Nutrition and Metabolism Practice Questions

Q: Soya bean is rich in which of the following amino acids?

Lysine. **Explanation:** The nutritional quality of a protein is determined by its **essential amino acid (EAA)** profile. Most plant-based proteins are "incomplete" because they are deficient in one or more EAAs. However, **Soybean** is a unique exception in the plant kingdom as it contains all essential amino acids in sufficient quantities, making it a "complete protein." **1. Why Lysine is Correct:** Cereals (like wheat, rice, and maize) are notoriously deficient in **Lysine** but rich in methionine. Conversely, pulses and legumes (like soybeans) are rich in **Lysine** but deficient in methionine. This complementary relationship is the basis of "mutual supplementation" in vegetarian diets (e.g., eating dal with rice). Soybean stands out because it has the highest lysine content among common plant sources, often used to fortify cereal-based diets. **2. Why Other Options are Incorrect:** * **Aspartic acid, Glycine, and Alanine:** These are **non-essential amino acids**. The body can synthesize them endogenously. In the context of nutrition and NEET-PG questions, the focus is almost always on the "limiting" or "abundant" **essential** amino acids, as these dictate the biological value of the food. While soybean contains these amino acids, they do not define its unique nutritional importance. **High-Yield Clinical Pearls for NEET-PG:** * **Limiting Amino Acids:** * **Pulses:** Methionine (and Cysteine). * **Cereals:** Lysine (and Threonine). * **Maize:** Tryptophan and Lysine (leads to Pellagra-like symptoms if maize is the sole staple). * **Reference Protein:** Egg (Albumin) is considered the reference protein with a biological value of 100. * **Antinutritional Factor:** Raw soybeans contain **Trypsin inhibitors**, which must be inactivated by heat (cooking) to ensure proper protein digestion.

Q: Which of the following food items has the highest Glycemic Index?

Corn flakes. **Explanation:** The **Glycemic Index (GI)** is a ranking of carbohydrates on a scale of 0 to 100 based on how quickly they raise blood glucose levels after consumption. Foods with a high GI (>70) are rapidly digested and absorbed, causing a sharp spike in blood sugar. **Why Corn Flakes is the correct answer:** Corn flakes undergo extensive industrial processing (extrusion and high-heat treatment), which gelatinizes the starch. This makes the starch highly accessible to digestive enzymes like alpha-amylase. Consequently, corn flakes have a very high GI (approximately **81–93**), leading to a rapid postprandial glucose surge. **Analysis of Incorrect Options:** * **Brown rice (GI ~50–55):** It is a whole grain that retains the bran and germ layer. The high fiber content slows down the enzymatic breakdown of starch, resulting in a low-to-medium GI. * **Ice-cream (GI ~50–60):** Despite the high sugar content, ice cream contains significant amounts of fat and sometimes protein. Fat delays gastric emptying, which slows the absorption of glucose into the bloodstream, resulting in a lower GI than many processed cereals. * **Whole wheat bread (GI ~71–75):** While considered "high" GI, it is generally lower than corn flakes. The presence of intact fiber and complex structures in whole wheat slightly moderates the glycemic response compared to highly processed corn grits. **High-Yield Clinical Pearls for NEET-PG:** * **Reference Standard:** The GI is usually measured against **Glucose or White Bread** (both assigned a value of 100). * **Glycemic Load (GL):** This is a more practical clinical measure as it accounts for both the GI and the actual portion size (GL = GI × Carbohydrate amount / 100). * **Clinical Utility:** Low GI diets are recommended in the management of **Diabetes Mellitus, PCOS, and Metabolic Syndrome** to improve insulin sensitivity and weight loss.

Q: Which of the following statements about nutrition is FALSE?

