Q: Which of the following is a correct summary of the ATP yield from one round of the Krebs cycle per acetyl CoA?

$$3\ \text{NADH} + 1\ \text{FADH}_2 + 1\ \text{ATP}$$

Question 1

Which of the following best describes the role of creatine phosphate in muscle cell metabolism during the initial seconds of intense exercise?

Accepted Answer

It provides a rapid source of ATP by donating a phosphate group to ADP.

Question 2

Given the equation for palmitic acid oxidation: $$\mathrm{C$$_{16}$$H_{32}O_2$} + 23\ \mathrm{O_2$} ightarrow 16\ \mathrm{CO_2$} + 16\ \mathrm{H_2O} + 	ext{Energy}$$, what is the respiratory exchange ratio (RER) for this reaction?

Accepted Answer

$$0.7$$

Question 3

During prolonged, moderate-intensity exercise, which energy system is primarily responsible for ATP production?

Accepted Answer

Oxidative phosphorylation using carbohydrates and fats

Question 4

Which enzyme catalyzes the reaction $$	ext{Creatine phosphate} + 	ext{ADP} ightleftharpoons 	ext{Creatine} + 	ext{ATP} in $$muscle cells?

Accepted Answer

Creatine kinase

Question 5

A sprinter runs a 100-meter dash in 10 seconds. Which energy system provides the majority of ATP during this activity?

Accepted Answer

Creatine phosphate system

Question 6

What is the net ATP yield from the complete oxidation of one molecule of palmitic acid ($$\mathrm{C$$_{16}$$H_{32}O_2$}) $$via beta-oxidation and the Krebs cycle?

Accepted Answer

$$106\ 	ext{ATP}$$

Question 7

Which of the following statements about beta-oxidation is correct?

Accepted Answer

It breaks down fatty acids two carbons at a time to produce acetyl CoA.

Question 8

If a person is exercising at a low intensity and their RER is measured at $$0.7$$, which substrate are they primarily metabolizing for energy?

Accepted Answer

Fatty acids

Question 9

Which process directly links glycolysis to the Krebs cycle in cellular respiration?

Accepted Answer

Conversion of pyruvate to acetyl CoA

Question 10

During the breakdown of triglycerides, which enzyme is responsible for splitting them into glycerol and fatty acids?

Accepted Answer

Lipase

Question 11

Which of the following best explains why oxidative phosphorylation produces more ATP than glycolysis?

Accepted Answer

It uses NADH and FADH$$_2 to $$drive the electron transport chain, generating a proton gradient for ATP synthesis.

Question 12

A patient with a metabolic disorder cannot efficiently convert pyruvate to acetyl CoA. Which energy system will be most affected?

Accepted Answer

Aerobic metabolism (Krebs cycle and oxidative phosphorylation)

Question 13

Which of the following is a correct summary of the ATP yield from one round of the Krebs cycle per acetyl CoA?

Accepted Answer

$$3\ 	ext{NADH} + 1\ 	ext{FADH}_2 + 1\ 	ext{ATP}$$

Question 14

Which of the following is true regarding the time course of energy system contribution during exercise?

Accepted Answer

Stored ATP and creatine phosphate dominate in the first 30 seconds, then glycolysis and oxidative phosphorylation increase.

Question 15

If the equation for fat oxidation is $$\mathrm{C$$_{16}$$H_{32}O_2$} + 23\ \mathrm{O_2$} ightarrow 16\ \mathrm{CO_2$} + 16\ \mathrm{H_2O} + 	ext{Energy}$$, what is the ratio of $$\mathrm{CO_2$}$$ produced to $$\mathrm{O_2$}$$ consumed?

Accepted Answer

$$\frac{16}{23}$$

Question 16

Which metabolic pathway is responsible for the breakdown of glycerol from triglycerides for ATP production?

Accepted Answer

Glycolysis

Question 17

Why does fat metabolism require more oxygen per molecule than carbohydrate metabolism?

Accepted Answer

Fatty acids are more reduced and require more oxygen to be fully oxidized to $$\mathrm{CO_2$}$$ and $$\mathrm{H_2O}.$$

Question 18

Which of the following is a direct product of beta-oxidation of fatty acids?

Accepted Answer

Acetyl CoA

Question 19

A marathon runner is primarily using which substrate for energy after 2 hours of continuous running?

Accepted Answer

Fatty acids

Muscle Cell Metabolism and Energy Systems

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