Question

Why does darkness affect the light-independent reactions of photosynthesis?
A: Plants stop their daytime activities and rest during the night, much like animals do.
B: Light independent reactions need more heat energy than nighttime temperatures often provide.
C: Mitochondria produce sugars more effectively in the darkness than chloroplasts do.
D: Light independent reactions require the energy gathered in the thylakoids.

Answer 1

Hello! Your answer is D, light independent reactions require the energy gathered in the thylakoids.

The light independent reactions occur in the thylakoid membrane (Eukaryotes). They require light, as they use energy from the sun to change water, ADP, and NADP+ to ATP, NADPH, and O2.

The light energy is necessary as it excites the electrons, which is essential for  ATP creation. This is because the energy moves H+ ions, giving the thylakoid lumen a positive charge, and the stroma a negative. This charge difference pushes H+ ions through ATP synthase to create ATP. This "excitement" of the electrons is also necessary because it provides an essential reactant for the Calvin Cycle (also known as the light-independent reaction), or high energy electrons (which are carried by NADP+)

Hope this helps!