05.2 - The Process of Cellular Respiration (25pts.)

The first stage of cellular respiration is glycolysis, which literally means

“sugar splitting.” Look at the diagram.

When glucose, a 6-carbon sugar, is broken down during glycolysis, what product forms?

• 2 molecules of lactic acid, C3H6O3

• 3 molecules of ethanol, C2H5OH

• 2 molecules of pyruvic acid, C3H4O3

• 6 molecules of carbon dioxide, CO2

Answer explanation

During glycolysis, glucose is broken down into 2 molecules of pyruvic acid, C3H4O3, as the end product.

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The ​ ​ (a)   is the innermost compartment of a ​ (b)   . Here, ​ (c)   occur(s), breaking down ​ (d)   into carbon dioxide in a series of reactions.

• matrix

• mitochondria

• the Krebs Cycle

• pyruvic acid

• chloroplast

• Glycolysis

Answer explanation

The innermost compartment of a mitochondria is the matrix where the Krebs Cycle occurs, breaking down pyruvic acid into carbon dioxide in a series of reactions.

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Aerobic cellular respiration traps energy in ATP in 3 stages.

Look at the model.

In which stage or set of stages is carbon dioxide released?

• Glycolysis

• Krebs Cycle

• Electron Transport Chain

• All of the Above

Answer explanation

Carbon dioxide is released during the Krebs Cycle stage of aerobic cellular respiration.

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Which two molecules generated by the Krebs cycle pass their high-

energy electrons to the electron transport chain?

Select two answer choices.

• NADH

• Glucose

• FADH2

• NAD+

Answer explanation

NADH and FADH2 are the two molecules generated by the Krebs cycle that pass their high-energy electrons to the electron transport chain, making them the correct answer choices.

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How do high-energy electrons from glycolysis and the Krebs cycle

contribute to the FORMATION of ATP from ADP in the electron transport chain [ETC]?

• High-energy electrons increase the temperature of ADP so it readily reacts

  with a phosphate group to form ATP.

• High-energy electrons supply a negative charge which causes the citric acid

  to oxidize, forming a phosphate group to bond with ADP.

• High-energy electrons pass through the electron transport chain to supply the

  needed energy to synthesize ATP from ADP.

• High-energy electrons interact with pyruvic acid to create a phosphate bond

  with ADP, forming ATP.

Answer explanation

High-energy electrons pass through the electron transport chain to supply the needed energy to synthesize ATP from ADP.

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Together, the stages of cellular respiration break down one molecule of ​ (a)   into a total of ​ (b)   molecules of ATP. The remaining energy is released as ​ (c)   .

• glucose

• 36

• heat

• 12

• 72

• protein

• lactic acid

Answer explanation

Cellular respiration breaks down one molecule of glucose into a total of 36 molecules of ATP. The remaining energy is released as heat.

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Which stage makes water as a waste product?

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Which stage(s) require Oxygen?

[Select all that apply]

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Which of the following best describes the net gain of ATP from one molecule of glucose during glycolysis?

• 2 ATP

• 4 ATP

• 32 ATP

• 36 ATP

Answer explanation

The correct answer is 2 ATP because glycolysis produces a net gain of 2 ATP molecules from one molecule of glucose.

Organize these options based on the 3 stages of Cellular Respiration

Groups:

(a) Glycolysis

,

(b) Krebs Cycle

,

(c) Electron Transport Chain

• Produces CO2

• Requires Pyruvate

• Happens in the Cytoplasm

• Produces Pyruvate

• 
• Requires Glucose

• 
• Produces more than 30 ATP

• Requires NADH and FADH2

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