Nutrition and Metabolism Practice Questions

Q: In which part of the body is the highest concentration of zinc found?

Prostate. **Explanation:** **Correct Option: A (Prostate)** Zinc is an essential trace element required for the catalytic activity of over 300 enzymes. While the majority of total body zinc is stored in skeletal muscle and bone (due to their large mass), the **highest concentration** (amount per gram of tissue) is found in the **prostate gland**, specifically in the prostatic fluid. Zinc plays a crucial role in the prostate by inhibiting the enzyme m-aconitase, which redirects citrate metabolism toward secretion into seminal plasma rather than oxidation in the TCA cycle. This high concentration also serves an antimicrobial function in the male reproductive tract. **Incorrect Options:** * **B. Skin:** While the skin contains about 5-6% of total body zinc (primarily in the epidermis) and is vital for wound healing, its concentration is significantly lower than that of the prostate. * **C. Hair:** Zinc is present in hair and is often used as a marker for long-term nutritional status, but it does not reach the physiological concentrations found in prostatic tissue. * **D. Bone:** Bone contains a large *reservoir* of zinc (approximately 30% of total body stores), but the *density* or concentration per unit of tissue is less than that of the prostate. **NEET-PG High-Yield Pearls:** * **Acrodermatitis Enteropathica:** An autosomal recessive disorder caused by a mutation in the **ZIP4 transporter**, leading to zinc malabsorption. Clinical triad: Dermatitis (periorificial/acral), Alopecia, and Diarrhea. * **Enzymes:** Zinc is a cofactor for Carbonic Anhydrase, Alcohol Dehydrogenase, Alkaline Phosphatase, and RNA Polymerase. * **Zinc Fingers:** These are structural motifs in proteins that allow for DNA binding, essential for steroid hormone receptor function. * **Wound Healing:** Zinc is critical for collagen synthesis and cell division; deficiency leads to poor wound healing and gustatory dysfunction (hypogeusia).

Q: Which of the following acts as a defence against E. coli?

Lactoferrin. **Explanation:** The correct answer is **Lactoferrin**. **1. Why Lactoferrin is correct:** Lactoferrin is an iron-binding glycoprotein found in high concentrations in human colostrum and milk. It acts as a potent bacteriostatic agent against iron-dependent bacteria like *E. coli*. The underlying mechanism is **"Nutritional Immunity"**: Lactoferrin sequesters free ferric iron ($Fe^{3+}$) in the gut, depriving bacteria of the essential iron required for their growth and replication. Additionally, it can directly bind to the lipopolysaccharides (LPS) on the bacterial cell wall, increasing membrane permeability and causing lysis. **2. Why the other options are incorrect:** * **Lactoglobulin:** This is a major whey protein found in cow’s milk but is notably **absent in human milk**. While it serves as a source of amino acids, it does not possess specific antimicrobial properties against *E. coli*. * **Lactalbumin ($\alpha$-lactalbumin):** This is the principal sugar-binding protein in human milk. Its primary physiological role is to act as a regulatory subunit for **lactose synthase**, the enzyme responsible for lactose synthesis. It does not function as a defense protein. **3. High-Yield Clinical Pearls for NEET-PG:** * **Lysozyme:** Another key defense factor in breast milk that works synergistically with lactoferrin by cleaving the peptidoglycan layer of bacterial cell walls. * **Bifidus Factor:** A carbohydrate in human milk that promotes the growth of *Lactobacillus bifidus*, which produces lactic acid, lowering intestinal pH and inhibiting *E. coli* growth. * **Secretory IgA:** The most abundant immunoglobulin in colostrum, providing mucosal immunity against enteric pathogens.

Q: A 52-year-old female patient complains of abdominal pain. General examination reveals a BMI of 30 kg/m2. X-ray examination reveals osteoporotic changes. The physician suspects impaired absorption of calcium in this patient. All of the following could be the reason for this, except:

Decreased iron intake. **Explanation:** The absorption of calcium in the gastrointestinal tract is a complex process influenced by various dietary factors. The correct answer is **D (Decreased iron intake)** because iron and calcium actually compete for the same transport mechanisms; therefore, a *decrease* in iron intake would theoretically favor, rather than impair, calcium absorption. **Why the other options are incorrect (Factors that impair calcium absorption):** * **Inositol hexaphosphate (Phytates):** Found in cereals and grains, phytates form insoluble complexes with calcium, preventing its absorption. * **Oxalates:** Present in leafy greens (like spinach) and berries, oxalates bind to calcium to form insoluble calcium oxalate, which is excreted in feces. * **High concentrations of fatty acids:** In conditions of fat malabsorption (steatorrhea), unabsorbed fatty acids react with calcium to form insoluble "calcium soaps." This is particularly relevant in this patient’s profile (BMI 30), where underlying metabolic or biliary issues might be present. **Clinical Pearls for NEET-PG:** 1. **Vitamin D:** The most potent stimulator of calcium absorption (via synthesis of Calbindin in intestinal cells). 2. **pH Effect:** An **acidic medium** (e.g., Vitamin C, HCl) increases calcium solubility and absorption, while an **alkaline medium** (e.g., antacids) inhibits it. 3. **Calcium-Iron Interaction:** High doses of calcium can inhibit the absorption of both heme and non-heme iron. Clinically, patients are advised not to take iron supplements with milk or calcium tablets. 4. **Phosphate Ratio:** An ideal dietary Calcium:Phosphorus ratio for optimum absorption is **1:1 to 2:1**. Excess phosphorus inhibits calcium uptake.

