Biochemistry for Exercise

Question 1

Which energy system provides the fastest source of ATP but lasts for only a few seconds?
a) ATP-PCr system
b) Anaerobic glycolysis
c) Aerobic metabolism
d) Beta-oxidation

Answer 1

Answer: a) ATP-PCr system

✅ Correct: The ATP-PCr (phosphagen) system provides immediate ATP for high-intensity, short-duration activities (e.g., sprinting, weightlifting). It uses phosphocreatine to regenerate ATP rapidly but depletes within 10–15 seconds.

❌ b) Anaerobic glycolysis – Produces ATP quickly but not as fast as the ATP-PCr system. It lasts longer (~30 sec to 2 min) and results in lactic acid accumulation.
❌ c) Aerobic metabolism – Provides long-term energy but is much slower due to oxygen dependence.
❌ d) Beta-oxidation – A slow process used for fat metabolism, requiring oxygen and primarily active in low-intensity, long-duration exercise.

Question 2

What is the primary purpose of the Cori cycle?
a) Convert lactic acid into pyruvate for aerobic metabolism
b) Store excess glucose as glycogen in muscles
c) Transport free fatty acids for beta-oxidation
d) Generate ATP directly in anaerobic conditions

Answer 2

Answer: a) Convert lactic acid into pyruvate for aerobic metabolism

✅ Correct: The Cori cycle shuttles lactic acid from muscles to the liver, where it is converted into glucose through gluconeogenesis. This glucose can then be used by muscles for ATP production.

❌ b) Store excess glucose as glycogen – Glycogen storage occurs within muscles and liver, but this is not the function of the Cori cycle.
❌ c) Transport free fatty acids – This is related to beta-oxidation, not the Cori cycle.
❌ d) Generate ATP directly – The Cori cycle itself does not generate ATP; it recycles lactate to maintain energy supply.

Question 3

Which metabolic pathway is the primary source of ATP during prolonged, moderate-intensity exercise?
a) ATP-PCr system
b) Anaerobic glycolysis
c) Aerobic metabolism
d) Protein catabolism

Answer 3

Answer: c) Aerobic metabolism

✅ Correct: Aerobic metabolism is the dominant system during prolonged exercise because it efficiently produces large amounts of ATP from carbohydrates and fats.

❌ a) ATP-PCr system – Used for short bursts of energy (~10 seconds).
❌ b) Anaerobic glycolysis – Dominates during short, intense efforts (30 sec to 2 min), but fatigue from lactic acid buildup limits its duration.
❌ d) Protein catabolism – Not a primary energy source unless in extreme conditions like starvation or prolonged fasting.

Question 4

Which vitamin is crucial for energy metabolism and acts as a coenzyme in ATP production?
a) Vitamin A
b) Vitamin C
c) Vitamin B1 (Thiamine)
d) Vitamin K

Answer 4

Answer: c) Vitamin B1 (Thiamine)
✅ Correct: Thiamine (Vitamin B1) is a coenzyme in carbohydrate metabolism, particularly in the Krebs cycle and pyruvate dehydrogenase complex, helping convert nutrients into ATP.

❌ a) Vitamin A – Important for vision and cell differentiation but not directly involved in energy metabolism.
❌ b) Vitamin C – Acts as an antioxidant and supports immune function, but does not play a major role in ATP production.
❌ d) Vitamin K – Essential for blood clotting, not metabolism.

Question 5

Which metabolic pathway breaks down fatty acids to generate ATP?
a) Glycolysis
b) Beta-oxidation
c) Protein catabolism
d) Cori cycle

Answer 5

Answer: b) Beta-oxidation
✅ Correct: Beta-oxidation occurs in the mitochondria, breaking down fatty acids into acetyl-CoA, which enters the Krebs cycle to generate ATP.

❌ a) Glycolysis – Breaks down glucose into pyruvate, not fats.
❌ c) Protein catabolism – Involves amino acid breakdown, but proteins are not a preferred energy source.
❌ d) Cori cycle – Involves lactate recycling, not fat metabolism.

