Nutrition and Metabolism Practice Questions

Q: Which one among the following essential amino acids is usually the "limiting" amino acid in most of the pulses?

Methionine. ***Methionine*** - In **pulses** (legumes), the sulfur-containing amino acids, primarily **methionine** and **cysteine**, are often the first limiting amino acids. - This means that the amount of protein synthesis that can occur is restricted by the availability of methionine, even if other essential amino acids are abundant. *Valine* - **Valine** is an essential branched-chain amino acid, but it is typically not the limiting amino acid in pulses. - It is more likely to be limiting in certain grains or in specific diets lacking a variety of protein sources. *Threonine* - **Threonine** is an essential amino acid that can be limiting in some cereals, but it is not typically the primary limiting amino acid in pulses. - Its deficiency is less common in a balanced diet including legumes. *Lysine* - **Lysine** is often the limiting amino acid in most **cereal grains** (e.g., wheat, corn, rice). - Pulses, however, are generally good sources of lysine, making its deficiency less likely when consumed.

Q: Egg proteins are considered to be the best among food proteins because : I. of their biological value II. of their digestibility III. they contain all the essential amino acids IV. their calorie content is higher than in proteins of vegetable sources Which of the statements given above is/are correct?

I, II and III. ***I, II and III*** - Egg proteins are considered high-quality due to their **high biological value**, meaning they are efficiently utilized by the body. This is a direct consequence of their **excellent digestibility** and complete amino acid profile. - They contain **all nine essential amino acids** in proportions that closely match human needs, making them a complete protein source. This characteristic is crucial for muscle repair, enzyme production, and overall bodily functions. *II, III and IV* - While egg proteins are highly digestible and contain all essential amino acids (II and III are correct), their **calorie content is not necessarily higher than proteins from vegetable sources (IV is incorrect)**. Calorie content depends on the specific food and its overall macronutrient composition, not just the protein source. - **Biological value** is a key reason egg proteins are considered superior, and this option omits it. *I only* - While the **high biological value (I)** of egg proteins is a fundamental reason for their quality, it is not the only reason. Their excellent digestibility and comprehensive essential amino acid profile are equally important factors. - This option is incomplete as it fails to acknowledge the other critical attributes that contribute to the superiority of egg proteins. *I, III and IV* - Egg proteins do have a **high biological value (I)** and contain **all essential amino acids (III)**. However, statement IV, which claims their calorie content is higher than vegetable proteins, is generally **incorrect**. - This option is incorrect because it includes an inaccurate statement about calorie content and overlooks the crucial aspect of **digestibility (II)**.

Q: Dietary fibres have :

no metabolic effect. ***no metabolic effect*** - Dietary fibers are **indigestible polysaccharides** that cannot be broken down by human digestive enzymes. - Humans lack enzymes like **cellulase** necessary to hydrolyze the β-glycosidic bonds in dietary fiber. - Dietary fibers pass through the gastrointestinal tract **without being metabolized** by human cells, meaning they do not participate in anabolic or catabolic pathways. - While gut bacteria can ferment some fibers producing short-chain fatty acids (SCFAs), this is **bacterial metabolism**, not human metabolism. - The physiological effects of fiber (improved bowel motility, reduced cholesterol absorption, glycemic control) are **mechanical and physicochemical**, not metabolic. *catabolic effect* - Catabolic processes involve **breakdown of molecules with energy release** (e.g., glycolysis, lipolysis). - Dietary fibers cannot undergo catabolism in humans because we lack the enzymes to break them down. - The fermentation by gut bacteria is not human catabolism. *anabolic effect* - Anabolic processes involve **synthesis of complex molecules** from simpler ones (e.g., protein synthesis, glycogenesis). - Dietary fibers are not absorbed or incorporated into human tissues, so they cannot participate in anabolic reactions. *sometimes anabolic and sometimes catabolic effect, depending on the type* - Regardless of fiber type (soluble or insoluble), **all dietary fibers remain non-metabolizable** by human enzymes. - Neither type undergoes anabolic or catabolic metabolism in human cells.

Q: Consider the following with regard to Amino Acids : I. Essential Amino Acids are those that the body cannot synthesize and they must be obtained from dietary proteins. II. Not just the Essential Amino Acids, Non-essential Amino Acids are also needed by the body for synthesis of tissue proteins. III. Unless a protein contains all the Essential Amino Acids in amounts corresponding to human needs, a protein is said to be biologically incomplete. IV. Animal proteins are rated superior to vegetable proteins. Of the above statements, how many are correct?

