Nutrition and Metabolism Practice Questions

Q: Which substance is NOT known to have an anti-infective property, either directly or indirectly, in milk?

Lactalbumin. **Explanation:** The anti-infective properties of breast milk are primarily mediated by specific proteins and enzymes that inhibit microbial growth. **Why Lactalbumin is the correct answer:** **Lactalbumin** (specifically alpha-lactalbumin) is the principal whey protein in human milk. Its primary biological role is nutritional; it serves as a high-quality source of essential amino acids and acts as a regulatory subunit in the **lactose synthase** complex for lactose production. Unlike the other options, it does not possess direct or indirect antimicrobial or anti-infective properties in its native state. **Why the other options are incorrect:** * **Lactoferrin:** This is a potent bacteriostatic iron-binding protein. It sequesters free iron in the gut, making it unavailable to iron-dependent pathogenic bacteria (like *E. coli*), thereby inhibiting their proliferation. * **Lysozyme:** This enzyme directly attacks the cell walls of Gram-positive bacteria by cleaving the peptidoglycan layer. It remains stable at the low pH of the stomach and works synergistically with lactoferrin. * **Secretory IgA (SIgA):** (Though not listed, it is the most important) It provides mucosal immunity by preventing the attachment of pathogens to the intestinal epithelium. **NEET-PG High-Yield Pearls:** * **Bifidus Factor:** A carbohydrate in milk that promotes the growth of *Lactobacillus bifidus*, which produces lactic acid, lowering intestinal pH and inhibiting pathogens. * **Casein vs. Whey:** Human milk has a higher **Whey:Casein ratio (60:40)** compared to cow’s milk (20:80), making it more digestible for infants. * **HAMLET:** When alpha-lactalbumin binds to oleic acid in the infant's stomach, it forms a complex called HAMLET, which has been shown to induce apoptosis in tumor cells (a niche research fact).

Q: Which milk has the highest content of lactose?

Human milk. **Explanation:** The correct answer is **Human milk**. Lactose, a disaccharide composed of glucose and galactose, is the primary carbohydrate found in mammalian milk. The concentration of lactose is inversely proportional to the protein content of the milk and is directly related to the brain development requirements of the species. 1. **Why Human Milk is Correct:** Human milk contains the highest concentration of lactose among common mammals, typically ranging from **6.7 to 7.2 g/dL**. This high lactose content is essential for human infants as it provides a critical energy source for rapid brain growth and serves as a precursor for galactolipids (cerebrosides) required for CNS myelination. 2. **Why Other Options are Incorrect:** * **Cow Milk:** Contains approximately **4.4 to 4.8 g/dL** of lactose. It has higher protein and mineral content but lower carbohydrate content compared to human milk. * **Buffalo Milk:** Contains about **4.8 g/dL** of lactose. While it is richer in fats and proteins, its sugar content is significantly lower than human milk. * **Goat Milk:** Contains roughly **4.1 to 4.5 g/dL** of lactose. It is often used as an alternative for those with minor sensitivities but still contains significant lactose and is not the highest source. **High-Yield NEET-PG Pearls:** * **Energy Distribution:** In human milk, approximately 40% of total calories are derived from lactose, whereas 50% come from fats. * **Bifidogenic Effect:** Lactose promotes the growth of *Lactobacillus bifidus* in the infant gut, which lowers intestinal pH and inhibits the growth of pathogens. * **Calcium Absorption:** Lactose enhances the absorption of calcium and magnesium in the neonatal gut. * **Comparison:** Human milk is **High in Lactose/Fat** and **Low in Protein/Minerals** (specifically Calcium/Phosphorus) compared to Cow milk.

Q: Which plasma protein is the first to be generated after a severe protein deficiency?