Question 6

Basic Biochemistry

Which of the following macromolecules is the primary source of quick energy in the body?

a) Proteins
b) Lipids
c) Carbohydrates
d) Nucleic acids

Question 7

Cellular Physiology

Which organelle is responsible for most of the ATP production in aerobic metabolism?

a) Ribosome
b) Mitochondrion
c) Endoplasmic reticulum
d) Nucleus

Question 8

Which fat-soluble vitamin is important for calcium absorption and bone health?

a) Vitamin A
b) Vitamin D
c) Vitamin E
d) Vitamin K

Answer 8

✅ Correct Answer: (b) Vitamin D

Why? Vitamin D helps the body absorb calcium, which is essential for strong bones.
❌ (a) Vitamin A – Important for vision and immune function but not calcium absorption.
❌ (c) Vitamin E – Acts as an antioxidant, does not regulate calcium.
❌ (d) Vitamin K – Helps with blood clotting but does not directly impact calcium absorption.

Question 9

Which mineral is essential for ATP production because it stabilizes ATP molecules?

a) Sodium
b) Magnesium
c) Iron
d) Iodine

Answer 9

✅ Correct Answer: (b) Magnesium

Why? Magnesium binds to ATP and helps activate enzymes involved in energy production.
❌ (a) Sodium – Important for nerve function but not ATP stabilization.
❌ (c) Iron – Helps carry oxygen in the blood but does not stabilize ATP.
❌ (d) Iodine – Needed for thyroid hormone production, not ATP.

Question 10

Protein Catabolism

When the body breaks down protein for energy, what toxic byproduct is produced?

a) Lactic acid
b) Ammonia
c) Carbon dioxide
d) Glucose

Answer 10

**✅ Correct Answer: (b) Ammonia

Why? Breaking down amino acids produces ammonia, which is later converted to urea in the liver.**

❌ (a) Lactic acid – Produced during anaerobic metabolism, not protein breakdown.
❌ (c) Carbon dioxide – A byproduct of aerobic metabolism, not protein catabolism.
❌ (d) Glucose – Comes from carbohydrate metabolism, not protein breakdown.

Question 11

Which energy source is primarily used during long-duration, low-intensity exercise?

a) Carbohydrates
b) Proteins
c) Fats
d) ATP-PCr system

Answer 11

✅ Correct Answer: (c) Fats

Why? During prolonged, low-intensity exercise (like walking), the body prefers to burn fats for energy.
❌ (a) Carbohydrates – Used more during moderate-to-high-intensity exercise.
❌ (b) Proteins – Only used when energy sources are depleted.
❌ (d) ATP-PCr system – Provides quick bursts of energy but lasts only a few seconds.

Question 12

What is the primary focus of an athlete’s nutrition plan?
(a) Only improving performance.
(b) Only maintaining health.
(c) Optimizing both health and performance
(d) Reducing calorie intake

Answer 12

What is the primary focus of an athlete’s nutrition plan?
✅ Correct Answer: (c) Optimizing both health and performance

(c) Optimizing both health and performance → The goal is to ensure athletes stay healthy while maximizing their training and recovery.
❌ (a) Only improving performance → Performance matters, but neglecting health can lead to injury, burnout, or illness.
❌ (b) Only maintaining health → While health is crucial, athletes also need strategies to enhance endurance, strength, and recovery.
❌ (d) Reducing calorie intake → Athletes often need higher caloric intake to match their energy expenditure.

Question 13

Which of the following is the most accurate way to measure energy expenditure?

(a) Calorimetry → This is the gold standard because it directly measures oxygen consumption and energy output.
(b) Equations.
(c) Activity trackers.
(d) Self-reported food intake.

Answer 13

✅ Correct Answer: (a) Calorimetry→ This is the gold standard because it directly measures oxygen consumption and energy output.
❌ (b) Equations → These provide an estimate but are not 100% accurate.
❌ (c) Activity trackers → Trackers can underestimate or overestimate caloric burn, as they rely on general algorithms.
❌ (d) Self-reported food intake → People tend to underreport or overreport food consumption, making this less reliable.

Question 14

What is the primary function of carbohydrates in an athlete’s diet?

