, CHAPTER LIST
Chapter: 1. Nutrients and Recommended Intakes
Chapter: 2. Healthy Eating
Chapter: 3. Fuel Sources for Muscle and Exercise Metabolism
Chapter: 4. Energy
Chapter: 5. Gastric Emptying, Digestion, and Absorption
Chapter: 6. Carbohydrate
Chapter: 7. Fat
Chapter: 8. Protein and Amino Acids
Chapter: 9. Fluid and Electrolytes
Chapter: 10. Vitamins and Minerals
Chapter: 11. Nutrition Supplements
Chapter: 12. Nutrition and Training Adaptations
Chapter: 13. Nutrition and Immune Function in Athletes
Chapter: 14. Body Composition
Chapter: 15. Weight Management
Chapter: 16. Eating Disorders and Low Energy Availability in Athletes
Chapter: 17. Personalized Nutrition
,Chapter 1: Nutrients and Recommended Intakes
25 Multiple-Choice Questions | Physiological Foundations & Applied Athletic Practice
1. Which of the following dietary reference values is defined as the average daily nutrient intake level
estimated to meet the requirement of half of the healthy individuals in a particular life stage and sex group?
A. Tolerable Upper Intake Level (UL)
B. Adequate Intake (AI)
C. Estimated Average Requirement (EAR)
D. Recommended Dietary Allowance (RDA)
Answer: C
Rationale:
The Estimated Average Requirement (EAR) represents the median daily intake value that meets the physiological
requirements of 50% of healthy individuals in a defined life-stage and sex group, serving as the statistical foundation
from which the Recommended Dietary Allowance (RDA) is derived.
Keywords: Estimated Average Requirement; EAR; Dietary Reference Intakes; nutrient standards
2. How is the Recommended Dietary Allowance (RDA) statistically established when the nutrient requirement
distribution is normally distributed?
A. EAR minus 1 standard deviation
B. EAR plus 1 standard deviation
C. EAR plus 2 standard deviations
D. EAR multiplied by a safety factor of 1.5
Answer: C
Rationale:
The RDA is set at 2 standard deviations (SD) above the EAR (RDA = EAR + 2 SD), which statistically ensures that the
recommended intake meets or exceeds the physiological nutrient requirements of 97.5% of all healthy individuals within
a specific population group.
Keywords: Recommended Dietary Allowance; RDA; statistical derivation; population requirements
3. What is the primary physiological justification for establishing sport nutrition as a distinct scientific
discipline separate from general population nutrition?
A. Athletes possess distinct digestive enzymes not found in sedentary individuals
B. Athletes cannot synthesize non-essential amino acids during high-intensity training
C. Athletes require synthetic dietary supplements to prevent chronic nutrient deficiencies
D. Athletes exhibit unique metabolic, energetic, and recovery demands driven by physical training
Answer: D
Rationale:
Sport nutrition exists as an independent discipline because athletic training imposes extreme metabolic turnover,
substantially elevated energetic demands, accelerated substrate depletion, altered fluid-electrolyte fluxes, and
heightened tissue remodeling requirements that require specialized nutrient timing, composition, and periodization.
Keywords: sport nutrition discipline; athletic metabolic demands; substrate turnover; training adaptation
,4. Which nutrient class provides the primary oxidative fuel substrate during moderate-to-high intensity
exercise above 70% of maximal oxygen uptake (VO2max)?
A. Lipids
B. Minerals
C. Carbohydrates
D. Proteins
Answer: C
Rationale:
Carbohydrates, stored as muscle and liver glycogen and circulating blood glucose, yield more ATP per mole of oxygen
consumed compared to fatty acids and can be metabolized via both non-oxidative glycolysis and oxidative
phosphorylation, making them the obligatory dominant fuel at exercise intensities exceeding 70% VO2max.
Keywords: carbohydrate oxidation; substrate utilization; high-intensity exercise; energetic efficiency
5. What is a major methodological limitation inherent to the 24-hour dietary recall method when assessing
nutritional intake in athletic populations?
