Download Certified Nutrition Specialist (CNS) Examination Questions And Correct Answers and more Exams Nutrition in PDF only on Docsity!
Certified Nutrition Specialist (CNS)
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
- A patient presents with classic signs of scurvy. Which nutrient deficiency is primarily responsible for the impaired collagen synthesis observed in this condition? A. Vitamin A B. Vitamin C C. Vitamin E D. Vitamin K Rationale: Vitamin C acts as a co-factor for the enzymes prolyl and lysyl hydroxylase, which are essential for the stabilization of the collagen triple helix structure. Deficiency leads to defective collagen, manifesting as scurvy.
- Which of the following pathways is responsible for the production of NADPH and ribose- 5 - phosphate? A. Glycolysis B. Pentose phosphate pathway C. Gluconeogenesis D. Citric acid cycle
Rationale: The pentose phosphate pathway serves two main functions: generating NADPH for reductive biosynthesis and producing ribose- 5 - phosphate for nucleotide biosynthesis.
- In a patient with malabsorption, which fat-soluble vitamin is most likely to be deficient first due to its limited storage capacity? A. Vitamin K B. Vitamin A C. Vitamin D D. Vitamin E Rationale: Vitamin K has the smallest body stores among the fat-soluble vitamins and is rapidly depleted when fat absorption is compromised.
- Which hormone is primarily responsible for stimulating gluconeogenesis in the liver during periods of fasting? A. Insulin B. Glucagon C. Thyroxine D. Aldosterone Rationale: Glucagon is secreted by the pancreas in response to low blood glucose, signaling the liver to initiate glycogenolysis and gluconeogenesis to maintain homeostasis.
- A deficiency in which mineral is most strongly associated with impaired taste perception (hypogeusia)? A. Selenium B. Iron C. Zinc D. Magnesium
D. Night blindness Rationale: Dry beriberi is characterized by peripheral neuropathy, muscle atrophy, and sensory loss due to the central role of thiamin in glucose metabolism in nerve tissue.
- Iron absorption in the small intestine is significantly enhanced by the concurrent ingestion of which substance? A. Calcium B. Phytates C. Ascorbic acid D. Polyphenols Rationale: Ascorbic acid (Vitamin C) reduces ferric iron ( 𝐹𝑒 3 + ) to ferrous iron ( 𝐹𝑒 2 + ) and forms a chelate with iron, keeping it soluble in the alkaline environment of the duodenum. 10.A deficiency of Vitamin B12 often presents with neurological symptoms because: A. It is required for hemoglobin synthesis. B. It is a cofactor in the conversion of methylmalonyl-CoA to succinyl-CoA, preventing myelin degeneration. C. It acts as an antioxidant in the nervous system. D. It regulates neurotransmitter release. Rationale: The inability to convert methylmalonyl-CoA to succinyl-CoA leads to the accumulation of methylmalonic acid, which disrupts myelin sheath synthesis and maintenance. 11.Which glycemic index (GI) value is considered "low"? A. 85 B. 65
C. 45
D. 95
Rationale: Glycemic index values are categorized as follows: Low (55 or less), Medium (56–69), and High (70 or more). 12.The urea cycle occurs primarily in which organ? A. Kidney B. Liver C. Small intestine D. Muscle Rationale: The urea cycle is a liver-specific metabolic pathway that converts toxic ammonia, derived from amino acid catabolism, into urea for excretion. 13.Which fatty acid is an essential precursor for the synthesis of eicosanoids that promote inflammation? A. Alpha-linolenic acid B. Arachidonic acid C. Docosahexaenoic acid D. Eicosapentaenoic acid Rationale: Arachidonic acid, an omega-6 fatty acid, serves as the primary substrate for cyclooxygenase and lipoxygenase enzymes, which produce pro- inflammatory prostaglandins and leukotrienes. 14.How does fiber help reduce serum cholesterol levels? A. By increasing the absorption of dietary cholesterol B. By binding bile acids in the intestine and promoting their excretion C. By inhibiting the liver’s synthesis of VLDL D. By directly oxidizing LDL in the bloodstream
Rationale: HMG-CoA reductase converts HMG-CoA to mevalonate; it is the major control point for cholesterol synthesis and the target of statin medications. 18.What is the primary function of Intrinsic Factor? A. Facilitating folate absorption B. Protecting Vitamin B12 from degradation and assisting its absorption C. Enhancing iron uptake in the ileum D. Activating pepsinogen in the stomach Rationale: Intrinsic factor, produced by gastric parietal cells, binds to Vitamin B in the small intestine to protect it from digestion and enable its absorption in the terminal ileum. 19.Which of the following is a symptom of severe iodine deficiency in adults? A. Goiter B. Cretinism C. Xerophthalmia D. Rickets Rationale: Iodine is essential for thyroid hormone production. A deficiency causes the thyroid gland to enlarge (goiter) in an attempt to capture more iodine from the blood. 20.What describes the effect of high dietary sodium on calcium metabolism? A. It increases calcium absorption. B. It increases urinary calcium excretion. C. It has no effect on calcium homeostasis. D. It causes calcium deposition in joints.