(a) Building muscle tissue.
(b) Providing immediate energy.
(c) Carrying fat-soluble vitamins.
(d) Regulating electrolyte balance.

Answer 14

✅ Correct Answer: (b) Providing immediate energy→ Carbs are the body’s quickest and preferred energy source.
❌ (a) Building muscle tissue → Protein, not carbohydrates, is responsible for muscle growth.
❌ (c) Carrying fat-soluble vitamins → Fats, not carbohydrates, transport vitamins A, D, E, and K.
❌ (d) Regulating electrolyte balance → Sodium, potassium, and other minerals regulate electrolytes, not carbs.

Question 15

Which type of carbohydrate is best for sustained energy release?
✅ Correct Answer: (c) Complex carbohydrates

(a) Simple sugars
(b) Fiber
(c) Complex carbohydrates
(d) Artificial sweeteners

Answer 15

Which type of carbohydrate is best for sustained energy release?
✅ Correct Answer: (c) Complex carbohydrates

(c) Complex carbohydrates → These take longer to digest, providing steady energy over time (e.g., whole grains, legumes).
❌ (a) Simple sugars → These provide a quick energy spike but cause blood sugar crashes.✅ Main Types of Simple Sugars:
1️⃣ Monosaccharides (Single Sugar Molecules)
Glucose → Primary energy source for cells, found in honey, fruits, and bloodstream.
Fructose → Found in fruit, honey, and high-fructose corn syrup.
Galactose → Found in dairy products.

2️⃣ Disaccharides (Two Monosaccharides Linked Together)
Sucrose (Glucose + Fructose) → Table sugar, found in sugarcane and beets.
Lactose (Glucose + Galactose) → Found in milk and dairy.
Maltose (Glucose + Glucose) → Found in malted grains and beer.
❌ (b) Fiber → Fiber is important for digestion but does not provide direct energy.
❌ (d) Artificial sweeteners → These do not provide usable energy for the body.

Question 16

Why is protein essential for athletes?
✅ Correct Answer: (b) Muscle repair and enzyme production

(a) Primary energy source.
(b) Muscle repair and enzyme production
(c) Only for bodybuilders
(d) Used mainly for hydration

Answer 16

✅ Correct Answer: (b) Muscle repair and enzyme production

(b) Muscle repair and enzyme production → Proteins repair muscle damage after exercise and form enzymes that support metabolism.
❌ (a) Primary energy source → Protein is not the body’s first choice for energy; carbs and fats are preferred.
❌ (c) Only for bodybuilders → All athletes, not just bodybuilders, need protein for muscle maintenance and recovery.
❌ (d) Used mainly for hydration → Protein plays no direct role in hydration.

Question 17

Which of the following are functions of fats in an athlete’s diet?

(a) Immediate energy supply
(b) Hydration regulation
(c) Breaking down proteins
(d) Carrying fat-soluble vitamins and providing long-term energy

Answer 17

✅ Correct Answer: (d) Carrying fat-soluble vitamins and providing long-term energy

(d) Carrying fat-soluble vitamins and providing long-term energy → Fats transport vitamins A, D, E, and K and serve as an energy reserve.
❌ (a) Immediate energy supply → Carbs, not fats, provide quick energy.
❌ (b) Hydration regulation → Water and electrolytes regulate hydration, not fats.
❌ (c) Breaking down proteins → Proteins are broken down by enzymes, not fats.

Question 18

Why should athletes prioritize nutrient-dense foods?

(a) They are lower in calories.
(b) They only benefit endurance athletes
(c) They provide essential vitamins, minerals, and macronutrients without excessive empty calories
(d) They are always organic.

Answer 18

✅ Correct Answer: (c) They provide essential vitamins, minerals, and macronutrients without excessive empty calories

(c) Nutrient-dense foods provide essential nutrients → Whole foods support overall health and performance without unnecessary sugar, salt, or fat.
❌ (a) They are lower in calories → Some nutrient-dense foods, like nuts, are high in calories but still healthy.
❌ (b) They only benefit endurance athletes → All athletes benefit from nutrient-dense foods, not just endurance athletes.
❌ (d) They are always organic → While organic foods can be nutrient-dense, non-organic foods can also provide high-quality nutrition.