Zinc deficiency is associated with pulmonary fibrosis.. **Explanation:** **Why Option B is the Correct (False) Statement:** Zinc deficiency is not associated with pulmonary fibrosis. Instead, its classic clinical presentation includes **acrodermatitis enteropathica** (periorificial and acral dermatitis), alopecia, diarrhea, impaired wound healing, hypogonadism, and growth retardation. Zinc is a critical cofactor for over 300 enzymes, including carbonic anhydrase and alkaline phosphatase. While zinc toxicity (via inhalation) can cause lung irritation, deficiency has no established link to pulmonary fibrosis. **Analysis of Incorrect (True) Options:** * **Option A:** Vitamin A is a fat-soluble vitamin stored extensively in the **Ito cells** of the liver. These reserves are sufficient to last for 1–2 years in a well-nourished individual, meaning clinical symptoms like night blindness take a long time to manifest after intake stops. * **Option C:** Selenium is a component of **glutathione peroxidase**. Its deficiency leads to **Keshan disease**, an endemic cardiomyopathy characterized by cardiac enlargement and heart failure (originally described in China). * **Option D:** Calcium and iron compete for the same transport mechanisms in the intestinal mucosa (specifically the DMT1 transporter). High calcium intake, particularly from dairy or supplements, significantly inhibits the absorption of non-heme iron. **High-Yield NEET-PG Pearls:** 1. **Zinc:** Essential for "Zinc Finger" motifs in DNA-binding proteins. Deficiency causes **dysgeusia** (distorted taste). 2. **Selenium:** Deficiency is also linked to **Kashin-Beck disease** (an osteoarthropathy). 3. **Iron Absorption:** Enhanced by Vitamin C (reduces $Fe^{3+}$ to $Fe^{2+}$) and inhibited by phytates, oxalates, and calcium. 4. **Vitamin A:** The earliest clinical sign of deficiency is **Nyctalopia** (night blindness); the earliest conjunctival sign is **Conjunctival Xerosis**.

Q: A 50-year-old diabetic man asks about a low glycemic index diet. Which of the following food items has a low glycemic index?

Whole grains. **Explanation:** The **Glycemic Index (GI)** is a ranking of carbohydrates on a scale of 0 to 100 based on how quickly they raise blood glucose levels after consumption. Foods with a **low GI (≤ 55)** are digested and absorbed slowly, causing a gradual rise in blood sugar, which is ideal for managing Diabetes Mellitus. **Why Whole Grains are correct:** Whole grains (like oats, barley, and broken wheat) contain intact bran and germ layers. These layers are rich in **dietary fiber**, which acts as a physical barrier to digestive enzymes and slows down the hydrolysis of starch. This results in a slow, sustained release of glucose into the bloodstream. **Analysis of Incorrect Options:** * **White bread (GI ≈ 75):** Made from refined flour (maida), it lacks fiber and is rapidly hydrolyzed into glucose, making it a high-GI food. * **Corn flakes (GI ≈ 80-90):** These are highly processed and gelatinized, leading to a very rapid glycemic response. * **Brown rice (GI ≈ 68):** While healthier than white rice, brown rice typically falls into the **medium GI** category. In the context of this question, "Whole grains" is the most accurate representation of a low-GI choice. **NEET-PG High-Yield Pearls:** 1. **Glycemic Load (GL):** A more accurate predictor of glycemic response than GI, calculated as: $GL = \frac{GI \times \text{Net Carbohydrates (g)}}{100}$. 2. **Factors lowering GI:** High fiber content, presence of fat/protein, acidity (vinegar/lemon), and less processing/cooking time. 3. **Clinical Significance:** Low GI diets improve HbA1c levels, reduce insulin resistance, and aid in weight management by increasing satiety.

Q: Methionine is a limiting amino acid in which food group?