A. Inability to be administered across large epidemiological study cohorts
B. Requirement for continuous real-time photographic logging of all ingested items
C. Reliance on short-term memory and frequent underreporting of portion sizes
D. High respondent burden causing immediate alteration of current eating habits
Answer: C
Rationale:
The 24-hour dietary recall is subject to recall bias, inaccurate estimation of portion sizes, and intentional or
unintentional underreporting of energy-dense foods, while also failing to capture day-to-day variations in an athlete's
periodized dietary intake.
Keywords: 24-hour dietary recall; dietary assessment; recall bias; underreporting
6. Which dietary assessment tool is considered the clinical standard for capturing habitual intake but imposes
the highest subject burden and risk of reactivity bias?
A. Estimated food record using household measures
B. Multiple-pass 24-hour recall with photographic verification
C. Single 24-hour recall administered twice
D. Weighed food record (3- to 7-day)
Answer: D
Rationale:
Weighed food records recorded over 3 to 7 consecutive days provide highly detailed quantitative intake data at the time
of consumption, but the intensive measurement burden frequently causes participants to alter their habitual food
choices to simplify recording (reactivity bias).
Keywords: weighed food record; dietary assessment; reactivity bias; measurement validity
7. Why are Food Frequency Questionnaires (FFQs) generally poorly suited for evaluating acute nutrient timing
in elite athletes?
A. They rely on a fixed list of foods that omits many pre-workout products
B. They require a trained dietitian present at every single meal
C. They average intake into weekly totals that mask day-to-day macronutrient swings
D. They measure long-term qualitative intake patterns rather than precise meal timing and daily variations
Answer: D
Rationale:
,FFQs are designed to capture broad, retrospective food consumption patterns over extended durations (e.g., months or
years) and lack the granular temporal resolution required to assess pre-, during-, and post-exercise nutrient
periodization.
Keywords: Food Frequency Questionnaire; FFQ; nutrient timing; dietary assessment limitations
8. Which of the following describes the physiological role of phytonutrients in the human body?
A. Nitrogen-containing precursors used in de novo purine synthesis
B. Bioactive plant compounds that modulate cellular antioxidant defense and inflammatory pathways
C. Osmotically active solutes that regulate intracellular fluid distribution
D. Structural glycoproteins that anchor the sarcolemma during eccentric loading
Answer: B
Rationale:
Phytonutrients (such as polyphenols, flavonoids, and carotenoids) are non-nutritive plant bioactives that exert biological
effects by upregulating endogenous antioxidant enzymes (via Nrf2 signaling), modulating inflammatory signaling
cascades, and promoting vascular endothelial function.
Keywords: phytonutrients; polyphenols; antioxidant signaling; cellular protection
9. How does chronic alcohol consumption directly impair athletic recovery following strenuous exercise?
A. By accelerating gastric emptying and increasing carbohydrate absorption rate
B. By enhancing renal sodium retention and expanding plasma volume
C. By suppressing myofibrillar protein synthesis, compromising rehydration, and impairing sleep architecture
D. By upregulating insulin sensitivity and glycogen synthase activity
Answer: C
Rationale:
Ethanol ingestion post-exercise suppresses mTORC1-mediated myofibrillar protein synthesis, induces peripheral
vasodilation and mild diuresis that hinders fluid retention, and disrupts slow-wave sleep architecture crucial for
hormonal recovery.
Keywords: alcohol metabolism; muscle protein synthesis; recovery impairment; rehydration
10. Which trace element functions as an essential structural component of selenoproteins, including
glutathione peroxidase, involved in cellular antioxidant protection?
A. Selenium
B. Zinc
C. Copper
D. Manganese
Answer: A
Rationale:
Selenium is incorporated as selenocysteine into the catalytic sites of antioxidant enzymes such as glutathione peroxidase
and thioredoxin reductase, which reduce reactive oxygen species (ROS) produced during high-volume oxidative
metabolism.
