AP Biology : Understand structure and importance of ATP

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #4 : Cellular Energetics

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

Possible Answers:

Entropy is increased when bonds are broken

Resonance stabilization of products of ATP hydrolysis

Large mass of phosphate provides significant energy when combusted

Repulsion of positively charged phosphate and negatively charged oxygen

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 #1 : Cellular Energetics

Which is not part of an ATP molecule?

Possible Answers:

ribose sugar

adenine

threonine

alpha phosphate, beta phosphate, and gamma phosphate groups

Correct answer:

threonine

Explanation:

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

Example Question #3 : Understand Structure And Importance Of Atp

Which is true of an ATP molecule?

Possible Answers:

It is used for long-term energy storage

It is unstable

When hydrolyzed, delta G> 0

When hydrolyzed, a phosphoanhydride bond is formed

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 #1 : Understand Structure And Importance Of Atp

Which is true of ADP

Possible Answers:

It contains more energy than ATP

ATP is produced when ADP is broken down

It contains 2 phosphate groups

It contains 3 phosphate groups

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:

Cellular respiration

mitosis

Na+/K+ pump

DNA synthesis

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:

ATP

GTP

carbohydrate

oxygen

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. 

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