Pulses. **Explanation:** The concept of "limiting amino acids" refers to the essential amino acid present in the lowest quantity in a specific food source, thereby limiting the body's ability to synthesize proteins from that source. **Why Pulses are the correct answer:** Pulses (legumes) are rich in the essential amino acid **Lysine** but are characteristically deficient in sulfur-containing amino acids, specifically **Methionine** and Cysteine. Therefore, Methionine is the limiting amino acid in pulses. To achieve a "complete protein" profile, pulses are traditionally consumed with cereals. **Analysis of Incorrect Options:** * **A, B, and C (Cereals, Maize, Wheat):** These are all grain-based sources. Cereals (including wheat and maize) have a reverse profile compared to pulses. They are adequate in sulfur-containing amino acids (Methionine) but are characteristically deficient in **Lysine**. * **Maize** is unique because it is "doubly deficient," lacking both **Lysine and Tryptophan**. This is clinically significant as Tryptophan is a precursor for Niacin (Vitamin B3); hence, maize-dependent populations are at risk for Pellagra. **High-Yield Clinical Pearls for NEET-PG:** * **Complementary Proteins:** The practice of mixing cereals (low Lysine, high Methionine) with pulses (high Lysine, low Methionine) provides a balanced amino acid profile. * **Limiting Amino Acid Summary:** * **Pulses:** Methionine * **Cereals:** Lysine * **Maize:** Lysine and Tryptophan * **Metabolic Link:** Methionine is a precursor for S-adenosylmethionine (SAM), the universal methyl donor in the body, and its metabolism is closely linked to Vitamin B12 and Folate.

Q: Refeeding syndrome is primarily associated with the release of which hormone?

Insulin. **Explanation:** Refeeding syndrome is a potentially fatal metabolic complication that occurs when nutritional support is reintroduced to severely malnourished or starved patients. **Why Insulin is the Correct Answer:** During prolonged starvation, the body shifts from using glucose to using fat and ketones for energy; insulin levels are low, and glucagon levels are high. When feeding is reintroduced (especially carbohydrates), there is a sudden, massive surge in **Insulin** secretion. Insulin acts as an anabolic hormone, driving glucose, water, and electrolytes—specifically **Potassium, Magnesium, and Phosphate**—from the extracellular space into the cells. This leads to profound **hypophosphatemia** (the hallmark of the syndrome), hypokalemia, and hypomagnesemia, which can cause cardiac arrhythmias, seizures, and respiratory failure. **Why Incorrect Options are Wrong:** * **Growth Hormone (A):** While involved in growth and metabolism, it does not surge acutely in response to refeeding nor does it drive the rapid intracellular electrolyte shifts seen in this syndrome. * **Glucocorticoids (B):** Cortisol levels are typically elevated during the stress of starvation (catabolic state) and decrease upon refeeding. They do not mediate the acute electrolyte shifts. * **Thyroxine (D):** Thyroid hormones regulate the basal metabolic rate. While starvation can lead to "Sick Euthyroid Syndrome," thyroxine is not the primary mediator of the refeeding response. **High-Yield Clinical Pearls for NEET-PG:** * **Hallmark Electrolyte Abnormality:** Hypophosphatemia. * **Vitamin Deficiency:** Thiamine (Vitamin B1) deficiency is often exacerbated during refeeding as it is a co-factor for glucose metabolism, potentially leading to Wernicke’s Encephalopathy. * **Prevention:** "Start low and go slow" with caloric intake and proactively supplement thiamine and electrolytes.

Q: A 42-year-old man with a small-bowel fistula has been receiving TPN with a standard hypertonic glucose-amino acid solution for the previous 3 weeks. The patient has developed scaly, hyperpigmented lesions over the acral surfaces of elbows and knees, resembling acrodermatitis enteropathica. What is the most likely cause of this condition?

