AP Biology : Understanding Glycolysis

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #1 : Cellular Respiration

Where does glycolysis take place in the cell? 

Possible Answers:

Nucleus

Endoplasmic reticulum 

Mitochondria

Cytosol

Golgi body

Correct answer:

Cytosol

Explanation:

Glycolysis happens in the cytosol (the fluid containing the organelles) of the cell. The next step in cellular respiration, the citric acid cycle, occurs in the mitochondria.

Example Question #1 : Cellular Respiration

Which of the following reflects a function of fermentation?

Possible Answers:

It oxidizes NADH to NAD+

It leads to the production of ethanol in muscle cells

It leads to the production of lactic acid in yeast cells

It produes two molecules of ATP

Correct answer:

It oxidizes NADH to NAD+

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.

Example Question #1 : Cellular Respiration

Where in the cell does glycolysis take place?

Possible Answers:

Mitochondria

Nucleus

Cytosol

Endoplasmic reticulum

Correct answer:

Cytosol

Explanation:

Glycolysis occurs in the cytosol of cells. Once finished, the two pyruvate products are transported into the mitochondria to go through the citric acid cycle, at a cost of 1 ATP per pyruvate. Neither the nucleus, nor the endoplasmic reticulum have any function in glycolysis or the citric acid cycle.

Example Question #1 : Cellular Respiration

How many direct ATP are made if fructose-1,6-bisphosphate is put through glycolysis?

Possible Answers:

4

0

1

3

2

Correct answer:

4

Explanation:

The conversion of glucose to two pyruvate molecules in glycolysis produces a net total of two direct ATP. When fructose-1,6-bisphosphate enters glycolysis, it bypasses the two steps involved that normally cost one ATP each, therefore, there is no required input and the net total is four produced ATP.

We have to remember that each step beyond the conversion of fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate happens twice, or we would come up with two ATP created.

Example Question #3 : Understanding Glycolysis

Which of the following products is not created during glycolysis?

Possible Answers:

NADH

ATP

Pyruvate

Oxygen

Correct answer:

Oxygen

Explanation:

Glycolysis is the first step in cellular respiration, and is seen in both aerobic and anaerobic respiration. The products of glycolysis are pyruvate, NADH, ATP, and water. Oxygen is only a product of the light reactions of photosynthesis; it is consumed as a reactant in the electron transport chain.

Example Question #2 : Cellular Respiration

Which of the following processes does not take place during glycolysis?

Possible Answers:

An end result is the production of 3-carbon molecules that are later fed into the citric acid cycle

Two  molecules are produced

One molecule of glucose eventually yields two molecules of pyruvate

Via a complex chain of steps,  and  transfer electrons to the process's final electron acceptor,

Four ATP molecules are produced for every molecule of glucose, but the net production is only two molecules of ATP

Correct answer:

Via a complex chain of steps,  and  transfer electrons to the process's final electron acceptor,

Explanation:

Glycolysis, which occurs in the cytoplasm, is the first step of cellular respiration. Though it does not produce a large amount of ATP by itself, it incorporates several important steps that must take place to yield a much more significant amount of ATP later. Notable events that occur during this multi-step process include the breakdown of each glucose molecule into two 3-carbon pyruvate molecules, the production of two molecules of , and the net production of two ATP molecules.

Unlike the next two steps (the citric acid cycle and oxidative phosphorylation), glycolysis can occur in the absence of oxygen. The only step given that is not part of glycolysis is the transfer of electrons from carrier molecules to oxygen via a series of steps. This happens during oxidative phosphorylation and, unlike glycolysis, is an aerobic process.

Example Question #3 : Cellular Respiration

In comparison to fermentation, the aerobic pathways of glucose metabolism yield more __________.

 

Possible Answers:

pyruvate

acetaldehyde 

ethanol

adenosine triphosphate 

Correct answer:

adenosine triphosphate 

Explanation:

Fermentation is the metabolic process that takes place in anaerobic environments to regenerate for glycolysis, which takes place in both aerobic and anaerobic environments. Since glycolysis is unaffected by the presence of oxygen, pyruvate concentrations will be the same in either environment. During fermentation the cell changes the pyruvate into acetaldehyde. Ethanol is also a product of fermentation. We would not expect to see more acetaldehyde or ethanol in aerobic metabolism.

Adenosine triphosphate (ATP) is the main product of cellular respiration, and the molecular energy of the cell. Aerobic metabolism results in a much higher yield of these energy carrying molecules due to the fact that it can use oxygen as a final electron acceptor in the electron transport chain.

Example Question #1 : Cellular Respiration

Where does glycolysis take place in the cell?

Possible Answers:

Nucleus

Endoplasmic reticulum

Mitochondria

Cytosol

Correct answer:

Cytosol

Explanation:

Glycolysis takes place in the cell cytosol, and can take place under anaerobic conditions. After the completion of glycolysis, the product pyruvate is transported to the mitochondria for the citric acid cycle and electron transport chain.

The nucleus houses the cell's DNA, and the endoplasmic reticulum is involved with protein modification.

Example Question #1 : Cellular Respiration

Which of the following stages of cellular respiration generates ATP, regardless of the presence of oxygen?

Possible Answers:

Oxidative phosphorylation

Glycolysis

Krebs cycle

Citric acid cycle

Electron transport chain

Correct answer:

Glycolysis

Explanation:

Glycolysis is the process that converts glucose to pyruvate. It produces a total of four ATP, but consumes two ATP, for a net yield of two ATP. Glycolysis is not dependent on the presence of oxygen and can occur in either aerobic or anaerobic environments.

The citric acid cycle, or Krebs cycle, is used to generate NADH from pyruvate. The NADH is then used in the electron transport chain to generate a proton gradient, which fuels oxidative phosphorylation. Since oxidative phosphorylation requires an oxygen molecule, the citric acid cycle and electron transport chain cannot continue in anaerobic environments.

Example Question #2 : Cellular Respiration

What is the net production of ATP from one glucose molecule in glycolysis?

Possible Answers:

Correct answer:

Explanation:

Glycolysis produces four molecules of ATP, but two molecules are used to complete reactions during the initial steps of the process. With four molecules produced and two molecules consumed in the process, there is a net yield of two ATP from each glucose molecule in glycolysis

During ATP synthesis in the electron transport chain, approximately 32 additional ATP are generated.

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