Nutrition and Metabolism Practice Questions

Q: Magnesium is not involved in ?

Hemoglobin synthesis. ***Hemoglobin synthesis*** - **Magnesium** is not directly involved in the synthesis of **hemoglobin**; **iron** is the crucial mineral for this process. - While magnesium is vital for many enzymatic reactions, it does not play a direct role in forming the heme structure or globin chains. *Cellular oxidation* - **Magnesium** acts as a **cofactor** for numerous enzymes involved in **cellular respiration** and **oxidative phosphorylation**, which are key processes in cellular oxidation. - These enzymatic reactions are critical for energy production within the cell. *Membrane transport* - **Magnesium** ions are essential for the proper functioning of various **ion channels** and **pumps**, such as the **Na+/K+ ATPase**, which are fundamental for maintaining **membrane potential** and **active transport**. - It influences the permeability of cell membranes and the movement of substances across them. *Glucose tolerance* - **Magnesium** plays a significant role in **glucose metabolism** and **insulin signaling**, affecting **glucose uptake** and utilization by cells, thereby influencing **glucose tolerance**. - Deficiency in magnesium has been linked to **insulin resistance** and an increased risk of **type 2 diabetes**.

Q: The skin changes seen in protein energy malnutrition can be due to deficiency of all of the following nutrients except:

Pyridoxine. ***Pyridoxine*** - **Pyridoxine (vitamin B6)** deficiency can lead to **seborrheic dermatitis-like lesions**, glossitis, and cheilosis, but these are not the characteristic skin changes directly attributed to **protein-energy malnutrition (PEM)** itself. - While essential for many metabolic processes, its deficiency symptoms are distinct from the typical **dermatological manifestations of PEM**, such as those seen in kwashiorkor or marasmus [3]. *Essential fatty acids* - Deficiency of **essential fatty acids (EFAs)**, particularly **linoleic and alpha-linolenic acids**, can cause **scaly dermatitis**, **xerosis (dry skin)**, and **impaired skin barrier function**. - These conditions often contribute to the skin changes seen in **malnutrition**, making the skin more susceptible to infection and damage. *Zinc* - **Zinc deficiency** is a common complication of **protein-energy malnutrition** and can cause distinctive skin lesions, including **acrodermatitis enteropathica-like rash**, characterized by **vesiculobullous or pustular lesions** around body orifices and on the extremities. - It plays a crucial role in **skin integrity, wound healing**, and immune function, and its absence severely impacts cellular processes in the skin. *Tryptophan* - **Tryptophan** is an essential amino acid and a precursor to **niacin (vitamin B3)** [1]. - Deficiency can lead to **pellagra-like dermatosis**, characterized by the "necklace" sign, symmetrical, pigmented, and erythematous lesions on sun-exposed areas [2]. This is often seen in **severe protein-energy malnutrition** cases where overall intake of essential amino acids and vitamins is compromised.

Q: What is the average daily requirement of zinc in adult humans?

11 mg/day. ***11 mg/day*** - The recommended daily allowance (RDA) for **zinc** in adult humans is **11 mg/day** as per standard nutritional guidelines. - This is the most commonly cited value in medical textbooks including **Harper's Biochemistry** and represents the general adult requirement. - While females have a slightly lower requirement (8 mg/day), **11 mg/day** is the standard reference value used in clinical practice and examinations. *15 mg/day* - This value is higher than the standard **RDA** for adult populations. - May be recommended in specific situations such as **vegetarian diets** (due to lower bioavailability from plant sources) or during **increased physiological demands**. - Regular intake significantly above the RDA without specific medical indication could potentially lead to adverse effects. *8 mg/day* - This is the **RDA** specifically for adult females. - While adequate for adult women under normal conditions, it represents the lower end of requirements and is not the standard general adult value cited in medical literature. *9.4 mg/day* - This appears to be a calculated average between male (11 mg) and female (8 mg) requirements. - However, this is **not a standard reference value** found in authoritative nutritional guidelines or medical textbooks. - Exam questions typically use established RDA values rather than calculated averages.

Q: Which of the following is not a dietary fiber?

Starch. ***Starch*** - **Starch** is a **complex carbohydrate** that serves as a major energy source for humans and can be digested into glucose. - Unlike dietary fiber, starch is broken down by enzymes (like **amylase**) in the digestive tract, absorbed, and used for energy. *Cellulose* - **Cellulose** is a **polysaccharide** found in the cell walls of plants and is a major component of dietary fiber. - Humans lack the enzymes to digest cellulose, so it passes through the digestive system largely intact, adding **bulk to stool**. *Pectin* - **Pectin** is a **soluble dietary fiber** found in fruits, particularly apples and citrus. - It forms a gel-like substance when mixed with water and is known for its ability to lower cholesterol and regulate blood sugar. *Inulin* - **Inulin** is a **soluble dietary fiber** and a type of fructan, found in many plants like chicory root, onions, and garlic. - It acts as a **prebiotic**, promoting the growth of beneficial gut bacteria in the colon.

Q: Which of the following minerals is needed for fertility?

Zinc. ***Zinc*** - Zinc is crucial for **reproductive health** in both men and women, impacting **testosterone synthesis**, **spermatogenesis**, egg quality, and **hormone regulation**. - Essential for **gonadal development** and function in both sexes. - Deficiency leads to **hypogonadism**, reduced fertility, impaired sperm production, and increased risk of **miscarriage**. - Most commonly deficient mineral affecting fertility globally. *Selenium* - Selenium is also **essential for male fertility**, being a critical component of **glutathione peroxidase** in sperm mitochondria. - Required for **sperm motility**, morphology, and structural integrity of the sperm midpiece. - Deficiency can cause male infertility due to impaired sperm function. - However, zinc deficiency is more prevalent and has broader effects across both male and female reproductive systems. *Iron* - Iron is vital for **red blood cell formation** and preventing **anemia**. - Severe iron deficiency anemia can **impair ovulation** and indirectly affect fertility in women. - Not directly involved in reproductive processes at the cellular level like zinc. *Copper* - Essential for various enzymatic functions but not primarily associated with fertility. - **Excessive copper** can negatively impact fertility and cause hormonal imbalances. - Deficiency is rare and not a primary cause of infertility.