Zinc deficiency. **Explanation:** The clinical presentation of scaly, hyperpigmented lesions over acral surfaces (elbows, knees, and periorificial areas) in a patient on long-term Total Parenteral Nutrition (TPN) is classic for **Zinc deficiency**. 1. **Why Zinc Deficiency is correct:** Zinc is an essential cofactor for over 300 enzymes, including those involved in DNA synthesis and cell division. Patients on TPN are at high risk if supplementation is inadequate, especially those with small-bowel fistulas, as zinc is primarily excreted via gastrointestinal secretions. The symptoms mimic **Acrodermatitis Enteropathica**, an autosomal recessive disorder of zinc absorption. Key features include dermatitis (acral and periorificial), alopecia, diarrhea, and impaired wound healing. 2. **Why other options are incorrect:** * **Copper deficiency:** Typically presents with hematological abnormalities (microcytic anemia, neutropenia) and neurological symptoms (ataxia, myelopathy) resembling Vitamin B12 deficiency. * **Chromium deficiency:** Primarily manifests as **glucose intolerance** or insulin resistance, as chromium facilitates insulin binding to its receptor. * **Manganese deficiency:** Rare in humans; may cause weight loss, transient dermatitis, and changes in hair color/growth, but does not present with acral dermatitis. **High-Yield Clinical Pearls for NEET-PG:** * **Zinc & TPN:** Always suspect Zinc deficiency in TPN patients with skin rashes or poor wound healing. * **Zinc & Enzymes:** It is a component of **Carbonic Anhydrase**, **Alkaline Phosphatase**, and **RNA Polymerase**. * **Selenium Deficiency:** Another TPN-related deficiency to remember; it causes **Cardiomyopathy** (Keshan disease). * **Iodine Deficiency:** Causes goiter and hypothyroidism.

Question 1

Which of the following best assesses protein quality?

Accepted Answer

Net protein utilization

Answer

Protein biological value

Answer

Digestibility coefficient

Answer

Protein energy ratio

Question 2

Soya bean is rich in which of the following amino acids?

Accepted Answer

Lysine

Answer

Aspartic acid

Answer

Glycine

Answer

Alanine

Question 3

Which of the following food items has the highest Glycemic Index?

Accepted Answer

Corn flakes

Answer

Brown rice

Answer

Ice-cream

Answer

Whole wheat bread

Question 4

Which of the following statements is true regarding the Recommended Dietary Allowance (RDA)?

Accepted Answer

RDA is statistically defined as two standard deviations above the estimated average requirement (EAR).

Answer

RDA is statistically defined as equal to the estimated average requirement.

Answer

RDA is statistically defined as equal to the adequate intake.

Answer

RDA is defined as the recommended minimum requirement.

Question 5

Which of the following statements about nutrition is FALSE?

Accepted Answer

Zinc deficiency is associated with pulmonary fibrosis.

Answer

Vitamin A deficiency does not typically manifest for a year or more after cessation of intake.

Answer

Selenium deficiency can lead to cardiomyopathy.

Answer

A diet high in calcium can reduce iron absorption.

Question 6

Net Protein Utilization is maximum (100%) for:

Accepted Answer

Egg

Answer

Ragi

Answer

Soyabean

Answer

Pulses

Question 7

A 50-year-old diabetic man asks about a low glycemic index diet. Which of the following food items has a low glycemic index?

Accepted Answer

Whole grains

Answer

Brown rice

Answer

White bread

Answer

Corn flakes

Question 8

Methionine is a limiting amino acid in which food group?

Accepted Answer

Pulses

Answer

Cereals

Answer

Maize

Answer

Wheat

Question 9

Refeeding syndrome is primarily associated with the release of which hormone?

Accepted Answer

Insulin

Answer

Growth hormone

Answer

Glucocorticoids

Answer

Thyroxine

Question 10

A 42-year-old man with a small-bowel fistula has been receiving TPN with a standard hypertonic glucose-amino acid solution for the previous 3 weeks. The patient has developed scaly, hyperpigmented lesions over the acral surfaces of elbows and knees, resembling acrodermatitis enteropathica. What is the most likely cause of this condition?

Accepted Answer

Zinc deficiency

Answer

Copper deficiency

Answer

Chromium deficiency

Answer

Manganese deficiency

Nutrition and Metabolism — MCQs

Nutrition and Metabolism — MCQs

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