All four. ***All four*** - **Statement I is correct:** Essential amino acids cannot be synthesized by the body and must be obtained from dietary sources. The 9 essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. - **Statement II is correct:** Both essential and non-essential amino acids are required for tissue protein synthesis. Non-essential amino acids (like alanine, aspartic acid, glutamic acid, etc.) are equally important for building proteins, even though the body can synthesize them. - **Statement III is correct:** A protein is considered **biologically incomplete** if it lacks one or more essential amino acids in adequate amounts. Complete proteins contain all essential amino acids in proportions that meet human nutritional requirements. - **Statement IV is correct:** Animal proteins (meat, fish, eggs, dairy) are traditionally rated as superior to most plant proteins because they are **complete proteins** containing all essential amino acids in adequate proportions with high biological value. Most plant proteins (except soy, quinoa) are incomplete or limiting in one or more essential amino acids. Since all four statements (I, II, III, and IV) are factually correct, the answer is **all four**. *Only three* - This option is incorrect because all four statements about amino acids are medically accurate, not just three of them. *Only two* - This option is incorrect as it significantly underestimates the number of correct statements. All four statements are valid principles in biochemistry and nutrition. *Only one* - This option is incorrect as multiple statements are correct. All four statements represent established knowledge about protein nutrition and amino acid classification.

Q: Acrodermatitis enteropathica is an autosomal recessive metabolic disorder which affects the absorption of which one of the following micronutrients?

Zinc. ***Correct: Zinc*** - **Acrodermatitis enteropathica** is an autosomal recessive disorder caused by a defect in the absorption of **zinc** from the intestines (due to mutations in the *SLC39A4* gene encoding the ZIP4 zinc transporter). - This leads to the characteristic clinical triad: periorificial and acral **dermatitis**, **alopecia**, and **diarrhea**. - Treatment involves lifelong zinc supplementation. *Incorrect: Selenium* - **Selenium** deficiency can lead to **Keshan disease** (cardiomyopathy) and **Kashin-Beck disease** (osteoarthropathy), which are distinct from acrodermatitis enteropathica. - Symptoms related to selenium deficiency do not typically include the prominent dermatological and gastrointestinal features seen in acrodermatitis enteropathica. *Incorrect: Iron* - **Iron** deficiency primarily causes **anemia** and symptoms like fatigue, pallor, and pica. - While iron is a crucial micronutrient, its malabsorption does not result in the specific skin, hair, and gastrointestinal manifestations of acrodermatitis enteropathica. *Incorrect: Iodine* - **Iodine** deficiency is strongly associated with **goiter** and various thyroid dysfunctions, including **hypothyroidism** and **cretinism**. - These conditions are entirely different from the syndrome of acrodermatitis enteropathica, which is characterized by zinc malabsorption.

Q: Which food proteins among the following are considered to be the best and are used in nutritional studies as 'reference protein' ?

Egg proteins. ***Egg proteins*** - **Egg proteins** provide all **essential amino acids** in proportions that closely match human requirements, making them a **high-quality protein**. - Due to their excellent amino acid profile and high digestibility, **egg proteins** are often used as a **reference protein** in nutritional studies to evaluate the biological value of other proteins. *Milk proteins* - While **milk proteins** (casein and whey) are generally considered high-quality, their amino acid profile is not as perfectly balanced for human needs as egg protein. - They are commonly used as a reference for assessing protein quality, but **egg protein** often serves as the gold standard for comparison. *Legume proteins* - **Legume proteins** are typically deficient in **methionine and cysteine**, essential amino acids, making them an incomplete protein when consumed alone. - Their overall **biological value** is lower than animal proteins, and they are not considered a reference protein. *Wheat proteins* - **Wheat proteins** (gluten) are deficient in the **essential amino acid lysine**. - They have a lower **biological value** and are not as easily digestible as animal proteins, thus not suitable as a reference protein.

Q: The milk of which of the following contains the least amount of calcium?

Human. ***Human*** - **Human breast milk** contains the lowest concentration of calcium compared to the milk of other mammals listed. - This is physiologically appropriate as infants absorb calcium very efficiently from human milk, and higher concentrations are not necessary. *Cow* - **Cow's milk** has a significantly higher calcium content than human milk, which is suitable for the rapid growth of calf bones. - The **calcium-to-phosphorus ratio** in cow's milk is also different, which can affect absorption and metabolism in infants. *Buffalo* - **Buffalo milk** generally has an even higher calcium content than cow's milk. - It is known for its **richness in nutrients** and higher fat and protein content, contributing to its denser consistency. *Goat* - **Goat's milk** has a calcium content that is higher than human milk, though often slightly less than cow's milk. - Its calcium is absorbed relatively well, but its overall composition is still very different from human milk, particularly in terms of **protein and micronutrient balance**.

Q: Which of the following dietary sources contains the lowest percent of linoleic acid?

Coconut oil. ***Coconut oil*** - Coconut oil is primarily composed of **saturated fats**, particularly **lauric acid**, and has a very low percentage of linoleic acid. - Its high saturated fat content distinguishes it from most other vegetable oils, which are generally rich in unsaturated fats. *Corn oil* - Corn oil is a **polyunsaturated fatty acid (PUFA)**-rich oil, with a significant proportion of **linoleic acid** (an omega-6 fatty acid). - It is often used in cooking for its neutral flavor and high smoke point. *Mustard oil* - Mustard oil contains a substantial amount of **monounsaturated fatty acids (MUFA)**, like **erucic acid**, and also a notable percentage of **linoleic acid**. - Its distinct pungent flavor is popular in certain cuisines. *Groundnut oil* - Groundnut oil, also known as peanut oil, is rich in both **monounsaturated** and **polyunsaturated fatty acids**, including a good percentage of **linoleic acid**. - It is commonly used for frying due to its high smoke point and mild flavor.