Q: Which of the following is not a type of dietary fiber?

Starch. ***Starch*** - **Starch** is a **complex carbohydrate** that serves as a storage form of glucose in plants and is readily digestible by human enzymes (amylase) into monosaccharides. - While it is a carbohydrate, its ability to be enzymatically broken down and absorbed means it does not meet the definition of dietary fiber. *Pectin* - **Pectin** is a type of **soluble dietary fiber** found in fruits, particularly apples and citrus, and is known for its gelling properties. - It is not digested or absorbed in the small intestine but is fermented by bacteria in the large intestine. *Lignin* - **Lignin** is a **non-carbohydrate dietary fiber**, a complex polymer that provides structural support to plants. - It is generally considered an **insoluble fiber** and passes largely unchanged through the human digestive tract. *Cellulose* - **Cellulose** is a major component of plant cell walls and is a type of **insoluble dietary fiber**. - Humans lack the enzymes to digest cellulose, so it passes through the digestive system largely intact, aiding in bowel regularity.

Q: Pulses are deficient in which amino acid?

Methionine. **Methionine (Correct)** - Pulses (legumes) are generally **deficient in sulfur-containing amino acids**, with methionine being the primary limiting one. - This deficiency makes it important to combine pulses with other foods rich in methionine, such as **grains**, to achieve a complete protein profile. *Lysine (Incorrect)* - Lysine is a **limiting amino acid in grains**, but pulses are generally a good source of lysine. - Therefore, combining grains and pulses (e.g., rice and dal) can provide a **complete essential amino acid profile**. *Threonine (Incorrect)* - While threonine is an essential amino acid, it is **not typically the limiting amino acid in pulses**. - The primary limiting factor in pulses related to essential amino acids is **methionine**. *None of the options (Incorrect)* - This option is incorrect because pulses do have a **limiting amino acid**, which is methionine. - Identifying the limiting amino acid is crucial for understanding **dietary protein complementarity**.

Q: Pulses are known to be low in which of the following amino acids?

Cysteine. ***Cysteine*** - Pulses (legumes) are typically deficient in the sulfur-containing amino acids, **methionine** and **cysteine**. - This makes them an incomplete protein source if consumed exclusively, as these amino acids are essential for human nutrition. *Lysine* - Lysine is often a **limiting amino acid** in cereals, but pulses are generally **rich in lysine**. - This **complementarity** is why combining cereals and pulses creates a complete protein profile. *Methionine* - Methionine is a **sulfur-containing amino acid** that, along with cysteine, is deficient in pulses. - This is why pulses are often combined with cereals (which contain adequate methionine) to provide complete protein nutrition. *Arginine* - Arginine is an amino acid that is often found in good quantities in pulses. - It is not typically considered a **limiting amino acid** in legumes.

Question 1

Magnesium is not involved in ?

Accepted Answer

Hemoglobin synthesis

Answer

Cellular oxidation

Answer

Membrane transport

Answer

Glucose tolerance

Question 2

Which of the following statements regarding adult nutrition is INCORRECT?

Accepted Answer

Daily calorie intake in a sedentary adults is 40-45kcal/kg/day

Answer

one gram nitrogen yields 6.25 gm of protein

Answer

Nitrogen requirement is 0.8 gm/kg

Answer

Daily calorie intake in a sedentary adult is 25-30 kcal/kg/day

Question 3

The skin changes seen in protein energy malnutrition can be due to deficiency of all of the following nutrients except:

Accepted Answer

Pyridoxine

Answer

Essential fatty acids

Answer

Zinc

Answer

Tryptophan

Question 4

What is the average daily requirement of zinc in adult humans?

Accepted Answer

11 mg/day

Answer

15 mg/day

Answer

8 mg/day

Answer

9.4 mg/day

Question 5

A young man weighing 65 kg was admitted to the hospital with severe burns in a severe catabolic state. An individual in this state requires 40 kcal per kg body weight per day and 2 gms of protein/kg body weight/day. This young man was given a solution containing 20% glucose and 4.25% protein. If 3000 ml of solution is infused per day, which of the following statements is most accurate regarding the nutritional provision?

Accepted Answer

The calories provided are insufficient for the patient's needs

Answer

The protein provided exceeds the patient's requirement

Answer

The protein provided is insufficient for the patient's requirement

Answer

The solution provides adequate protein and calories for the patient

Question 6

Which of the following is not a dietary fiber?

Accepted Answer

Starch

Answer

Cellulose

Answer

Pectin

Answer

Inulin

Question 7

Which of the following minerals is needed for fertility?

Accepted Answer

Zinc

Answer

Copper

Answer

Iron

Answer

Selenium

Question 8

Which of the following is not a type of dietary fiber?

Accepted Answer

Starch

Answer

Lignin

Answer

Cellulose

Answer

Pectin

Question 9

Pulses are deficient in which amino acid?

Accepted Answer

Methionine

Answer

Lysine

Answer

Threonine

Answer

None of the options

Question 10

Pulses are known to be low in which of the following amino acids?

Accepted Answer

Cysteine

Answer

Lysine

Answer

Methionine

Answer

Arginine

Nutrition and Metabolism — MCQs

Nutrition and Metabolism — MCQs

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