Rationale: High sodium intake competes with calcium for reabsorption in the renal tubules, leading to increased urinary calcium loss and potentially negative calcium balance. 21.Which molecule acts as the primary energy currency of the cell? A. NADH B. ATP C. Glucose D. Acetyl-CoA Rationale: Adenosine triphosphate (ATP) serves as the universal energy carrier for cellular processes, providing the free energy required for most biochemical reactions. 22.A patient with alcoholism is at high risk for Wernicke-Korsakoff syndrome, which is caused by a deficiency of: A. Thiamin B. Niacin C. Riboflavin D. Pyridoxine Rationale: Alcohol interferes with thiamin absorption and increases its requirement, leading to severe neurological damage if the vitamin is not supplemented. 23.Which of the following is a characteristic of trans-fatty acids? A. They are naturally found in high amounts in fish oil. B. They increase LDL and decrease HDL cholesterol levels. C. They are essential for prostaglandin synthesis. D. They improve insulin sensitivity.
27.What is the primary physiological function of vitamin D? A. Blood clotting B. Maintaining serum calcium and phosphorus levels for bone health C. Vision at night D. DNA replication Rationale: Vitamin D is critical for increasing intestinal absorption of calcium and phosphorus, which are necessary for bone mineralization and the prevention of rickets or osteomalacia. 28.Which amino acid is the primary precursor for the synthesis of serotonin? A. Tryptophan B. Tyrosine C. Phenylalanine D. Histidine Rationale: Tryptophan is hydroxylated and decarboxylated to form 5- hydroxytryptamine (serotonin) in the brain and gut. 29.An individual with chronic kidney disease (CKD) may need to restrict which of the following due to potential accumulation? A. Potassium B. Chloride C. Vitamin C D. Vitamin E Rationale: The kidneys are responsible for the excretion of potassium; in patients with CKD, hyperkalemia can occur and lead to life-threatening cardiac arrhythmias. 30.Which metabolic process occurs in the mitochondria?
A. Glycolysis B. Beta-oxidation of fatty acids C. Fatty acid synthesis D. Pentose phosphate pathway Rationale: Beta-oxidation, the process of breaking down fatty acids into acetyl- CoA, takes place within the mitochondrial matrix. 31.Which of the following is an example of an incomplete protein? A. Egg B. Wheat C. Soy D. Beef Rationale: Incomplete proteins lack one or more of the essential amino acids in sufficient quantities; grains like wheat are typically limiting in lysine. 32.What is the primary purpose of the folate-B12 connection? A. The folate trap hypothesis, where B12 deficiency prevents folate from being converted to its active form. B. Facilitating iron absorption in the stomach. C. Synthesizing cholesterol. D. Regulating thyroid hormone production. Rationale: In B12 deficiency, folate becomes trapped as 5-methyltetrahydrofolate and cannot be utilized, leading to signs of folate deficiency even if folate levels are normal. 33.Which mineral is an essential component of hemoglobin? A. Zinc B. Iron
Rationale: C-reactive protein (CRP) is an acute-phase protein synthesized by the liver in response to cytokines released during inflammation. 37.Which vitamin is known to facilitate the synthesis of clotting factors II, VII, IX, and X? A. Vitamin A B. Vitamin D C. Vitamin K D. Vitamin E Rationale: Vitamin K is a necessary cofactor for the gamma-carboxylation of glutamic acid residues in clotting factors, allowing them to bind calcium and become functional. 38.The process of converting ammonia to urea is necessary because: A. Ammonia is toxic to the central nervous system. B. Urea is needed for kidney function. C. It produces energy. D. Ammonia is too large to be excreted. Rationale: Ammonia is highly neurotoxic; the liver converts it to the safer, nitrogen-rich compound urea for safe transport through the blood and excretion in the urine. 39.What is the primary function of the hormone leptin? A. Stimulating hunger B. Signaling satiety and regulating long-term energy balance C. Increasing blood glucose D. Promoting lipogenesis
Rationale: Leptin is secreted by adipose tissue and acts on the hypothalamus to decrease food intake and increase energy expenditure. 40.Which mineral is essential for the function of the enzyme superoxide dismutase (SOD)? A. Copper B. Iron C. Calcium D. Chloride Rationale: Copper is a critical cofactor for the copper-zinc SOD enzyme, which protects cells from oxidative stress. 41.Which of the following is the most calorie-dense nutrient? A. Carbohydrates B. Proteins C. Fats D. Alcohol Rationale: Fats provide 9 kcal/gram, whereas carbohydrates and proteins provide 4 kcal/gram, and alcohol provides 7 kcal/gram. 42.The "plate method" for diabetes management generally recommends: A. 50% protein, 25% starch, 25% fat. B. 50% non-starchy vegetables, 25% protein, 25% starch. C. 75% grains, 25% protein. D. 25% fruit, 25% vegetables, 50% fat. Rationale: The plate method is a simple visual tool to encourage portion control, specifically emphasizing high fiber/low calorie vegetables to manage blood glucose levels.