Fibrinogen. **Explanation:** The correct answer is **Fibrinogen (Option C)**. The synthesis of plasma proteins in the liver is highly sensitive to the availability of amino acids. In states of severe protein deficiency (such as Kwashiorkor or starvation), the liver prioritizes the synthesis of proteins essential for immediate survival and homeostasis. **Fibrinogen** is an acute-phase reactant and a critical component of the coagulation cascade. When protein intake resumes after a period of deficiency, fibrinogen is the first plasma protein to be regenerated and return to normal levels. This is due to its relatively shorter half-life compared to albumin and its physiological priority in maintaining hemostasis. **Analysis of Incorrect Options:** * **Albumin (A):** Although it is the most abundant plasma protein, it has a long half-life (approx. 20 days). Its levels drop significantly in protein-energy malnutrition (PEM) and take the longest time to recover during nutritional rehabilitation. * **Globulin (B):** This is a broad category including immunoglobulins (produced by B-cells, not the liver) and transport globulins. They do not show the same rapid restorative kinetics as fibrinogen. * **Thrombin (D):** Thrombin is an enzyme (activated Factor II) rather than a primary structural plasma protein synthesized in bulk for osmotic or transport purposes. **NEET-PG High-Yield Pearls:** * **Albumin** is the best indicator of **chronic** nutritional status due to its long half-life. * **Pre-albumin (Transthyretin)** is the best indicator of **acute** nutritional changes (half-life of ~2 days). * In **Kwashiorkor**, the decrease in albumin leads to a drop in plasma oncotic pressure, resulting in the characteristic finding of **edema**. * **Transferrin** is another protein used to monitor nutritional status, with a half-life of ~8 days.

Q: All of the following are characteristic features of Kwashiorkor, except –

High blood osmolarity. **Explanation:** The correct answer is **A. High blood osmolarity**. In Kwashiorkor, the primary physiological state is actually **low blood osmolarity (hypoosmolarity)**. **1. Why "High blood osmolarity" is the correct (incorrect feature) answer:** Kwashiorkor is characterized by a severe deficiency of dietary protein despite adequate calorie intake. This leads to a profound decrease in the synthesis of plasma proteins, primarily albumin. According to Starling’s forces, a decrease in plasma proteins reduces the **plasma oncotic pressure**. This results in a shift of fluid from the intravascular compartment to the interstitial space, leading to hemodilution and a decrease in serum sodium (dilutional hyponatremia), which results in **low blood osmolarity**. **2. Analysis of other options:** * **Hypoalbuminemia (B):** This is the hallmark of Kwashiorkor. Protein deficiency leads to the liver's inability to synthesize albumin. * **Edema (C):** This is the clinical diagnostic feature that distinguishes Kwashiorkor from Marasmus. It is caused by the loss of oncotic pressure due to hypoalbuminemia, leading to "pitting edema" (starting in the feet). * **Fatty liver (D):** Protein deficiency impairs the synthesis of **Apolipoprotein B-100**. Without this protein, VLDLs cannot be formed to export triglycerides out of the liver, leading to hepatic steatosis (fatty change) and hepatomegaly. **Clinical Pearls for NEET-PG:** * **Kwashiorkor:** "Sickness of the older child when the next baby is born." Features: Edema, "Flaky paint" dermatosis, "Flag sign" (banded hair discoloration), and fatty liver. * **Marasmus:** Total calorie malnutrition. Features: Generalized muscle wasting, "Old man/Monkey facies," and **absence of edema**. * **Key differentiator:** Edema is present in Kwashiorkor but absent in Marasmus.

Q: Which of the following fats and oils contains the highest proportion of polyunsaturated fatty acids (PUFA)?