Keywords: selenium; selenoproteins; glutathione peroxidase; antioxidant defense
11. Under what circumstance is an Adequate Intake (AI) established instead of a Recommended Dietary
Allowance (RDA)?
A. When insufficient scientific evidence exists to calculate an Estimated Average Requirement (EAR)
B. When toxicity data are more complete than requirement data
C. When a nutrient is only required during pregnancy or lactation
, D. When the nutrient's requirement varies too widely to average across a population
Answer: A
Rationale:
An Adequate Intake (AI) is established when available scientific data are insufficient to accurately determine an EAR and
subsequent RDA; it is based on experimentally observed or epidemiologically estimated mean nutrient intakes of
healthy population groups.
Keywords: Adequate Intake; AI; Dietary Reference Intakes; EAR determination
12. Which lipid class serves as the primary storage form of energy in human adipose tissue and skeletal muscle
fibers?
A. Sterols
B. Sphingolipids
C. Triacylglycerols
D. Phospholipids
Answer: C
Rationale:
Triacylglycerols (triglycerides) consist of a glycerol backbone esterified to three fatty acids and constitute over 90% of
stored dietary and body fat, serving as the dense, anhydrous energetic reservoir in both subcutaneous adipose tissue
and intramuscular lipid droplets.
Keywords: triacylglycerols; intramuscular triglycerides; lipid storage; energy substrate
13. What is the primary physiological function of macrominerals such as calcium, magnesium, potassium, and
sodium during exercise?
A. Serving as direct electron donors in the electron transport chain
B. Binding oxygen directly within arterial blood circulation
C. Maintaining transmembrane electrical potentials, neuromuscular excitability, and fluid balance
D. Acting as primary substrates for mitochondrial beta-oxidation
Answer: C
Rationale:
Macrominerals act as critical electrolytes that maintain resting membrane potentials, propagate action potentials along
sarcolemma membranes, trigger excitation-contraction coupling (e.g., Ca2+ release), and regulate osmotic pressure
across fluid compartments.
Keywords: macrominerals; electrolytes; action potential; neuromuscular function
14. Which water-soluble vitamin acts as the central precursor for the coenzymes FMN and FAD involved in
mitochondrial oxidative phosphorylation?
A. Thiamin (Vitamin B1)
B. Pyridoxine (Vitamin B6)
C. Riboflavin (Vitamin B2)
D. Niacin (Vitamin B3)
Answer: C
Rationale:
Riboflavin (vitamin B2) is the biochemical precursor for flavin mononucleotide (FMN) and flavin adenine dinucleotide
(FAD), which serve as essential prosthetic electron acceptors in the Krebs cycle (succinate dehydrogenase) and
mitochondrial electron transport chain Complex I and II.
Keywords: riboflavin; FAD; electron transport chain; energy metabolism
,15. Why do endurance athletes participating in heavy training blocks often require higher daily protein intakes
than the standard sedentary RDA of 0.8 g/kg/day?
A. To compensate for exercise-induced amino acid oxidation and support mitochondrial protein remodeling
B. Because endurance athletes cannot digest dietary plant proteins efficiently
C. To replace direct protein losses excreted in sweat and respiratory moisture
D. Because endurance exercise downregulates all endogenous proteolytic pathways
Answer: A
Rationale:
Endurance athletes experience elevated leucine and branched-chain amino acid oxidation during prolonged exercise
(contributing 2–8% of total energy) and require additional amino acids post-exercise to repair exercise-induced
microtrauma and synthesize new mitochondrial enzymes and structural proteins.
Keywords: protein requirements; endurance athletes; amino acid oxidation; mitochondrial biogenesis
16. What distinguishes trace elements (microminerals) from macrominerals in human nutritional
classification?
A. Trace elements are only required in quantities less than 100 mg/day
B. Trace elements are stored indefinitely in bone trabeculae
C. Trace elements are organic compounds synthesized by human tissue
D. Trace elements do not contain metallic ions
Answer: A
Rationale:
Macrominerals (e.g., calcium, sodium, phosphorus) are required in amounts exceeding 100 mg/day, whereas
microminerals or trace elements (e.g., iron, zinc, selenium, copper) are required in quantities less than 100 mg/day,
typically in microgram or low milligram amounts.