A. Glucose B. Ketone bodies C. Free fatty acids D. Amino acids Rationale: While the brain prefers glucose, it cannot burn fatty acids. After several days of fasting, the liver produces ketones from fatty acids to provide an alternative fuel source for the brain. 47.A patient with hemochromatosis should avoid: A. Calcium supplements B. Iron supplements C. High-fiber diets D. Vitamin D intake Rationale: Hemochromatosis is a genetic condition causing excessive iron absorption and tissue iron overload; iron supplementation is contraindicated. 48.Which amino acid is the primary precursor for the neurotransmitter dopamine? A. Tryptophan B. Tyrosine C. Alanine D. Serine Rationale: Tyrosine is the precursor for the catecholamines dopamine, norepinephrine, and epinephrine. 49.What is the main benefit of including insoluble fiber in the diet? A. Lowering blood cholesterol B. Increasing fecal bulk and preventing constipation
C. Slowing glucose absorption D. Providing a source of short-chain fatty acids Rationale: Insoluble fiber (like cellulose) does not dissolve in water; it adds bulk to the stool and promotes regular bowel movements. 50.Which deficiency is responsible for Pellagra? A. Niacin B. Thiamin C. Folate D. Vitamin B Rationale: Pellagra is the classic clinical manifestation of niacin (Vitamin B3) deficiency, historically described by the "four Ds": dermatitis, diarrhea, dementia, and death. 51.The primary role of VLDL (Very Low-Density Lipoprotein) is: A. Transport of endogenously produced triglycerides from the liver to tissues B. Transport of dietary fats from the intestine C. Removal of excess cholesterol from tissues D. Storage of fat in the liver Rationale: The liver synthesizes VLDL to transport lipids manufactured within the body (endogenous) to various peripheral tissues. 52.Which mineral is vital for thyroid hormone synthesis? A. Selenium B. Iodine C. Zinc D. Iron
Rationale: Riboflavin is highly photosensitive; milk stored in clear glass containers, for example, can lose a significant portion of its riboflavin content when exposed to light. 56.What is the main function of the sodium-potassium pump? A. Maintaining cell membrane potential by active transport of ions B. Synthesizing ATP C. Facilitating glucose absorption D. Regulating water temperature Rationale: The 𝑁𝑎+/𝐾+ - ATPase pump is critical for maintaining the electrochemical gradient across the cell membrane, which is essential for nerve conduction and muscle contraction. 57.Which nutrient is required for the conversion of pyruvate to oxaloacetate? A. Biotin B. Thiamin C. Niacin D. Folate Rationale: Biotin is a mandatory cofactor for carboxylase enzymes, including pyruvate carboxylase, which converts pyruvate to oxaloacetate in gluconeogenesis. 58.Which of the following is true regarding omega-3 fatty acids? A. They promote clotting. B. They have anti-inflammatory and anti-arrhythmic effects. C. They are primarily found in processed vegetable oils. D. They increase blood pressure.
Rationale: EPA and DHA (omega-3s) are known to lower triglycerides, improve endothelial function, and exert anti-inflammatory effects that are cardioprotective. 59.What happens to nitrogen balance during a state of starvation? A. Positive B. Negative C. Neutral D. Fluctuating Rationale: In starvation, the body breaks down its own muscle tissue for amino acids to support essential metabolic processes, leading to an overall loss of nitrogen (negative nitrogen balance). 60.Which organ is the primary site for the detoxification of drugs and toxins? A. Kidney B. Liver C. Small intestine D. Skin Rationale: The liver contains complex cytochrome P450 enzyme systems responsible for the metabolic transformation and detoxification of various exogenous substances. 61.What is the recommended percentage of daily calories from added sugars according to most health organizations? A. <20% B. <10% C. <5% D. <15%