Safflower oil. **Explanation:** The correct answer is **Safflower oil**. The classification of dietary fats is based on the predominant type of fatty acid chains they contain: Saturated Fatty Acids (SFA), Monounsaturated Fatty Acids (MUFA), or Polyunsaturated Fatty Acids (PUFA). **1. Why Safflower oil is correct:** Safflower oil contains the highest concentration of PUFA (approximately **73–78%**), primarily in the form of Linoleic acid (an omega-6 essential fatty acid). In medical biochemistry, PUFAs are known to lower serum LDL cholesterol levels, making them a key dietary component for cardiovascular health. **2. Why the other options are incorrect:** * **Coconut oil:** This is a highly **saturated fat** (~90% SFA). It is unique because it is rich in Medium-Chain Triglycerides (MCTs), which are absorbed directly into the portal circulation. * **Groundnut (Peanut) oil:** This is primarily a **MUFA-rich** oil (containing about 40–50% Oleic acid). While it contains PUFA, the proportion is significantly lower than in safflower oil. * **Butter:** This is an animal fat high in **saturated fatty acids** and cholesterol. It also contains short-chain fatty acids like butyric acid. **High-Yield Clinical Pearls for NEET-PG:** * **PUFA Hierarchy:** Safflower oil (75%) > Sunflower oil (65%) > Corn oil (59%) > Soya bean oil (54%). * **MUFA King:** Olive oil is the richest source of MUFA (Oleic acid). * **Essential Fatty Acids:** Linoleic acid (ω-6) and Linolenic acid (ω-3) are PUFAs that cannot be synthesized by the body and must be obtained from the diet. * **P/S Ratio:** The ratio of Polyunsaturated to Saturated fats. A healthy diet typically aims for a P/S ratio of approximately 0.8 to 1.0.

Q: Sorghum contains an excess of which amino acid?

Leucine. **Explanation:** **Sorghum (Jowar)** is a staple cereal in many parts of India. The correct answer is **Leucine** because sorghum is unique among cereals for containing high concentrations of this branched-chain amino acid. **Why Leucine is the correct answer:** The high leucine content in sorghum has significant clinical implications. Excess leucine interferes with the metabolic pathway of Tryptophan. Specifically, high levels of leucine inhibit the enzyme **Quinolinate Phosphoribosyl Transferase (QPRT)**, which is essential for converting Tryptophan into Niacin (Vitamin B3). Consequently, populations consuming a diet predominantly based on sorghum are at a high risk of developing **Pellagra**, even if their niacin intake seems borderline adequate. **Analysis of Incorrect Options:** * **A. Lysine:** This is the **limiting amino acid** in almost all cereals, including sorghum. Cereals are characteristically deficient in lysine. * **B. Arginine:** While present in plants, it is not found in "excess" in sorghum and does not carry the same clinical diagnostic weight as leucine. * **D. Histidine:** This is an essential amino acid for children, but it is not a distinguishing feature of sorghum's nutritional profile. **High-Yield Clinical Pearls for NEET-PG:** * **Pellagra 4 D’s:** Dermatitis (Casal’s necklace), Diarrhea, Dementia, and Death. * **Maize vs. Sorghum:** Maize causes Pellagra because it is deficient in Tryptophan and contains "Niacytin" (bound niacin). Sorghum causes Pellagra due to **excess Leucine**. * **Limiting Amino Acids:** * Cereals: Lysine (and Threonine). * Pulses: Methionine (and Cysteine). * **Complementary Proteins:** Mixing cereals (low lysine) with pulses (low methionine) provides a complete amino acid profile.

Q: All of the following are trace elements except:

Potassium. In Community Medicine and Biochemistry, minerals are classified based on the body's daily requirement and their concentration in the body. ### 1. Why Potassium is the Correct Answer **Potassium** is classified as a **Macro-mineral (Major element)**, not a trace element. Macro-minerals are required by the body in amounts greater than **100 mg/day**. Other major minerals include Calcium, Phosphorus, Sodium, Magnesium, and Chloride. These elements are essential for structural integrity (bone) and maintaining osmotic pressure and acid-base balance. ### 2. Analysis of Incorrect Options (Trace Elements) Trace elements are required in amounts less than **100 mg/day** (often categorized further into "Ultra-trace" if <1 mg/day). * **Iron (A):** The most important trace element. It is essential for hemoglobin synthesis and oxygen transport. * **Fluoride (B):** A trace element vital for dental health (prevents caries) and bone mineralization. * **Zinc (D):** A trace element acting as a cofactor for over 300 enzymes; it is crucial for immunity, wound healing, and growth. ### 3. High-Yield Clinical Pearls for NEET-PG * **Classification Tip:** Remember the mnemonic **"Magical Cats Play Soccer Near Clouds"** for Macro-minerals: **Mag**nesium, **Ca**lcium, **P**hosphorus, **S**ulfur, **N**atrium (Sodium), **C**hloride, and **K** (Potassium). * **Iron Paradox:** Although Iron is needed in larger quantities than other trace elements, it is still biologically classified as a trace element because the total body content is only about 3–5 grams. * **Iodine:** Often tested as a trace element; its deficiency leads to Goiter and Cretinism. * **Selenium:** A trace element that acts as an antioxidant (part of Glutathione Peroxidase).

