Question 1

Which of the following vitamins is synthesized by the human body when skin is exposed to sunlight?

Accepted Answer

Vitamin D is synthesized in the skin when exposed to ultraviolet B (UVB) radiation from sunlight. This is a static biological fact about human physiology. The conversion occurs through a series of reactions: 7-dehydrocholesterol in the skin converts to previtamin D3, which then isomerizes to vitamin D3 (cholecalciferol). Therefore, the answer is B.

Question 2

Beriberi is a deficiency disease caused by the lack of which vitamin, and which body system is primarily affected?

Accepted Answer

Beriberi is caused by deficiency of Vitamin B1 (thiamine). Thiamine is essential for carbohydrate metabolism and nerve function. The disease primarily affects the nervous system (peripheral neuropathy, Wernicke-Korsakoff syndrome) and the cardiovascular system (wet beriberi causes heart failure). Beriberi was historically common in populations consuming polished white rice without thiamine-rich bran. The disease manifests as 'wet beriberi' (cardiac involvement) or 'dry beriberi' (neurological involvement).

Question 3

Kwashiorkor is a severe malnutrition disease characterized by protein deficiency. Which of the following is NOT a typical clinical feature of kwashiorkor?

Accepted Answer

Kwashiorkor is a form of protein-energy malnutrition (PEM) caused by severe protein deficiency with relatively adequate calorie intake. Typical clinical features include: edema (especially in legs and face, giving a 'moon face' appearance), hepatomegaly (enlarged liver with fatty infiltration), skin lesions (dermatitis, hyperpigmentation), hair changes (depigmentation, brittleness), and growth retardation. Hyperglycemia (elevated blood glucose) is NOT a typical feature of kwashiorkor; rather, hypoglycemia may occur. Marasmus (not kwashiorkor) presents with severe wasting and absence of edema.

Question 4

Scurvy is a deficiency disease caused by lack of Vitamin C. Which of the following is the primary biochemical reason why Vitamin C deficiency leads to defective collagen synthesis?

Accepted Answer

Vitamin C (ascorbic acid) is a cofactor for prolyl and lysyl hydroxylase enzymes, which catalyze the hydroxylation of proline and lysine residues in collagen. These hydroxylated residues are essential for cross-linking and stabilizing the collagen triple helix structure. Without adequate Vitamin C, collagen cannot be properly hydroxylated, resulting in defective, unstable collagen that cannot form proper connective tissue. This leads to scurvy symptoms: bleeding gums, poor wound healing, joint pain, and weakened blood vessels. Vitamin C also acts as an antioxidant but this is not the primary reason for collagen defects.

Question 5

Iodine deficiency leads to the development of goiter and cretinism. Which hormone's synthesis is directly impaired due to iodine deficiency?

Accepted Answer

Iodine is an essential component of thyroid hormones thyroxine (T4) and triiodothyronine (T3). Iodine deficiency impairs the synthesis of these thyroid hormones, leading to compensatory enlargement of the thyroid gland (goiter) as it attempts to produce adequate hormone. In severe cases, especially during fetal development and infancy, iodine deficiency causes cretinism, characterized by severe intellectual disability, stunted growth, and developmental abnormalities. The thyroid hormones are critical for metabolism, growth, and neurological development. Insulin, cortisol, and parathyroid hormone are not directly dependent on iodine for their synthesis.

Question 6

Beriberi is a deficiency disease caused by the lack of which vitamin?

Accepted Answer

Beriberi is caused by deficiency of Vitamin B1 (thiamine). This is a well-established medical fact. Thiamine is essential for carbohydrate metabolism and nerve function. The disease manifests in two forms: wet beriberi (affecting the cardiovascular system) and dry beriberi (affecting the nervous system). Therefore, the answer is A.

Question 7

Which of the following is the primary function of hemoglobin in the human body?

Accepted Answer

Hemoglobin is an iron-containing protein in red blood cells whose primary function is to transport oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs. Hemoglobin consists of four polypeptide chains (two alpha and two beta) and four heme groups, each containing iron. Therefore, the answer is C.

Question 8

Scurvy is a deficiency disease caused by the lack of which vitamin, and what is its primary symptom?

Accepted Answer

Scurvy is caused by Vitamin C (ascorbic acid) deficiency. Vitamin C is essential for collagen synthesis, and its deficiency leads to weakened connective tissue. The primary symptoms include bleeding gums, poor wound healing, and weakened blood vessels. This is a well-documented historical and medical fact. Therefore, the answer is B.

Question 9

Which of the following is the correct SI unit for measuring energy in nutrition and food science?

Accepted Answer

The SI unit for energy is the joule (J). In nutrition, energy is often expressed in kilocalories (kcal) or kilojoules (kJ), where 1 kcal = 4.184 kJ. However, the standard SI unit is the joule. Food labels in many countries now display energy in both kilocalories and kilojoules. Therefore, the answer is D.

Question 10

Which of the following vitamins is synthesized by the human body and does NOT require dietary intake for its primary source?

