Q: Which equation correctly represents the energy yield (in kcal/g) for the major macronutrients in the human body?

$$\text{Carbohydrate: } 4 \text{ kcal/g}$$, $$\text{Fat: } 9 \text{ kcal/g}$$, $$\text{Protein: } 4 \text{ kcal/g}$$

Q: Which of the following equations correctly represents the ATP yield from NADH and FADH$$_2$$ during oxidative phosphorylation?

$$\text{NADH: } 2.5 \text{ ATP}$$, $$\text{FADH}_2: 1.5 \text{ ATP}$$

Question 1

Which process describes the breakdown of triglycerides into glycerol and fatty acids, and what is the primary enzyme involved?

Accepted Answer

Lipolysis; lipase

Question 2

During beta-oxidation, how many carbon atoms are removed from a fatty acid chain in each cycle, and what is the resulting molecule that enters the Krebs cycle?

Accepted Answer

2 carbons; acetyl CoA

Question 3

Calculate the net ATP yield from the complete oxidation of one molecule of palmitic acid ($$C_{16}H$$_{32}$$O_2) $$via beta-oxidation and the Krebs cycle. Use the following: 10 ATP per cycle, 7 cycles, and 4 ATP from NADH and FADH$$_2$$ per cycle.

Accepted Answer

$$106$$ ATP

Question 4

Which of the following statements best explains why fats provide more energy per gram than carbohydrates?

Accepted Answer

Fats have longer carbon chains, resulting in more cycles of beta-oxidation and more ATP.

Question 5

A patient is experiencing rapid weight loss due to cancer cachexia. Which macronutrient is most likely being catabolized to meet energy demands, and what is a byproduct of this process?

Accepted Answer

Proteins; urea

Question 6

Which equation correctly represents the energy yield (in kcal/g) for the major macronutrients in the human body?

Accepted Answer

$$	ext{Carbohydrate: } 4 	ext{ kcal/g}$$, $$	ext{Fat: } 9 	ext{ kcal/g}$$, $$	ext{Protein: } 4 	ext{ kcal/g}$$

Question 7

If a person has 15 kg of body fat, approximately how many kilocalories of energy does this represent? Use $$1 	ext{ kg fat} = 9,400 	ext{ kcal}.$$

Accepted Answer

$$140,000$$ kcal

Question 8

Which metabolic pathway is required as a 'primer' for the oxidation of fatty acids during exercise?

Accepted Answer

Glycolysis

Question 9

During prolonged fasting, which molecule is synthesized from fatty acids to provide energy for the brain?

Accepted Answer

Ketone bodies

Question 10

Which process describes the formation of glycogen from glucose, and what is its physiological significance?

Accepted Answer

Glycogenesis; stores glucose for future energy needs

Question 11

A student is exercising at increasing workloads. Which physiological response is most likely to occur as workload increases?

Accepted Answer

The rate of energy supply increases and reaches a steady state until workload changes.

Question 12

Which of the following best describes the role of adipocytes in energy metabolism?

Accepted Answer

Adipocytes synthesize and store fat during periods of food uptake and release fat during exercise.

Question 13

Which of the following is NOT a correct match between a metabolic process and its definition?

Accepted Answer

Lipolysis: formation of triglycerides from fatty acids

Question 14

Which of the following equations correctly represents the ATP yield from NADH and FADH$$_2$$ during oxidative phosphorylation?

Accepted Answer

$$	ext{NADH: } 2.5 	ext{ ATP}$$, $$	ext{FADH}_2: 1.5 	ext{ ATP}$$

Question 15

Which of the following is a correct sequence of events for the metabolism of a triglyceride molecule?

Accepted Answer

Lipolysis → Beta-oxidation → Acetyl CoA formation → Krebs cycle → Electron transport chain

Question 16

Which of the following statements about the energy content of protein is true?

Accepted Answer

Protein provides 5.6 kcal/g, but only 4 kcal/g is metabolizable due to urea formation.

Question 17

Which metabolic pathway is responsible for the conversion of dihydroxyacetone phosphate (DHAP) to glycolysis intermediates?

Accepted Answer

Glycolysis

Question 18

A person consumes excess carbohydrates. Which process will be activated to store the excess glucose, and where is this storage primarily located?

Accepted Answer

Glycogenesis; liver and skeletal muscle

Question 19

Which of the following is a correct description of the 'fed state' in human metabolism?

Accepted Answer

Nutrients are stored; carbohydrates as glycogen, fats as triglycerides.

Energy Metabolism and Storage: Lipid and Carbohydrate Pathways in Human Physiology

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