Question

where do photosynthetic organisms get the energy needed to make sugars during the light - independent (dark) reactions?

• they use the adp and carbon dioxide produced during the light - dependent reactions.
• they convert the 6 - carbon sugars into 5 - carbon sugars.
• they use the atp and nadph that are produced during the light - dependent reactions.
• they obtain the energy directly from the sun.

Explanation:

• For the first option: Light - dependent reactions produce ATP and NADPH, not ADP and CO₂ for energy in dark reactions, so this is wrong.
• For the second option: Converting 6 - carbon to 5 - carbon sugars is part of the Calvin cycle (dark reactions) but not the source of energy, so this is wrong.
• For the third option: In photosynthesis, light - dependent reactions generate ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which provide the energy and reducing power for the light - independent (dark) reactions (Calvin cycle) to synthesize sugars from CO₂.
• For the fourth option: Light - independent reactions do not get energy directly from the Sun; the Sun's energy is captured in light - dependent reactions first.

Answer:

They use the ATP and NADPH that are produced during the light - dependent reactions.