Keywords: trace elements; microminerals; dietary classification; mineral requirements
17. What is the primary role of water as an essential nutrient during physical exertion in hot environments?
A. Directly fueling muscular cross-bridge cycling
B. Increasing peripheral vascular resistance to elevate central venous pressure
C. Facilitating evaporative heat dissipation via sweat production to prevent hyperthermia
D. Buffering intramuscular lactic acid accumulation via bicarbonate synthesis
Answer: C
Rationale:
Water provides the aqueous solvent for thermoregulatory sweat secretion; evaporation of sweat from the skin surface is
the primary physiological mechanism for dissipating metabolic heat during exercise in warm environments.
Keywords: thermoregulation; water balance; evaporative cooling; exercise in heat
18. Which of the following is an example of an essential (indispensable) amino acid that must be supplied by
the diet?
A. Alanine
B. Glutamine
C. Glycine
D. Leucine
Answer: D
Rationale:
Leucine is an essential (indispensable) branched-chain amino acid that cannot be synthesized de novo by humans and
must be ingested through food to stimulate the mTORC1 signaling pathway and initiate muscle protein synthesis.
, Keywords: essential amino acids; leucine; indispensability; protein synthesis
19. How is the Tolerable Upper Intake Level (UL) defined within the Dietary Reference Intake (DRI)
framework?
A. The highest average daily nutrient intake level likely to pose no risk of adverse health effects
B. The threshold above which a nutrient must be reported on food labels
C. The average daily intake associated with peak competitive performance
D. The intake level set specifically for pregnant and lactating athletes
Answer: A
Rationale:
The Tolerable Upper Intake Level (UL) is the highest average daily nutrient intake level that is likely to pose no risk of
adverse health effects to almost all individuals in the general population; intakes above the UL increase the potential risk
of toxic adverse effects.
Keywords: Tolerable Upper Intake Level; UL; nutrient toxicity; safety margin
20. Why is nutrient density an especially important concept when planning dietary strategies for weight-class
athletes restricting energy intake?
A. It increases reliance on single-nutrient supplements over whole foods
B. It shifts the primary fuel source from carbohydrate to protein
C. It allows total energy intake to be reduced without any dietary planning
D. It ensures that micronutrient requirements are fulfilled despite a reduced total energy intake
Answer: D
Rationale:
Nutrient-dense foods provide high amounts of essential vitamins, minerals, and high-quality protein relative to their
total caloric content, ensuring that athletes who operate in caloric deficits do not develop micro- or macronutrient
insufficiencies.
Keywords: nutrient density; energy restriction; weight-class athletes; micronutrient adequacy
21. Which physiological process explains why carbohydrates yield more energy per liter of oxygen consumed
than fats (approx. 5.05 kcal/L O2 vs. 4.69 kcal/L O2)?
A. Fatty acid chains are longer and yield more ATP per gram consumed
B. Fat oxidation generates additional heat that carbohydrate oxidation does not
C. Carbohydrates are already more highly oxygenated than fatty acids at the molecular level
D. Carbohydrate metabolism recycles NADH more efficiently than fat metabolism
Answer: C
Rationale:
Carbohydrates have a chemical formula of approximately (CH2O)n and possess a higher oxygen-to-carbon ratio than
lipids, requiring less external oxygen to completely oxidize each carbon atom to CO2 and H2O, yielding higher energetic
efficiency per unit of O2 consumed.
