AP Biology : AP Biology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #6 : Understand Atp Coupling

If the reaction for ATP hydrolysis  is coupled with the reaction glucose+ sucrose-> fructose,, what is the net delta G?

Possible Answers:

Correct answer:

Explanation:

 Through ATP coupling, the hydrolysis of ATP can allow the second, thermodynamically unfavorable reaction to proceed. . As the resulting delta  is negative, this will be thermodynamically favorable.

Example Question #1 : Understand Structure And Importance Of Atp

Which is NOT a reason that the phosphoanhydride bonds of ATP are high energy?

Possible Answers:

Repulsion of positively charged phosphate and negatively charged oxygen

Large mass of phosphate provides significant energy when combusted

Entropy is increased when bonds are broken

Resonance stabilization of products of ATP hydrolysis

Correct answer:

Large mass of phosphate provides significant energy when combusted

Explanation:

The phosphoanhydride bonds of ATP, or the bonds between phosphate molecules, are high energy. This is due to the close proximity of positively charged phosphate and negatively charged oxygen; these charges repel. Also, there is resonance stabilization of the products of ATP hydrolysis (ADP and Pi); thus ADP is more stable than ATP. Additionally, entropy is increased when ATP is hydrolyzed; the second law of thermodynamics states that the entropy of a system always increases.

Example Question #2 : Understand Structure And Importance Of Atp

Which is not part of an ATP molecule?

Possible Answers:

ribose sugar

alpha phosphate, beta phosphate, and gamma phosphate groups

adenine

threonine

Correct answer:

threonine

Explanation:

ATP consists of 3 phosphate groups, a ribose sugar, and adenine.

Example Question #3 : Cellular Energetics

Which is true of an ATP molecule?

Possible Answers:

It is used for long-term energy storage

When hydrolyzed, delta G> 0

When hydrolyzed, a phosphoanhydride bond is formed

It is unstable

Correct answer:

It is unstable

Explanation:

ATP is unstable; there is close proximity of positively charged phosphate and negatively charged oxygen; these charges repel. When hydrolyzed, delta G is <0 (exergonic). ATP is not used for long term-energy storage, as it is unstable. When hydrolyzed, a phosphoanhydride bond is broken.

Example Question #3 : Understand Structure And Importance Of Atp

Which is true of ADP

Possible Answers:

It contains 3 phosphate groups

It contains more energy than ATP

It contains 2 phosphate groups

ATP is produced when ADP is broken down

Correct answer:

It contains 2 phosphate groups

Explanation:

When ATP is hydrolyzed and a phosphoanhydride bond is broken, ADP and a phosphate are the products. ADP then has 2 phosphate groups.

Example Question #1 : Understand Structure And Importance Of Atp

Which cellular process produces ATP?

Possible Answers:

DNA synthesis

Na+/K+ pump

mitosis

Cellular respiration

Correct answer:

Cellular respiration

Explanation:

Cellular respiration is the process through which ATP is produced through the oxidation of glucose.

Example Question #2 : Understand Structure And Importance Of Atp

What is the primary energy currency for cells?

Possible Answers:

oxygen

ATP

GTP

carbohydrate

Correct answer:

ATP

Explanation:

 ATP is the primary energy currency for cells. The phosphoanhydride bonds of ATP, or the bonds between phosphate molecules, are high energy. This is due to the close proximity of positively charged phosphate and negatively charged oxygen; these charges repel. Also, there is resonance stabilization of the products of ATP hydrolysis (ADP and Pi); thus ADP is more stable than ATP. Carbohydrates are broken down during glycolysis to produce ATP. 

Example Question #121 : Cellular Respiration

During pyruvate decarboxylation reaction, pyruvate is converted to _______________ compound, through a reaction called ______________ .

Possible Answers:

NADH; oxidative decarboxylation

ATP; decomposition

acetyl CoA; oxidative decarboxylation

acetyl CoA; reductive decarboxylation

Correct answer:

acetyl CoA; oxidative decarboxylation

Explanation:

Pyruvate decarboxylation is an oxidative decarboxylation reaction, or an oxidation reaction where a carboxylate group is removed. This reaction converts pyruvate which was produced through glycolysis to acetyl CoA to be used in the Citric Acid Cycle.

Example Question #121 : Cellular Respiration

Which enzyme complex catalyzes the pyruvate decarboxylation reaction?

Possible Answers:

pyruvate oxidase

acetyl dehydrogenase

pyruvate dehydrogenase complex

pyruvate reductase

Correct answer:

pyruvate dehydrogenase complex

Explanation:

The pyruvate dehydrogenase complex is an enzyme complex that consists of 3 enzymes, which work together to catalyze the pyruvate decarboxylation reaction, where pyruvate is converted to acetyl CoA.

Example Question #123 : Cellular Respiration

Where does the pyruvate decarboxylation reaction occur?

Possible Answers:

Cytosol

Cristae

Outer mitochondrial membrane

Mitochondrial matrix

Correct answer:

Mitochondrial matrix

Explanation:

Pyruvate decarboxylation occurs in the mitochondrial matrix. The acetyl CoA produced from the pyruvate decarboxylation reaction will undergo the Citric Acid cycle also in the mitochondrial matrix.

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