Accepted Answer

Vitamin D is synthesized in the skin upon exposure to ultraviolet-B (UVB) radiation from sunlight. While dietary sources exist, the body can produce sufficient quantities endogenously. Other vitamins (A, B12, C) must be obtained primarily from dietary sources as the body cannot synthesize them.

Question 11

Beriberi, a disease caused by deficiency of Vitamin B1 (thiamine), primarily affects which of the following systems in the human body?

Accepted Answer

Beriberi is a disease caused by thiamine (Vitamin B1) deficiency and manifests in two forms: wet beriberi (affecting the cardiovascular system, causing heart failure and edema) and dry beriberi (affecting the nervous system, causing peripheral neuropathy and muscle weakness). Both forms involve multiple systems, but the disease is fundamentally a metabolic disorder affecting energy production in nerve and muscle tissues.

Question 12

Kwashiorkor is a severe form of protein-energy malnutrition characterized by which of the following clinical features?

Accepted Answer

Kwashiorkor is a form of protein malnutrition (despite adequate caloric intake) characterized by edema (swelling), hepatomegaly (enlarged liver with fatty infiltration), skin depigmentation, hair changes (reddish/blonde discoloration), and a distended abdomen. It occurs when protein intake is severely deficient relative to caloric intake, commonly seen in weaned children in developing countries.

Question 13

Scurvy, a disease caused by Vitamin C deficiency, results in impaired collagen synthesis. Which of the following is the primary biochemical reason for this?

Accepted Answer

Vitamin C (ascorbic acid) is a cofactor for prolyl and lysyl hydroxylase enzymes, which hydroxylate proline and lysine residues in collagen. These hydroxylated residues are essential for cross-linking and stabilizing the collagen triple helix structure. Without adequate Vitamin C, collagen cannot be properly cross-linked, resulting in defective connective tissue.

Question 14

Rickets, a disease caused by Vitamin D deficiency in children, primarily results in which of the following skeletal manifestations?

Accepted Answer

Rickets is a metabolic bone disease in children caused by Vitamin D deficiency, leading to impaired calcium absorption and defective mineralization of the growth plate cartilage and bone matrix. Primary manifestations include: bowing of legs, delayed closure of fontanelles, delayed tooth eruption, rachitic rosary (beading of costochondral junctions), frontal bossing, and dental enamel defects.

Question 15

Pellagra is a disease caused by deficiency of which B vitamin, and it is characterized by the '4 Ds' syndrome?

Accepted Answer

Pellagra is caused by niacin (Vitamin B3, also called nicotinic acid) deficiency. It is characterized by the '4 Ds': Dermatitis, Diarrhea, Dementia, and Death (if untreated). The disease was historically prevalent in populations with diets heavily dependent on corn that had not been treated with alkali (nixtamalization), which would release bound niacin. Therefore, the answer is C.

Question 16

Which vitamin deficiency causes Beriberi, a disease affecting the nervous and cardiovascular systems?

Accepted Answer

Beriberi is caused by deficiency of Vitamin B1 (Thiamine). This water-soluble vitamin is essential for carbohydrate metabolism and nerve function. The disease was historically prevalent in populations consuming polished white rice as a staple. Therefore, answer is B.

Question 17

Kwashiorkor is a severe form of protein-energy malnutrition. Which of the following is NOT a characteristic clinical feature of Kwashiorkor?

Accepted Answer

Kwashiorkor is characterized by edema (puffiness), hepatomegaly (enlarged liver), skin depigmentation, hair changes, and a distended abdomen. Marasmus (not Kwashiorkor) is characterized by severe wasting and absence of edema. Therefore, answer is C.

Question 18

Scurvy, a disease caused by Vitamin C deficiency, historically affected sailors on long voyages. Which of the following is the primary biochemical role of Vitamin C that explains the symptoms of scurvy?

Accepted Answer

Vitamin C (Ascorbic Acid) is essential for collagen synthesis as a cofactor for prolyl and lysyl hydroxylase enzymes. Deficiency leads to defective collagen, causing bleeding gums, poor wound healing, and joint pain. Therefore, answer is D.

Question 19

Pellagra is a disease caused by deficiency of Vitamin B3 (Niacin). The disease is characterized by the '4 Ds'. Which of the following is NOT one of the classic '4 Ds' of Pellagra?

Accepted Answer

The classic '4 Ds' of Pellagra are: Dermatitis, Diarrhea, Dementia, and Death. Dysentery (bloody diarrhea) is not part of the classic tetrad, though diarrhea is. Therefore, answer is A.

Question 20

Rickets is a metabolic bone disease in children caused by deficiency of Vitamin D and/or calcium. Which of the following is the primary mechanism by which Vitamin D deficiency leads to rickets?

Accepted Answer

Vitamin D is essential for calcium absorption in the small intestine and for maintaining serum calcium levels. Deficiency leads to impaired calcium absorption, resulting in hypocalcemia, which triggers secondary hyperparathyroidism and defective mineralization of the growth plate cartilage matrix. Therefore, answer is B.

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