Keywords: caloric equivalent of oxygen; carbohydrate efficiency; substrate oxidation; energetic yield
22. What is the main function of dietary insoluble fiber in gastrointestinal health?
A. Serving as a fermentable substrate for colonic short-chain fatty acid production
B. Increasing fecal bulk and promoting regular intestinal transit through mechanical stimulation
C. Slowing gastric emptying to blunt the postprandial glucose response
D. Binding bile acids to lower circulating LDL cholesterol concentrations
Answer: B
Chapter: 1. Nutrients and Recommended Intakes
Chapter: 2. Healthy Eating
Chapter: 3. Fuel Sources for Muscle and Exercise Metabolism
Chapter: 4. Energy
Chapter: 5. Gastric Emptying, Digestion, and Absorption
Chapter: 6. Carbohydrate
Chapter: 7. Fat
Chapter: 8. Protein and Amino Acids
Chapter: 9. Fluid and Electrolytes
Chapter: 10. Vitamins and Minerals
Chapter: 11. Nutrition Supplements
Chapter: 12. Nutrition and Training Adaptations
Chapter: 13. Nutrition and Immune Function in Athletes
Chapter: 14. Body Composition
Chapter: 15. Weight Management
Chapter: 16. Eating Disorders and Low Energy Availability in Athletes
Chapter: 17. Personalized Nutrition
,Chapter 1: Nutrients and Recommended Intakes
25 Multiple-Choice Questions | Physiological Foundations & Applied Athletic Practice
1. Which of the following dietary reference values is defined as the average daily nutrient intake level
estimated to meet the requirement of half of the healthy individuals in a particular life stage and sex group?
A. Tolerable Upper Intake Level (UL)
B. Adequate Intake (AI)
C. Estimated Average Requirement (EAR)
D. Recommended Dietary Allowance (RDA)
Answer: C
Rationale:
The Estimated Average Requirement (EAR) represents the median daily intake value that meets the physiological
requirements of 50% of healthy individuals in a defined life-stage and sex group, serving as the statistical foundation
from which the Recommended Dietary Allowance (RDA) is derived.
Keywords: Estimated Average Requirement; EAR; Dietary Reference Intakes; nutrient standards
2. How is the Recommended Dietary Allowance (RDA) statistically established when the nutrient requirement
distribution is normally distributed?
A. EAR minus 1 standard deviation
B. EAR plus 1 standard deviation
C. EAR plus 2 standard deviations
D. EAR multiplied by a safety factor of 1.5
Answer: C
Rationale:
The RDA is set at 2 standard deviations (SD) above the EAR (RDA = EAR + 2 SD), which statistically ensures that the
recommended intake meets or exceeds the physiological nutrient requirements of 97.5% of all healthy individuals within
a specific population group.
Keywords: Recommended Dietary Allowance; RDA; statistical derivation; population requirements
3. What is the primary physiological justification for establishing sport nutrition as a distinct scientific
discipline separate from general population nutrition?
A. Athletes possess distinct digestive enzymes not found in sedentary individuals
B. Athletes cannot synthesize non-essential amino acids during high-intensity training
C. Athletes require synthetic dietary supplements to prevent chronic nutrient deficiencies
D. Athletes exhibit unique metabolic, energetic, and recovery demands driven by physical training
Answer: D
Rationale:
Sport nutrition exists as an independent discipline because athletic training imposes extreme metabolic turnover,
substantially elevated energetic demands, accelerated substrate depletion, altered fluid-electrolyte fluxes, and
heightened tissue remodeling requirements that require specialized nutrient timing, composition, and periodization.
Keywords: sport nutrition discipline; athletic metabolic demands; substrate turnover; training adaptation
,4. Which nutrient class provides the primary oxidative fuel substrate during moderate-to-high intensity
exercise above 70% of maximal oxygen uptake (VO2max)?
A. Lipids
B. Minerals
C. Carbohydrates
D. Proteins
Answer: C
Rationale:
Carbohydrates, stored as muscle and liver glycogen and circulating blood glucose, yield more ATP per mole of oxygen
consumed compared to fatty acids and can be metabolized via both non-oxidative glycolysis and oxidative
phosphorylation, making them the obligatory dominant fuel at exercise intensities exceeding 70% VO2max.
Keywords: carbohydrate oxidation; substrate utilization; high-intensity exercise; energetic efficiency
5. What is a major methodological limitation inherent to the 24-hour dietary recall method when assessing
nutritional intake in athletic populations?
