To determine through which conversion energy is released, it's important to understand the roles and characteristics of the molecules involved.
1. ADP to ATP:
- ATP (Adenosine Triphosphate) is a high-energy molecule used to store and transfer energy within cells.
- ADP (Adenosine Diphosphate) is a lower-energy molecule.
- The conversion of ADP to ATP requires the addition of a phosphate group and an input of energy (phosphorylation).
2. ATP to ADP:
- The conversion of ATP to ADP releases energy because a phosphate group is removed from ATP. This reaction is commonly referred to as the "hydrolysis of ATP", which results in the release of energy that is used for various cellular processes.
3. [tex]$NADP ^{+}$[/tex] to NADPH:
- [tex]$NADP^{+}$[/tex] (Nicotinamide adenine dinucleotide phosphate) is an oxidized form of NADPH.
- NADPH is a reduced form and acts as a carrier for electrons and hydrogen ions.
- The conversion of [tex]$NADP^{+}$[/tex] to NADPH requires energy input (reduction process).
4. [tex]$CO _2$[/tex] and [tex]$H _2 O$[/tex] to [tex]$C _6 H _{12} O _6$[/tex] and [tex]$O _2$[/tex]:
- This is the process of photosynthesis, where carbon dioxide and water are converted into glucose ([tex]$C_6H_{12}O_6$[/tex]) and oxygen ([tex]$O_2$[/tex]).
- This process requires a significant amount of energy, which is provided by sunlight.
Given the understanding of these conversions, the conversion that releases energy is the conversion from ATP to ADP. The breakdown of ATP into ADP and a free phosphate group releases energy that can be harnessed for various biochemical processes in the cell.
Therefore, the correct answer is:
ATP to ADP.