Question 19

Why is blood sugar control important for athletes?

(a) It reduces muscle soreness
(b) Preventing energy crashes and supporting performance
(c) It makes exercise easier
(d) It eliminates the need for carbohydrate

Answer 19

✅ Correct Answer: (b) It prevents energy crashes and supports sustained performance

(b) Preventing energy crashes and supporting performance → Balanced blood sugar ensures steady energy levels during training and competition.
❌ (a) It reduces muscle soreness → Muscle soreness is affected by recovery time, hydration, and protein intake, not blood sugar.
❌ (c) It makes exercise easier → Proper nutrition optimizes performance but does not necessarily make exercise feel easier.
❌ (d) It eliminates the need for carbohydrates → Carbohydrates are still essential for energy production.

Question 20

What should athletes look for on food labels?

(a) Only calorie content → Calories alone don’t reflect the food’s nutrient quality.
(b) Only protein amount
(c) Foods labeled as “low-fat” or “sugar-free”
(d) Ingredient lists, nutrition facts, and deceptive marketing terms.

Answer 20

✅ Correct Answer: (d) Ingredient lists, nutrition facts, and deceptive marketing terms → Understanding hidden sugars, misleading claims, and actual nutrient content is key.

(a) Only calorie content → Calories alone don’t reflect the food’s nutrient quality.
(b) Only protein amount → While protein is important, balance with fats, carbs, and micronutrients is necessary.
(c) Foods labeled as “low-fat” or “sugar-free” → These may still contain unhealthy additives or artificial ingredients.

Question 21

Why should athletes limit simple sugars to pre- and post-exercise?

(a) Simple sugars should always be avoided.
(b) They provide a quick energy boost when needed
(c) Simple sugars build muscle.
(d) Simple sugars hydrate the body

Answer 21

✅ Correct Answer: (b) They provide a quick energy boost when needed

(b) Simple sugars provide a quick energy boost → They are useful before or after training when quick fuel or glycogen replenishment is needed.
❌ (a) Simple sugars should always be avoided → Not true! They can be strategically used during performance.
❌ (c) Simple sugars build muscle → Protein and resistance training build muscle, not sugar.
❌ (d) Simple sugars hydrate the body → Water and electrolytes, not sugar, manage hydration.

Question 22

Quality Fats

• Fats & oils are essential to the body – they aren’t all bad!!
  – Provide structure and fluidity or our cells
  – Stimulate appetite and satiety – needed to feel full
  – Carry the fat soluble vitamins – A, D, E and K
  – Omega 3’s help decrease risk of heart disease
  – Modulate the inflammatory response (improved adaptations to training
  – Steroid hormones: sex hormones, cortisol, calcitriol/calcidiol (Vit D)
• 1g of fat = 9 calories

Question 23

Quality Proteins
* Provides the building blocks for the body
* Composed of amino acids
* Protein is used for:
– Building muscles, ligaments, tendons, cartilage
– Enzymes to make chemical reactions happen more efficiently
– Creating peptide hormones like epinephrine, norepinephrine, insulin, glucagon, gastrin, grehlin, sex hormones, calcitonin, cholesystokinin, enkaphalin, erythropoietiun, human chorionic gonadotropin, growth hormone, IGF, TSH

• Inadequate protein in the diet can lead to:
  – Decreased immunity, fatigue and irritability, loss of muscle mass, failure to grow and skin conditions.
• 1g of protein = 4 calories

Answer 23

• Optial strategy RDA for athletes (1.3-1.8g/kg/d)
• Emphasize proteins high in leucine
• Consume protein in doses of 0.25- 0.3g/serving to maximize responses
• Equally spaced protein throughout the day
• Consumption of protein immediately after exercise or before or during still needs research

Question 24

Quality Carbs
* Fuel our body’s vital needs – our kidneys and brain use it as their primary fuel source
* Derived from plant sources
* More immediate source of energy

• Two main types:
  – Simple carbs – simple sugars that are easy to break down
  – Complex carbs – long chains of simple sugars and divided into starches and fiber
• Fiber – feel full longer, proper digestion, heart friendly
• 1g of cabs = 4 calories