A. Inability to be administered across large epidemiological study cohorts
B. Requirement for continuous real-time photographic logging of all ingested items
C. Reliance on short-term memory and frequent underreporting of portion sizes
D. High respondent burden causing immediate alteration of current eating habits
Answer: C
Rationale:
The 24-hour dietary recall is subject to recall bias, inaccurate estimation of portion sizes, and intentional or
unintentional underreporting of energy-dense foods, while also failing to capture day-to-day variations in an athlete's
periodized dietary intake.
Keywords: 24-hour dietary recall; dietary assessment; recall bias; underreporting
6. Which dietary assessment tool is considered the clinical standard for capturing habitual intake but imposes
the highest subject burden and risk of reactivity bias?
A. Estimated food record using household measures
B. Multiple-pass 24-hour recall with photographic verification
C. Single 24-hour recall administered twice
D. Weighed food record (3- to 7-day)
Answer: D
Rationale:
Weighed food records recorded over 3 to 7 consecutive days provide highly detailed quantitative intake data at the time
of consumption, but the intensive measurement burden frequently causes participants to alter their habitual food
choices to simplify recording (reactivity bias).
Keywords: weighed food record; dietary assessment; reactivity bias; measurement validity
7. Why are Food Frequency Questionnaires (FFQs) generally poorly suited for evaluating acute nutrient timing
in elite athletes?
A. They rely on a fixed list of foods that omits many pre-workout products
B. They require a trained dietitian present at every single meal
C. They average intake into weekly totals that mask day-to-day macronutrient swings
D. They measure long-term qualitative intake patterns rather than precise meal timing and daily variations
Answer: D
Rationale:
,FFQs are designed to capture broad, retrospective food consumption patterns over extended durations (e.g., months or
years) and lack the granular temporal resolution required to assess pre-, during-, and post-exercise nutrient
periodization.
Keywords: Food Frequency Questionnaire; FFQ; nutrient timing; dietary assessment limitations
8. Which of the following describes the physiological role of phytonutrients in the human body?
A. Nitrogen-containing precursors used in de novo purine synthesis
B. Bioactive plant compounds that modulate cellular antioxidant defense and inflammatory pathways
C. Osmotically active solutes that regulate intracellular fluid distribution
D. Structural glycoproteins that anchor the sarcolemma during eccentric loading
Answer: B
Rationale:
Phytonutrients (such as polyphenols, flavonoids, and carotenoids) are non-nutritive plant bioactives that exert biological
effects by upregulating endogenous antioxidant enzymes (via Nrf2 signaling), modulating inflammatory signaling
cascades, and promoting vascular endothelial function.
Keywords: phytonutrients; polyphenols; antioxidant signaling; cellular protection
9. How does chronic alcohol consumption directly impair athletic recovery following strenuous exercise?
A. By accelerating gastric emptying and increasing carbohydrate absorption rate
B. By enhancing renal sodium retention and expanding plasma volume
C. By suppressing myofibrillar protein synthesis, compromising rehydration, and impairing sleep architecture
D. By upregulating insulin sensitivity and glycogen synthase activity
Answer: C
Rationale:
Ethanol ingestion post-exercise suppresses mTORC1-mediated myofibrillar protein synthesis, induces peripheral
vasodilation and mild diuresis that hinders fluid retention, and disrupts slow-wave sleep architecture crucial for
hormonal recovery.
Keywords: alcohol metabolism; muscle protein synthesis; recovery impairment; rehydration
10. Which trace element functions as an essential structural component of selenoproteins, including
glutathione peroxidase, involved in cellular antioxidant protection?
A. Selenium
B. Zinc
C. Copper
D. Manganese
Answer: A
Rationale:
Selenium is incorporated as selenocysteine into the catalytic sites of antioxidant enzymes such as glutathione peroxidase
and thioredoxin reductase, which reduce reactive oxygen species (ROS) produced during high-volume oxidative
metabolism.
Keywords: selenium; selenoproteins; glutathione peroxidase; antioxidant defense
11. Under what circumstance is an Adequate Intake (AI) established instead of a Recommended Dietary
Allowance (RDA)?