Q: Which is the limiting amino acid in wheat?

Lysine. **Explanation:** The concept of a **limiting amino acid** refers to the essential amino acid present in the lowest quantity relative to the body's requirements in a specific food source. When this amino acid is exhausted, protein synthesis in the body stops, regardless of the availability of other amino acids. **Why Lysine is Correct:** Cereals, including **wheat**, rice, and maize, are characteristically deficient in **Lysine**. In wheat specifically, the proteins (gliadin and glutenin) lack sufficient lysine to meet human nutritional needs. Therefore, lysine is the primary limiting amino acid in wheat. Threonine is often considered the second limiting amino acid in wheat. **Analysis of Incorrect Options:** * **A. Methionine:** This is the limiting amino acid in **pulses/legumes** (like beans and lentils). Pulses are rich in lysine but poor in sulfur-containing amino acids like methionine and cysteine. * **B. Tryptophan:** This is the limiting amino acid in **Maize** (along with Lysine). A diet solely dependent on maize can lead to Pellagra because tryptophan is a precursor for Niacin (Vitamin B3) synthesis. * **D. Alanine:** This is a non-essential amino acid. Limiting amino acids must be "essential" because the body cannot synthesize them endogenously. **High-Yield NEET-PG Pearls:** * **Mutual Supplementation:** This is the nutritional principle of combining cereals (low lysine, high methionine) with pulses (high lysine, low methionine) to provide a complete amino acid profile (e.g., "Dal-Chawal"). * **Reference Protein:** Egg albumin is considered the "standard" or reference protein (Biological Value = 100) as it contains all essential amino acids in ideal proportions. * **Limiting Amino Acid Summary:** * Wheat/Rice: Lysine * Pulses: Methionine * Maize: Tryptophan and Lysine

Q: Hypogonadism, reduced immunity, and alopecia may be a deficiency manifestation of which of the following?

Zinc. **Explanation:** **Zinc deficiency** is the correct answer because Zinc is a vital trace element required for the structural integrity of over 300 enzymes (e.g., Carbonic anhydrase, Alcohol dehydrogenase, and DNA polymerase). It plays a crucial role in protein synthesis, cell division, and nucleic acid metabolism. * **Hypogonadism:** Zinc is essential for the synthesis of testosterone and the maturation of sperm. Deficiency leads to primary hypogonadism and delayed puberty. * **Reduced Immunity:** Zinc is critical for T-lymphocyte maturation and function. Deficiency causes thymic atrophy and impaired cell-mediated immunity. * **Alopecia and Skin Changes:** Zinc is required for keratinocyte proliferation. Deficiency leads to hair loss and characteristic periorificial/acral dermatitis. **Analysis of Incorrect Options:** * **Iron:** Deficiency typically presents with microcytic hypochromic anemia, pica, and koilonychia (spoon-shaped nails), not primary hypogonadism. * **Copper:** Deficiency leads to Menkes Kinky Hair Syndrome (presents with brittle "steely" hair), microcytic anemia, and neurological degradation. * **Magnesium:** Deficiency (hypomagnesemia) is characterized by neuromuscular irritability, tetany, and cardiac arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Acrodermatitis Enteropathica:** An autosomal recessive disorder causing impaired zinc absorption, presenting with the triad of **alopecia, diarrhea, and vesiculobullous dermatitis** (periorificial and acral). * **Zinc Finger Motifs:** Zinc is a structural component of DNA-binding proteins (transcription factors), making it essential for gene expression. * **Wound Healing:** Zinc is a cofactor for collagenase; deficiency leads to poor wound healing.

Q: Which of the following are characteristic features of copper deficiency?

