Question

1. is photosynthesis endergonic or exergonic? what is the energy source that drives it? 11. to summarize, if energy is released, $delta g$ must be positive/negative. (circle your choice.) concept 8.3 atp powers cellular work by coupling exergonic reactions to endergonic reactions lo 8.3: use examples to illustrate the coupling of atp hydrolysis to endergonic reactions. 13. list the three main kinds of work that a cell does. give an example of each. a. b. c. 14. what is energy coupling?

Explanation:

1. Photosynthesis is an endergonic reaction as it requires energy input. The energy source driving it is sunlight.
2. When energy is released, $\Delta G$ is negative because exergonic reactions have a negative free - energy change.

13.
a. Chemical work: Protein synthesis. Enzymes use ATP to assemble amino acids into proteins.
b. Transport work: Sodium - potassium pump. ATP is used to pump sodium ions out of and potassium ions into the cell against their concentration gradients.
c. Mechanical work: Muscle contraction. Myosin and actin filaments use ATP for movement.

1. Energy coupling is the use of energy released from an exergonic reaction to drive an endergonic reaction. Usually, ATP hydrolysis (an exergonic reaction) provides the energy for endergonic cellular processes.

Answer:

1. Endergonic; Sunlight
2. negative

13.
a. Chemical work; Protein synthesis
b. Transport work; Sodium - potassium pump
c. Mechanical work; Muscle contraction

1. The use of energy released from an exergonic reaction to drive an endergonic reaction, often with ATP hydrolysis providing the energy for endergonic processes.