A. When insufficient scientific evidence exists to calculate an Estimated Average Requirement (EAR)
B. When toxicity data are more complete than requirement data
C. When a nutrient is only required during pregnancy or lactation
, D. When the nutrient's requirement varies too widely to average across a population
Answer: A
Rationale:
An Adequate Intake (AI) is established when available scientific data are insufficient to accurately determine an EAR and
subsequent RDA; it is based on experimentally observed or epidemiologically estimated mean nutrient intakes of
healthy population groups.
Keywords: Adequate Intake; AI; Dietary Reference Intakes; EAR determination
12. Which lipid class serves as the primary storage form of energy in human adipose tissue and skeletal muscle
fibers?
A. Sterols
B. Sphingolipids
C. Triacylglycerols
D. Phospholipids
Answer: C
Rationale:
Triacylglycerols (triglycerides) consist of a glycerol backbone esterified to three fatty acids and constitute over 90% of
stored dietary and body fat, serving as the dense, anhydrous energetic reservoir in both subcutaneous adipose tissue
and intramuscular lipid droplets.
Keywords: triacylglycerols; intramuscular triglycerides; lipid storage; energy substrate
13. What is the primary physiological function of macrominerals such as calcium, magnesium, potassium, and
sodium during exercise?
A. Serving as direct electron donors in the electron transport chain
B. Binding oxygen directly within arterial blood circulation
C. Maintaining transmembrane electrical potentials, neuromuscular excitability, and fluid balance
D. Acting as primary substrates for mitochondrial beta-oxidation
Answer: C
Rationale:
Macrominerals act as critical electrolytes that maintain resting membrane potentials, propagate action potentials along
sarcolemma membranes, trigger excitation-contraction coupling (e.g., Ca2+ release), and regulate osmotic pressure
across fluid compartments.
Keywords: macrominerals; electrolytes; action potential; neuromuscular function
14. Which water-soluble vitamin acts as the central precursor for the coenzymes FMN and FAD involved in
mitochondrial oxidative phosphorylation?
A. Thiamin (Vitamin B1)
B. Pyridoxine (Vitamin B6)
C. Riboflavin (Vitamin B2)
D. Niacin (Vitamin B3)
Answer: C
Rationale:
Riboflavin (vitamin B2) is the biochemical precursor for flavin mononucleotide (FMN) and flavin adenine dinucleotide
(FAD), which serve as essential prosthetic electron acceptors in the Krebs cycle (succinate dehydrogenase) and
mitochondrial electron transport chain Complex I and II.
Keywords: riboflavin; FAD; electron transport chain; energy metabolism
,15. Why do endurance athletes participating in heavy training blocks often require higher daily protein intakes
than the standard sedentary RDA of 0.8 g/kg/day?
A. To compensate for exercise-induced amino acid oxidation and support mitochondrial protein remodeling
B. Because endurance athletes cannot digest dietary plant proteins efficiently
C. To replace direct protein losses excreted in sweat and respiratory moisture
D. Because endurance exercise downregulates all endogenous proteolytic pathways
Answer: A
Rationale:
Endurance athletes experience elevated leucine and branched-chain amino acid oxidation during prolonged exercise
(contributing 2–8% of total energy) and require additional amino acids post-exercise to repair exercise-induced
microtrauma and synthesize new mitochondrial enzymes and structural proteins.
Keywords: protein requirements; endurance athletes; amino acid oxidation; mitochondrial biogenesis
16. What distinguishes trace elements (microminerals) from macrominerals in human nutritional
classification?
A. Trace elements are only required in quantities less than 100 mg/day
B. Trace elements are stored indefinitely in bone trabeculae
C. Trace elements are organic compounds synthesized by human tissue
D. Trace elements do not contain metallic ions
Answer: A
Rationale:
Macrominerals (e.g., calcium, sodium, phosphorus) are required in amounts exceeding 100 mg/day, whereas
microminerals or trace elements (e.g., iron, zinc, selenium, copper) are required in quantities less than 100 mg/day,
typically in microgram or low milligram amounts.