Q: Which of the following minerals can induce the synthesis of metallothionein?

Zinc. **Explanation:** **Metallothioneins (MTs)** are a family of low-molecular-weight, cysteine-rich proteins that play a vital role in metal homeostasis and detoxification. 1. **Why Zinc is Correct:** Zinc is the primary physiological inducer of metallothionein synthesis. When intracellular zinc levels rise, zinc ions bind to the **Metal-responsive Transcription Factor-1 (MTF-1)**. This complex then binds to **Metal Response Elements (MRE)** in the promoter region of the metallothionein gene, stimulating its transcription. Metallothionein acts as a "buffer" by sequestering excess free zinc, regulating its bioavailability, and preventing toxicity. 2. **Why Other Options are Incorrect:** * **Calcium:** Calcium levels are regulated by hormones like PTH, Vitamin D, and Calcitonin, primarily through bone remodeling and renal excretion, not metallothionein. * **Iron:** Iron homeostasis is managed by proteins like **Ferritin** (storage) and **Transferrin** (transport). Its synthesis is regulated by Iron Response Elements (IRE) and Iron Regulatory Proteins (IRP). * **Phosphorous:** Phosphorus levels are regulated by the kidneys and FGF-23; it does not interact with metallothionein. **High-Yield Clinical Pearls for NEET-PG:** * **Zinc-Copper Interaction:** High doses of Zinc induce metallothionein in intestinal mucosal cells. Metallothionein has a higher affinity for **Copper** than Zinc. Consequently, Copper becomes trapped within the mucosal cells and is sloughed off, leading to **secondary Copper deficiency**. This principle is used therapeutically in treating **Wilson’s Disease**. * **Detoxification:** Besides Zinc and Copper, metallothionein also binds and detoxifies heavy metals like **Cadmium and Mercury**. * **Antioxidant Role:** Due to its high cysteine content, metallothionein also acts as a scavenger for free radicals.

Question 1

Which of the following is the mechanism of action of dietary fiber in reducing atherosclerosis?

Accepted Answer

Binding to cholesterol

Answer

Decreases VLDL

Answer

Increasing fluid retention

Answer

Forming antioxidants

Question 2

Which of the following is the least cariogenic?

Accepted Answer

Raw starch

Answer

Cooked starch

Answer

Sucrose

Answer

Fructose

Question 3

Which substance is NOT known to have an anti-infective property, either directly or indirectly, in milk?

Accepted Answer

Lactalbumin

Answer

Lactoferrin

Answer

Lysozyme

Answer

All of the above

Question 4

Which milk has the highest content of lactose?

Accepted Answer

Human milk

Answer

Buffalo milk

Answer

Goat milk

Answer

Cow milk

Question 5

Which plasma protein is the first to be generated after a severe protein deficiency?

Accepted Answer

Fibrinogen

Answer

Albumin

Answer

Globulin

Answer

Thrombin

Question 6

All of the following are characteristic features of Kwashiorkor, except –

Accepted Answer

High blood osmolarity

Answer

Hypoalbuminemia

Answer

Edema

Answer

Fatty liver

Question 7

Which of the following fats and oils contains the highest proportion of polyunsaturated fatty acids (PUFA)?

Accepted Answer

Safflower oil

Answer

Coconut oil

Answer

Groundnut oil

Answer

Butter

Question 8

Sorghum contains an excess of which amino acid?

Accepted Answer

Leucine

Answer

Lysine

Answer

Arginine

Answer

Histidine

Question 9

All of the following are trace elements except:

Accepted Answer

Potassium

Answer

Iron

Answer

Fluoride

Answer

Zinc

Question 10

Which of the following minerals can induce the synthesis of metallothionein?

Accepted Answer

Zinc

Answer

Calcium

Answer

Iron

Answer

Phosphorous

Nutrition and Metabolism — MCQs

Nutrition and Metabolism — MCQs

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