Understanding Glycolysis

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AP Biology › Understanding Glycolysis

Questions 1 - 10
1

What is the netproduction of ATP molecules in glycolysis?

2

1

3

4

5

Explanation

The net production of ATP is 2.

This is because for glycolysis to occur, 2 ATP must be used. Glycolysis goes on to produce 4 ATP. The loss of 2 ATP and the gain of 4 ATP results in a total net gain of 2 ATP molecules. Note that the ATP produced during glycolysis are via substrate level phosphorylation.

2

Where does glycolysis take place?

Cytosol

Mitochondrial matrix

Inner mitochondrial membrane

Smooth endoplasmic reticulum

Rough endoplasmic retculum

Explanation

Glycolysis is the first step of cellular respiration where glucose is broken down down into pyruvate. It occurs in the cytosol. In the presence of oxygen, pyruvate is exported to the mitochondria where it is further oxidized. In the absence of oxygen, pyruvate is converted into ethyl alcohol or lactic acid (fermentation) in the cytoplasm.

3

In what part of the cell does glycolysis occur?

Cytoplasm

Mitochondrial matrix

Inner mitochondrial membrane

Golgi apparatus

Endoplasmic reticulum

Explanation

Glycolysis is an anaerobic process that occurs in the cytosol or the cytoplasm of the cell. This process does not require any organelles to take place. The mitochondria is where the Krebs cycle and the electron transport chain occur.

4

Which of the following statements regarding glycolysis is correct?

glycolysis occurs in the cytoplasm

glycolysis can occur only with oxygen

glycolysis is the first step in anaerobic respiration but not aerobic respiration

glycolysis leads to the production of 2 ATP, 1 NADH, and 2 pyruvate

glycolysis involves the production of G5P or glucose-5-phosphate

Explanation

The process of glycolysis indeed occurs in the cytoplasm. Answer 'glycolysis can occur only with oxygen' is incorrect, because glycolysis can actually occur with or without oxygen, due to oxygen playing no role in glycolysis.

Answer 'glycolysis is the first step in anaerobic respiration but not aerobic respiration' is incorrect, because glycolysis is simply the first step in BOTH anaerobic respiration and aerobic respiration.

Answer 'glycolysis leads to the production of 2 ATP, 1 NADH, and 2 pyruvate' is incorrect, because the end product of glycolysis is 2 NADH, not 1 NADH.

Answer 'glycolysis involves the production of G5P or glucose-5-phosphate' is incorrect, because glycolysis involves the production of G6P, not G5P.

5

Which of the following is NOT a product of glycolysis?

FADH2

NADH

ATP

Pyruvate

Explanation

Glycolysis is the first step of cellular respiration, and creates molecules of ATP, pyruvate, and NADH. FADH2 is produced later, during the citric acid cycle. Both NADH and FADH2 serve as electron carriers, depositing electrons in the electron transport chain to generate the proton gradient that powers ATP synthase.

6

What causes muscle soreness?

lactic acid fermentation

aerobic respiration

alcohol fermentation

substrate level phosphorylation

reduction of glucose

Explanation

When the body isn't getting enough oxygen, it undergoes lactic acid fermentation. The purpose of lactic acid fermentation is so that your body can generate ATP through glycolysis by turning pyruvate into lactate and in the processes regenerating NAD+. Since lactate is poisonous, we eventually have to breathe. When oxygen combines with lactate it turns into lactic acid, which in turn causes muscle soreness.

7

What is the end product of fermentation after glycolysis in animal cells when no oxygen is present?

Lactic acid

Alcohol

Glucose

Sucrose

Explanation

Lactic acid is produced in animal cells when no oxygen is present in order to keep making ATP. Alcohol is produced in yeast cells in fermentation. Glucose is broken down in the entire cycle of respiration, and sucrose is a disaccharide.

8

In cell respiration, glucose is converted to pyruvate in which of the following metabolic pathways?

Glycolysis

Light dependent reaction

Oxidative phosphorylation

Krebs cycle

Gluconeogenesis

Explanation

The correct answer to this question is glycolysis.

We can know this if we remember that glycolysis is a ten step anaerobic, not aerobic pathway that uses the 6 carbon sugar known as glucose and converts it to 2 pyruvate molecules. All of the other answers do not use glucose and convert it to pyruvate.

9

In glycolysis, what three-carbon compound is produced?

Pyruvic acid

Acetyl-CoA

Glucose

Ribose

Explanation

Pyruvic acid is the three-carbon compound produced in glycolysis, the first stage in cellular respiration. Acetyl-CoA is a two-carbon molecule that is the result of the pyruvate dehydrogenase complex that follows glycolysis. Glucose is broken down in respiration, and ribose is a five-carbon sugar in RNA.

10

Which of the following reflects a function of fermentation?

It oxidizes NADH to NAD+

It produes two molecules of ATP

It leads to the production of lactic acid in yeast cells

It leads to the production of ethanol in muscle cells

Explanation

Fermentation oxidizes molecules of NADH to NAD+ so the cell can have oxidizing agents for any subsequent glycolysis reactions. It does not, however, produce any usable energy in the process.

Fermentation leads to the production of ethanol in yeast cells and lactic acid in muscle cells.

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