Keywords: trace elements; microminerals; dietary classification; mineral requirements
17. What is the primary role of water as an essential nutrient during physical exertion in hot environments?
A. Directly fueling muscular cross-bridge cycling
B. Increasing peripheral vascular resistance to elevate central venous pressure
C. Facilitating evaporative heat dissipation via sweat production to prevent hyperthermia
D. Buffering intramuscular lactic acid accumulation via bicarbonate synthesis
Answer: C
Rationale:
Water provides the aqueous solvent for thermoregulatory sweat secretion; evaporation of sweat from the skin surface is
the primary physiological mechanism for dissipating metabolic heat during exercise in warm environments.
Keywords: thermoregulation; water balance; evaporative cooling; exercise in heat
18. Which of the following is an example of an essential (indispensable) amino acid that must be supplied by
the diet?
A. Alanine
B. Glutamine
C. Glycine
D. Leucine
Answer: D
Rationale:
Leucine is an essential (indispensable) branched-chain amino acid that cannot be synthesized de novo by humans and
must be ingested through food to stimulate the mTORC1 signaling pathway and initiate muscle protein synthesis.
, Keywords: essential amino acids; leucine; indispensability; protein synthesis
19. How is the Tolerable Upper Intake Level (UL) defined within the Dietary Reference Intake (DRI)
framework?
A. The highest average daily nutrient intake level likely to pose no risk of adverse health effects
B. The threshold above which a nutrient must be reported on food labels
C. The average daily intake associated with peak competitive performance
D. The intake level set specifically for pregnant and lactating athletes
Answer: A
Rationale:
The Tolerable Upper Intake Level (UL) is the highest average daily nutrient intake level that is likely to pose no risk of
adverse health effects to almost all individuals in the general population; intakes above the UL increase the potential risk
of toxic adverse effects.
Keywords: Tolerable Upper Intake Level; UL; nutrient toxicity; safety margin
20. Why is nutrient density an especially important concept when planning dietary strategies for weight-class
athletes restricting energy intake?
A. It increases reliance on single-nutrient supplements over whole foods
B. It shifts the primary fuel source from carbohydrate to protein
C. It allows total energy intake to be reduced without any dietary planning
D. It ensures that micronutrient requirements are fulfilled despite a reduced total energy intake
Answer: D
Rationale:
Nutrient-dense foods provide high amounts of essential vitamins, minerals, and high-quality protein relative to their
total caloric content, ensuring that athletes who operate in caloric deficits do not develop micro- or macronutrient
insufficiencies.
Keywords: nutrient density; energy restriction; weight-class athletes; micronutrient adequacy
21. Which physiological process explains why carbohydrates yield more energy per liter of oxygen consumed
than fats (approx. 5.05 kcal/L O2 vs. 4.69 kcal/L O2)?
A. Fatty acid chains are longer and yield more ATP per gram consumed
B. Fat oxidation generates additional heat that carbohydrate oxidation does not
C. Carbohydrates are already more highly oxygenated than fatty acids at the molecular level
D. Carbohydrate metabolism recycles NADH more efficiently than fat metabolism
Answer: C
Rationale:
Carbohydrates have a chemical formula of approximately (CH2O)n and possess a higher oxygen-to-carbon ratio than
lipids, requiring less external oxygen to completely oxidize each carbon atom to CO2 and H2O, yielding higher energetic
efficiency per unit of O2 consumed.
Keywords: caloric equivalent of oxygen; carbohydrate efficiency; substrate oxidation; energetic yield
22. What is the main function of dietary insoluble fiber in gastrointestinal health?
A. Serving as a fermentable substrate for colonic short-chain fatty acid production
B. Increasing fecal bulk and promoting regular intestinal transit through mechanical stimulation
C. Slowing gastric emptying to blunt the postprandial glucose response
D. Binding bile acids to lower circulating LDL cholesterol concentrations
Answer: B
