Cellular energetics
Help Questions
AP Biology › Cellular energetics
What is the primary energy currency for cells?
oxygen
GTP
ATP
carbohydrate
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.
Which is NOT a reason that the phosphoanhydride bonds of ATP are high energy?
Repulsion of positively charged phosphate and negatively charged oxygen
Resonance stabilization of products of ATP hydrolysis
Entropy is increased when bonds are broken
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.
Which is not part of an ATP molecule?
alpha phosphate, beta phosphate, and gamma phosphate groups
ribose sugar
adenine
threonine
Explanation
ATP consists of 3 phosphate groups, a ribose sugar, and adenine.
Which is NOT a reason that the phosphoanhydride bonds of ATP are high energy?
Repulsion of positively charged phosphate and negatively charged oxygen
Resonance stabilization of products of ATP hydrolysis
Entropy is increased when bonds are broken
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.
Which is not part of an ATP molecule?
alpha phosphate, beta phosphate, and gamma phosphate groups
ribose sugar
adenine
threonine
Explanation
ATP consists of 3 phosphate groups, a ribose sugar, and adenine.
What is the primary energy currency for cells?
oxygen
GTP
ATP
carbohydrate
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.
If the reaction for ATP hydrolysis is coupled with the reaction glucose+ sucrose-> fructose,
, what is the net delta G?
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.
Which of the following is an endergonic reaction?
Catabolism
Na+/K+ pump
Cellular respiration
Hydrolysis of ATP
Explanation
An endergonic reaction requires input of energy; delta G will be positive. Hydrolysis of ATP, cellular respiration, and catabolism (breakdown of a large molecule) are exergonic processes. The Na+/K+ pump is endergonic, as it requires energy. This process is coupled with ATP hydrolysis to allow it to proceed.
Which is true of an exergonic reaction?
The reaction will always be endothermic
The reaction will not occur spontaneously
Energy is required
Energy is released
Explanation
Exergonic reactions are reactions that release energy. Endergonic reactions are reactions that require energy to proceed. Exergonic reactions can occur spontaneously, or are thermodynamically favorable. Endergonic reactions cannot occur spontaneously, or are thermodynamically unfavorable.
If the reaction for ATP hydrolysis is coupled with the reaction glucose+ sucrose-> fructose,
, what is the net delta G?
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.