are
independent and normally distributed. It also assumes that the variance of intake is greater than the
variance of requirement, but the key assumption is normality and independence. Option B is incorrect
because correlation would bias the estimate.
8. Which of the following metabolic adaptations occurs during prolonged fasting (72 hours) that
distinguishes it from short-term starvation (24 hours)?
A. Increased muscle protein breakdown to provide gluconeogenic substrates
B. Increased ketone body production to supply energy to the brain
C. Depletion of liver glycogen stores leading to increased glucose production from glycerol
D. Increased insulin secretion to promote glucose uptake by peripheral tissues
Answer: B
Rationale: After 72 hours, ketogenesis is significantly upregulated, and the brain adapts to use ketones
for energy, reducing glucose demand. Option A occurs but is not unique to prolonged fasting; it also
occurs in short-term starvation. Option C occurs earlier. Option D is incorrect; insulin decreases.
9. A clinical trial investigates the effect of a Mediterranean diet supplemented with extra-virgin
olive oil (EVOO) on cardiovascular events. The hazard ratio for the primary endpoint is 0.70 (95%
CI 0.55-0.89) compared to a low-fat diet. Which interpretation is correct?
A. The Mediterranean diet with EVOO reduces the risk of cardiovascular events by 30% over the study period
B. The Mediterranean diet with EVOO reduces the hazard of cardiovascular events by 30% at any given time
point
C. The Mediterranean diet with EVOO increases the risk of cardiovascular events by 30%
D. The hazard ratio indicates a non-significant reduction because the confidence interval includes 1.0
Answer: B
Rationale: A hazard ratio of 0.70 means that at any given time, the instantaneous risk of the event is 30%
lower in the intervention group. Option A is a common misinterpretation; hazard ratio is not cumulative
risk. The CI does not include 1.0, so it is significant (D).
10. A patient with short bowel syndrome has an intact colon and is receiving parenteral nutrition.
Which dietary modification is most likely to reduce parenteral nutrition dependence?
A. High simple carbohydrate diet to increase caloric absorption
B. High fiber diet with soluble fiber to slow transit and enhance colonic fermentation
C. Low-fat diet to reduce steatorrhea
D. High protein diet to promote intestinal adaptation
Answer: B
Rationale: Soluble fiber is fermented in the colon to short-chain fatty acids, which are absorbed and
provide additional energy. This can reduce reliance on parenteral nutrition. Simple carbohydrates (A)
may worsen osmotic diarrhea. Low-fat diet (C) reduces calories and essential fatty acids. Protein (D) is
important but not the most effective for reducing PN dependence in this scenario.
Page 3
, 11. In a clinical trial, participants with metabolic syndrome are randomly assigned to either a
high-fiber diet (30 g/day) or a standard diet (<15 g/day). After 12 weeks, the high-fiber group
shows a significant reduction in serum C-reactive protein (CRP) levels compared to controls.
Which of the following mechanisms most likely explains the observed anti-inflammatory effect of
dietary fiber?
A. Direct inhibition of cyclooxygenase-2 (COX-2) by short-chain fatty acids (SCFAs) in adipocytes
B. Reduction of intestinal permeability and subsequent decrease in lipopolysaccharide (LPS) translocation,
attenuating Toll-like receptor 4 (TLR4) signaling
C. Increased renal excretion of pro-inflammatory cytokines due to enhanced glomerular filtration rate
D. Competitive antagonism of interleukin-6 (IL-6) receptors by butyrate at the hepatocyte membrane
Answer: B
Rationale: Dietary fiber is fermented by gut microbiota to produce SCFAs, which strengthen gut barrier
function, reducing LPS translocation. Lower systemic LPS reduces TLR4 activation and downstream
inflammation. Direct COX-2 inhibition (A) is not a primary mechanism; SCFAs act via
G-protein-coupled receptors and histone deacetylase inhibition. Renal excretion (C) and IL-6 receptor
antagonism (D) are not established effects of dietary fiber.
12. A researcher is investigating the bioavailability of a novel iron-fortified food product. She
administers the product to a group of non-anemic, iron-replete volunteers and measures serum
iron levels over 8 hours. The area under the curve (AUC) for iron absorption is significantly lower
than that of a reference dose of ferrous sulfate. Which factor is most likely responsible for the
reduced iron absorption from the fortified food?
A. The food contains high levels of ascorbic acid, which chelates iron and prevents mucosal uptake
B. The iron in the food is predominantly in the ferric (Fe3+) form and is complexed with phytates present in the
food matrix
C. The food has a high pH (>8) that promotes the conversion of ferrous iron to insoluble ferric hydroxide
D. The iron is encapsulated in a lipid matrix that requires bile salt emulsification before release in the duodenum
Answer: B
Rationale: Phytates, common in plant-based foods, strongly chelate ferric iron (Fe3+), forming insoluble
complexes that reduce absorption. Ferrous sulfate provides Fe2+, which is more bioavailable. Ascorbic
acid enhances iron absorption, not reduces it (A). High pH can reduce solubility, but typical food pH is
not >8 (C). Lipid encapsulation might delay release but is not the most likely factor in a standard food
matrix (D).
13. A 45-year-old individual with a family history of type 2 diabetes undergoes an oral glucose
tolerance test (OGTT). Fasting plasma glucose is 108 mg/dL, and 2-hour plasma glucose is 155
mg/dL. Hemoglobin A1c is 6.2%. According to the American Diabetes Association criteria, which
of the following best categorizes this individual's glycemic status?
A. Normal glucose tolerance
B. Impaired fasting glucose (IFG) only
C. Impaired glucose tolerance (IGT) only
D. Both IFG and IGT (prediabetes)
Answer: D
Page 4