Anemia, Osteopenia, Growth retardation. Copper is an essential trace element required for the function of several key enzymes (metalloenzymes). Its deficiency manifests through multi-system involvement: **1. Why Option A is Correct:** * **Anemia:** Copper is a component of **Hephaestin** and **Ceruloplasmin** (ferroxidases). These enzymes convert ferrous iron ($Fe^{2+}$) to ferric iron ($Fe^{3+}$), allowing iron to bind to transferrin for transport. Deficiency leads to "iron-block anemia," typically presenting as **microcytic hypochromic anemia** that is unresponsive to iron therapy. * **Osteopenia:** Copper is a cofactor for **Lysyl Oxidase**, which is essential for the cross-linking of collagen and elastin. Defective cross-linking leads to a weak bone matrix and skeletal abnormalities (osteopenia/osteoporosis). * **Growth Retardation:** Impaired collagen synthesis and reduced activity of cytochrome c oxidase (limiting ATP production) result in failure to thrive and stunted growth. **2. Why Other Options are Incorrect:** * **Options B & C (Cardiomyopathy):** While copper deficiency can affect the heart in animal models, **Cardiomyopathy** is the hallmark clinical feature of **Selenium deficiency** (Keshan Disease). * **Option D:** While correct, it is incomplete. NEET-PG questions often require the most comprehensive clinical triad. **Clinical Pearls for NEET-PG:** * **Menkes Disease:** An X-linked recessive disorder caused by a mutation in the **ATP7A** gene, leading to systemic copper deficiency. Look for "Kinky/Steely hair" and seizures. * **Pancytopenia:** Severe copper deficiency can also cause neutropenia. * **Wilson Disease:** Caused by a mutation in **ATP7B**, leading to copper *toxicity* (Kayser-Fleischer rings). * **Key Enzyme:** Remember **Lysyl Oxidase**—it is the most high-yield link between copper and connective tissue/bone defects.

Q: Which of the following is the richest source of essential fatty acids?

Safflower oil. **Explanation:** Essential Fatty Acids (EFAs), primarily **Linoleic acid (Omega-6)** and **Alpha-linolenic acid (Omega-3)**, cannot be synthesized by the human body and must be obtained through diet. The richness of an oil in EFAs is generally determined by its Linoleic acid content. **1. Why Safflower Oil is Correct:** Safflower oil contains the highest concentration of Linoleic acid among common vegetable oils, typically ranging from **70% to 75%**. This makes it the "richest" source of EFAs. In medical biochemistry, it is often cited as the gold standard for treating EFA deficiency. **2. Analysis of Incorrect Options:** * **Sunflower oil:** While a very good source, it contains approximately **60-65%** Linoleic acid, which is lower than Safflower oil. * **Corn oil:** Contains roughly **55-60%** Linoleic acid. * **Soyabean oil:** Contains about **50-55%** Linoleic acid. While it is unique for having a decent amount of Alpha-linolenic acid (~7%), its total EFA percentage remains lower than Safflower oil. **3. Clinical Pearls for NEET-PG:** * **EFA Deficiency:** Leads to **Phrynoderma** (follicular hyperkeratosis/toad skin), poor wound healing, and hair loss. * **Omega-6 vs. Omega-3:** Linoleic acid (18:2; Δ9,12) is the precursor for Arachidonic acid. Alpha-linolenic acid (18:3; Δ9,12,15) is the precursor for EPA and DHA. * **P/S Ratio:** Safflower oil has a high Polyunsaturated to Saturated fatty acid (P/S) ratio, which is beneficial for lowering serum cholesterol. * **Coconut Oil:** Note that coconut oil is a rich source of Medium Chain Triglycerides (MCTs) but is very poor in EFAs.

Q: Which of the following characterizes the Atkins diet?

Severely reduced carbohydrate content. The **Atkins diet** is a classic example of a **Low-Carbohydrate, High-Fat, High-Protein diet**. It is designed to induce a metabolic state known as **ketosis**, where the body shifts from using glucose as its primary fuel source to burning stored fats and dietary fats, producing ketone bodies (acetoacetate and β-hydroxybutyrate). ### **Explanation of Options:** * **Option B (Correct):** The hallmark of the Atkins diet is the severe restriction of carbohydrates (typically <20g/day in the induction phase). By limiting glucose availability, insulin levels drop, and glucagon levels rise, stimulating lipolysis and ketogenesis. * **Option A:** Incorrect. Unlike traditional low-calorie diets, the Atkins diet encourages high fat intake to provide satiety and energy. * **Option C:** Incorrect. Protein intake is usually moderate to high in this diet to maintain muscle mass and promote thermogenesis. * **Option D:** Incorrect. While the diet doesn't focus on minerals, it does not intentionally reduce them; in fact, supplementation is often recommended to prevent electrolyte imbalances (the "keto flu"). ### **High-Yield Clinical Pearls for NEET-PG:** * **Metabolic Shift:** The diet mimics the biochemical state of **starvation** (increased Acetyl-CoA leading to Ketogenesis). * **Therapeutic Use:** Ketogenic diets are clinically indicated for **refractory epilepsy** in children. * **Adverse Effects:** Potential risks include hyperuricemia (gout), nephrolithiasis (kidney stones), and "Ketoacidosis" (rare in non-diabetics, but metabolic acidosis can occur). * **Biochemical Marker:** The presence of **ketonuria** is a sign of adherence to the restrictive phase of the diet.