Q: The biological value of a given protein depends upon

Digestibility and amino acid composition. ***Digestibility and amino acid composition*** - The **biological value (BV)** of a protein measures how efficiently the body can use the absorbed protein from a food source for growth and maintenance. - It is primarily determined by two factors: the **digestibility** of the protein (how much is absorbed) and its **amino acid composition** (the proportion and availability of essential amino acids). *Digestibility and leucine content* - While **digestibility** is an important factor for biological value, **leucine content** alone is not sufficient to determine it. - The biological value depends on the **overall balance of essential amino acids**, not just one specific amino acid. *Amino acid composition and specific dynamic effect* - **Amino acid composition** is crucial for biological value, but the **specific dynamic effect (SDE)**, also known as the thermic effect of food, refers to the energy expended during the digestion, absorption, and assimilation of food. - SDE is related to energy metabolism, not directly to the protein's utility for tissue synthesis. *Amino acid composition alone* - **Amino acid composition** is a key determinant, particularly the presence and proportion of **essential amino acids**. - However, for a protein to be utilized, it must first be **digested and absorbed**, making digestibility an equally critical factor affecting its overall biological value.

Q: Consider the following: 1. Coconut oil 2. Groundnut oil 3. Mustard oil Which of the above is/are dietary sources of linoleic acid?

2 and 3 only. ***2 and 3 only*** - **Groundnut oil** (peanut oil) is a good source of **linoleic acid** (omega-6 fatty acid), containing around 20-40% of this polyunsaturated fat. - **Mustard oil** also contains a significant amount of **linoleic acid**, typically ranging from 9% to 21% of its total fatty acid content. *1, 2 and 3* - **Coconut oil** is primarily composed of **saturated fats**, particularly **lauric acid**, and contains very little linoleic acid. - While groundnut and mustard oil are sources, coconut oil is not. *1 and 2 only* - This option incorrectly includes **coconut oil** as a source of linoleic acid, which it is not. - It also excludes **mustard oil**, which is a dietary source of linoleic acid. *3 only* - This option is incomplete as it correctly identifies **mustard oil** but fails to include **groundnut oil**, which is also a significant source of linoleic acid. - Many common vegetable oils are rich in linoleic acid, not just mustard oil.

Question 1

Which one among the following essential amino acids is usually the "limiting" amino acid in most of the pulses?

Accepted Answer

Methionine

Answer

Valine

Answer

Threonine

Answer

Lysine

Question 2

Egg proteins are considered to be the best among food proteins because :
I. of their biological value
II. of their digestibility
III. they contain all the essential amino acids
IV. their calorie content is higher than in proteins of vegetable sources

Which of the statements given above is/are correct?

Accepted Answer

I, II and III

Answer

II, III and IV

Answer

I only

Answer

I, III and IV

Question 3

Dietary fibres have :

Accepted Answer

no metabolic effect

Answer

catabolic effect

Answer

sometimes anabolic and sometimes catabolic effect, depending on the type

Answer

anabolic effect

Question 4

Consider the following with regard to Amino Acids :
I. Essential Amino Acids are those that the body cannot synthesize and they must be obtained from dietary proteins.
II. Not just the Essential Amino Acids, Non-essential Amino Acids are also needed by the body for synthesis of tissue proteins.
III. Unless a protein contains all the Essential Amino Acids in amounts corresponding to human needs, a protein is said to be biologically incomplete.
IV. Animal proteins are rated superior to vegetable proteins.

Of the above statements, how many are correct?

Accepted Answer

All four

Answer

Only two

Answer

Only three

Answer

Only one

Question 5

Acrodermatitis enteropathica is an autosomal recessive metabolic disorder which affects the absorption of which one of the following micronutrients?

Accepted Answer

Zinc

Answer

Selenium

Answer

Iron

Answer

Iodine

Question 6

Which food proteins among the following are considered to be the best and are used in nutritional studies as 'reference protein' ?

Accepted Answer

Egg proteins

Answer

Milk proteins

Answer

Legume proteins

Answer

Wheat proteins

Question 7

The milk of which of the following contains the least amount of calcium?

Accepted Answer

Human

Answer

Cow

Answer

Buffalo

Answer

Goat

Question 8

Which of the following dietary sources contains the lowest percent of linoleic acid?

Accepted Answer

Coconut oil

Answer

Corn oil

Answer

Mustard oil

Answer

Groundnut oil

Question 9

The biological value of a given protein depends upon

Accepted Answer

Digestibility and amino acid composition

Answer

Digestibility and leucine content

Answer

Amino acid composition and specific dynamic effect

Answer

Amino acid composition alone

Question 10

Consider the following:

1. Coconut oil
2. Groundnut oil
3. Mustard oil

Which of the above is/are dietary sources of linoleic acid?

Accepted Answer

2 and 3 only

Answer

1, 2 and 3

Answer

1 and 2 only

Answer

3 only

Nutrition and Metabolism — MCQs

Nutrition and Metabolism — MCQs

On this page

Practice by Chapter

Want unlimited practice?