Q: Which of the following is NOT reported as a clinical manifestation of zinc deficiency in children?

Macrocytic anemia. **Explanation:** Zinc is an essential trace element required for the function of over 300 enzymes, playing a critical role in growth, immune function, and protein synthesis. **Why Macrocytic Anemia is the Correct Answer:** Zinc deficiency is characteristically associated with **Microcytic Hypochromic Anemia**, not macrocytic anemia. Macrocytic anemia is typically caused by deficiencies in Vitamin B12 or Folic acid. In zinc deficiency, the anemia occurs due to impaired hemoglobin synthesis and altered iron metabolism. **Analysis of Incorrect Options:** * **A. Dwarfism and Hypogonadism:** These are classic hallmarks of chronic zinc deficiency. Zinc is vital for the action of growth hormone and the development of reproductive organs. The "Prasad’s Syndrome" (described in the 1960s) specifically links zinc deficiency to growth retardation and delayed sexual maturation. * **B. Liver and Spleen Enlargement:** Hepatosplenomegaly is a documented clinical finding in children with severe zinc deficiency, often seen alongside growth stunting and anemia. * **C. Impaired Cell-Mediated Immunity:** Zinc is crucial for T-lymphocyte function and thymic hormones. Deficiency leads to lymphoid atrophy and increased susceptibility to infections (especially diarrhea and pneumonia). **High-Yield Clinical Pearls for NEET-PG:** * **Acrodermatitis Enteropathica:** An autosomal recessive disorder of zinc absorption characterized by periorificial and acral dermatitis, alopecia, and diarrhea. * **Zinc & Diarrhea:** WHO/UNICEF recommend 20 mg of zinc daily for 10–14 days for children with acute diarrhea to reduce severity and recurrence. * **Hypogeusia:** Zinc deficiency leads to a decreased sense of taste. * **Wound Healing:** Zinc is essential for collagen synthesis; deficiency causes delayed wound healing.

Question 1

In which part of the body is the highest concentration of zinc found?

Accepted Answer

Prostate

Answer

Skin

Answer

Hair

Answer

Bone

Question 2

Which of the following acts as a defence against E. coli?

Accepted Answer

Lactoferrin

Answer

Lactoglobulin

Answer

Lactalbumin

Answer

None of the above

Question 3

A 52-year-old female patient complains of abdominal pain. General examination reveals a BMI of 30 kg/m2. X-ray examination reveals osteoporotic changes. The physician suspects impaired absorption of calcium in this patient. All of the following could be the reason for this, except:

Accepted Answer

Decreased iron intake

Answer

Inositol hexaphosphate in cereals

Answer

High intake of oxalate

Answer

High concentrations of fatty acids in the intestinal lumen

Question 4

Which is the limiting amino acid in wheat?

Accepted Answer

Lysine

Answer

Methionine

Answer

Tryptophan

Answer

Alanine

Question 5

Hypogonadism, reduced immunity, and alopecia may be a deficiency manifestation of which of the following?

Accepted Answer

Zinc

Answer

Iron

Answer

Copper

Answer

Magnesium

Question 6

Why are cereals and pulses typically combined in dietary planning?

Accepted Answer

Cereals are deficient in lysine, and methionine is deficient in pulses.

Answer

Cereals contain 10% protein, while pulses contain 40% protein.

Answer

Cereals are deficient in methionine, and lysine is deficient in pulses.

Answer

Cereals are rich in essential amino acids.

Question 7

Which of the following are characteristic features of copper deficiency?

Accepted Answer

Anemia, Osteopenia, Growth retardation

Answer

Cardiomyopathy, Osteopenia, Growth retardation

Answer

Cardiomyopathy, Osteopenia

Answer

Anemia, Osteopenia

Question 8

Which of the following is the richest source of essential fatty acids?

Accepted Answer

Safflower oil

Answer

Corn oil

Answer

Sunflower oil

Answer

Soyabean oil

Question 9

Which of the following characterizes the Atkins diet?

Accepted Answer

Severely reduced carbohydrate content

Answer

Severely reduced fat content

Answer

Severely reduced protein content

Answer

Reduced mineral content

Question 10

Which of the following is NOT reported as a clinical manifestation of zinc deficiency in children?

Accepted Answer

Macrocytic anemia

Answer

Dwarfism and hypogonadism

Answer

Liver and spleen enlargement

Answer

Impaired cell-mediated immunity

Nutrition and Metabolism — MCQs

Nutrition and Metabolism — MCQs

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